File Coverage

blib/lib/Euhc.pm

Criterion	Covered	Total	%
statement	1204	4693	25.6
branch	1360	4684	29.0
condition	162	496	32.6
subroutine	68	190	35.7
pod	8	148	5.4
total	2802	10211	27.4

package Euhc;
use strict;
######################################################################
#
# Euhc - Run-time routines for UHC.pm
#
# http://search.cpan.org/dist/Char-UHC/
#
# Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2018, 2019 INABA Hitoshi
######################################################################

use 5.00503;    # Galapagos Consensus 1998 for primetools
# use 5.008001; # Lancaster Consensus 2013 for toolchains

# 12.3. Delaying use Until Runtime
# in Chapter 12. Packages, Libraries, and Modules
# of ISBN 0-596-00313-7 Perl Cookbook, 2nd Edition.
# (and so on)

# Version numbers should be boring
# http://www.dagolden.com/index.php/369/version-numbers-should-be-boring/
# For the impatient, the disinterested or those who just want to follow
# a recipe, my advice for all modules is this:
# our $VERSION = "0.001"; # or "0.001_001" for a dev release
# $VERSION = eval $VERSION; # No!! because '1.10' makes '1.1'

use vars qw($VERSION);
$VERSION = '1.15';
$VERSION = $VERSION;

BEGIN {
    if ($^X =~ / jperl /oxmsi) {
        die __FILE__, ": needs perl(not jperl) 5.00503 or later. (\$^X==$^X)\n";
    }
    if (CORE::ord('A') == 193) {
        die __FILE__, ": is not US-ASCII script (may be EBCDIC or EBCDIK script).\n";
    }
    if (CORE::ord('A') != 0x41) {
        die __FILE__, ": is not US-ASCII script (must be US-ASCII script).\n";
    }
}

BEGIN {

    # instead of utf8.pm
    CORE::eval q{
        no warnings qw(redefine);
        *utf8::upgrade   = sub { CORE::length $_[0] };
        *utf8::downgrade = sub { 1 };
        *utf8::encode    = sub {   };
        *utf8::decode    = sub { 1 };
        *utf8::is_utf8   = sub {   };
        *utf8::valid     = sub { 1 };
    };
    if ($@) {
        *utf8::upgrade   = sub { CORE::length $_[0] };
        *utf8::downgrade = sub { 1 };
        *utf8::encode    = sub {   };
        *utf8::decode    = sub { 1 };
        *utf8::is_utf8   = sub {   };
        *utf8::valid     = sub { 1 };
    }
}

# instead of Symbol.pm
BEGIN {
    sub gensym () {
        if ($] < 5.006) {
            return \do { local *_ };
        }
        else {
            return undef;
        }
    }

    sub qualify ($$) {
        my($name) = @_;

        if (ref $name) {
            return $name;
        }
        elsif (Euhc::index($name,'::') >= 0) {
            return $name;
        }
        elsif (Euhc::index($name,"'") >= 0) {
            return $name;
        }

        # special character, "^xyz"
        elsif ($name =~ /\A \^ [ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_]+ \z/x) {

            # RGS 2001-11-05 : translate leading ^X to control-char
            $name =~ s{\A \^ ([ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_]) }{'qq(\c'.$1.')'}xee;
            return 'main::' . $name;
        }

        # Global names
        elsif ($name =~ /\A (?: ARGV | ARGVOUT | ENV | INC | SIG | STDERR | STDIN | STDOUT ) \z/x) {
            return 'main::' . $name;
        }

        # or other
        elsif ($name =~ /\A [^ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz] \z/x) {
            return 'main::' . $name;
        }

        elsif (defined $_[1]) {
            return $_[1] . '::' . $name;
        }
        else {
            return (caller)[0] . '::' . $name;
        }
    }

    sub qualify_to_ref ($;$) {
        if (defined $_[1]) {
            no strict qw(refs);
            return \*{ qualify $_[0], $_[1] };
        }
        else {
            no strict qw(refs);
            return \*{ qualify $_[0], (caller)[0] };
        }
    }
}

# P.714 29.2.39. flock
# in Chapter 29: Functions
# of ISBN 0-596-00027-8 Programming Perl Third Edition.

# P.863 flock
# in Chapter 27: Functions
# of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

sub LOCK_SH() {1}
sub LOCK_EX() {2}
sub LOCK_UN() {8}
sub LOCK_NB() {4}

# instead of Carp.pm
sub carp;
sub croak;
sub cluck;
sub confess;

# 6.18. Matching Multiple-Byte Characters
# in Chapter 6. Pattern Matching
# of ISBN 978-1-56592-243-3 Perl Perl Cookbook.
# (and so on)

# regexp of character
my $your_char = q{[\x81-\xFE][\x00-\xFF]|[\x00-\xFF]};
use vars qw($qq_char); $qq_char = qr/\\c[\x40-\x5F]|\\?(?:$your_char)/oxms;
use vars qw($q_char);  $q_char  = qr/$your_char/oxms;

#
# UHC character range per length
#
my %range_tr = ();

#
# UHC case conversion
#
my %lc = ();
@lc{qw(A B C D E F G H I J K L M N O P Q R S T U V W X Y Z)} =
    qw(a b c d e f g h i j k l m n o p q r s t u v w x y z);
my %uc = ();
@uc{qw(a b c d e f g h i j k l m n o p q r s t u v w x y z)} =
    qw(A B C D E F G H I J K L M N O P Q R S T U V W X Y Z);
my %fc = ();
@fc{qw(A B C D E F G H I J K L M N O P Q R S T U V W X Y Z)} =
    qw(a b c d e f g h i j k l m n o p q r s t u v w x y z);

if (0) {
}

elsif (__PACKAGE__ =~ / \b Euhc \z/oxms) {
    %range_tr = (
        1 => [ [0x00..0x80],
               [0xFF..0xFF],
             ],
        2 => [ [0x81..0xFE],[0x41..0x5A],
               [0x81..0xFE],[0x61..0x7A],
               [0x81..0xFE],[0x81..0xFE],
             ],
    );
}

else {
    croak "Don't know my package name '@{[__PACKAGE__]}'";
}

#
# @ARGV wildcard globbing
#
sub import {

    if ($^O =~ /\A (?: MSWin32 | NetWare | symbian | dos ) \z/oxms) {
        my @argv = ();
        for (@ARGV) {

            # has space
            if (/\A (?:$q_char)*? [ ] /oxms) {
                if (my @glob = Euhc::glob(qq{"$_"})) {
                    push @argv, @glob;
                }
                else {
                    push @argv, $_;
                }
            }

            # has wildcard metachar
            elsif (/\A (?:$q_char)*? [*?] /oxms) {
                if (my @glob = Euhc::glob($_)) {
                    push @argv, @glob;
                }
                else {
                    push @argv, $_;
                }
            }

            # no wildcard globbing
            else {
                push @argv, $_;
            }
        }
        @ARGV = @argv;
    }

    *Char::ord           = \&UHC::ord;
    *Char::ord_          = \&UHC::ord_;
    *Char::reverse       = \&UHC::reverse;
    *Char::getc          = \&UHC::getc;
    *Char::length        = \&UHC::length;
    *Char::substr        = \&UHC::substr;
    *Char::index         = \&UHC::index;
    *Char::rindex        = \&UHC::rindex;
    *Char::eval          = \&UHC::eval;
    *Char::escape        = \&UHC::escape;
    *Char::escape_token  = \&UHC::escape_token;
    *Char::escape_script = \&UHC::escape_script;
}

# P.230 Care with Prototypes
# in Chapter 6: Subroutines
# of ISBN 0-596-00027-8 Programming Perl Third Edition.
#
# If you aren't careful, you can get yourself into trouble with prototypes.
# But if you are careful, you can do a lot of neat things with them. This is
# all very powerful, of course, and should only be used in moderation to make
# the world a better place.

# P.332 Care with Prototypes
# in Chapter 7: Subroutines
# of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.
#
# If you aren't careful, you can get yourself into trouble with prototypes.
# But if you are careful, you can do a lot of neat things with them. This is
# all very powerful, of course, and should only be used in moderation to make
# the world a better place.

#
# Prototypes of subroutines
#
sub unimport {}
sub Euhc::split(;$$$);
sub Euhc::tr($$$$;$);
sub Euhc::chop(@);
sub Euhc::index($$;$);
sub Euhc::rindex($$;$);
sub Euhc::lcfirst(@);
sub Euhc::lcfirst_();
sub Euhc::lc(@);
sub Euhc::lc_();
sub Euhc::ucfirst(@);
sub Euhc::ucfirst_();
sub Euhc::uc(@);
sub Euhc::uc_();
sub Euhc::fc(@);
sub Euhc::fc_();
sub Euhc::ignorecase;
sub Euhc::classic_character_class;
sub Euhc::capture;
sub Euhc::chr(;$);
sub Euhc::chr_();
sub Euhc::filetest;
sub Euhc::r(;*@);
sub Euhc::w(;*@);
sub Euhc::x(;*@);
sub Euhc::o(;*@);
sub Euhc::R(;*@);
sub Euhc::W(;*@);
sub Euhc::X(;*@);
sub Euhc::O(;*@);
sub Euhc::e(;*@);
sub Euhc::z(;*@);
sub Euhc::s(;*@);
sub Euhc::f(;*@);
sub Euhc::d(;*@);
sub Euhc::l(;*@);
sub Euhc::p(;*@);
sub Euhc::S(;*@);
sub Euhc::b(;*@);
sub Euhc::c(;*@);
sub Euhc::u(;*@);
sub Euhc::g(;*@);
sub Euhc::k(;*@);
sub Euhc::T(;*@);
sub Euhc::B(;*@);
sub Euhc::M(;*@);
sub Euhc::A(;*@);
sub Euhc::C(;*@);
sub Euhc::filetest_;
sub Euhc::r_();
sub Euhc::w_();
sub Euhc::x_();
sub Euhc::o_();
sub Euhc::R_();
sub Euhc::W_();
sub Euhc::X_();
sub Euhc::O_();
sub Euhc::e_();
sub Euhc::z_();
sub Euhc::s_();
sub Euhc::f_();
sub Euhc::d_();
sub Euhc::l_();
sub Euhc::p_();
sub Euhc::S_();
sub Euhc::b_();
sub Euhc::c_();
sub Euhc::u_();
sub Euhc::g_();
sub Euhc::k_();
sub Euhc::T_();
sub Euhc::B_();
sub Euhc::M_();
sub Euhc::A_();
sub Euhc::C_();
sub Euhc::glob($);
sub Euhc::glob_();
sub Euhc::lstat(*);
sub Euhc::lstat_();
sub Euhc::opendir(*$);
sub Euhc::stat(*);
sub Euhc::stat_();
sub Euhc::unlink(@);
sub Euhc::chdir(;$);
sub Euhc::do($);
sub Euhc::require(;$);
sub Euhc::telldir(*);

sub UHC::ord(;$);
sub UHC::ord_();
sub UHC::reverse(@);
sub UHC::getc(;*@);
sub UHC::length(;$);
sub UHC::substr($$;$$);
sub UHC::index($$;$);
sub UHC::rindex($$;$);
sub UHC::escape(;$);

#
# Regexp work
#
use vars qw(
    $re_a
    $re_t
    $re_n
    $re_r
);

#
# Character class
#
use vars qw(
    $dot
    $dot_s
    $eD
    $eS
    $eW
    $eH
    $eV
    $eR
    $eN
    $not_alnum
    $not_alpha
    $not_ascii
    $not_blank
    $not_cntrl
    $not_digit
    $not_graph
    $not_lower
    $not_lower_i
    $not_print
    $not_punct
    $not_space
    $not_upper
    $not_upper_i
    $not_word
    $not_xdigit
    $eb
    $eB
);

use vars qw(
    $anchor
    $matched
);
${Euhc::anchor} = qr{\G(?>[^\x81-\xFE]|[\x81-\xFE][\x00-\xFF])*?}oxms;
my $q_char_SADAHIRO_Tomoyuki_2002_01_17 = '';

# Quantifiers
#   {n,m}  ---  Match at least n but not more than m times
#
# n and m are limited to non-negative integral values less than a
# preset limit defined when perl is built. This is usually 32766 on
# the most common platforms.
#
# The following code is an attempt to solve the above limitations
# in a multi-byte anchoring.

# avoid "Segmentation fault" and "Error: Parse exception"

# perl5101delta
# http://perldoc.perl.org/perl5101delta.html
# In 5.10.0, the * quantifier in patterns was sometimes treated as {0,32767}
# [RT #60034, #60464]. For example, this match would fail:
#   ("ab" x 32768) =~ /^(ab)*$/

# SEE ALSO
#
# Complex regular subexpression recursion limit
# http://www.perlmonks.org/?node_id=810857
#
# regexp iteration limits
# http://www.nntp.perl.org/group/perl.perl5.porters/2009/02/msg144065.html
#
# latest Perl won't match certain regexes more than 32768 characters long
# http://stackoverflow.com/questions/26226630/latest-perl-wont-match-certain-regexes-more-than-32768-characters-long
#
# Break through the limitations of regular expressions of Perl
# http://d.hatena.ne.jp/gfx/20110212/1297512479

if (($] >= 5.010001) or
    # ActivePerl 5.6 or later (include 5.10.0)
    (defined($ActivePerl::VERSION) and ($ActivePerl::VERSION > 800)) or
    (($^O eq 'MSWin32') and ($] =~ /\A 5\.006/oxms))
) {
    my $sbcs = ''; # Single Byte Character Set
    for my $range (@{ $range_tr{1} }) {
        $sbcs .= sprintf('\\x%02X-\\x%02X', $range->[0], $range->[-1]);
    }

    if (0) {
    }

    # other encoding
    else {
        ${Euhc::q_char_SADAHIRO_Tomoyuki_2002_01_17} = qr{.*?[$sbcs](?:[^$sbcs][^$sbcs])*?}oxms;
        #                                                     ******* octets not in multiple octet char (always char boundary)
        #                                                               **************** 2 octet chars
    }

    ${Euhc::anchor_SADAHIRO_Tomoyuki_2002_01_17} =
    qr{\G(?(?=.{0,32766}\z)(?:[^\x81-\xFE]|[\x81-\xFE][\x00-\xFF])*?|(?(?=[$sbcs]+\z).*?|(?:${Euhc::q_char_SADAHIRO_Tomoyuki_2002_01_17})))}oxms;
#   qr{
#      \G # (1), (2)
#        (? # (3)
#          (?=.{0,32766}\z) # (4)
#                          (?:[^\x81-\xFE]|[\x81-\xFE][\x00-\xFF])*?| # (5)
#                                                                                      (?(?=[$sbcs]+\z) # (6)
#                                                                                                      .*?| #(7)
#                                                                                                          (?:${Euhc::q_char_SADAHIRO_Tomoyuki_2002_01_17}) # (8)
#                                                                                                                                           ))}oxms;

    # avoid: Complex regular subexpression recursion limit (32766) exceeded at here.
    local $^W = 0;

    if (((('A' x 32768).'B') !~ / ${Euhc::anchor}                              B /oxms) and
        ((('A' x 32768).'B') =~ / ${Euhc::anchor_SADAHIRO_Tomoyuki_2002_01_17} B /oxms)
    ) {
        ${Euhc::anchor} = ${Euhc::anchor_SADAHIRO_Tomoyuki_2002_01_17};
    }
    else {
        undef ${Euhc::q_char_SADAHIRO_Tomoyuki_2002_01_17};
    }
}

# (1)
# P.128 Start of match (or end of previous match): \G
# P.130 Advanced Use of \G with Perl
# in Chapter3: Over view of Regular Expression Features and Flavors
# of ISBN 0-596-00289-0 Mastering Regular Expressions, Second edition

# (2)
# P.255 Use leading anchors
# P.256 Expose ^ and \G at the front of expressions
# in Chapter6: Crafting an Efficient Expression
# of ISBN 0-596-00289-0 Mastering Regular Expressions, Second edition

# (3)
# P.138 Conditional: (? if then| else)
# in Chapter3: Over view of Regular Expression Features and Flavors
# of ISBN 0-596-00289-0 Mastering Regular Expressions, Second edition

# (4)
# perlre
# http://perldoc.perl.org/perlre.html
# The "*" quantifier is equivalent to {0,} , the "+" quantifier to {1,} ,
# and the "?" quantifier to {0,1}, ., n, and m are limited to non-negative
# integral values less than a preset limit defined when perl is built.
# This is usually 32766 on the most common platforms. The actual limit
# can be seen in the error message generated by code such as this:
#  $_ **= $_ , / {$_} / for 2 .. 42;

# (5)
# P.1023 Multiple-Byte Anchoring
# in Appendix W Perl Code Examples
# of ISBN 1-56592-224-7 CJKV Information Processing

# (6)
# if string has only SBCS (Single Byte Character Set)

# (7)
# then .*? (isn't limited to 32766)

# (8)
# else UHC::Regexp::Const (SADAHIRO Tomoyuki)
# http://homepage1.nifty.com/nomenclator/perl/shiftjis.htm#long
# http://search.cpan.org/~sadahiro/UHC-Regexp/
# $PadA  = '  (?:\A|                                           [\x00-\x80\xA0-\xDF])(?:[\x81-\xFE]{2})*?';
# $PadG  = '\G(?:                                |[\x00-\xFF]*?[\x00-\x80\xA0-\xDF])(?:[\x81-\xFE]{2})*?';
# $PadGA = '\G(?:\A|(?:[\x81-\xFE]{2})+?|[\x00-\xFF]*?[\x00-\x80\xA0-\xDF] (?:[\x81-\xFE]{2})*?)';

${Euhc::dot}         = qr{(?>[^\x81-\xFE\x0A]|[\x81-\xFE][\x00-\xFF])};
${Euhc::dot_s}       = qr{(?>[^\x81-\xFE]|[\x81-\xFE][\x00-\xFF])};
${Euhc::eD}          = qr{(?>[^\x81-\xFE0-9]|[\x81-\xFE][\x00-\xFF])};

# Vertical tabs are now whitespace
# \s in a regex now matches a vertical tab in all circumstances.
# http://search.cpan.org/dist/perl-5.18.0/pod/perldelta.pod#Vertical_tabs_are_now_whitespace
# ${Euhc::eS}          = qr{(?>[^\x81-\xFE\x09\x0A    \x0C\x0D\x20]|[\x81-\xFE][\x00-\xFF])};
# ${Euhc::eS}          = qr{(?>[^\x81-\xFE\x09\x0A\x0B\x0C\x0D\x20]|[\x81-\xFE][\x00-\xFF])};
${Euhc::eS}            = qr{(?>[^\x81-\xFE\s]|[\x81-\xFE][\x00-\xFF])};

${Euhc::eW}            = qr{(?>[^\x81-\xFE0-9A-Z_a-z]|[\x81-\xFE][\x00-\xFF])};
${Euhc::eH}            = qr{(?>[^\x81-\xFE\x09\x20]|[\x81-\xFE][\x00-\xFF])};
${Euhc::eV}            = qr{(?>[^\x81-\xFE\x0A\x0B\x0C\x0D]|[\x81-\xFE][\x00-\xFF])};
${Euhc::eR}            = qr{(?>\x0D\x0A|[\x0A\x0D])};
${Euhc::eN}            = qr{(?>[^\x81-\xFE\x0A]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_alnum}     = qr{(?>[^\x81-\xFE\x30-\x39\x41-\x5A\x61-\x7A]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_alpha}     = qr{(?>[^\x81-\xFE\x41-\x5A\x61-\x7A]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_ascii}     = qr{(?>[^\x81-\xFE\x00-\x7F]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_blank}     = qr{(?>[^\x81-\xFE\x09\x20]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_cntrl}     = qr{(?>[^\x81-\xFE\x00-\x1F\x7F]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_digit}     = qr{(?>[^\x81-\xFE\x30-\x39]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_graph}     = qr{(?>[^\x81-\xFE\x21-\x7F]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_lower}     = qr{(?>[^\x81-\xFE\x61-\x7A]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_lower_i}   = qr{(?>[^\x81-\xFE\x41-\x5A\x61-\x7A]|[\x81-\xFE][\x00-\xFF])}; # Perl 5.16 compatible
# ${Euhc::not_lower_i} = qr{(?>[^\x81-\xFE]|[\x81-\xFE][\x00-\xFF])};                   # older Perl compatible
${Euhc::not_print}     = qr{(?>[^\x81-\xFE\x20-\x7F]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_punct}     = qr{(?>[^\x81-\xFE\x21-\x2F\x3A-\x3F\x40\x5B-\x5F\x60\x7B-\x7E]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_space}     = qr{(?>[^\x81-\xFE\s\x0B]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_upper}     = qr{(?>[^\x81-\xFE\x41-\x5A]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_upper_i}   = qr{(?>[^\x81-\xFE\x41-\x5A\x61-\x7A]|[\x81-\xFE][\x00-\xFF])}; # Perl 5.16 compatible
# ${Euhc::not_upper_i} = qr{(?>[^\x81-\xFE]|[\x81-\xFE][\x00-\xFF])};                   # older Perl compatible
${Euhc::not_word}      = qr{(?>[^\x81-\xFE\x30-\x39\x41-\x5A\x5F\x61-\x7A]|[\x81-\xFE][\x00-\xFF])};
${Euhc::not_xdigit}    = qr{(?>[^\x81-\xFE\x30-\x39\x41-\x46\x61-\x66]|[\x81-\xFE][\x00-\xFF])};
${Euhc::eb}            = qr{(?:\A(?=[0-9A-Z_a-z])|(?<=[\x00-\x2F\x40\x5B-\x5E\x60\x7B-\xFF])(?=[0-9A-Z_a-z])|(?<=[0-9A-Z_a-z])(?=[\x00-\x2F\x40\x5B-\x5E\x60\x7B-\xFF]|\z))};
${Euhc::eB}            = qr{(?:(?<=[0-9A-Z_a-z])(?=[0-9A-Z_a-z])|(?<=[\x00-\x2F\x40\x5B-\x5E\x60\x7B-\xFF])(?=[\x00-\x2F\x40\x5B-\x5E\x60\x7B-\xFF]))};

# avoid: Name "Euhc::foo" used only once: possible typo at here.
${Euhc::dot}         = ${Euhc::dot};
${Euhc::dot_s}       = ${Euhc::dot_s};
${Euhc::eD}          = ${Euhc::eD};
${Euhc::eS}          = ${Euhc::eS};
${Euhc::eW}          = ${Euhc::eW};
${Euhc::eH}          = ${Euhc::eH};
${Euhc::eV}          = ${Euhc::eV};
${Euhc::eR}          = ${Euhc::eR};
${Euhc::eN}          = ${Euhc::eN};
${Euhc::not_alnum}   = ${Euhc::not_alnum};
${Euhc::not_alpha}   = ${Euhc::not_alpha};
${Euhc::not_ascii}   = ${Euhc::not_ascii};
${Euhc::not_blank}   = ${Euhc::not_blank};
${Euhc::not_cntrl}   = ${Euhc::not_cntrl};
${Euhc::not_digit}   = ${Euhc::not_digit};
${Euhc::not_graph}   = ${Euhc::not_graph};
${Euhc::not_lower}   = ${Euhc::not_lower};
${Euhc::not_lower_i} = ${Euhc::not_lower_i};
${Euhc::not_print}   = ${Euhc::not_print};
${Euhc::not_punct}   = ${Euhc::not_punct};
${Euhc::not_space}   = ${Euhc::not_space};
${Euhc::not_upper}   = ${Euhc::not_upper};
${Euhc::not_upper_i} = ${Euhc::not_upper_i};
${Euhc::not_word}    = ${Euhc::not_word};
${Euhc::not_xdigit}  = ${Euhc::not_xdigit};
${Euhc::eb}          = ${Euhc::eb};
${Euhc::eB}          = ${Euhc::eB};

#
# UHC split
#
sub Euhc::split(;$$$) {

    # P.794 29.2.161. split
    # in Chapter 29: Functions
    # of ISBN 0-596-00027-8 Programming Perl Third Edition.

    # P.951 split
    # in Chapter 27: Functions
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    my $pattern = $_[0];
    my $string  = $_[1];
    my $limit   = $_[2];

    # if $pattern is also omitted or is the literal space, " "
    if (not defined $pattern) {
        $pattern = ' ';
    }

    # if $string is omitted, the function splits the $_ string
    if (not defined $string) {
        if (defined $_) {
            $string = $_;
        }
        else {
            $string = '';
        }
    }

    my @split = ();

    # when string is empty
    if ($string eq '') {

        # resulting list value in list context
        if (wantarray) {
            return @split;
        }

        # count of substrings in scalar context
        else {
            carp "Use of implicit split to \@_ is deprecated" if $^W;
            @_ = @split;
            return scalar @_;
        }
    }

    # split's first argument is more consistently interpreted
    #
    # After some changes earlier in v5.17, split's behavior has been simplified:
    # if the PATTERN argument evaluates to a string containing one space, it is
    # treated the way that a literal string containing one space once was.
    # http://search.cpan.org/dist/perl-5.18.0/pod/perldelta.pod#split's_first_argument_is_more_consistently_interpreted

    # if $pattern is also omitted or is the literal space, " ", the function splits
    # on whitespace, /\s+/, after skipping any leading whitespace
    # (and so on)

    elsif ($pattern eq ' ') {
        if (not defined $limit) {
            return CORE::split(' ', $string);
        }
        else {
            return CORE::split(' ', $string, $limit);
        }
    }

    local $q_char = $q_char;
    if (CORE::length($string) > 32766) {
        if ($string =~ /\A [\x00-\x7F]+ \z/oxms) {
            $q_char = qr{.}s;
        }
        elsif (defined ${Euhc::q_char_SADAHIRO_Tomoyuki_2002_01_17}) {
            $q_char = ${Euhc::q_char_SADAHIRO_Tomoyuki_2002_01_17};
        }
    }

    # if $limit is negative, it is treated as if an arbitrarily large $limit has been specified
    if ((not defined $limit) or ($limit <= 0)) {

        # a pattern capable of matching either the null string or something longer than the
        # null string will split the value of $string into separate characters wherever it
        # matches the null string between characters
        # (and so on)

        if ('' =~ / \A $pattern \z /xms) {
            my $last_subexpression_offsets = _last_subexpression_offsets($pattern);
            my $limit = scalar(() = $string =~ /($pattern)/oxmsg);

            # P.1024 Appendix W.10 Multibyte Processing
            # of ISBN 1-56592-224-7 CJKV Information Processing
            # (and so on)

            # the //m modifier is assumed when you split on the pattern /^/
            # (and so on)

            #                                                     V
            while ((--$limit > 0) and ($string =~ s/\A((?:$q_char)+?)$pattern//m)) {

                # if the $pattern contains parentheses, then the substring matched by each pair of parentheses
                # is included in the resulting list, interspersed with the fields that are ordinarily returned
                # (and so on)

                local $@;
                for (my $digit=1; $digit <= ($last_subexpression_offsets + 1); $digit++) {
                    push @split, CORE::eval('$' . $digit);
                }
            }
        }

        else {
            my $last_subexpression_offsets = _last_subexpression_offsets($pattern);

            #                                 V
            while ($string =~ s/\A((?:$q_char)*?)$pattern//m) {
                local $@;
                for (my $digit=1; $digit <= ($last_subexpression_offsets + 1); $digit++) {
                    push @split, CORE::eval('$' . $digit);
                }
            }
        }
    }

    elsif ($limit > 0) {
        if ('' =~ / \A $pattern \z /xms) {
            my $last_subexpression_offsets = _last_subexpression_offsets($pattern);
            while ((--$limit > 0) and (CORE::length($string) > 0)) {

                #                              V
                if ($string =~ s/\A((?:$q_char)+?)$pattern//m) {
                    local $@;
                    for (my $digit=1; $digit <= ($last_subexpression_offsets + 1); $digit++) {
                        push @split, CORE::eval('$' . $digit);
                    }
                }
            }
        }
        else {
            my $last_subexpression_offsets = _last_subexpression_offsets($pattern);
            while ((--$limit > 0) and (CORE::length($string) > 0)) {

                #                              V
                if ($string =~ s/\A((?:$q_char)*?)$pattern//m) {
                    local $@;
                    for (my $digit=1; $digit <= ($last_subexpression_offsets + 1); $digit++) {
                        push @split, CORE::eval('$' . $digit);
                    }
                }
            }
        }
    }

    if (CORE::length($string) > 0) {
        push @split, $string;
    }

    # if $_[2] (NOT "$limit") is omitted or zero, trailing null fields are stripped from the result
    if ((not defined $_[2]) or ($_[2] == 0)) {
        while ((scalar(@split) >= 1) and ($split[-1] eq '')) {
            pop @split;
        }
    }

    # resulting list value in list context
    if (wantarray) {
        return @split;
    }

    # count of substrings in scalar context
    else {
        carp "Use of implicit split to \@_ is deprecated" if $^W;
        @_ = @split;
        return scalar @_;
    }
}

#
# get last subexpression offsets
#
sub _last_subexpression_offsets {
    my $pattern = $_[0];

    # remove comment
    $pattern =~ s/\(\?\# .*? \)//oxmsg;

    my $modifier = '';
    if ($pattern =~ /\(\?\^? ([\-A-Za-z]+) :/oxms) {
        $modifier = $1;
        $modifier =~ s/-[A-Za-z]*//;
    }

    # with /x modifier
    my @char = ();
    if ($modifier =~ /x/oxms) {
        @char = $pattern =~ /\G((?>
            [^\x81-\xFE\\\#\[\(]|[\x81-\xFE][\x00-\xFF] |
            \\ $q_char      |
            \# (?>[^\n]*) $ |
            \[ (?>(?:[^\x81-\xFE\\\]]|[\x81-\xFE][\x00-\xFF]|\\\\|\\\]|$q_char)+) \] |
            \(\?            |
                $q_char
        ))/oxmsg;
    }

    # without /x modifier
    else {
        @char = $pattern =~ /\G((?>
            [^\x81-\xFE\\\[\(]|[\x81-\xFE][\x00-\xFF] |
            \\ $q_char      |
            \[ (?>(?:[^\x81-\xFE\\\]]|[\x81-\xFE][\x00-\xFF]|\\\\|\\\]|$q_char)+) \] |
            \(\?            |
                $q_char
        ))/oxmsg;
    }

    return scalar grep { $_ eq '(' } @char;
}

#
# UHC transliteration (tr///)
#
sub Euhc::tr($$$$;$) {

    my $bind_operator   = $_[1];
    my $searchlist      = $_[2];
    my $replacementlist = $_[3];
    my $modifier        = $_[4] || '';

    if ($modifier =~ /r/oxms) {
        if ($bind_operator =~ / !~ /oxms) {
            croak "Using !~ with tr///r doesn't make sense";
        }
    }

    my @char            = $_[0] =~ /\G (?>$q_char) /oxmsg;
    my @searchlist      = _charlist_tr($searchlist);
    my @replacementlist = _charlist_tr($replacementlist);

    my %tr = ();
    for (my $i=0; $i <= $#searchlist; $i++) {
        if (not exists $tr{$searchlist[$i]}) {
            if (defined $replacementlist[$i] and ($replacementlist[$i] ne '')) {
                $tr{$searchlist[$i]} = $replacementlist[$i];
            }
            elsif ($modifier =~ /d/oxms) {
                $tr{$searchlist[$i]} = '';
            }
            elsif (defined $replacementlist[-1] and ($replacementlist[-1] ne '')) {
                $tr{$searchlist[$i]} = $replacementlist[-1];
            }
            else {
                $tr{$searchlist[$i]} = $searchlist[$i];
            }
        }
    }

    my $tr = 0;
    my $replaced = '';
    if ($modifier =~ /c/oxms) {
        while (defined(my $char = shift @char)) {
            if (not exists $tr{$char}) {
                if (defined $replacementlist[0]) {
                    $replaced .= $replacementlist[0];
                }
                $tr++;
                if ($modifier =~ /s/oxms) {
                    while (@char and (not exists $tr{$char[0]})) {
                        shift @char;
                        $tr++;
                    }
                }
            }
            else {
                $replaced .= $char;
            }
        }
    }
    else {
        while (defined(my $char = shift @char)) {
            if (exists $tr{$char}) {
                $replaced .= $tr{$char};
                $tr++;
                if ($modifier =~ /s/oxms) {
                    while (@char and (exists $tr{$char[0]}) and ($tr{$char[0]} eq $tr{$char})) {
                        shift @char;
                        $tr++;
                    }
                }
            }
            else {
                $replaced .= $char;
            }
        }
    }

    if ($modifier =~ /r/oxms) {
        return $replaced;
    }
    else {
        $_[0] = $replaced;
        if ($bind_operator =~ / !~ /oxms) {
            return not $tr;
        }
        else {
            return $tr;
        }
    }
}

#
# UHC chop
#
sub Euhc::chop(@) {

    my $chop;
    if (@_ == 0) {
        my @char = /\G (?>$q_char) /oxmsg;
        $chop = pop @char;
        $_ = join '', @char;
    }
    else {
        for (@_) {
            my @char = /\G (?>$q_char) /oxmsg;
            $chop = pop @char;
            $_ = join '', @char;
        }
    }
    return $chop;
}

#
# UHC index by octet
#
sub Euhc::index($$;$) {

    my($str,$substr,$position) = @_;
    $position ||= 0;
    my $pos = 0;

    while ($pos < CORE::length($str)) {
        if (CORE::substr($str,$pos,CORE::length($substr)) eq $substr) {
            if ($pos >= $position) {
                return $pos;
            }
        }
        if (CORE::substr($str,$pos) =~ /\A ($q_char) /oxms) {
            $pos += CORE::length($1);
        }
        else {
            $pos += 1;
        }
    }
    return -1;
}

#
# UHC reverse index
#
sub Euhc::rindex($$;$) {

    my($str,$substr,$position) = @_;
    $position ||= CORE::length($str) - 1;
    my $pos = 0;
    my $rindex = -1;

    while (($pos < CORE::length($str)) and ($pos <= $position)) {
        if (CORE::substr($str,$pos,CORE::length($substr)) eq $substr) {
            $rindex = $pos;
        }
        if (CORE::substr($str,$pos) =~ /\A ($q_char) /oxms) {
            $pos += CORE::length($1);
        }
        else {
            $pos += 1;
        }
    }
    return $rindex;
}

#
# UHC lower case first with parameter
#
sub Euhc::lcfirst(@) {
    if (@_) {
        my $s = shift @_;
        if (@_ and wantarray) {
            return Euhc::lc(CORE::substr($s,0,1)) . CORE::substr($s,1), @_;
        }
        else {
            return Euhc::lc(CORE::substr($s,0,1)) . CORE::substr($s,1);
        }
    }
    else {
        return Euhc::lc(CORE::substr($_,0,1)) . CORE::substr($_,1);
    }
}

#
# UHC lower case first without parameter
#
sub Euhc::lcfirst_() {
    return Euhc::lc(CORE::substr($_,0,1)) . CORE::substr($_,1);
}

#
# UHC lower case with parameter
#
sub Euhc::lc(@) {
    if (@_) {
        my $s = shift @_;
        if (@_ and wantarray) {
            return join('', map {defined($lc{$_}) ? $lc{$_} : $_} ($s =~ /\G ($q_char) /oxmsg)), @_;
        }
        else {
            return join('', map {defined($lc{$_}) ? $lc{$_} : $_} ($s =~ /\G ($q_char) /oxmsg));
        }
    }
    else {
        return Euhc::lc_();
    }
}

#
# UHC lower case without parameter
#
sub Euhc::lc_() {
    my $s = $_;
    return join '', map {defined($lc{$_}) ? $lc{$_} : $_} ($s =~ /\G ($q_char) /oxmsg);
}

#
# UHC upper case first with parameter
#
sub Euhc::ucfirst(@) {
    if (@_) {
        my $s = shift @_;
        if (@_ and wantarray) {
            return Euhc::uc(CORE::substr($s,0,1)) . CORE::substr($s,1), @_;
        }
        else {
            return Euhc::uc(CORE::substr($s,0,1)) . CORE::substr($s,1);
        }
    }
    else {
        return Euhc::uc(CORE::substr($_,0,1)) . CORE::substr($_,1);
    }
}

#
# UHC upper case first without parameter
#
sub Euhc::ucfirst_() {
    return Euhc::uc(CORE::substr($_,0,1)) . CORE::substr($_,1);
}

#
# UHC upper case with parameter
#
sub Euhc::uc(@) {
    if (@_) {
        my $s = shift @_;
        if (@_ and wantarray) {
            return join('', map {defined($uc{$_}) ? $uc{$_} : $_} ($s =~ /\G ($q_char) /oxmsg)), @_;
        }
        else {
            return join('', map {defined($uc{$_}) ? $uc{$_} : $_} ($s =~ /\G ($q_char) /oxmsg));
        }
    }
    else {
        return Euhc::uc_();
    }
}

#
# UHC upper case without parameter
#
sub Euhc::uc_() {
    my $s = $_;
    return join '', map {defined($uc{$_}) ? $uc{$_} : $_} ($s =~ /\G ($q_char) /oxmsg);
}

#
# UHC fold case with parameter
#
sub Euhc::fc(@) {
    if (@_) {
        my $s = shift @_;
        if (@_ and wantarray) {
            return join('', map {defined($fc{$_}) ? $fc{$_} : $_} ($s =~ /\G ($q_char) /oxmsg)), @_;
        }
        else {
            return join('', map {defined($fc{$_}) ? $fc{$_} : $_} ($s =~ /\G ($q_char) /oxmsg));
        }
    }
    else {
        return Euhc::fc_();
    }
}

#
# UHC fold case without parameter
#
sub Euhc::fc_() {
    my $s = $_;
    return join '', map {defined($fc{$_}) ? $fc{$_} : $_} ($s =~ /\G ($q_char) /oxmsg);
}

#
# UHC regexp capture
#
{
    # 10.3. Creating Persistent Private Variables
    # in Chapter 10. Subroutines
    # of ISBN 0-596-00313-7 Perl Cookbook, 2nd Edition.

    my $last_s_matched = 0;

    sub Euhc::capture {
        if ($last_s_matched and ($_[0] =~ /\A (?>[1-9][0-9]*) \z/oxms)) {
            return $_[0] + 1;
        }
        return $_[0];
    }

    # UHC mark last regexp matched
    sub Euhc::matched() {
        $last_s_matched = 0;
    }

    # UHC mark last s/// matched
    sub Euhc::s_matched() {
        $last_s_matched = 1;
    }

    # P.854 31.17. use re
    # in Chapter 31. Pragmatic Modules
    # of ISBN 0-596-00027-8 Programming Perl Third Edition.

    # P.1026 re
    # in Chapter 29. Pragmatic Modules
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    $Euhc::matched = qr/(?{Euhc::matched})/;
}

#
# UHC regexp ignore case modifier
#
sub Euhc::ignorecase {

    my @string = @_;
    my $metachar = qr/[\@\\|[\]{]/oxms;

    # ignore case of $scalar or @array
    for my $string (@string) {

        # split regexp
        my @char = $string =~ /\G (?>\[\^|\\$q_char|$q_char) /oxmsg;

        # unescape character
        for (my $i=0; $i <= $#char; $i++) {
            next if not defined $char[$i];

            # open character class [...]
            if ($char[$i] eq '[') {
                my $left = $i;

                # [] make die "unmatched [] in regexp ...\n"

                if ($char[$i+1] eq ']') {
                    $i++;
                }

                while (1) {
                    if (++$i > $#char) {
                        croak "Unmatched [] in regexp";
                    }
                    if ($char[$i] eq ']') {
                        my $right = $i;
                        my @charlist = charlist_qr(@char[$left+1..$right-1], 'i');

                        # escape character
                        for my $char (@charlist) {
                            if (0) {
                            }

                            # do not use quotemeta here
                            elsif ($char =~ /\A ([\x80-\xFF].*) ($metachar) \z/oxms) {
                                $char = $1 . '\\' . $2;
                            }
                            elsif ($char =~ /\A [.|)] \z/oxms) {
                                $char = '\\' . $char;
                            }
                        }

                        # [...]
                        splice @char, $left, $right-$left+1, '(?:' . join('|', @charlist) . ')';

                        $i = $left;
                        last;
                    }
                }
            }

            # open character class [^...]
            elsif ($char[$i] eq '[^') {
                my $left = $i;

                # [^] make die "unmatched [] in regexp ...\n"

                if ($char[$i+1] eq ']') {
                    $i++;
                }

                while (1) {
                    if (++$i > $#char) {
                        croak "Unmatched [] in regexp";
                    }
                    if ($char[$i] eq ']') {
                        my $right = $i;
                        my @charlist = charlist_not_qr(@char[$left+1..$right-1], 'i');

                        # escape character
                        for my $char (@charlist) {
                            if (0) {
                            }

                            # do not use quotemeta here
                            elsif ($char =~ /\A ([\x80-\xFF].*) ($metachar) \z/oxms) {
                                $char = $1 . '\\' . $2;
                            }
                            elsif ($char =~ /\A [.|)] \z/oxms) {
                                $char = '\\' . $char;
                            }
                        }

                        # [^...]
                        splice @char, $left, $right-$left+1, '(?!' . join('|', @charlist) . ")(?:$your_char)";

                        $i = $left;
                        last;
                    }
                }
            }

            # rewrite classic character class or escape character
            elsif (my $char = classic_character_class($char[$i])) {
                $char[$i] = $char;
            }

            # with /i modifier
            elsif ($char[$i] =~ /\A [\x00-\xFF] \z/oxms) {
                my $uc = Euhc::uc($char[$i]);
                my $fc = Euhc::fc($char[$i]);
                if ($uc ne $fc) {
                    if (CORE::length($fc) == 1) {
                        $char[$i] = '['   . $uc       . $fc . ']';
                    }
                    else {
                        $char[$i] = '(?:' . $uc . '|' . $fc . ')';
                    }
                }
            }
        }

        # characterize
        for (my $i=0; $i <= $#char; $i++) {
            next if not defined $char[$i];

            if (0) {
            }

            # escape last octet of multiple-octet
            elsif ($char[$i] =~ /\A ([\x80-\xFF].*) ($metachar) \z/oxms) {
                $char[$i] = $1 . '\\' . $2;
            }

            # quote character before ? + * {
            elsif (($i >= 1) and ($char[$i] =~ /\A [\?\+\*\{] \z/oxms)) {
                if ($char[$i-1] !~ /\A [\x00-\xFF] \z/oxms) {
                    $char[$i-1] = '(?:' . $char[$i-1] . ')';
                }
            }
        }

        $string = join '', @char;
    }

    # make regexp string
    return @string;
}

#
# classic character class ( \D \S \W \d \s \w \C \X \H \V \h \v \R \N \b \B )
#
sub Euhc::classic_character_class {
    my($char) = @_;

    return {
        '\D' => '${Euhc::eD}',
        '\S' => '${Euhc::eS}',
        '\W' => '${Euhc::eW}',
        '\d' => '[0-9]',

        # Before Perl 5.6, \s only matched the five whitespace characters
        # tab, newline, form-feed, carriage return, and the space character
        # itself, which, taken together, is the character class [\t\n\f\r ].

        # Vertical tabs are now whitespace
        # \s in a regex now matches a vertical tab in all circumstances.
        # http://search.cpan.org/dist/perl-5.18.0/pod/perldelta.pod#Vertical_tabs_are_now_whitespace
        #            \t  \n  \v  \f  \r space
        # '\s' => '[\x09\x0A    \x0C\x0D\x20]',
        # '\s' => '[\x09\x0A\x0B\x0C\x0D\x20]',
        '\s'   => '\s',

        '\w' => '[0-9A-Z_a-z]',
        '\C' => '[\x00-\xFF]',
        '\X' => 'X',

        # \h \v \H \V

        # P.114 Character Class Shortcuts
        # in Chapter 7: In the World of Regular Expressions
        # of ISBN 978-0-596-52010-6 Learning Perl, Fifth Edition

        # P.357 13.2.3 Whitespace
        # in Chapter 13: perlrecharclass: Perl Regular Expression Character Classes
        # of ISBN-13: 978-1-906966-02-7 The Perl Language Reference Manual (for Perl version 5.12.1)
        #
        # 0x00009   CHARACTER TABULATION  h s
        # 0x0000a         LINE FEED (LF)   vs
        # 0x0000b        LINE TABULATION   v
        # 0x0000c         FORM FEED (FF)   vs
        # 0x0000d   CARRIAGE RETURN (CR)   vs
        # 0x00020                  SPACE  h s

        # P.196 Table 5-9. Alphanumeric regex metasymbols
        # in Chapter 5. Pattern Matching
        # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

        # (and so on)

        '\H' => '${Euhc::eH}',
        '\V' => '${Euhc::eV}',
        '\h' => '[\x09\x20]',
        '\v' => '[\x0A\x0B\x0C\x0D]',
        '\R' => '${Euhc::eR}',

        # \N
        #
        # http://perldoc.perl.org/perlre.html
        # Character Classes and other Special Escapes
        # Any character but \n (experimental). Not affected by /s modifier

        '\N' => '${Euhc::eN}',

        # \b \B

        # P.180 Boundaries: The \b and \B Assertions
        # in Chapter 5: Pattern Matching
        # of ISBN 0-596-00027-8 Programming Perl Third Edition.

        # P.219 Boundaries: The \b and \B Assertions
        # in Chapter 5: Pattern Matching
        # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

        # \b really means (?:(?<=\w)(?!\w)|(?
        #           or (?:(?<=\A|\W)(?=\w)|(?<=\w)(?=\W|\z))
        '\b' => '${Euhc::eb}',

        # \B really means (?:(?<=\w)(?=\w)|(?
        #              or (?:(?<=\w)(?=\w)|(?<=\W)(?=\W))
        '\B' => '${Euhc::eB}',

    }->{$char} || '';
}

#
# prepare UHC characters per length
#

# 1 octet characters
my @chars1 = ();
sub chars1 {
    if (@chars1) {
        return @chars1;
    }
    if (exists $range_tr{1}) {
        my @ranges = @{ $range_tr{1} };
        while (my @range = splice(@ranges,0,1)) {
            for my $oct0 (@{$range[0]}) {
                push @chars1, pack 'C', $oct0;
            }
        }
    }
    return @chars1;
}

# 2 octets characters
my @chars2 = ();
sub chars2 {
    if (@chars2) {
        return @chars2;
    }
    if (exists $range_tr{2}) {
        my @ranges = @{ $range_tr{2} };
        while (my @range = splice(@ranges,0,2)) {
            for my $oct0 (@{$range[0]}) {
                for my $oct1 (@{$range[1]}) {
                    push @chars2, pack 'CC', $oct0,$oct1;
                }
            }
        }
    }
    return @chars2;
}

# 3 octets characters
my @chars3 = ();
sub chars3 {
    if (@chars3) {
        return @chars3;
    }
    if (exists $range_tr{3}) {
        my @ranges = @{ $range_tr{3} };
        while (my @range = splice(@ranges,0,3)) {
            for my $oct0 (@{$range[0]}) {
                for my $oct1 (@{$range[1]}) {
                    for my $oct2 (@{$range[2]}) {
                        push @chars3, pack 'CCC', $oct0,$oct1,$oct2;
                    }
                }
            }
        }
    }
    return @chars3;
}

# 4 octets characters
my @chars4 = ();
sub chars4 {
    if (@chars4) {
        return @chars4;
    }
    if (exists $range_tr{4}) {
        my @ranges = @{ $range_tr{4} };
        while (my @range = splice(@ranges,0,4)) {
            for my $oct0 (@{$range[0]}) {
                for my $oct1 (@{$range[1]}) {
                    for my $oct2 (@{$range[2]}) {
                        for my $oct3 (@{$range[3]}) {
                            push @chars4, pack 'CCCC', $oct0,$oct1,$oct2,$oct3;
                        }
                    }
                }
            }
        }
    }
    return @chars4;
}

#
# UHC open character list for tr
#
sub _charlist_tr {

    local $_ = shift @_;

    # unescape character
    my @char = ();
    while (not /\G \z/oxmsgc) {
        if (/\G (\\0?55|\\x2[Dd]|\\-) /oxmsgc) {
            push @char, '\-';
        }
        elsif (/\G \\ ([0-7]{2,3}) /oxmsgc) {
            push @char, CORE::chr(oct $1);
        }
        elsif (/\G \\x ([0-9A-Fa-f]{1,2}) /oxmsgc) {
            push @char, CORE::chr(hex $1);
        }
        elsif (/\G \\c ([\x40-\x5F]) /oxmsgc) {
            push @char, CORE::chr(CORE::ord($1) & 0x1F);
        }
        elsif (/\G (\\ [0nrtfbae]) /oxmsgc) {
            push @char, {
                '\0' => "\0",
                '\n' => "\n",
                '\r' => "\r",
                '\t' => "\t",
                '\f' => "\f",
                '\b' => "\x08", # \b means backspace in character class
                '\a' => "\a",
                '\e' => "\e",
            }->{$1};
        }
        elsif (/\G \\ ($q_char) /oxmsgc) {
            push @char, $1;
        }
        elsif (/\G ($q_char) /oxmsgc) {
            push @char, $1;
        }
    }

    # join separated multiple-octet
    @char = join('',@char) =~ /\G (?>\\-|$q_char) /oxmsg;

    # unescape '-'
    my @i = ();
    for my $i (0 .. $#char) {
        if ($char[$i] eq '\-') {
            $char[$i] = '-';
        }
        elsif ($char[$i] eq '-') {
            if ((0 < $i) and ($i < $#char)) {
                push @i, $i;
            }
        }
    }

    # open character list (reverse for splice)
    for my $i (CORE::reverse @i) {
        my @range = ();

        # range error
        if ((CORE::length($char[$i-1]) > CORE::length($char[$i+1])) or ($char[$i-1] gt $char[$i+1])) {
            croak "Invalid tr/// range \"\\x" . unpack('H*',$char[$i-1]) . '-\x' . unpack('H*',$char[$i+1]) . '"';
        }

        # range of multiple-octet code
        if (CORE::length($char[$i-1]) == 1) {
            if (CORE::length($char[$i+1]) == 1) {
                push @range, grep {($char[$i-1] le $_) and ($_ le $char[$i+1])} chars1();
            }
            elsif (CORE::length($char[$i+1]) == 2) {
                push @range, grep {$char[$i-1] le $_}                           chars1();
                push @range, grep {$_ le $char[$i+1]}                           chars2();
            }
            elsif (CORE::length($char[$i+1]) == 3) {
                push @range, grep {$char[$i-1] le $_}                           chars1();
                push @range,                                                    chars2();
                push @range, grep {$_ le $char[$i+1]}                           chars3();
            }
            elsif (CORE::length($char[$i+1]) == 4) {
                push @range, grep {$char[$i-1] le $_}                           chars1();
                push @range,                                                    chars2();
                push @range,                                                    chars3();
                push @range, grep {$_ le $char[$i+1]}                           chars4();
            }
            else {
                croak "Invalid tr/// range (over 4octets) \"\\x" . unpack('H*',$char[$i-1]) . '-\x' . unpack('H*',$char[$i+1]) . '"';
            }
        }
        elsif (CORE::length($char[$i-1]) == 2) {
            if (CORE::length($char[$i+1]) == 2) {
                push @range, grep {($char[$i-1] le $_) and ($_ le $char[$i+1])} chars2();
            }
            elsif (CORE::length($char[$i+1]) == 3) {
                push @range, grep {$char[$i-1] le $_}                           chars2();
                push @range, grep {$_ le $char[$i+1]}                           chars3();
            }
            elsif (CORE::length($char[$i+1]) == 4) {
                push @range, grep {$char[$i-1] le $_}                           chars2();
                push @range,                                                    chars3();
                push @range, grep {$_ le $char[$i+1]}                           chars4();
            }
            else {
                croak "Invalid tr/// range (over 4octets) \"\\x" . unpack('H*',$char[$i-1]) . '-\x' . unpack('H*',$char[$i+1]) . '"';
            }
        }
        elsif (CORE::length($char[$i-1]) == 3) {
            if (CORE::length($char[$i+1]) == 3) {
                push @range, grep {($char[$i-1] le $_) and ($_ le $char[$i+1])} chars3();
            }
            elsif (CORE::length($char[$i+1]) == 4) {
                push @range, grep {$char[$i-1] le $_}                           chars3();
                push @range, grep {$_ le $char[$i+1]}                           chars4();
            }
            else {
                croak "Invalid tr/// range (over 4octets) \"\\x" . unpack('H*',$char[$i-1]) . '-\x' . unpack('H*',$char[$i+1]) . '"';
            }
        }
        elsif (CORE::length($char[$i-1]) == 4) {
            if (CORE::length($char[$i+1]) == 4) {
                push @range, grep {($char[$i-1] le $_) and ($_ le $char[$i+1])} chars4();
            }
            else {
                croak "Invalid tr/// range (over 4octets) \"\\x" . unpack('H*',$char[$i-1]) . '-\x' . unpack('H*',$char[$i+1]) . '"';
            }
        }
        else {
            croak "Invalid tr/// range (over 4octets) \"\\x" . unpack('H*',$char[$i-1]) . '-\x' . unpack('H*',$char[$i+1]) . '"';
        }

        splice @char, $i-1, 3, @range;
    }

    return @char;
}

#
# UHC open character class
#
sub _cc {
    if (scalar(@_) == 0) {
        die __FILE__, ": subroutine cc got no parameter.\n";
    }
    elsif (scalar(@_) == 1) {
        return sprintf('\x%02X',$_[0]);
    }
    elsif (scalar(@_) == 2) {
        if ($_[0] > $_[1]) {
            die __FILE__, ": subroutine cc got \$_[0] > \$_[1] parameters).\n";
        }
        elsif ($_[0] == $_[1]) {
            return sprintf('\x%02X',$_[0]);
        }
        elsif (($_[0]+1) == $_[1]) {
            return sprintf('[\\x%02X\\x%02X]',$_[0],$_[1]);
        }
        else {
            return sprintf('[\\x%02X-\\x%02X]',$_[0],$_[1]);
        }
    }
    else {
        die __FILE__, ": subroutine cc got 3 or more parameters (@{[scalar(@_)]} parameters).\n";
    }
}

#
# UHC octet range
#
sub _octets {
    my $length = shift @_;

    if ($length == 1) {
        my($a1) = unpack 'C', $_[0];
        my($z1) = unpack 'C', $_[1];

        if ($a1 > $z1) {
            croak 'Invalid [] range in regexp (CORE::ord(A) > CORE::ord(B)) ' . '\x' . unpack('H*',$a1) . '-\x' . unpack('H*',$z1);
        }

        if ($a1 == $z1) {
            return sprintf('\x%02X',$a1);
        }
        elsif (($a1+1) == $z1) {
            return sprintf('\x%02X\x%02X',$a1,$z1);
        }
        else {
            return sprintf('\x%02X-\x%02X',$a1,$z1);
        }
    }
    elsif ($length == 2) {
        my($a1,$a2) = unpack 'CC', $_[0];
        my($z1,$z2) = unpack 'CC', $_[1];
        my($A1,$A2) = unpack 'CC', $_[2];
        my($Z1,$Z2) = unpack 'CC', $_[3];

        if ($a1 == $z1) {
            return (
            #   11111111   222222222222
            #        A          A   Z
                _cc($a1) . _cc($a2,$z2), # a2-z2
            );
        }
        elsif (($a1+1) == $z1) {
            return (
            #   11111111111   222222222222
            #        A  Z          A   Z
                _cc($a1)    . _cc($a2,$Z2), # a2-
                _cc(   $z1) . _cc($A2,$z2), #   -z2
            );
        }
        else {
            return (
            #   1111111111111111   222222222222
            #        A     Z            A   Z
                _cc($a1)         . _cc($a2,$Z2), # a2-
                _cc($a1+1,$z1-1) . _cc($A2,$Z2), #   -
                _cc(      $z1)   . _cc($A2,$z2), #   -z2
            );
        }
    }
    elsif ($length == 3) {
        my($a1,$a2,$a3) = unpack 'CCC', $_[0];
        my($z1,$z2,$z3) = unpack 'CCC', $_[1];
        my($A1,$A2,$A3) = unpack 'CCC', $_[2];
        my($Z1,$Z2,$Z3) = unpack 'CCC', $_[3];

        if ($a1 == $z1) {
            if ($a2 == $z2) {
                return (
                #   11111111   22222222   333333333333
                #        A          A          A   Z
                    _cc($a1) . _cc($a2) . _cc($a3,$z3), # a3-z3
                );
            }
            elsif (($a2+1) == $z2) {
                return (
                #   11111111   22222222222   333333333333
                #        A          A  Z          A   Z
                    _cc($a1) . _cc($a2)    . _cc($a3,$Z3), # a3-
                    _cc($a1) . _cc(   $z2) . _cc($A3,$z3), #   -z3
                );
            }
            else {
                return (
                #   11111111   2222222222222222   333333333333
                #        A          A     Z            A   Z
                    _cc($a1) . _cc($a2)         . _cc($a3,$Z3), # a3-
                    _cc($a1) . _cc($a2+1,$z2-1) . _cc($A3,$Z3), #   -
                    _cc($a1) . _cc(      $z2)   . _cc($A3,$z3), #   -z3
                );
            }
        }
        elsif (($a1+1) == $z1) {
            return (
            #   11111111111   22222222222222   333333333333
            #        A  Z          A     Z          A   Z
                _cc($a1)    . _cc($a2)       . _cc($a3,$Z3), # a3-
                _cc($a1)    . _cc($a2+1,$Z2) . _cc($A3,$Z3), #   -
                _cc(   $z1) . _cc($A2,$z2-1) . _cc($A3,$Z3), #   -
                _cc(   $z1) . _cc(    $z2)   . _cc($A3,$z3), #   -z3
            );
        }
        else {
            return (
            #   1111111111111111   22222222222222   333333333333
            #        A     Z            A     Z          A   Z
                _cc($a1)         . _cc($a2)       . _cc($a3,$Z3), # a3-
                _cc($a1)         . _cc($a2+1,$Z2) . _cc($A3,$Z3), #   -
                _cc($a1+1,$z1-1) . _cc($A2,$Z2)   . _cc($A3,$Z3), #   -
                _cc(      $z1)   . _cc($A2,$z2-1) . _cc($A3,$Z3), #   -
                _cc(      $z1)   . _cc(    $z2)   . _cc($A3,$z3), #   -z3
            );
        }
    }
    elsif ($length == 4) {
        my($a1,$a2,$a3,$a4) = unpack 'CCCC', $_[0];
        my($z1,$z2,$z3,$z4) = unpack 'CCCC', $_[1];
        my($A1,$A2,$A3,$A4) = unpack 'CCCC', $_[0];
        my($Z1,$Z2,$Z3,$Z4) = unpack 'CCCC', $_[1];

        if ($a1 == $z1) {
            if ($a2 == $z2) {
                if ($a3 == $z3) {
                    return (
                    #   11111111   22222222   33333333   444444444444
                    #        A          A          A          A   Z
                        _cc($a1) . _cc($a2) . _cc($a3) . _cc($a4,$z4), # a4-z4
                    );
                }
                elsif (($a3+1) == $z3) {
                    return (
                    #   11111111   22222222   33333333333   444444444444
                    #        A          A          A  Z          A   Z
                        _cc($a1) . _cc($a2) . _cc($a3)    . _cc($a4,$Z4), # a4-
                        _cc($a1) . _cc($a2) . _cc(   $z3) . _cc($A4,$z4), #   -z4
                    );
                }
                else {
                    return (
                    #   11111111   22222222   3333333333333333   444444444444
                    #        A          A          A     Z            A   Z
                        _cc($a1) . _cc($a2) . _cc($a3)         . _cc($a4,$Z4), # a4-
                        _cc($a1) . _cc($a2) . _cc($a3+1,$z3-1) . _cc($A4,$Z4), #   -
                        _cc($a1) . _cc($a2) . _cc(      $z3)   . _cc($A4,$z4), #   -z4
                    );
                }
            }
            elsif (($a2+1) == $z2) {
                return (
                #   11111111   22222222222   33333333333333   444444444444
                #        A          A  Z          A     Z          A   Z
                    _cc($a1) . _cc($a2)    . _cc($a3)       . _cc($a4,$Z4), # a4-
                    _cc($a1) . _cc($a2)    . _cc($a3+1,$Z3) . _cc($A4,$Z4), #   -
                    _cc($a1) . _cc(   $z2) . _cc($A3,$z3-1) . _cc($A4,$Z4), #   -
                    _cc($a1) . _cc(   $z2) . _cc(    $z3)   . _cc($A4,$z4), #   -z4
                );
            }
            else {
                return (
                #   11111111   2222222222222222   33333333333333   444444444444
                #        A          A     Z            A     Z          A   Z
                    _cc($a1) . _cc($a2)         . _cc($a3)       . _cc($a4,$Z4), # a4-
                    _cc($a1) . _cc($a2)         . _cc($a3+1,$Z3) . _cc($A4,$Z4), #   -
                    _cc($a1) . _cc($a2+1,$z2-1) . _cc($A3,$Z3)   . _cc($A4,$Z4), #   -
                    _cc($a1) . _cc(      $z2)   . _cc($A3,$z3-1) . _cc($A4,$Z4), #   -
                    _cc($a1) . _cc(      $z2)   . _cc(    $z3)   . _cc($A4,$z4), #   -z4
                );
            }
        }
        elsif (($a1+1) == $z1) {
            return (
            #   11111111111   22222222222222   33333333333333   444444444444
            #        A  Z          A     Z          A     Z          A   Z
                _cc($a1)    . _cc($a2)       . _cc($a3)       . _cc($a4,$Z4), # a4-
                _cc($a1)    . _cc($a2)       . _cc($a3+1,$Z3) . _cc($A4,$Z4), #   -
                _cc($a1)    . _cc($a2+1,$Z2) . _cc($A3,$Z3)   . _cc($A4,$Z4), #   -
                _cc(   $z1) . _cc($A2,$z2-1) . _cc($A3,$Z3)   . _cc($A4,$Z4), #   -
                _cc(   $z1) . _cc(    $z2)   . _cc($A3,$z3-1) . _cc($A4,$Z4), #   -
                _cc(   $z1) . _cc(    $z2)   . _cc(    $z3)   . _cc($A4,$z4), #   -z4
            );
        }
        else {
            return (
            #   1111111111111111   22222222222222   33333333333333   444444444444
            #        A     Z            A     Z          A     Z          A   Z
                _cc($a1)         . _cc($a2)       . _cc($a3)       . _cc($a4,$Z4), # a4-
                _cc($a1)         . _cc($a2)       . _cc($a3+1,$Z3) . _cc($A4,$Z4), #   -
                _cc($a1)         . _cc($a2+1,$Z2) . _cc($A3,$Z3)   . _cc($A4,$Z4), #   -
                _cc($a1+1,$z1-1) . _cc($A2,$Z2)   . _cc($A3,$Z3)   . _cc($A4,$Z4), #   -
                _cc(      $z1)   . _cc($A2,$z2-1) . _cc($A3,$Z3)   . _cc($A4,$Z4), #   -
                _cc(      $z1)   . _cc(    $z2)   . _cc($A3,$z3-1) . _cc($A4,$Z4), #   -
                _cc(      $z1)   . _cc(    $z2)   . _cc(    $z3)   . _cc($A4,$z4), #   -z4
            );
        }
    }
    else {
        die __FILE__, ": subroutine _octets got invalid length ($length).\n";
    }
}

#
# UHC range regexp
#
sub _range_regexp {
    my($length,$first,$last) = @_;

    my @range_regexp = ();
    if (not exists $range_tr{$length}) {
        return @range_regexp;
    }

    my @ranges = @{ $range_tr{$length} };
    while (my @range = splice(@ranges,0,$length)) {
        my $min = '';
        my $max = '';
        for (my $i=0; $i < $length; $i++) {
            $min .= pack 'C', $range[$i][0];
            $max .= pack 'C', $range[$i][-1];
        }

# min___max
#            FIRST_____________LAST
#       (nothing)

        if ($max lt $first) {
        }

#            **********
#       min_________max
#            FIRST_____________LAST
#            **********

        elsif (($min le $first) and ($first le $max) and ($max le $last)) {
            push @range_regexp, _octets($length,$first,$max,$min,$max);
        }

#            **********************
#            min________________max
#            FIRST_____________LAST
#            **********************

        elsif (($min eq $first) and ($max eq $last)) {
            push @range_regexp, _octets($length,$first,$last,$min,$max);
        }

#                   *********
#                   min___max
#            FIRST_____________LAST
#                   *********

        elsif (($first le $min) and ($max le $last)) {
            push @range_regexp, _octets($length,$min,$max,$min,$max);
        }

#            **********************
#       min__________________________max
#            FIRST_____________LAST
#            **********************

        elsif (($min le $first) and ($last le $max)) {
            push @range_regexp, _octets($length,$first,$last,$min,$max);
        }

#                         *********
#                         min________max
#            FIRST_____________LAST
#                         *********

        elsif (($first le $min) and ($min le $last) and ($last le $max)) {
            push @range_regexp, _octets($length,$min,$last,$min,$max);
        }

#                                    min___max
#            FIRST_____________LAST
#                              (nothing)

        elsif ($last lt $min) {
        }

        else {
            die __FILE__, ": subroutine _range_regexp panic.\n";
        }
    }

    return @range_regexp;
}

#
# UHC open character list for qr and not qr
#
sub _charlist {

    my $modifier = pop @_;
    my @char = @_;

    my $ignorecase = ($modifier =~ /i/oxms) ? 1 : 0;

    # unescape character
    for (my $i=0; $i <= $#char; $i++) {

        # escape - to ...
        if ($char[$i] eq '-') {
            if ((0 < $i) and ($i < $#char)) {
                $char[$i] = '...';
            }
        }

        # octal escape sequence
        elsif ($char[$i] =~ /\A \\o \{ ([0-7]+) \} \z/oxms) {
            $char[$i] = octchr($1);
        }

        # hexadecimal escape sequence
        elsif ($char[$i] =~ /\A \\x \{ ([0-9A-Fa-f]+) \} \z/oxms) {
            $char[$i] = hexchr($1);
        }

        # \b{...}      --> b\{...}
        # \B{...}      --> B\{...}
        # \N{CHARNAME} --> N\{CHARNAME}
        # \p{PROPERTY} --> p\{PROPERTY}
        # \P{PROPERTY} --> P\{PROPERTY}
        elsif ($char[$i] =~ /\A \\ ([bBNpP]) ( \{ ([^\x81-\xFE0-9\}][^\x81-\xFE\}]*) \} ) \z/oxms) {
            $char[$i] = $1 . '\\' . $2;
        }

        # \p, \P, \X --> p, P, X
        elsif ($char[$i] =~ /\A \\ ( [pPX] ) \z/oxms) {
            $char[$i] = $1;
        }

        elsif ($char[$i] =~ /\A \\ ([0-7]{2,3}) \z/oxms) {
            $char[$i] = CORE::chr oct $1;
        }
        elsif ($char[$i] =~ /\A \\x ([0-9A-Fa-f]{1,2}) \z/oxms) {
            $char[$i] = CORE::chr hex $1;
        }
        elsif ($char[$i] =~ /\A \\c ([\x40-\x5F]) \z/oxms) {
            $char[$i] = CORE::chr(CORE::ord($1) & 0x1F);
        }
        elsif ($char[$i] =~ /\A (\\ [0nrtfbaedswDSWHVhvR]) \z/oxms) {
            $char[$i] = {
                '\0' => "\0",
                '\n' => "\n",
                '\r' => "\r",
                '\t' => "\t",
                '\f' => "\f",
                '\b' => "\x08", # \b means backspace in character class
                '\a' => "\a",
                '\e' => "\e",
                '\d' => '[0-9]',

                # Vertical tabs are now whitespace
                # \s in a regex now matches a vertical tab in all circumstances.
                # http://search.cpan.org/dist/perl-5.18.0/pod/perldelta.pod#Vertical_tabs_are_now_whitespace
                #            \t  \n  \v  \f  \r space
                # '\s' => '[\x09\x0A    \x0C\x0D\x20]',
                # '\s' => '[\x09\x0A\x0B\x0C\x0D\x20]',
                '\s'   => '\s',

                '\w' => '[0-9A-Z_a-z]',
                '\D' => '${Euhc::eD}',
                '\S' => '${Euhc::eS}',
                '\W' => '${Euhc::eW}',

                '\H' => '${Euhc::eH}',
                '\V' => '${Euhc::eV}',
                '\h' => '[\x09\x20]',
                '\v' => '[\x0A\x0B\x0C\x0D]',
                '\R' => '${Euhc::eR}',

            }->{$1};
        }

        # POSIX-style character classes
        elsif ($ignorecase and ($char[$i] =~ /\A ( \[\: \^? (?:lower|upper) :\] ) \z/oxms)) {
            $char[$i] = {

                '[:lower:]'   => '[\x41-\x5A\x61-\x7A]',
                '[:upper:]'   => '[\x41-\x5A\x61-\x7A]',
                '[:^lower:]'  => '${Euhc::not_lower_i}',
                '[:^upper:]'  => '${Euhc::not_upper_i}',

            }->{$1};
        }
        elsif ($char[$i] =~ /\A ( \[\: \^? (?:alnum|alpha|ascii|blank|cntrl|digit|graph|lower|print|punct|space|upper|word|xdigit) :\] ) \z/oxms) {
            $char[$i] = {

                '[:alnum:]'   => '[\x30-\x39\x41-\x5A\x61-\x7A]',
                '[:alpha:]'   => '[\x41-\x5A\x61-\x7A]',
                '[:ascii:]'   => '[\x00-\x7F]',
                '[:blank:]'   => '[\x09\x20]',
                '[:cntrl:]'   => '[\x00-\x1F\x7F]',
                '[:digit:]'   => '[\x30-\x39]',
                '[:graph:]'   => '[\x21-\x7F]',
                '[:lower:]'   => '[\x61-\x7A]',
                '[:print:]'   => '[\x20-\x7F]',
                '[:punct:]'   => '[\x21-\x2F\x3A-\x3F\x40\x5B-\x5F\x60\x7B-\x7E]',

                # P.174 POSIX-Style Character Classes
                # in Chapter 5: Pattern Matching
                # of ISBN 0-596-00027-8 Programming Perl Third Edition.

                # P.311 11.2.4 Character Classes and other Special Escapes
                # in Chapter 11: perlre: Perl regular expressions
                # of ISBN-13: 978-1-906966-02-7 The Perl Language Reference Manual (for Perl version 5.12.1)

                # P.210 POSIX-Style Character Classes
                # in Chapter 5: Pattern Matching
                # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

                '[:space:]'   => '[\s\x0B]', # "\s" plus vertical tab ("\cK")

                '[:upper:]'   => '[\x41-\x5A]',
                '[:word:]'    => '[\x30-\x39\x41-\x5A\x5F\x61-\x7A]',
                '[:xdigit:]'  => '[\x30-\x39\x41-\x46\x61-\x66]',
                '[:^alnum:]'  => '${Euhc::not_alnum}',
                '[:^alpha:]'  => '${Euhc::not_alpha}',
                '[:^ascii:]'  => '${Euhc::not_ascii}',
                '[:^blank:]'  => '${Euhc::not_blank}',
                '[:^cntrl:]'  => '${Euhc::not_cntrl}',
                '[:^digit:]'  => '${Euhc::not_digit}',
                '[:^graph:]'  => '${Euhc::not_graph}',
                '[:^lower:]'  => '${Euhc::not_lower}',
                '[:^print:]'  => '${Euhc::not_print}',
                '[:^punct:]'  => '${Euhc::not_punct}',
                '[:^space:]'  => '${Euhc::not_space}',
                '[:^upper:]'  => '${Euhc::not_upper}',
                '[:^word:]'   => '${Euhc::not_word}',
                '[:^xdigit:]' => '${Euhc::not_xdigit}',

            }->{$1};
        }
        elsif ($char[$i] =~ /\A \\ ($q_char) \z/oxms) {
            $char[$i] = $1;
        }
    }

    # open character list
    my @singleoctet   = ();
    my @multipleoctet = ();
    for (my $i=0; $i <= $#char; ) {

        # escaped -
        if (defined($char[$i+1]) and ($char[$i+1] eq '...')) {
            $i += 1;
            next;
        }

        # make range regexp
        elsif ($char[$i] eq '...') {

            # range error
            if (CORE::length($char[$i-1]) > CORE::length($char[$i+1])) {
                croak 'Invalid [] range in regexp (length(A) > length(B)) ' . '\x' . unpack('H*',$char[$i-1]) . '-\x' . unpack('H*',$char[$i+1]);
            }
            elsif (CORE::length($char[$i-1]) == CORE::length($char[$i+1])) {
                if ($char[$i-1] gt $char[$i+1]) {
                    croak 'Invalid [] range in regexp (CORE::ord(A) > CORE::ord(B)) ' . '\x' . unpack('H*',$char[$i-1]) . '-\x' . unpack('H*',$char[$i+1]);
                }
            }

            # make range regexp per length
            for my $length (CORE::length($char[$i-1]) .. CORE::length($char[$i+1])) {
                my @regexp = ();

                # is first and last
                if (($length == CORE::length($char[$i-1])) and ($length == CORE::length($char[$i+1]))) {
                    push @regexp, _range_regexp($length, $char[$i-1], $char[$i+1]);
                }

                # is first
                elsif ($length == CORE::length($char[$i-1])) {
                    push @regexp, _range_regexp($length, $char[$i-1], "\xFF" x $length);
                }

                # is inside in first and last
                elsif ((CORE::length($char[$i-1]) < $length) and ($length < CORE::length($char[$i+1]))) {
                    push @regexp, _range_regexp($length, "\x00" x $length, "\xFF" x $length);
                }

                # is last
                elsif ($length == CORE::length($char[$i+1])) {
                    push @regexp, _range_regexp($length, "\x00" x $length, $char[$i+1]);
                }

                else {
                    die __FILE__, ": subroutine make_regexp panic.\n";
                }

                if ($length == 1) {
                    push @singleoctet, @regexp;
                }
                else {
                    push @multipleoctet, @regexp;
                }
            }

            $i += 2;
        }

        # with /i modifier
        elsif ($char[$i] =~ /\A [\x00-\xFF] \z/oxms) {
            if ($modifier =~ /i/oxms) {
                my $uc = Euhc::uc($char[$i]);
                my $fc = Euhc::fc($char[$i]);
                if ($uc ne $fc) {
                    if (CORE::length($fc) == 1) {
                        push @singleoctet, $uc, $fc;
                    }
                    else {
                        push @singleoctet,   $uc;
                        push @multipleoctet, $fc;
                    }
                }
                else {
                    push @singleoctet, $char[$i];
                }
            }
            else {
                push @singleoctet, $char[$i];
            }
            $i += 1;
        }

        # single character of single octet code
        elsif ($char[$i] =~ /\A (?: \\h ) \z/oxms) {
            push @singleoctet, "\t", "\x20";
            $i += 1;
        }
        elsif ($char[$i] =~ /\A (?: \\v ) \z/oxms) {
            push @singleoctet, "\x0A", "\x0B", "\x0C", "\x0D";
            $i += 1;
        }
        elsif ($char[$i] =~ /\A (?: \\d | \\s | \\w ) \z/oxms) {
            push @singleoctet, $char[$i];
            $i += 1;
        }

        # single character of multiple-octet code
        else {
            push @multipleoctet, $char[$i];
            $i += 1;
        }
    }

    # quote metachar
    for (@singleoctet) {
        if ($_ eq '...') {
            $_ = '-';
        }
        elsif (/\A \n \z/oxms) {
            $_ = '\n';
        }
        elsif (/\A \r \z/oxms) {
            $_ = '\r';
        }
        elsif (/\A ([\x00-\x20\x7F-\xFF]) \z/oxms) {
            $_ = sprintf('\x%02X', CORE::ord $1);
        }
        elsif (/\A [\x00-\xFF] \z/oxms) {
            $_ = quotemeta $_;
        }
    }
    for (@multipleoctet) {
        if (/\A ([\x80-\xFF].*) ([\x00-\xFF]) \z/oxms) {
            $_ = $1 . quotemeta $2;
        }
    }

    # return character list
    return \@singleoctet, \@multipleoctet;
}

#
# UHC octal escape sequence
#
sub octchr {
    my($octdigit) = @_;

    my @binary = ();
    for my $octal (split(//,$octdigit)) {
        push @binary, {
            '0' => '000',
            '1' => '001',
            '2' => '010',
            '3' => '011',
            '4' => '100',
            '5' => '101',
            '6' => '110',
            '7' => '111',
        }->{$octal};
    }
    my $binary = join '', @binary;

    my $octchr = {
        #                1234567
        1 => pack('B*', "0000000$binary"),
        2 => pack('B*', "000000$binary"),
        3 => pack('B*', "00000$binary"),
        4 => pack('B*', "0000$binary"),
        5 => pack('B*', "000$binary"),
        6 => pack('B*', "00$binary"),
        7 => pack('B*', "0$binary"),
        0 => pack('B*', "$binary"),

    }->{CORE::length($binary) % 8};

    return $octchr;
}

#
# UHC hexadecimal escape sequence
#
sub hexchr {
    my($hexdigit) = @_;

    my $hexchr = {
        1 => pack('H*', "0$hexdigit"),
        0 => pack('H*', "$hexdigit"),

    }->{CORE::length($_[0]) % 2};

    return $hexchr;
}

#
# UHC open character list for qr
#
sub charlist_qr {

    my $modifier = pop @_;
    my @char = @_;

    my($singleoctet, $multipleoctet) = _charlist(@char, $modifier);
    my @singleoctet   = @$singleoctet;
    my @multipleoctet = @$multipleoctet;

    # return character list
    if (scalar(@singleoctet) >= 1) {

        # with /i modifier
        if ($modifier =~ m/i/oxms) {
            my %singleoctet_ignorecase = ();
            for (@singleoctet) {
                while (s/ \A \\x(..) - \\x(..) //oxms or s/ \A \\x((..)) //oxms) {
                    for my $ord (hex($1) .. hex($2)) {
                        my $char = CORE::chr($ord);
                        my $uc = Euhc::uc($char);
                        my $fc = Euhc::fc($char);
                        if ($uc eq $fc) {
                            $singleoctet_ignorecase{unpack 'C*', $char} = 1;
                        }
                        else {
                            if (CORE::length($fc) == 1) {
                                $singleoctet_ignorecase{unpack 'C*', $uc} = 1;
                                $singleoctet_ignorecase{unpack 'C*', $fc} = 1;
                            }
                            else {
                                $singleoctet_ignorecase{unpack 'C*', $uc} = 1;
                                push @multipleoctet, join '', map {sprintf('\x%02X',$_)} unpack 'C*', $fc;
                            }
                        }
                    }
                }
                if ($_ ne '') {
                    $singleoctet_ignorecase{unpack 'C*', $_} = 1;
                }
            }
            my $i = 0;
            my @singleoctet_ignorecase = ();
            for my $ord (0 .. 255) {
                if (exists $singleoctet_ignorecase{$ord}) {
                    push @{$singleoctet_ignorecase[$i]}, $ord;
                }
                else {
                    $i++;
                }
            }
            @singleoctet = ();
            for my $range (@singleoctet_ignorecase) {
                if (ref $range) {
                    if (scalar(@{$range}) == 1) {
                        push @singleoctet, sprintf('\x%02X', @{$range}[0]);
                    }
                    elsif (scalar(@{$range}) == 2) {
                        push @singleoctet, sprintf('\x%02X\x%02X', @{$range}[0], @{$range}[-1]);
                    }
                    else {
                        push @singleoctet, sprintf('\x%02X-\x%02X', @{$range}[0], @{$range}[-1]);
                    }
                }
            }
        }

        my $not_anchor = '';
        $not_anchor = '(?![\x81-\xFE])';

        push @multipleoctet, join('', $not_anchor, '[', @singleoctet, ']' );
    }
    if (scalar(@multipleoctet) >= 2) {
        return '(?:' . join('|', @multipleoctet) . ')';
    }
    else {
        return $multipleoctet[0];
    }
}

#
# UHC open character list for not qr
#
sub charlist_not_qr {

    my $modifier = pop @_;
    my @char = @_;

    my($singleoctet, $multipleoctet) = _charlist(@char, $modifier);
    my @singleoctet   = @$singleoctet;
    my @multipleoctet = @$multipleoctet;

    # with /i modifier
    if ($modifier =~ m/i/oxms) {
        my %singleoctet_ignorecase = ();
        for (@singleoctet) {
            while (s/ \A \\x(..) - \\x(..) //oxms or s/ \A \\x((..)) //oxms) {
                for my $ord (hex($1) .. hex($2)) {
                    my $char = CORE::chr($ord);
                    my $uc = Euhc::uc($char);
                    my $fc = Euhc::fc($char);
                    if ($uc eq $fc) {
                        $singleoctet_ignorecase{unpack 'C*', $char} = 1;
                    }
                    else {
                        if (CORE::length($fc) == 1) {
                            $singleoctet_ignorecase{unpack 'C*', $uc} = 1;
                            $singleoctet_ignorecase{unpack 'C*', $fc} = 1;
                        }
                        else {
                            $singleoctet_ignorecase{unpack 'C*', $uc} = 1;
                            push @multipleoctet, join '', map {sprintf('\x%02X',$_)} unpack 'C*', $fc;
                        }
                    }
                }
            }
            if ($_ ne '') {
                $singleoctet_ignorecase{unpack 'C*', $_} = 1;
            }
        }
        my $i = 0;
        my @singleoctet_ignorecase = ();
        for my $ord (0 .. 255) {
            if (exists $singleoctet_ignorecase{$ord}) {
                push @{$singleoctet_ignorecase[$i]}, $ord;
            }
            else {
                $i++;
            }
        }
        @singleoctet = ();
        for my $range (@singleoctet_ignorecase) {
            if (ref $range) {
                if (scalar(@{$range}) == 1) {
                    push @singleoctet, sprintf('\x%02X', @{$range}[0]);
                }
                elsif (scalar(@{$range}) == 2) {
                    push @singleoctet, sprintf('\x%02X\x%02X', @{$range}[0], @{$range}[-1]);
                }
                else {
                    push @singleoctet, sprintf('\x%02X-\x%02X', @{$range}[0], @{$range}[-1]);
                }
            }
        }
    }

    # return character list
    if (scalar(@multipleoctet) >= 1) {
        if (scalar(@singleoctet) >= 1) {

            # any character other than multiple-octet and single octet character class
            return '(?!' . join('|', @multipleoctet) . ')(?:[^\x81-\xFE' . join('', @singleoctet) . ']|[\x81-\xFE][\x00-\xFF])';
        }
        else {

            # any character other than multiple-octet character class
            return '(?!' . join('|', @multipleoctet) . ")(?:$your_char)";
        }
    }
    else {
        if (scalar(@singleoctet) >= 1) {

            # any character other than single octet character class
            return                                      '(?:[^\x81-\xFE' . join('', @singleoctet) . ']|[\x81-\xFE][\x00-\xFF])';
        }
        else {

            # any character
            return                                      "(?:$your_char)";
        }
    }
}

#
# open file in read mode
#
sub _open_r {
    my(undef,$file) = @_;
    use Fcntl qw(O_RDONLY);
    return CORE::sysopen($_[0], $file, &O_RDONLY);
}

#
# open file in append mode
#
sub _open_a {
    my(undef,$file) = @_;
    use Fcntl qw(O_WRONLY O_APPEND O_CREAT);
    return CORE::sysopen($_[0], $file, &O_WRONLY|&O_APPEND|&O_CREAT);
}

#
# safe system
#
sub _systemx {

    # P.707 29.2.33. exec
    # in Chapter 29: Functions
    # of ISBN 0-596-00027-8 Programming Perl Third Edition.
    #
    # Be aware that in older releases of Perl, exec (and system) did not flush
    # your output buffer, so you needed to enable command buffering by setting $|
    # on one or more filehandles to avoid lost output in the case of exec, or
    # misordererd output in the case of system. This situation was largely remedied
    # in the 5.6 release of Perl. (So, 5.005 release not yet.)

    # P.855 exec
    # in Chapter 27: Functions
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.
    #
    # In very old release of Perl (before v5.6), exec (and system) did not flush
    # your output buffer, so you needed to enable command buffering by setting $|
    # on one or more filehandles to avoid lost output with exec or misordered
    # output with system.

    $| = 1;

    # P.565 23.1.2. Cleaning Up Your Environment
    # in Chapter 23: Security
    # of ISBN 0-596-00027-8 Programming Perl Third Edition.

    # P.656 Cleaning Up Your Environment
    # in Chapter 20: Security
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    # local $ENV{'PATH'} = '.';
    local @ENV{qw(IFS CDPATH ENV BASH_ENV)}; # Make %ENV safer

    # P.707 29.2.33. exec
    # in Chapter 29: Functions
    # of ISBN 0-596-00027-8 Programming Perl Third Edition.
    #
    # As we mentioned earlier, exec treats a discrete list of arguments as an
    # indication that it should bypass shell processing. However, there is one
    # place where you might still get tripped up. The exec call (and system, too)
    # will not distinguish between a single scalar argument and an array containing
    # only one element.
    #
    #     @args = ("echo surprise");  # just one element in list
    #     exec @args                  # still subject to shell escapes
    #         or die "exec: $!";      #   because @args == 1
    #
    # To avoid this, you can use the PATHNAME syntax, explicitly duplicating the
    # first argument as the pathname, which forces the rest of the arguments to be
    # interpreted as a list, even if there is only one of them:
    #
    #     exec { $args[0] } @args  # safe even with one-argument list
    #         or die "can't exec @args: $!";

    # P.855 exec
    # in Chapter 27: Functions
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.
    #
    # As we mentioned earlier, exec treats a discrete list of arguments as a
    # directive to bypass shell processing. However, there is one place where
    # you might still get tripped up. The exec call (and system, too) cannot
    # distinguish between a single scalar argument and an array containing
    # only one element.
    #
    #     @args = ("echo surprise");  # just one element in list
    #     exec @args                  # still subject to shell escapes
    #         || die "exec: $!";      #   because @args == 1
    #
    # To avoid this, use the PATHNAME syntax, explicitly duplicating the first
    # argument as the pathname, which forces the rest of the arguments to be
    # interpreted as a list, even if there is only one of them:
    #
    #     exec { $args[0] } @args  # safe even with one-argument list
    #         || die "can't exec @args: $!";

    return CORE::system { $_[0] } @_; # safe even with one-argument list
}

#
# UHC order to character (with parameter)
#
sub Euhc::chr(;$) {

    my $c = @_ ? $_[0] : $_;

    if ($c == 0x00) {
        return "\x00";
    }
    else {
        my @chr = ();
        while ($c > 0) {
            unshift @chr, ($c % 0x100);
            $c = int($c / 0x100);
        }
        return pack 'C*', @chr;
    }
}

#
# UHC order to character (without parameter)
#
sub Euhc::chr_() {

    my $c = $_;

    if ($c == 0x00) {
        return "\x00";
    }
    else {
        my @chr = ();
        while ($c > 0) {
            unshift @chr, ($c % 0x100);
            $c = int($c / 0x100);
        }
        return pack 'C*', @chr;
    }
}

#
# UHC stacked file test expr
#
sub Euhc::filetest {

    my $file     = pop @_;
    my $filetest = substr(pop @_, 1);

    unless (CORE::eval qq{Euhc::$filetest(\$file)}) {
        return '';
    }
    for my $filetest (CORE::reverse @_) {
        unless (CORE::eval qq{ $filetest _ }) {
            return '';
        }
    }
    return 1;
}

#
# UHC file test -r expr
#
sub Euhc::r(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -r (Euhc::r)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-r _,@_) : -r _;
    }

    # P.908 32.39. Symbol
    # in Chapter 32: Standard Modules
    # of ISBN 0-596-00027-8 Programming Perl Third Edition.

    # P.326 Prototypes
    # in Chapter 7: Subroutines
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    # (and so on)

    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-r $fh,@_) : -r $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-r _,@_) : -r _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-r _,@_) : -r _;
        }
        else {

            # Even if ${^WIN32_SLOPPY_STAT} is set to a true value, Euhc::*()
            # on Windows opens the file for the path which has 5c at end.
            # (and so on)

            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $r = -r $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($r,@_) : $r;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -w expr
#
sub Euhc::w(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -w (Euhc::w)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-w _,@_) : -w _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-w $fh,@_) : -w $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-w _,@_) : -w _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-w _,@_) : -w _;
        }
        else {
            my $fh = gensym();
            if (_open_a($fh, $_)) {
                my $w = -w $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($w,@_) : $w;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -x expr
#
sub Euhc::x(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -x (Euhc::x)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-x _,@_) : -x _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-x $fh,@_) : -x $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-x _,@_) : -x _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-x _,@_) : -x _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $dummy_for_underline_cache = -x $fh;
                close($fh) or die "Can't close file: $_: $!";
            }

            # filename is not .COM .EXE .BAT .CMD
            return wantarray ? ('',@_) : '';
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -o expr
#
sub Euhc::o(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -o (Euhc::o)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-o _,@_) : -o _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-o $fh,@_) : -o $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-o _,@_) : -o _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-o _,@_) : -o _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $o = -o $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($o,@_) : $o;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -R expr
#
sub Euhc::R(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -R (Euhc::R)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-R _,@_) : -R _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-R $fh,@_) : -R $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-R _,@_) : -R _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-R _,@_) : -R _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $R = -R $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($R,@_) : $R;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -W expr
#
sub Euhc::W(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -W (Euhc::W)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-W _,@_) : -W _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-W $fh,@_) : -W $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-W _,@_) : -W _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-W _,@_) : -W _;
        }
        else {
            my $fh = gensym();
            if (_open_a($fh, $_)) {
                my $W = -W $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($W,@_) : $W;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -X expr
#
sub Euhc::X(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -X (Euhc::X)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-X _,@_) : -X _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-X $fh,@_) : -X $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-X _,@_) : -X _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-X _,@_) : -X _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $dummy_for_underline_cache = -X $fh;
                close($fh) or die "Can't close file: $_: $!";
            }

            # filename is not .COM .EXE .BAT .CMD
            return wantarray ? ('',@_) : '';
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -O expr
#
sub Euhc::O(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -O (Euhc::O)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-O _,@_) : -O _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-O $fh,@_) : -O $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-O _,@_) : -O _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-O _,@_) : -O _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $O = -O $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($O,@_) : $O;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -e expr
#
sub Euhc::e(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -e (Euhc::e)' if @_ and not wantarray;

    local $^W = 0;

    my $fh = qualify_to_ref $_;
    if ($_ eq '_') {
        return wantarray ? (-e _,@_) : -e _;
    }

    # return false if directory handle
    elsif (defined Euhc::telldir($fh)) {
        return wantarray ? ('',@_) : '';
    }

    # return true if file handle
    elsif (defined fileno $fh) {
        return wantarray ? (1,@_) : 1;
    }

    elsif (-e $_) {
        return wantarray ? (1,@_) : 1;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (1,@_) : 1;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $e = -e $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($e,@_) : $e;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -z expr
#
sub Euhc::z(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -z (Euhc::z)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-z _,@_) : -z _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-z $fh,@_) : -z $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-z _,@_) : -z _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-z _,@_) : -z _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $z = -z $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($z,@_) : $z;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -s expr
#
sub Euhc::s(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -s (Euhc::s)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-s _,@_) : -s _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-s $fh,@_) : -s $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-s _,@_) : -s _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-s _,@_) : -s _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $s = -s $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($s,@_) : $s;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -f expr
#
sub Euhc::f(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -f (Euhc::f)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-f _,@_) : -f _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-f $fh,@_) : -f $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-f _,@_) : -f _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? ('',@_) : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $f = -f $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($f,@_) : $f;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -d expr
#
sub Euhc::d(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -d (Euhc::d)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-d _,@_) : -d _;
    }

    # return false if file handle or directory handle
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? ('',@_) : '';
    }
    elsif (-e $_) {
        return wantarray ? (-d _,@_) : -d _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        return wantarray ? (-d "$_/.",@_) : -d "$_/.";
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -l expr
#
sub Euhc::l(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -l (Euhc::l)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-l _,@_) : -l _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-l $fh,@_) : -l $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-l _,@_) : -l _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-l _,@_) : -l _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $l = -l $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($l,@_) : $l;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -p expr
#
sub Euhc::p(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -p (Euhc::p)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-p _,@_) : -p _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-p $fh,@_) : -p $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-p _,@_) : -p _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-p _,@_) : -p _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $p = -p $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($p,@_) : $p;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -S expr
#
sub Euhc::S(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -S (Euhc::S)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-S _,@_) : -S _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-S $fh,@_) : -S $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-S _,@_) : -S _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-S _,@_) : -S _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $S = -S $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($S,@_) : $S;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -b expr
#
sub Euhc::b(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -b (Euhc::b)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-b _,@_) : -b _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-b $fh,@_) : -b $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-b _,@_) : -b _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-b _,@_) : -b _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $b = -b $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($b,@_) : $b;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -c expr
#
sub Euhc::c(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -c (Euhc::c)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-c _,@_) : -c _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-c $fh,@_) : -c $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-c _,@_) : -c _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-c _,@_) : -c _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $c = -c $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($c,@_) : $c;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -u expr
#
sub Euhc::u(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -u (Euhc::u)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-u _,@_) : -u _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-u $fh,@_) : -u $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-u _,@_) : -u _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-u _,@_) : -u _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $u = -u $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($u,@_) : $u;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -g expr
#
sub Euhc::g(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -g (Euhc::g)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-g _,@_) : -g _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-g $fh,@_) : -g $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-g _,@_) : -g _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-g _,@_) : -g _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $g = -g $fh;
                close($fh) or die "Can't close file: $_: $!";
                return wantarray ? ($g,@_) : $g;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -k expr
#
sub Euhc::k(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -k (Euhc::k)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? ('',@_) : '';
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? ('',@_) : '';
    }
    elsif ($] =~ /^5\.008/oxms) {
        return wantarray ? ('',@_) : '';
    }
    return wantarray ? ($_,@_) : $_;
}

#
# UHC file test -T expr
#
sub Euhc::T(;*@) {

    local $_ = shift if @_;

    # Use of croak without parentheses makes die on Strawberry Perl 5.008 and 5.010, like:
    #     croak 'Too many arguments for -T (Euhc::T)';
    # Must be used by parentheses like:
    #     croak('Too many arguments for -T (Euhc::T)');

    if (@_ and not wantarray) {
        croak('Too many arguments for -T (Euhc::T)');
    }

    my $T = 1;

    my $fh = qualify_to_ref $_;
    if (defined fileno $fh) {

        if (defined Euhc::telldir($fh)) {
            return wantarray ? (undef,@_) : undef;
        }

        # P.813 29.2.176. tell
        # in Chapter 29: Functions
        # of ISBN 0-596-00027-8 Programming Perl Third Edition.

        # P.970 tell
        # in Chapter 27: Functions
        # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

        # (and so on)

        my $systell = sysseek $fh, 0, 1;

        if (sysread $fh, my $block, 512) {

            # P.163 Binary file check in Little Perl Parlor 16
            # of Book No. T1008901080816 ZASSHI 08901-8 UNIX MAGAZINE 1993 Aug VOL8#8
            # (and so on)

            if ($block =~ /[\000\377]/oxms) {
                $T = '';
            }
            elsif (($block =~ tr/\000-\007\013\016-\032\034-\037\377//) * 10 > CORE::length $block) {
                $T = '';
            }
        }

        # 0 byte or eof
        else {
            $T = 1;
        }

        my $dummy_for_underline_cache = -T $fh;
        sysseek $fh, $systell, 0;
    }
    else {
        if (-d $_ or -d "$_/.") {
            return wantarray ? (undef,@_) : undef;
        }

        $fh = gensym();
        if (_open_r($fh, $_)) {
        }
        else {
            return wantarray ? (undef,@_) : undef;
        }
        if (sysread $fh, my $block, 512) {
            if ($block =~ /[\000\377]/oxms) {
                $T = '';
            }
            elsif (($block =~ tr/\000-\007\013\016-\032\034-\037\377//) * 10 > CORE::length $block) {
                $T = '';
            }
        }

        # 0 byte or eof
        else {
            $T = 1;
        }
        my $dummy_for_underline_cache = -T $fh;
        close($fh) or die "Can't close file: $_: $!";
    }

    return wantarray ? ($T,@_) : $T;
}

#
# UHC file test -B expr
#
sub Euhc::B(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -B (Euhc::B)' if @_ and not wantarray;
    my $B = '';

    my $fh = qualify_to_ref $_;
    if (defined fileno $fh) {

        if (defined Euhc::telldir($fh)) {
            return wantarray ? (undef,@_) : undef;
        }

        my $systell = sysseek $fh, 0, 1;

        if (sysread $fh, my $block, 512) {
            if ($block =~ /[\000\377]/oxms) {
                $B = 1;
            }
            elsif (($block =~ tr/\000-\007\013\016-\032\034-\037\377//) * 10 > CORE::length $block) {
                $B = 1;
            }
        }

        # 0 byte or eof
        else {
            $B = 1;
        }

        my $dummy_for_underline_cache = -B $fh;
        sysseek $fh, $systell, 0;
    }
    else {
        if (-d $_ or -d "$_/.") {
            return wantarray ? (undef,@_) : undef;
        }

        $fh = gensym();
        if (_open_r($fh, $_)) {
        }
        else {
            return wantarray ? (undef,@_) : undef;
        }
        if (sysread $fh, my $block, 512) {
            if ($block =~ /[\000\377]/oxms) {
                $B = 1;
            }
            elsif (($block =~ tr/\000-\007\013\016-\032\034-\037\377//) * 10 > CORE::length $block) {
                $B = 1;
            }
        }

        # 0 byte or eof
        else {
            $B = 1;
        }
        my $dummy_for_underline_cache = -B $fh;
        close($fh) or die "Can't close file: $_: $!";
    }

    return wantarray ? ($B,@_) : $B;
}

#
# UHC file test -M expr
#
sub Euhc::M(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -M (Euhc::M)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-M _,@_) : -M _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-M $fh,@_) : -M $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-M _,@_) : -M _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-M _,@_) : -M _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks) = CORE::stat $fh;
                close($fh) or die "Can't close file: $_: $!";
                my $M = ($^T - $mtime) / (24*60*60);
                return wantarray ? ($M,@_) : $M;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -A expr
#
sub Euhc::A(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -A (Euhc::A)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-A _,@_) : -A _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-A $fh,@_) : -A $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-A _,@_) : -A _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-A _,@_) : -A _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks) = CORE::stat $fh;
                close($fh) or die "Can't close file: $_: $!";
                my $A = ($^T - $atime) / (24*60*60);
                return wantarray ? ($A,@_) : $A;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC file test -C expr
#
sub Euhc::C(;*@) {

    local $_ = shift if @_;
    croak 'Too many arguments for -C (Euhc::C)' if @_ and not wantarray;

    if ($_ eq '_') {
        return wantarray ? (-C _,@_) : -C _;
    }
    elsif (defined fileno(my $fh = qualify_to_ref $_)) {
        return wantarray ? (-C $fh,@_) : -C $fh;
    }
    elsif (-e $_) {
        return wantarray ? (-C _,@_) : -C _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return wantarray ? (-C _,@_) : -C _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks) = CORE::stat $fh;
                close($fh) or die "Can't close file: $_: $!";
                my $C = ($^T - $ctime) / (24*60*60);
                return wantarray ? ($C,@_) : $C;
            }
        }
    }
    return wantarray ? (undef,@_) : undef;
}

#
# UHC stacked file test $_
#
sub Euhc::filetest_ {

    my $filetest = substr(pop @_, 1);

    unless (CORE::eval qq{Euhc::${filetest}_}) {
        return '';
    }
    for my $filetest (CORE::reverse @_) {
        unless (CORE::eval qq{ $filetest _ }) {
            return '';
        }
    }
    return 1;
}

#
# UHC file test -r $_
#
sub Euhc::r_() {

    if (-e $_) {
        return -r _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -r _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $r = -r $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $r ? 1 : '';
            }
        }
    }

# 10.10. Returning Failure
# in Chapter 10. Subroutines
# of ISBN 0-596-00313-7 Perl Cookbook, 2nd Edition.
# (and so on)

# 2010-01-26 The difference of "return;" and "return undef;"
# http://d.hatena.ne.jp/gfx/20100126/1264474754
#
# "Perl Best Practices" recommends to use "return;"*1 to return nothing, but
# it might be wrong in some cases. If you use this idiom for those functions
# which are expected to return a scalar value, e.g. searching functions, the
# user of those functions will be surprised at what they return in list
# context, an empty list - note that many functions and all the methods
# evaluate their arguments in list context. You'd better to use "return undef;"
# for such scalar functions.
#
#     sub search_something {
#         my($arg) = @_;
#         # search_something...
#         if(defined $found){
#             return $found;
#         }
#         return; # XXX: you'd better to "return undef;"
#     }
#
#     # ...
#
#     # you'll get what you want, but ...
#     my $something = search_something($source);
#
#     # you won't get what you want here.
#     # @_ for doit() is (-foo => $opt), not (undef, -foo => $opt).
#     $obj->doit(search_something($source), -option=> $optval);
#
#     # you have to use the "scalar" operator in such a case.
#     $obj->doit(scalar search_something($source), ...);
#
# *1: it returns an empty list in list context, or returns undef in scalar
#     context
#
# (and so on)

    return undef;
}

#
# UHC file test -w $_
#
sub Euhc::w_() {

    if (-e $_) {
        return -w _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -w _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_a($fh, $_)) {
                my $w = -w $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $w ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -x $_
#
sub Euhc::x_() {

    if (-e $_) {
        return -x _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -x _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $dummy_for_underline_cache = -x $fh;
                close($fh) or die "Can't close file: $_: $!";
            }

            # filename is not .COM .EXE .BAT .CMD
            return '';
        }
    }
    return undef;
}

#
# UHC file test -o $_
#
sub Euhc::o_() {

    if (-e $_) {
        return -o _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -o _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $o = -o $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $o ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -R $_
#
sub Euhc::R_() {

    if (-e $_) {
        return -R _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -R _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $R = -R $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $R ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -W $_
#
sub Euhc::W_() {

    if (-e $_) {
        return -W _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -W _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_a($fh, $_)) {
                my $W = -W $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $W ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -X $_
#
sub Euhc::X_() {

    if (-e $_) {
        return -X _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -X _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $dummy_for_underline_cache = -X $fh;
                close($fh) or die "Can't close file: $_: $!";
            }

            # filename is not .COM .EXE .BAT .CMD
            return '';
        }
    }
    return undef;
}

#
# UHC file test -O $_
#
sub Euhc::O_() {

    if (-e $_) {
        return -O _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -O _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $O = -O $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $O ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -e $_
#
sub Euhc::e_() {

    if (-e $_) {
        return 1;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return 1;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $e = -e $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $e ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -z $_
#
sub Euhc::z_() {

    if (-e $_) {
        return -z _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -z _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $z = -z $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $z ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -s $_
#
sub Euhc::s_() {

    if (-e $_) {
        return -s _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -s _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $s = -s $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $s;
            }
        }
    }
    return undef;
}

#
# UHC file test -f $_
#
sub Euhc::f_() {

    if (-e $_) {
        return -f _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $f = -f $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $f ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -d $_
#
sub Euhc::d_() {

    if (-e $_) {
        return -d _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        return -d "$_/." ? 1 : '';
    }
    return undef;
}

#
# UHC file test -l $_
#
sub Euhc::l_() {

    if (-e $_) {
        return -l _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -l _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $l = -l $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $l ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -p $_
#
sub Euhc::p_() {

    if (-e $_) {
        return -p _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -p _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $p = -p $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $p ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -S $_
#
sub Euhc::S_() {

    if (-e $_) {
        return -S _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -S _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $S = -S $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $S ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -b $_
#
sub Euhc::b_() {

    if (-e $_) {
        return -b _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -b _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $b = -b $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $b ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -c $_
#
sub Euhc::c_() {

    if (-e $_) {
        return -c _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -c _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $c = -c $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $c ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -u $_
#
sub Euhc::u_() {

    if (-e $_) {
        return -u _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -u _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $u = -u $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $u ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -g $_
#
sub Euhc::g_() {

    if (-e $_) {
        return -g _ ? 1 : '';
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -g _ ? 1 : '';
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my $g = -g $fh;
                close($fh) or die "Can't close file: $_: $!";
                return $g ? 1 : '';
            }
        }
    }
    return undef;
}

#
# UHC file test -k $_
#
sub Euhc::k_() {

    if ($] =~ /^5\.008/oxms) {
        return wantarray ? ('',@_) : '';
    }
    return wantarray ? ($_,@_) : $_;
}

#
# UHC file test -T $_
#
sub Euhc::T_() {

    my $T = 1;

    if (-d $_ or -d "$_/.") {
        return undef;
    }
    my $fh = gensym();
    if (_open_r($fh, $_)) {
    }
    else {
        return undef;
    }

    if (sysread $fh, my $block, 512) {
        if ($block =~ /[\000\377]/oxms) {
            $T = '';
        }
        elsif (($block =~ tr/\000-\007\013\016-\032\034-\037\377//) * 10 > CORE::length $block) {
            $T = '';
        }
    }

    # 0 byte or eof
    else {
        $T = 1;
    }
    my $dummy_for_underline_cache = -T $fh;
    close($fh) or die "Can't close file: $_: $!";

    return $T;
}

#
# UHC file test -B $_
#
sub Euhc::B_() {

    my $B = '';

    if (-d $_ or -d "$_/.") {
        return undef;
    }
    my $fh = gensym();
    if (_open_r($fh, $_)) {
    }
    else {
        return undef;
    }

    if (sysread $fh, my $block, 512) {
        if ($block =~ /[\000\377]/oxms) {
            $B = 1;
        }
        elsif (($block =~ tr/\000-\007\013\016-\032\034-\037\377//) * 10 > CORE::length $block) {
            $B = 1;
        }
    }

    # 0 byte or eof
    else {
        $B = 1;
    }
    my $dummy_for_underline_cache = -B $fh;
    close($fh) or die "Can't close file: $_: $!";

    return $B;
}

#
# UHC file test -M $_
#
sub Euhc::M_() {

    if (-e $_) {
        return -M _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -M _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks) = CORE::stat $fh;
                close($fh) or die "Can't close file: $_: $!";
                my $M = ($^T - $mtime) / (24*60*60);
                return $M;
            }
        }
    }
    return undef;
}

#
# UHC file test -A $_
#
sub Euhc::A_() {

    if (-e $_) {
        return -A _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -A _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks) = CORE::stat $fh;
                close($fh) or die "Can't close file: $_: $!";
                my $A = ($^T - $atime) / (24*60*60);
                return $A;
            }
        }
    }
    return undef;
}

#
# UHC file test -C $_
#
sub Euhc::C_() {

    if (-e $_) {
        return -C _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        if (-d "$_/.") {
            return -C _;
        }
        else {
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                my($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks) = CORE::stat $fh;
                close($fh) or die "Can't close file: $_: $!";
                my $C = ($^T - $ctime) / (24*60*60);
                return $C;
            }
        }
    }
    return undef;
}

#
# UHC path globbing (with parameter)
#
sub Euhc::glob($) {

    if (wantarray) {
        my @glob = _DOS_like_glob(@_);
        for my $glob (@glob) {
            $glob =~ s{ \A (?:\./)+ }{}oxms;
        }
        return @glob;
    }
    else {
        my $glob = _DOS_like_glob(@_);
        $glob =~ s{ \A (?:\./)+ }{}oxms;
        return $glob;
    }
}

#
# UHC path globbing (without parameter)
#
sub Euhc::glob_() {

    if (wantarray) {
        my @glob = _DOS_like_glob();
        for my $glob (@glob) {
            $glob =~ s{ \A (?:\./)+ }{}oxms;
        }
        return @glob;
    }
    else {
        my $glob = _DOS_like_glob();
        $glob =~ s{ \A (?:\./)+ }{}oxms;
        return $glob;
    }
}

#
# UHC path globbing via File::DosGlob 1.10
#
# Often I confuse "_dosglob" and "_doglob".
# So, I renamed "_dosglob" to "_DOS_like_glob".
#
my %iter;
my %entries;
sub _DOS_like_glob {

    # context (keyed by second cxix argument provided by core)
    my($expr,$cxix) = @_;

    # glob without args defaults to $_
    $expr = $_ if not defined $expr;

    # represents the current user's home directory
    #
    # 7.3. Expanding Tildes in Filenames
    # in Chapter 7. File Access
    # of ISBN 0-596-00313-7 Perl Cookbook, 2nd Edition.
    #
    # and File::HomeDir, File::HomeDir::Windows module

    # DOS-like system
    if ($^O =~ /\A (?: MSWin32 | NetWare | symbian | dos ) \z/oxms) {
        $expr =~ s{ \A ~ (?= [^/\\] ) }
                  { my_home_MSWin32() }oxmse;
    }

    # UNIX-like system
    else {
        $expr =~ s{ \A ~ ( (?:[^\x81-\xFE/]|[\x81-\xFE][\x00-\xFF])* ) }
                  { $1 ? (CORE::eval(q{(getpwnam($1))[7]})||my_home()) : my_home() }oxmse;
    }

    # assume global context if not provided one
    $cxix = '_G_' if not defined $cxix;
    $iter{$cxix} = 0 if not exists $iter{$cxix};

    # if we're just beginning, do it all first
    if ($iter{$cxix} == 0) {
            $entries{$cxix} = [ _do_glob(1, _parse_line($expr)) ];
    }

    # chuck it all out, quick or slow
    if (wantarray) {
        delete $iter{$cxix};
        return @{delete $entries{$cxix}};
    }
    else {
        if ($iter{$cxix} = scalar @{$entries{$cxix}}) {
            return shift @{$entries{$cxix}};
        }
        else {
            # return undef for EOL
            delete $iter{$cxix};
            delete $entries{$cxix};
            return undef;
        }
    }
}

#
# UHC path globbing subroutine
#
sub _do_glob {

    my($cond,@expr) = @_;
    my @glob = ();
    my $fix_drive_relative_paths = 0;

OUTER:
    for my $expr (@expr) {
        next OUTER if not defined $expr;
        next OUTER if $expr eq '';

        my @matched = ();
        my @globdir = ();
        my $head    = '.';
        my $pathsep = '/';
        my $tail;

        # if argument is within quotes strip em and do no globbing
        if ($expr =~ /\A " ((?:$q_char)*?) " \z/oxms) {
            $expr = $1;
            if ($cond eq 'd') {
                if (Euhc::d $expr) {
                    push @glob, $expr;
                }
            }
            else {
                if (Euhc::e $expr) {
                    push @glob, $expr;
                }
            }
            next OUTER;
        }

        # wildcards with a drive prefix such as h:*.pm must be changed
        # to h:./*.pm to expand correctly
        if ($^O =~ /\A (?: MSWin32 | NetWare | symbian | dos ) \z/oxms) {
            if ($expr =~ s# \A ((?:[A-Za-z]:)?) ([^\x81-\xFE/\\]|[\x81-\xFE][\x00-\xFF]) #$1./$2#oxms) {
                $fix_drive_relative_paths = 1;
            }
        }

        if (($head, $tail) = _parse_path($expr,$pathsep)) {
            if ($tail eq '') {
                push @glob, $expr;
                next OUTER;
            }
            if ($head =~ / \A (?:$q_char)*? [*?] /oxms) {
                if (@globdir = _do_glob('d', $head)) {
                    push @glob, _do_glob($cond, map {"$_$pathsep$tail"} @globdir);
                    next OUTER;
                }
            }
            if ($head eq '' or $head =~ /\A [A-Za-z]: \z/oxms) {
                $head .= $pathsep;
            }
            $expr = $tail;
        }

        # If file component has no wildcards, we can avoid opendir
        if ($expr !~ / \A (?:$q_char)*? [*?] /oxms) {
            if ($head eq '.') {
                $head = '';
            }
            if ($head ne '' and ($head =~ / \G ($q_char) /oxmsg)[-1] ne $pathsep) {
                $head .= $pathsep;
            }
            $head .= $expr;
            if ($cond eq 'd') {
                if (Euhc::d $head) {
                    push @glob, $head;
                }
            }
            else {
                if (Euhc::e $head) {
                    push @glob, $head;
                }
            }
            next OUTER;
        }
        Euhc::opendir(*DIR, $head) or next OUTER;
        my @leaf = readdir DIR;
        closedir DIR;

        if ($head eq '.') {
            $head = '';
        }
        if ($head ne '' and ($head =~ / \G ($q_char) /oxmsg)[-1] ne $pathsep) {
            $head .= $pathsep;
        }

        my $pattern = '';
        while ($expr =~ / \G ($q_char) /oxgc) {
            my $char = $1;

            # 6.9. Matching Shell Globs as Regular Expressions
            # in Chapter 6. Pattern Matching
            # of ISBN 0-596-00313-7 Perl Cookbook, 2nd Edition.
            # (and so on)

            if ($char eq '*') {
                $pattern .= "(?:$your_char)*",
            }
            elsif ($char eq '?') {
                $pattern .= "(?:$your_char)?",  # DOS style
#               $pattern .= "(?:$your_char)",   # UNIX style
            }
            elsif ((my $fc = Euhc::fc($char)) ne $char) {
                $pattern .= $fc;
            }
            else {
                $pattern .= quotemeta $char;
            }
        }
        my $matchsub = sub { Euhc::fc($_[0]) =~ /\A $pattern \z/xms };

#       if ($@) {
#           print STDERR "$0: $@\n";
#           next OUTER;
#       }

INNER:
        for my $leaf (@leaf) {
            if ($leaf eq '.' or $leaf eq '..') {
                next INNER;
            }
            if ($cond eq 'd' and not Euhc::d "$head$leaf") {
                next INNER;
            }

            if (&$matchsub($leaf)) {
                push @matched, "$head$leaf";
                next INNER;
            }

            # [DOS compatibility special case]
            # Failed, add a trailing dot and try again, but only...

            if (Euhc::index($leaf,'.') == -1 and   # if name does not have a dot in it *and*
                CORE::length($leaf) <= 8 and        # name is shorter than or equal to 8 chars *and*
                Euhc::index($pattern,'\\.') != -1  # pattern has a dot.
            ) {
                if (&$matchsub("$leaf.")) {
                    push @matched, "$head$leaf";
                    next INNER;
                }
            }
        }
        if (@matched) {
            push @glob, @matched;
        }
    }
    if ($fix_drive_relative_paths) {
        for my $glob (@glob) {
            $glob =~ s# \A ([A-Za-z]:) \./ #$1#oxms;
        }
    }
    return @glob;
}

#
# UHC parse line
#
sub _parse_line {

    my($line) = @_;

    $line .= ' ';
    my @piece = ();
    while ($line =~ /
        " ( (?>(?: [^\x81-\xFE"]  |[\x81-\xFE][\x00-\xFF] )* ) ) " (?>\s+) |
          ( (?>(?: [^\x81-\xFE"\s]|[\x81-\xFE][\x00-\xFF] )* ) )   (?>\s+)
        /oxmsg
    ) {
        push @piece, defined($1) ? $1 : $2;
    }
    return @piece;
}

#
# UHC parse path
#
sub _parse_path {

    my($path,$pathsep) = @_;

    $path .= '/';
    my @subpath = ();
    while ($path =~ /
        ((?: [^\x81-\xFE\/\\]|[\x81-\xFE][\x00-\xFF] )+?) [\/\\]
        /oxmsg
    ) {
        push @subpath, $1;
    }

    my $tail = pop @subpath;
    my $head = join $pathsep, @subpath;
    return $head, $tail;
}

#
# via File::HomeDir::Windows 1.00
#
sub my_home_MSWin32 {

    # A lot of unix people and unix-derived tools rely on
    # the ability to overload HOME. We will support it too
    # so that they can replace raw HOME calls with File::HomeDir.
    if (exists $ENV{'HOME'} and $ENV{'HOME'}) {
        return $ENV{'HOME'};
    }

    # Do we have a user profile?
    elsif (exists $ENV{'USERPROFILE'} and $ENV{'USERPROFILE'}) {
        return $ENV{'USERPROFILE'};
    }

    # Some Windows use something like $ENV{'HOME'}
    elsif (exists $ENV{'HOMEDRIVE'} and exists $ENV{'HOMEPATH'} and $ENV{'HOMEDRIVE'} and $ENV{'HOMEPATH'}) {
        return join '', $ENV{'HOMEDRIVE'}, $ENV{'HOMEPATH'};
    }

    return undef;
}

#
# via File::HomeDir::Unix 1.00
#
sub my_home {
    my $home;

    if (exists $ENV{'HOME'} and defined $ENV{'HOME'}) {
        $home = $ENV{'HOME'};
    }

    # This is from the original code, but I'm guessing
    # it means "login directory" and exists on some Unixes.
    elsif (exists $ENV{'LOGDIR'} and $ENV{'LOGDIR'}) {
        $home = $ENV{'LOGDIR'};
    }

    ### More-desperate methods

    # Light desperation on any (Unixish) platform
    else {
        $home = CORE::eval q{ (getpwuid($<))[7] };
    }

    # On Unix in general, a non-existant home means "no home"
    # For example, "nobody"-like users might use /nonexistant
    if (defined $home and ! Euhc::d($home)) {
        $home = undef;
    }
    return $home;
}

#
# UHC file lstat (with parameter)
#
sub Euhc::lstat(*) {

    local $_ = shift if @_;

    if (-e $_) {
        return CORE::lstat _;
    }
    elsif (_MSWin32_5Cended_path($_)) {

        # Even if ${^WIN32_SLOPPY_STAT} is set to a true value, Euhc::lstat()
        # on Windows opens the file for the path which has 5c at end.
        # (and so on)

        local *MUST_BE_BAREWORD_AT_HERE;
        if (CORE::open(MUST_BE_BAREWORD_AT_HERE, $_)) {
            if (wantarray) {
                my @stat = CORE::stat MUST_BE_BAREWORD_AT_HERE; # not CORE::lstat
                close(MUST_BE_BAREWORD_AT_HERE) or die "Can't close file: $_: $!";
                return @stat;
            }
            else {
                my $stat = CORE::stat MUST_BE_BAREWORD_AT_HERE; # not CORE::lstat
                close(MUST_BE_BAREWORD_AT_HERE) or die "Can't close file: $_: $!";
                return $stat;
            }
        }
    }
    return wantarray ? () : undef;
}

#
# UHC file lstat (without parameter)
#
sub Euhc::lstat_() {

    if (-e $_) {
        return CORE::lstat _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        local *MUST_BE_BAREWORD_AT_HERE;
        if (CORE::open(MUST_BE_BAREWORD_AT_HERE, $_)) {
            if (wantarray) {
                my @stat = CORE::stat MUST_BE_BAREWORD_AT_HERE; # not CORE::lstat
                close(MUST_BE_BAREWORD_AT_HERE) or die "Can't close file: $_: $!";
                return @stat;
            }
            else {
                my $stat = CORE::stat MUST_BE_BAREWORD_AT_HERE; # not CORE::lstat
                close(MUST_BE_BAREWORD_AT_HERE) or die "Can't close file: $_: $!";
                return $stat;
            }
        }
    }
    return wantarray ? () : undef;
}

#
# UHC path opendir
#
sub Euhc::opendir(*$) {

    my $dh = qualify_to_ref $_[0];
    if (CORE::opendir $dh, $_[1]) {
        return 1;
    }
    elsif (_MSWin32_5Cended_path($_[1])) {
        if (CORE::opendir $dh, "$_[1]/.") {
            return 1;
        }
    }
    return undef;
}

#
# UHC file stat (with parameter)
#
sub Euhc::stat(*) {

    local $_ = shift if @_;

    my $fh = qualify_to_ref $_;
    if (defined fileno $fh) {
        return CORE::stat $fh;
    }
    elsif (-e $_) {
        return CORE::stat _;
    }
    elsif (_MSWin32_5Cended_path($_)) {

        # Even if ${^WIN32_SLOPPY_STAT} is set to a true value, Euhc::stat()
        # on Windows opens the file for the path which has 5c at end.
        # (and so on)

        local *MUST_BE_BAREWORD_AT_HERE;
        if (CORE::open(MUST_BE_BAREWORD_AT_HERE, $_)) {
            if (wantarray) {
                my @stat = CORE::stat MUST_BE_BAREWORD_AT_HERE;
                close(MUST_BE_BAREWORD_AT_HERE) or die "Can't close file: $_: $!";
                return @stat;
            }
            else {
                my $stat = CORE::stat MUST_BE_BAREWORD_AT_HERE;
                close(MUST_BE_BAREWORD_AT_HERE) or die "Can't close file: $_: $!";
                return $stat;
            }
        }
    }
    return wantarray ? () : undef;
}

#
# UHC file stat (without parameter)
#
sub Euhc::stat_() {

    my $fh = qualify_to_ref $_;
    if (defined fileno $fh) {
        return CORE::stat $fh;
    }
    elsif (-e $_) {
        return CORE::stat _;
    }
    elsif (_MSWin32_5Cended_path($_)) {
        local *MUST_BE_BAREWORD_AT_HERE;
        if (CORE::open(MUST_BE_BAREWORD_AT_HERE, $_)) {
            if (wantarray) {
                my @stat = CORE::stat MUST_BE_BAREWORD_AT_HERE;
                close(MUST_BE_BAREWORD_AT_HERE) or die "Can't close file: $_: $!";
                return @stat;
            }
            else {
                my $stat = CORE::stat MUST_BE_BAREWORD_AT_HERE;
                close(MUST_BE_BAREWORD_AT_HERE) or die "Can't close file: $_: $!";
                return $stat;
            }
        }
    }
    return wantarray ? () : undef;
}

#
# UHC path unlink
#
sub Euhc::unlink(@) {

    local @_ = ($_) unless @_;

    my $unlink = 0;
    for (@_) {
        if (CORE::unlink) {
            $unlink++;
        }
        elsif (Euhc::d($_)) {
        }
        elsif (_MSWin32_5Cended_path($_)) {
            my @char = /\G (?>$q_char) /oxmsg;
            my $file = join '', map {{'/' => '\\'}->{$_} || $_} @char;
            if ($file =~ / \A (?:$q_char)*? [ ] /oxms) {
                $file = qq{"$file"};
            }
            my $fh = gensym();
            if (_open_r($fh, $_)) {
                close($fh) or die "Can't close file: $_: $!";

                # cmd.exe on Windows NT, Windows 2000, Windows XP, Windows Vista, Windows 7, Windows 8, Windows 8.1, Windows 10 or later
                if ((defined $ENV{'OS'}) and ($ENV{'OS'} eq 'Windows_NT')) {
                    CORE::system 'DEL', '/F', $file, '2>NUL';
                }

                # Win95Cmd.exe on any Windows (when SET PERL5SHELL=Win95Cmd.exe /c, `var` returns "Windows 2000")
                elsif (qx{ver} =~ /\b(?:Windows 2000)\b/oms) {
                    CORE::system 'DEL', '/F', $file, '2>NUL';
                }

                # COMMAND.COM on Windows 95, Windows 98, Windows 98 Second Edition, Windows Millennium Edition
                # command.com can not "2>NUL"
                else {
                    CORE::system 'ATTRIB', '-R', $file; # clears Read-only file attribute
                    CORE::system 'DEL',          $file;
                }

                if (_open_r($fh, $_)) {
                    close($fh) or die "Can't close file: $_: $!";
                }
                else {
                    $unlink++;
                }
            }
        }
    }
    return $unlink;
}

#
# UHC chdir
#
sub Euhc::chdir(;$) {

    if (@_ == 0) {
        return CORE::chdir;
    }

    my($dir) = @_;

    if (_MSWin32_5Cended_path($dir)) {
        if (not Euhc::d $dir) {
            return 0;
        }

        if ($] =~ /^5\.005/oxms) {
            return CORE::chdir $dir;
        }
        elsif (($] =~ /^(?:5\.006|5\.008000)/oxms) and ($^O eq 'MSWin32')) {
            local $@;
            my $chdir = CORE::eval q{
                CORE::require 'jacode.pl';

                # P.676 ${^WIDE_SYSTEM_CALLS}
                # in Chapter 28: Special Names
                # of ISBN 0-596-00027-8 Programming Perl Third Edition.

                # P.790 ${^WIDE_SYSTEM_CALLS}
                # in Chapter 25: Special Names
                # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

                local ${^WIDE_SYSTEM_CALLS} = 1;
                return CORE::chdir jcode::utf8($dir,'sjis');
            };
            if (not $@) {
                return $chdir;
            }
        }

        # old idea (Win32 module required)
        elsif (0) {
            local $@;
            my $shortdir = '';
            my $chdir = CORE::eval q{
                use Win32;
                $shortdir = Win32::GetShortPathName($dir);
                if ($shortdir ne $dir) {
                    return CORE::chdir $shortdir;
                }
                else {
                    return 0;
                }
            };
            if ($@) {
                my @char = $dir =~ /\G (?>$q_char) /oxmsg;
                while ($char[-1] eq "\x5C") {
                    pop @char;
                }
                $dir = join '', @char;
                croak "Perl$] can't chdir to $dir (chr(0x5C) ended path), Win32.pm module may help you";
            }
            elsif ($shortdir eq $dir) {
                my @char = $dir =~ /\G (?>$q_char) /oxmsg;
                while ($char[-1] eq "\x5C") {
                    pop @char;
                }
                $dir = join '', @char;
                croak "Perl$] can't chdir to $dir (chr(0x5C) ended path)";
            }
            return $chdir;
        }

        # rejected idea ...
        elsif (0) {

            # MSDN SetCurrentDirectory function
            # http://msdn.microsoft.com/ja-jp/library/windows/desktop/aa365530(v=vs.85).aspx
            #
            # Data Execution Prevention (DEP)
            # http://vlaurie.com/computers2/Articles/dep.htm
            #
            # Learning x86 assembler with Perl -- Shibuya.pm#11
            # http://developer.cybozu.co.jp/takesako/2009/06/perl-x86-shibuy.html
            #
            # Introduction to Win32::API programming in Perl
            # http://d.hatena.ne.jp/TAKESAKO/20090324/1237879559
            #
            # DynaLoader - Dynamically load C libraries into Perl code
            # http://perldoc.perl.org/DynaLoader.html
            #
            # Basic knowledge of DynaLoader
            # http://blog.64p.org/entry/20090313/1236934042

            if (($] =~ /^5\.006/oxms)                     and
                ($^O eq 'MSWin32')                        and
                ($ENV{'PROCESSOR_ARCHITECTURE'} eq 'x86') and
                CORE::eval(q{CORE::require 'Dyna'.'Loader'})
            ) {
                my $x86 = join('',

                    # PUSH Iv
                    "\x68", pack('P', "$dir\\\0"),

                    # MOV eAX, Iv
                    "\xb8", pack('L',
                        *{'Dyna'.'Loader::dl_find_symbol'}{'CODE'}->(
                            *{'Dyna'.'Loader::dl_load_file'}{'CODE'}->("$ENV{'SystemRoot'}\\system32\\kernel32.dll"),
                            'SetCurrentDirectoryA'
                        )
                    ),

                    # CALL eAX
                    "\xff\xd0",

                    # RETN
                    "\xc3",
                );
                *{'Dyna'.'Loader::dl_install_xsub'}{'CODE'}->('_SetCurrentDirectoryA', unpack('L', pack 'P', $x86));
                _SetCurrentDirectoryA();
                chomp(my $chdir = qx{chdir});
                if (Euhc::fc($chdir) eq Euhc::fc($dir)) {
                    return 1;
                }
                else {
                    return 0;
                }
            }
        }

# COMMAND.COM's unhelpful tips:
# Displays a list of files and subdirectories in a directory.
# http://www.lagmonster.org/docs/DOS7/z-dir.html
#
# Syntax:
#
#   DIR [drive:] [path] [filename] [/Switches]
#
#   /Z Long file names are not displayed in the file listing
#
#  Limitations
#   The undocumented /Z switch (no long names) would appear to
#   have been not fully developed and has a couple of problems:
#
#  1. It will only work if:
#   There is no path specified (ie. for the current directory in
#   the current drive)
#   The path is specified as the root directory of any drive
#   (eg. C:\, D:\, etc.)
#   The path is specified as the current directory of any drive
#   by using the drive letter only (eg. C:, D:, etc.)
#   The path is specified as the parent directory using the ..
#   notation (eg. DIR .. /Z)
#   Any other syntax results in a "File Not Found" error message.
#
#  2. The /Z switch is compatable with the /S switch to show
#   subdirectories (as long as the above rules are followed) and
#   all the files are shown with short names only. The
#   subdirectories are also shown with short names only. However,
#   the header for each subdirectory after the first level gives
#   the subdirectory's long name.
#
#  3. The /Z switch is also compatable with the /B switch to give
#   a simple list of files with short names only. When used with
#   the /S switch as well, all files are listed with their full
#   paths. The file names themselves are all in short form, and
#   the path of those files in the current directory are in short
#   form, but the paths of any files in subdirectories are in
#   long filename form.

        my $shortdir = '';
        my $i = 0;
        my @subdir = ();
        while ($dir =~ / \G ($q_char) /oxgc) {
            my $char = $1;
            if (($char eq '\\') or ($char eq '/')) {
                $i++;
                $subdir[$i] = $char;
                $i++;
            }
            else {
                $subdir[$i] .= $char;
            }
        }
        if (($subdir[-1] eq '\\') or ($subdir[-1] eq '/')) {
            pop @subdir;
        }

        # P.504 PERL5SHELL (Microsoft ports only)
        # in Chapter 19: The Command-Line Interface
        # of ISBN 0-596-00027-8 Programming Perl Third Edition.

        # P.597 PERL5SHELL (Microsoft ports only)
        # in Chapter 17: The Command-Line Interface
        # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

        # Win95Cmd.exe on any Windows (when SET PERL5SHELL=Win95Cmd.exe /c, `var` returns "Windows 2000")
        # cmd.exe on Windows NT, Windows 2000
        if (qx{ver} =~ /\b(?:Windows NT|Windows 2000)\b/oms) {
            chomp(my @dirx = grep //oxms, qx{dir /ad /x "$dir*" 2>NUL});
            for my $dirx (sort { CORE::length($a) <=> CORE::length($b) } @dirx) {
                if (Euhc::fc(CORE::substr $dirx,-CORE::length($subdir[-1]),CORE::length($subdir[-1])) eq Euhc::fc($subdir[-1])) {

                    # short file name (8dot3name) here-----vv
                    my $shortleafdir = CORE::substr $dirx, 39, 8+1+3;
                    $shortleafdir =~ s/ [ ]+ \z//oxms;
                    $shortdir = join '', @subdir[0..$#subdir-1], $shortleafdir;
                    last;
                }
            }
        }

        # an idea (not so portable, only Windows 2000 or later)
        elsif (0) {
            chomp($shortdir = qx{for %I in ("$dir") do \@echo %~sI 2>NUL});
        }

        # cmd.exe on Windows XP, Windows Vista, Windows 7, Windows 8, Windows 8.1, Windows 10 or later
        elsif ((defined $ENV{'OS'}) and ($ENV{'OS'} eq 'Windows_NT')) {
            chomp(my @dirx = grep //oxms, qx{dir /ad /x "$dir*" 2>NUL});
            for my $dirx (sort { CORE::length($a) <=> CORE::length($b) } @dirx) {
                if (Euhc::fc(CORE::substr $dirx,-CORE::length($subdir[-1]),CORE::length($subdir[-1])) eq Euhc::fc($subdir[-1])) {

                    # short file name (8dot3name) here-----vv
                    my $shortleafdir = CORE::substr $dirx, 36, 8+1+3;
                    $shortleafdir =~ s/ [ ]+ \z//oxms;
                    $shortdir = join '', @subdir[0..$#subdir-1], $shortleafdir;
                    last;
                }
            }
        }

        # COMMAND.COM on Windows 95, Windows 98, Windows 98 Second Edition, Windows Millennium Edition
        else {
            chomp(my @dirx = grep //oxms, qx{dir /ad "$dir*"});
            for my $dirx (sort { CORE::length($a) <=> CORE::length($b) } @dirx) {
                if (Euhc::fc(CORE::substr $dirx,-CORE::length($subdir[-1]),CORE::length($subdir[-1])) eq Euhc::fc($subdir[-1])) {

                    # short file name (8dot3name) here-----v
                    my $shortleafdir = CORE::substr $dirx, 0, 8+1+3;
                    CORE::substr($shortleafdir,8,1) = '.';
                    $shortleafdir =~ s/ \. [ ]+ \z//oxms;
                    $shortdir = join '', @subdir[0..$#subdir-1], $shortleafdir;
                    last;
                }
            }
        }

        if ($shortdir eq '') {
            return 0;
        }
        elsif (Euhc::fc($shortdir) eq Euhc::fc($dir)) {
            return 0;
        }
        return CORE::chdir $shortdir;
    }
    else {
        return CORE::chdir $dir;
    }
}

#
# UHC chr(0x5C) ended path on MSWin32
#
sub _MSWin32_5Cended_path {

    if ((@_ >= 1) and ($_[0] ne '')) {
        if ($^O =~ /\A (?: MSWin32 | NetWare | symbian | dos ) \z/oxms) {
            my @char = $_[0] =~ /\G (?>$q_char) /oxmsg;
            if ($char[-1] =~ / \x5C \z/oxms) {
                return 1;
            }
        }
    }
    return undef;
}

#
# do UHC file
#
sub Euhc::do($) {

    my($filename) = @_;

    my $realfilename;
    my $result;
ITER_DO:
    {
        for my $prefix (@INC) {
            if ($^O eq 'MacOS') {
                $realfilename = "$prefix$filename";
            }
            else {
                $realfilename = "$prefix/$filename";
            }

            if (Euhc::f($realfilename)) {

                my $script = '';

                if (Euhc::e("$realfilename.e")) {
                    my $e_mtime      = (Euhc::stat("$realfilename.e"))[9];
                    my $mtime        = (Euhc::stat($realfilename))[9];
                    my $module_mtime = (Euhc::stat(__FILE__))[9];
                    if (($e_mtime < $mtime) or ($mtime < $module_mtime)) {
                        Euhc::unlink "$realfilename.e";
                    }
                }

                if (Euhc::e("$realfilename.e")) {
                    my $fh = gensym();
                    if (_open_r($fh, "$realfilename.e")) {
                        if ($^O eq 'MacOS') {
                            CORE::eval q{
                                CORE::require Mac::Files;
                                Mac::Files::FSpSetFLock("$realfilename.e");
                            };
                        }
                        elsif (exists $ENV{'CHAR_NONBLOCK'}) {

                            # P.419 File Locking
                            # in Chapter 16: Interprocess Communication
                            # of ISBN 0-596-00027-8 Programming Perl Third Edition.

                            # P.524 File Locking
                            # in Chapter 15: Interprocess Communication
                            # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

                            # (and so on)

                            CORE::eval q{ flock($fh, LOCK_SH | LOCK_NB) };
                            if ($@) {
                                carp "Can't immediately read-lock the file: $realfilename.e";
                            }
                        }
                        else {
                            CORE::eval q{ flock($fh, LOCK_SH) };
                        }
                        local $/ = undef; # slurp mode
                        $script = <$fh>;
                        if ($^O eq 'MacOS') {
                            CORE::eval q{
                                CORE::require Mac::Files;
                                Mac::Files::FSpRstFLock("$realfilename.e");
                            };
                        }
                        close($fh) or die "Can't close file: $realfilename.e: $!";
                    }
                }
                else {
                    my $fh = gensym();
                    if (_open_r($fh, $realfilename)) {
                        if ($^O eq 'MacOS') {
                            CORE::eval q{
                                CORE::require Mac::Files;
                                Mac::Files::FSpSetFLock($realfilename);
                            };
                        }
                        elsif (exists $ENV{'CHAR_NONBLOCK'}) {
                            CORE::eval q{ flock($fh, LOCK_SH | LOCK_NB) };
                            if ($@) {
                                carp "Can't immediately read-lock the file: $realfilename";
                            }
                        }
                        else {
                            CORE::eval q{ flock($fh, LOCK_SH) };
                        }
                        local $/ = undef; # slurp mode
                        $script = <$fh>;
                        if ($^O eq 'MacOS') {
                            CORE::eval q{
                                CORE::require Mac::Files;
                                Mac::Files::FSpRstFLock($realfilename);
                            };
                        }
                        close($fh) or die "Can't close file: $realfilename.e: $!";
                    }

                    if ($script =~ /^ (?>\s*) use (?>\s+) UHC (?>\s*) ([^\x81-\xFE;]*) ; (?>\s*) \n? $/oxms) {
                        CORE::require UHC;
                        $script = UHC::escape_script($script);
                        my $fh = gensym();
                        open($fh, ">$realfilename.e") or die __FILE__, ": Can't write open file: $realfilename.e\n";
                        if ($^O eq 'MacOS') {
                            CORE::eval q{
                                CORE::require Mac::Files;
                                Mac::Files::FSpSetFLock("$realfilename.e");
                            };
                        }
                        elsif (exists $ENV{'CHAR_NONBLOCK'}) {
                            CORE::eval q{ flock($fh, LOCK_EX | LOCK_NB) };
                            if ($@) {
                                carp "Can't immediately write-lock the file: $realfilename.e";
                            }
                        }
                        else {
                            CORE::eval q{ flock($fh, LOCK_EX) };
                        }
                        CORE::eval q{ truncate($fh, 0) };
                        seek($fh, 0, 0) or croak "Can't seek file: $realfilename.e";
                        print {$fh} $script;
                        if ($^O eq 'MacOS') {
                            CORE::eval q{
                                CORE::require Mac::Files;
                                Mac::Files::FSpRstFLock("$realfilename.e");
                            };
                        }
                        close($fh) or die "Can't close file: $realfilename.e: $!";
                    }
                }

                {
                    no strict;
                    $result = scalar CORE::eval $script;
                }
                last ITER_DO;
            }
        }
    }

    if ($@) {
        $INC{$filename} = undef;
        return undef;
    }
    elsif (not $result) {
        return undef;
    }
    else {
        $INC{$filename} = $realfilename;
        return $result;
    }
}

#
# require UHC file
#

# require
# in Chapter 3: Functions
# of ISBN 1-56592-149-6 Programming Perl, Second Edition.
#
# sub require {
#     my($filename) = @_;
#     return 1 if $INC{$filename};
#     my($realfilename, $result);
#     ITER: {
#         foreach $prefix (@INC) {
#             $realfilename = "$prefix/$filename";
#             if (-f $realfilename) {
#                 $result = CORE::eval `cat $realfilename`;
#                 last ITER;
#             }
#         }
#         die "Can't find $filename in \@INC";
#     }
#     die $@ if $@;
#     die "$filename did not return true value" unless $result;
#     $INC{$filename} = $realfilename;
#     return $result;
# }

# require
# in Chapter 9: perlfunc: Perl builtin functions
# of ISBN-13: 978-1-906966-02-7 The Perl Language Reference Manual (for Perl version 5.12.1)
#
# sub require {
#     my($filename) = @_;
#     if (exists $INC{$filename}) {
#         return 1 if $INC{$filename};
#         die "Compilation failed in require";
#     }
#     my($realfilename, $result);
#     ITER: {
#         foreach $prefix (@INC) {
#             $realfilename = "$prefix/$filename";
#             if (-f $realfilename) {
#                 $INC{$filename} = $realfilename;
#                 $result = do $realfilename;
#                 last ITER;
#             }
#         }
#         die "Can't find $filename in \@INC";
#     }
#     if ($@) {
#         $INC{$filename} = undef;
#         die $@;
#     }
#     elsif (!$result) {
#         delete $INC{$filename};
#         die "$filename did not return true value";
#     }
#     else {
#         return $result;
#     }
# }

sub Euhc::require(;$) {

    local $_ = shift if @_;

    if (exists $INC{$_}) {
        return 1 if $INC{$_};
        croak "Compilation failed in require: $_";
    }

    # jcode.pl
    # ftp://ftp.iij.ad.jp/pub/IIJ/dist/utashiro/perl/

    # jacode.pl
    # http://search.cpan.org/dist/jacode/

    if (/ \b (?: jcode\.pl | jacode(?>[0-9]*)\.pl ) \z /oxms) {
        return CORE::require($_);
    }

    my $realfilename;
    my $result;
ITER_REQUIRE:
    {
        for my $prefix (@INC) {
            if ($^O eq 'MacOS') {
                $realfilename = "$prefix$_";
            }
            else {
                $realfilename = "$prefix/$_";
            }

            if (Euhc::f($realfilename)) {
                $INC{$_} = $realfilename;

                my $script = '';

                if (Euhc::e("$realfilename.e")) {
                    my $e_mtime      = (Euhc::stat("$realfilename.e"))[9];
                    my $mtime        = (Euhc::stat($realfilename))[9];
                    my $module_mtime = (Euhc::stat(__FILE__))[9];
                    if (($e_mtime < $mtime) or ($mtime < $module_mtime)) {
                        Euhc::unlink "$realfilename.e";
                    }
                }

                if (Euhc::e("$realfilename.e")) {
                    my $fh = gensym();
                    _open_r($fh, "$realfilename.e") or croak "Can't open file: $realfilename.e";
                    if ($^O eq 'MacOS') {
                        CORE::eval q{
                            CORE::require Mac::Files;
                            Mac::Files::FSpSetFLock("$realfilename.e");
                        };
                    }
                    elsif (exists $ENV{'CHAR_NONBLOCK'}) {
                        CORE::eval q{ flock($fh, LOCK_SH | LOCK_NB) };
                        if ($@) {
                            carp "Can't immediately read-lock the file: $realfilename.e";
                        }
                    }
                    else {
                        CORE::eval q{ flock($fh, LOCK_SH) };
                    }
                    local $/ = undef; # slurp mode
                    $script = <$fh>;
                    if ($^O eq 'MacOS') {
                        CORE::eval q{
                            CORE::require Mac::Files;
                            Mac::Files::FSpRstFLock("$realfilename.e");
                        };
                    }
                    close($fh) or croak "Can't close file: $realfilename: $!";
                }
                else {
                    my $fh = gensym();
                    _open_r($fh, $realfilename) or croak "Can't open file: $realfilename";
                    if ($^O eq 'MacOS') {
                        CORE::eval q{
                            CORE::require Mac::Files;
                            Mac::Files::FSpSetFLock($realfilename);
                        };
                    }
                    elsif (exists $ENV{'CHAR_NONBLOCK'}) {
                        CORE::eval q{ flock($fh, LOCK_SH | LOCK_NB) };
                        if ($@) {
                            carp "Can't immediately read-lock the file: $realfilename";
                        }
                    }
                    else {
                        CORE::eval q{ flock($fh, LOCK_SH) };
                    }
                    local $/ = undef; # slurp mode
                    $script = <$fh>;
                    if ($^O eq 'MacOS') {
                        CORE::eval q{
                            CORE::require Mac::Files;
                            Mac::Files::FSpRstFLock($realfilename);
                        };
                    }
                    close($fh) or croak "Can't close file: $realfilename: $!";

                    if ($script =~ /^ (?>\s*) use (?>\s+) UHC (?>\s*) ([^\x81-\xFE;]*) ; (?>\s*) \n? $/oxms) {
                        CORE::require UHC;
                        $script = UHC::escape_script($script);
                        my $fh = gensym();
                        open($fh, ">$realfilename.e") or croak "Can't write open file: $realfilename.e";
                        if ($^O eq 'MacOS') {
                            CORE::eval q{
                                CORE::require Mac::Files;
                                Mac::Files::FSpSetFLock("$realfilename.e");
                            };
                        }
                        elsif (exists $ENV{'CHAR_NONBLOCK'}) {
                            CORE::eval q{ flock($fh, LOCK_EX | LOCK_NB) };
                            if ($@) {
                                carp "Can't immediately write-lock the file: $realfilename.e";
                            }
                        }
                        else {
                            CORE::eval q{ flock($fh, LOCK_EX) };
                        }
                        CORE::eval q{ truncate($fh, 0) };
                        seek($fh, 0, 0) or croak "Can't seek file: $realfilename.e";
                        print {$fh} $script;
                        if ($^O eq 'MacOS') {
                            CORE::eval q{
                                CORE::require Mac::Files;
                                Mac::Files::FSpRstFLock("$realfilename.e");
                            };
                        }
                        close($fh) or croak "Can't close file: $realfilename: $!";
                    }
                }

                {
                    no strict;
                    $result = scalar CORE::eval $script;
                }
                last ITER_REQUIRE;
            }
        }
        croak "Can't find $_ in \@INC";
    }

    if ($@) {
        $INC{$_} = undef;
        croak $@;
    }
    elsif (not $result) {
        delete $INC{$_};
        croak "$_ did not return true value";
    }
    else {
        return $result;
    }
}

#
# UHC telldir avoid warning
#
sub Euhc::telldir(*) {

    local $^W = 0;

    return CORE::telldir $_[0];
}

#
# ${^PREMATCH}, $PREMATCH, $` the string preceding what was matched
#
sub Euhc::PREMATCH {
    if (defined($&)) {
        if (defined($1) and (CORE::substr($&,-CORE::length($1),CORE::length($1)) eq $1)) {
            return CORE::substr($&,0,CORE::length($&)-CORE::length($1));
        }
        else {
            croak 'Use of "$`", $PREMATCH, and ${^PREMATCH} need to /( capture all )/ in regexp';
        }
    }
    else {
        return '';
    }
    return $`;
}

#
# ${^MATCH}, $MATCH, $& the string that matched
#
sub Euhc::MATCH {
    if (defined($&)) {
        if (defined($1)) {
            return $1;
        }
        else {
            croak 'Use of "$&", $MATCH, and ${^MATCH} need to /( capture all )/ in regexp';
        }
    }
    else {
        return '';
    }
    return $&;
}

#
# ${^POSTMATCH}, $POSTMATCH, $' the string following what was matched
#
sub Euhc::POSTMATCH {
    return $';
}

#
# UHC character to order (with parameter)
#
sub UHC::ord(;$) {

    local $_ = shift if @_;

    if (/\A ($q_char) /oxms) {
        my @ord = unpack 'C*', $1;
        my $ord = 0;
        while (my $o = shift @ord) {
            $ord = $ord * 0x100 + $o;
        }
        return $ord;
    }
    else {
        return CORE::ord $_;
    }
}

#
# UHC character to order (without parameter)
#
sub UHC::ord_() {

    if (/\A ($q_char) /oxms) {
        my @ord = unpack 'C*', $1;
        my $ord = 0;
        while (my $o = shift @ord) {
            $ord = $ord * 0x100 + $o;
        }
        return $ord;
    }
    else {
        return CORE::ord $_;
    }
}

#
# UHC reverse
#
sub UHC::reverse(@) {

    if (wantarray) {
        return CORE::reverse @_;
    }
    else {

        # One of us once cornered Larry in an elevator and asked him what
        # problem he was solving with this, but he looked as far off into
        # the distance as he could in an elevator and said, "It seemed like
        # a good idea at the time."

        return join '', CORE::reverse(join('',@_) =~ /\G ($q_char) /oxmsg);
    }
}

#
# UHC getc (with parameter, without parameter)
#
sub UHC::getc(;*@) {

    my($package) = caller;
    my $fh = @_ ? qualify_to_ref(shift,$package) : \*STDIN;
    croak 'Too many arguments for UHC::getc' if @_ and not wantarray;

    my @length = sort { $a <=> $b } keys %range_tr;
    my $getc = '';
    for my $length ($length[0] .. $length[-1]) {
        $getc .= CORE::getc($fh);
        if (exists $range_tr{CORE::length($getc)}) {
            if ($getc =~ /\A ${Euhc::dot_s} \z/oxms) {
                return wantarray ? ($getc,@_) : $getc;
            }
        }
    }
    return wantarray ? ($getc,@_) : $getc;
}

#
# UHC length by character
#
sub UHC::length(;$) {

    local $_ = shift if @_;

    local @_ = /\G ($q_char) /oxmsg;
    return scalar @_;
}

#
# UHC substr by character
#
BEGIN {

    # P.232 The lvalue Attribute
    # in Chapter 6: Subroutines
    # of ISBN 0-596-00027-8 Programming Perl Third Edition.

    # P.336 The lvalue Attribute
    # in Chapter 7: Subroutines
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    # P.144 8.4 Lvalue subroutines
    # in Chapter 8: perlsub: Perl subroutines
    # of ISBN-13: 978-1-906966-02-7 The Perl Language Reference Manual (for Perl version 5.12.1)

    CORE::eval sprintf(<<'END', ($] >= 5.014000) ? ':lvalue' : '');
    #                       vv----------------------*******
    sub UHC::substr($$;$$) %s {

        my @char = $_[0] =~ /\G (?>$q_char) /oxmsg;

        # If the substring is beyond either end of the string, substr() returns the undefined
        # value and produces a warning. When used as an lvalue, specifying a substring that
        # is entirely outside the string raises an exception.
        # http://perldoc.perl.org/functions/substr.html

        # A return with no argument returns the scalar value undef in scalar context,
        # an empty list () in list context, and (naturally) nothing at all in void
        # context.

        my $offset = $_[1];
        if (($offset > scalar(@char)) or ($offset < (-1 * scalar(@char)))) {
            return;
        }

        # substr($string,$offset,$length,$replacement)
        if (@_ == 4) {
            my(undef,undef,$length,$replacement) = @_;
            my $substr = join '', splice(@char, $offset, $length, $replacement);
            $_[0] = join '', @char;

            # return $substr; this doesn't work, don't say "return"
            $substr;
        }

        # substr($string,$offset,$length)
        elsif (@_ == 3) {
            my(undef,undef,$length) = @_;
            my $octet_offset = 0;
            my $octet_length = 0;
            if ($offset == 0) {
                $octet_offset = 0;
            }
            elsif ($offset > 0) {
                $octet_offset =      CORE::length(join '', @char[0..$offset-1]);
            }
            else {
                $octet_offset = -1 * CORE::length(join '', @char[$#char+$offset+1..$#char]);
            }
            if ($length == 0) {
                $octet_length = 0;
            }
            elsif ($length > 0) {
                $octet_length =      CORE::length(join '', @char[$offset..$offset+$length-1]);
            }
            else {
                $octet_length = -1 * CORE::length(join '', @char[$#char+$length+1..$#char]);
            }
            CORE::substr($_[0], $octet_offset, $octet_length);
        }

        # substr($string,$offset)
        else {
            my $octet_offset = 0;
            if ($offset == 0) {
                $octet_offset = 0;
            }
            elsif ($offset > 0) {
                $octet_offset =      CORE::length(join '', @char[0..$offset-1]);
            }
            else {
                $octet_offset = -1 * CORE::length(join '', @char[$#char+$offset+1..$#char]);
            }
            CORE::substr($_[0], $octet_offset);
        }
    }
END
}

#
# UHC index by character
#
sub UHC::index($$;$) {

    my $index;
    if (@_ == 3) {
        $index = Euhc::index($_[0], $_[1], CORE::length(UHC::substr($_[0], 0, $_[2])));
    }
    else {
        $index = Euhc::index($_[0], $_[1]);
    }

    if ($index == -1) {
        return -1;
    }
    else {
        return UHC::length(CORE::substr $_[0], 0, $index);
    }
}

#
# UHC rindex by character
#
sub UHC::rindex($$;$) {

    my $rindex;
    if (@_ == 3) {
        $rindex = Euhc::rindex($_[0], $_[1], CORE::length(UHC::substr($_[0], 0, $_[2])));
    }
    else {
        $rindex = Euhc::rindex($_[0], $_[1]);
    }

    if ($rindex == -1) {
        return -1;
    }
    else {
        return UHC::length(CORE::substr $_[0], 0, $rindex);
    }
}

# when 'm//', '/' means regexp match 'm//' and '?' means regexp match '??'
# when 'div', '/' means division operator and '?' means conditional operator (condition ? then : else)
use vars qw($slash); $slash = 'm//';

# ord() to ord() or UHC::ord()
my $function_ord = 'ord';

# ord to ord or UHC::ord_
my $function_ord_ = 'ord';

# reverse to reverse or UHC::reverse
my $function_reverse = 'reverse';

# getc to getc or UHC::getc
my $function_getc = 'getc';

# P.1023 Appendix W.9 Multibyte Anchoring
# of ISBN 1-56592-224-7 CJKV Information Processing

my $anchor = '';
$anchor = q{${Euhc::anchor}};

use vars qw($nest);

# regexp of nested parens in qqXX

# P.340 Matching Nested Constructs with Embedded Code
# in Chapter 7: Perl
# of ISBN 0-596-00289-0 Mastering Regular Expressions, Second edition

my $qq_paren   = qr{(?{local $nest=0}) (?>(?:
                       [^\x81-\xFE\\()] |
                           \(  (?{$nest++}) |
                           \)  (?(?{$nest>0})(?{$nest--})|(?!)))*) (?(?{$nest!=0})(?!)) |
                       [\x81-\xFE][\x00-\xFF] |
                    \\ [^\x81-\xFEc] |
                    \\c[\x40-\x5F] |
                    \\ [\x81-\xFE][\x00-\xFF] |
                       [\x00-\xFF]
                 }xms;

my $qq_brace   = qr{(?{local $nest=0}) (?>(?:
                       [^\x81-\xFE\\{}] |
                           \{  (?{$nest++}) |
                           \}  (?(?{$nest>0})(?{$nest--})|(?!)))*) (?(?{$nest!=0})(?!)) |
                       [\x81-\xFE][\x00-\xFF] |
                    \\ [^\x81-\xFEc] |
                    \\c[\x40-\x5F] |
                    \\ [\x81-\xFE][\x00-\xFF] |
                       [\x00-\xFF]
                 }xms;

my $qq_bracket = qr{(?{local $nest=0}) (?>(?:
                       [^\x81-\xFE\\\[\]] |
                           \[  (?{$nest++}) |
                           \]  (?(?{$nest>0})(?{$nest--})|(?!)))*) (?(?{$nest!=0})(?!)) |
                       [\x81-\xFE][\x00-\xFF] |
                    \\ [^\x81-\xFEc] |
                    \\c[\x40-\x5F] |
                    \\ [\x81-\xFE][\x00-\xFF] |
                       [\x00-\xFF]
                 }xms;

my $qq_angle   = qr{(?{local $nest=0}) (?>(?:
                       [^\x81-\xFE\\<>] |
                           \<  (?{$nest++}) |
                           \>  (?(?{$nest>0})(?{$nest--})|(?!)))*) (?(?{$nest!=0})(?!)) |
                       [\x81-\xFE][\x00-\xFF] |
                    \\ [^\x81-\xFEc] |
                    \\c[\x40-\x5F] |
                    \\ [\x81-\xFE][\x00-\xFF] |
                       [\x00-\xFF]
                 }xms;

my $qq_scalar  = qr{(?: \{ (?:$qq_brace)*? \} |
                       (?: ::)? (?:
                             (?> [a-zA-Z_][a-zA-Z_0-9]* (?: ::[a-zA-Z_][a-zA-Z_0-9]*)* )
                                                    (?>(?:                                   \[ (?: \$\[ | \$\] | $qq_char )*? \] |           \{ (?:$qq_brace)*? \} )*)
                                      (?>(?: (?: -> )? (?: [\$\@\%\&\*]\* | \$\#\* | [\@\%]? \[ (?: \$\[ | \$\] | $qq_char )*? \] | [\@\%\*]? \{ (?:$qq_brace)*? \} ) )*)
                   ))
                 }xms;

my $qq_variable = qr{(?: \{ (?:$qq_brace)*? \}                    |
                        (?: ::)? (?:
                              (?>[0-9]+)                          |
                              [^\x81-\xFEa-zA-Z_0-9\[\]] |
                              ^[A-Z]                              |
                              (?> [a-zA-Z_][a-zA-Z_0-9]* (?: ::[a-zA-Z_][a-zA-Z_0-9]*)* )
                                                     (?>(?:                                   \[ (?: \$\[ | \$\] | $qq_char )*? \] |           \{ (?:$qq_brace)*? \} )*)
                                       (?>(?: (?: -> )? (?: [\$\@\%\&\*]\* | \$\#\* | [\@\%]? \[ (?: \$\[ | \$\] | $qq_char )*? \] | [\@\%\*]? \{ (?:$qq_brace)*? \} ) )*)
                    ))
                  }xms;

my $qq_substr  = qr{(?> Char::substr | UHC::substr | CORE::substr | substr ) (?>\s*) \( $qq_paren \)
                 }xms;

# regexp of nested parens in qXX
my $q_paren    = qr{(?{local $nest=0}) (?>(?:
                       [^\x81-\xFE()] |
                       [\x81-\xFE][\x00-\xFF] |
                             \(  (?{$nest++}) |
                             \)  (?(?{$nest>0})(?{$nest--})|(?!)))*) (?(?{$nest!=0})(?!)) |
                       [\x00-\xFF]
                 }xms;

my $q_brace    = qr{(?{local $nest=0}) (?>(?:
                       [^\x81-\xFE\{\}] |
                       [\x81-\xFE][\x00-\xFF] |
                             \{  (?{$nest++}) |
                             \}  (?(?{$nest>0})(?{$nest--})|(?!)))*) (?(?{$nest!=0})(?!)) |
                       [\x00-\xFF]
                 }xms;

my $q_bracket  = qr{(?{local $nest=0}) (?>(?:
                       [^\x81-\xFE\[\]] |
                       [\x81-\xFE][\x00-\xFF] |
                             \[  (?{$nest++}) |
                             \]  (?(?{$nest>0})(?{$nest--})|(?!)))*) (?(?{$nest!=0})(?!)) |
                    [\x00-\xFF]
                 }xms;

my $q_angle    = qr{(?{local $nest=0}) (?>(?:
                    [^\x81-\xFE<>] |
                    [\x81-\xFE][\x00-\xFF] |
                             \<  (?{$nest++}) |
                             \>  (?(?{$nest>0})(?{$nest--})|(?!)))*) (?(?{$nest!=0})(?!)) |
                    [\x00-\xFF]
                 }xms;

my $matched     = '';
my $s_matched   = '';
$matched        = q{$Euhc::matched};
$s_matched      = q{ Euhc::s_matched();};

my $tr_variable   = '';   # variable of tr///
my $sub_variable  = '';   # variable of s///
my $bind_operator = '';   # =~ or !~

my @heredoc = ();         # here document
my @heredoc_delimiter = ();
my $here_script = '';     # here script

#
# escape UHC script
#
sub UHC::escape(;$) {
    local($_) = $_[0] if @_;

    # P.359 The Study Function
    # in Chapter 7: Perl
    # of ISBN 0-596-00289-0 Mastering Regular Expressions, Second edition

    study $_; # Yes, I studied study yesterday.

    # while all script

    # 6.14. Matching from Where the Last Pattern Left Off
    # in Chapter 6. Pattern Matching
    # of ISBN 0-596-00313-7 Perl Cookbook, 2nd Edition.
    # (and so on)

    # one member of Tag-team
    #
    # P.128 Start of match (or end of previous match): \G
    # P.130 Advanced Use of \G with Perl
    # in Chapter 3: Overview of Regular Expression Features and Flavors
    # P.255 Use leading anchors
    # P.256 Expose ^ and \G at the front expressions
    # in Chapter 6: Crafting an Efficient Expression
    # P.315 "Tag-team" matching with /gc
    # in Chapter 7: Perl
    # of ISBN 0-596-00289-0 Mastering Regular Expressions, Second edition

    my $e_script = '';
    while (not /\G \z/oxgc) { # member
        $e_script .= UHC::escape_token();
    }

    return $e_script;
}

#
# escape UHC token of script
#
sub UHC::escape_token {

# \n output here document

    my $ignore_modules = join('|', qw(
        utf8
        bytes
        charnames
        I18N::Japanese
        I18N::Collate
        I18N::JExt
        File::DosGlob
        Wild
        Wildcard
        Japanese
    ));

    # another member of Tag-team
    #
    # P.315 "Tag-team" matching with /gc
    # in Chapter 7: Perl
    # of ISBN 0-596-00289-0 Mastering Regular Expressions, Second edition

    if (/\G ( \n ) /oxgc) { # another member (and so on)
        my $heredoc = '';
        if (scalar(@heredoc_delimiter) >= 1) {
            $slash = 'm//';

            $heredoc = join '', @heredoc;
            @heredoc = ();

            # skip here document
            for my $heredoc_delimiter (@heredoc_delimiter) {
                /\G .*? \n $heredoc_delimiter \n/xmsgc;
            }
            @heredoc_delimiter = ();

            $here_script = '';
        }
        return "\n" . $heredoc;
    }

# ignore space, comment
    elsif (/\G ((?>\s+)|\#.*) /oxgc) { return $1; }

# if (, elsif (, unless (, while (, until (, given (, and when (

    # given, when

    # P.225 The given Statement
    # in Chapter 15: Smart Matching and given-when
    # of ISBN 978-0-596-52010-6 Learning Perl, Fifth Edition

    # P.133 The given Statement
    # in Chapter 4: Statements and Declarations
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    elsif (/\G ( (?: if | elsif | unless | while | until | given | when ) (?>\s*) \( ) /oxgc) {
        $slash = 'm//';
        return $1;
    }

# scalar variable ($scalar = ...) =~ tr///;
# scalar variable ($scalar = ...) =~ s///;

    # state

    # P.68 Persistent, Private Variables
    # in Chapter 4: Subroutines
    # of ISBN 978-0-596-52010-6 Learning Perl, Fifth Edition

    # P.160 Persistent Lexically Scoped Variables: state
    # in Chapter 4: Statements and Declarations
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    # (and so on)

    elsif (/\G ( \( (?>\s*) (?: local \b | my \b | our \b | state \b )? (?>\s*) \$ $qq_scalar ) /oxgc) {
        my $e_string = e_string($1);

        if (/\G ( (?>\s*) = $qq_paren \) ) ( (?>\s*) (?: =~ | !~ ) (?>\s*) ) (?= (?: tr | y ) \b ) /oxgc) {
            $tr_variable = $e_string . e_string($1);
            $bind_operator = $2;
            $slash = 'm//';
            return '';
        }
        elsif (/\G ( (?>\s*) = $qq_paren \) ) ( (?>\s*) (?: =~ | !~ ) (?>\s*) ) (?= s \b ) /oxgc) {
            $sub_variable = $e_string . e_string($1);
            $bind_operator = $2;
            $slash = 'm//';
            return '';
        }
        else {
            $slash = 'div';
            return $e_string;
        }
    }

# $`, ${`}, $PREMATCH, ${PREMATCH}, ${^PREMATCH} --> Euhc::PREMATCH()
    elsif (/\G ( \$` | \$\{`\} | \$ (?>\s*) PREMATCH  \b | \$ (?>\s*) \{ (?>\s*) PREMATCH  (?>\s*) \} | \$ (?>\s*) \{\^PREMATCH\}  ) /oxmsgc) {
        $slash = 'div';
        return q{Euhc::PREMATCH()};
    }

# $&, ${&}, $MATCH, ${MATCH}, ${^MATCH} --> Euhc::MATCH()
    elsif (/\G ( \$& | \$\{&\} | \$ (?>\s*) MATCH     \b | \$ (?>\s*) \{ (?>\s*) MATCH     (?>\s*) \} | \$ (?>\s*) \{\^MATCH\}     ) /oxmsgc) {
        $slash = 'div';
        return q{Euhc::MATCH()};
    }

# $', ${'} --> $', ${'}
    elsif (/\G ( \$' | \$\{'\}                                                                                                     ) /oxmsgc) {
        $slash = 'div';
        return $1;
    }

# $POSTMATCH, ${POSTMATCH}, ${^POSTMATCH} --> Euhc::POSTMATCH()
    elsif (/\G (                 \$ (?>\s*) POSTMATCH \b | \$ (?>\s*) \{ (?>\s*) POSTMATCH (?>\s*) \} | \$ (?>\s*) \{\^POSTMATCH\} ) /oxmsgc) {
        $slash = 'div';
        return q{Euhc::POSTMATCH()};
    }

# scalar variable $scalar =~ tr///;
# scalar variable $scalar =~ s///;
# substr() =~ tr///;
# substr() =~ s///;
    elsif (/\G ( \$ $qq_scalar | $qq_substr ) /oxgc) {
        my $scalar = e_string($1);

        if (/\G (    (?>\s*) (?: =~ | !~ ) (?>\s*) ) (?= (?: tr | y ) \b ) /oxgc) {
            $tr_variable = $scalar;
            $bind_operator = $1;
            $slash = 'm//';
            return '';
        }
        elsif (/\G ( (?>\s*) (?: =~ | !~ ) (?>\s*) ) (?= s            \b ) /oxgc) {
            $sub_variable = $scalar;
            $bind_operator = $1;
            $slash = 'm//';
            return '';
        }
        else {
            $slash = 'div';
            return $scalar;
        }
    }

    # end of statement
    elsif (/\G ( [,;] ) /oxgc) {
        $slash = 'm//';

        # clear tr/// variable
        $tr_variable  = '';

        # clear s/// variable
        $sub_variable  = '';

        $bind_operator = '';

        return $1;
    }

# bareword
    elsif (/\G ( \{ (?>\s*) (?: tr | index | rindex | reverse ) (?>\s*) \} ) /oxmsgc) {
        return $1;
    }

# $0 --> $0
    elsif (/\G ( \$ 0 ) /oxmsgc) {
        $slash = 'div';
        return $1;
    }
    elsif (/\G ( \$ \{ (?>\s*) 0 (?>\s*) \} ) /oxmsgc) {
        $slash = 'div';
        return $1;
    }

# $$ --> $$
    elsif (/\G ( \$ \$ ) (?![\w\{]) /oxmsgc) {
        $slash = 'div';
        return $1;
    }

# $1, $2, $3 --> $2, $3, $4 after s/// with multibyte anchoring
# $1, $2, $3 --> $1, $2, $3 otherwise
    elsif (/\G \$ ((?>[1-9][0-9]*)) /oxmsgc) {
        $slash = 'div';
        return e_capture($1);
    }
    elsif (/\G \$ \{ (?>\s*) ((?>[1-9][0-9]*)) (?>\s*) \} /oxmsgc) {
        $slash = 'div';
        return e_capture($1);
    }

# $$foo[ ... ] --> $ $foo->[ ... ]
    elsif (/\G \$ ( \$ (?> [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \[ .+? \] ) /oxmsgc) {
        $slash = 'div';
        return e_capture($1.'->'.$2);
    }

# $$foo{ ... } --> $ $foo->{ ... }
    elsif (/\G \$ ( \$ (?> [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \{ .+? \} ) /oxmsgc) {
        $slash = 'div';
        return e_capture($1.'->'.$2);
    }

# $$foo
    elsif (/\G \$ ( \$ (?> [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) /oxmsgc) {
        $slash = 'div';
        return e_capture($1);
    }

# ${ foo }
    elsif (/\G \$ (?>\s*) \{ ( (?>\s*) (?> [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* ) (?>\s*) ) \} /oxmsgc) {
        $slash = 'div';
        return '${' . $1 . '}';
    }

# ${ ... }
    elsif (/\G \$ (?>\s*) \{ (?>\s*) ( $qq_brace ) (?>\s*) \} /oxmsgc) {
        $slash = 'div';
        return e_capture($1);
    }

# variable or function
    #                  $ @ % & *     $ #
    elsif (/\G ( (?: [\$\@\%\&\*] | \$\# | -> | \b sub \b) (?>\s*) (?: split | chop | index | rindex | lc | uc | fc | chr | ord | reverse | getc | tr | y | q | qq | qx | qw | m | s | qr | glob | lstat | opendir | stat | unlink | chdir ) ) \b /oxmsgc) {
        $slash = 'div';
        return $1;
    }
    #                $ $ $ $ $ $ $ $ $ $ $ $ $ $
    #                $ @ # \ ' " / ? ( ) [ ] < >
    elsif (/\G ( \$[\$\@\#\\\'\"\/\?\(\)\[\]\<\>] ) /oxmsgc) {
        $slash = 'div';
        return $1;
    }

# while ()
    elsif (/\G \b (while (?>\s*) \( (?>\s*) <[\$]?[A-Za-z_][A-Za-z_0-9]*> (?>\s*) \)) \b /oxgc) {
        return $1;
    }

# while () --- glob

    # avoid "Error: Runtime exception" of perl version 5.005_03

    elsif (/\G \b while (?>\s*) \( (?>\s*) < ((?:[^\x81-\xFE>\0\a\e\f\n\r\t]|[\x81-\xFE][\x00-\xFF])+?) > (?>\s*) \) \b /oxgc) {
        return 'while ($_ = Euhc::glob("' . $1 . '"))';
    }

# while (glob)
    elsif (/\G \b while (?>\s*) \( (?>\s*) glob (?>\s*) \) /oxgc) {
        return 'while ($_ = Euhc::glob_)';
    }

# while (glob(WILDCARD))
    elsif (/\G \b while (?>\s*) \( (?>\s*) glob \b /oxgc) {
        return 'while ($_ = Euhc::glob';
    }

# doit if, doit unless, doit while, doit until, doit for, doit when
    elsif (/\G \b ( if | unless | while | until | for | when ) \b /oxgc) { $slash = 'm//'; return $1; }

# subroutines of package Euhc
    elsif (/\G \b (CORE:: | ->(>?\s*) (?: atan2 | [a-z]{2,})) \b       /oxgc) { $slash = 'm//'; return $1;                  }
    elsif (/\G \b Char::eval       (?= (?>\s*) \{ )                    /oxgc) { $slash = 'm//'; return 'eval';              }
    elsif (/\G \b UHC::eval       (?= (?>\s*) \{ )                    /oxgc) { $slash = 'm//'; return 'eval';              }
    elsif (/\G \b Char::eval    \b (?! (?>\s*) => )                    /oxgc) { $slash = 'm//'; return 'eval Char::escape'; }
    elsif (/\G \b UHC::eval    \b (?! (?>\s*) => )                    /oxgc) { $slash = 'm//'; return 'eval UHC::escape'; }
    elsif (/\G \b bytes::substr \b (?! (?>\s*) => )                    /oxgc) { $slash = 'm//'; return 'substr';            }
    elsif (/\G \b chop \b          (?! (?>\s*) => )                    /oxgc) { $slash = 'm//'; return 'Euhc::chop';       }
    elsif (/\G \b bytes::index \b  (?! (?>\s*) => )                    /oxgc) { $slash = 'm//'; return 'index';             }
    elsif (/\G \b Char::index \b   (?! (?>\s*) => )                    /oxgc) { $slash = 'm//'; return 'Char::index';       }
    elsif (/\G \b UHC::index \b   (?! (?>\s*) => )                    /oxgc) { $slash = 'm//'; return 'UHC::index';       }
    elsif (/\G \b index \b         (?! (?>\s*) => )                    /oxgc) { $slash = 'm//'; return 'Euhc::index';      }
    elsif (/\G \b bytes::rindex \b (?! (?>\s*) => )                    /oxgc) { $slash = 'm//'; return 'rindex';            }
    elsif (/\G \b Char::rindex \b  (?! (?>\s*) => )                    /oxgc) { $slash = 'm//'; return 'Char::rindex';      }
    elsif (/\G \b UHC::rindex \b  (?! (?>\s*) => )                    /oxgc) { $slash = 'm//'; return 'UHC::rindex';      }
    elsif (/\G \b rindex \b        (?! (?>\s*) => )                    /oxgc) { $slash = 'm//'; return 'Euhc::rindex';     }
    elsif (/\G \b lc      (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $slash = 'm//'; return 'Euhc::lc';         }
    elsif (/\G \b lcfirst (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $slash = 'm//'; return 'Euhc::lcfirst';    }
    elsif (/\G \b uc      (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $slash = 'm//'; return 'Euhc::uc';         }
    elsif (/\G \b ucfirst (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $slash = 'm//'; return 'Euhc::ucfirst';    }
    elsif (/\G \b fc      (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $slash = 'm//'; return 'Euhc::fc';         }

    # stacked file test operators

    # P.179 File Test Operators
    # in Chapter 12: File Tests
    # of ISBN 978-0-596-52010-6 Learning Perl, Fifth Edition

    # P.106 Named Unary and File Test Operators
    # in Chapter 3: Unary and Binary Operators
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    # (and so on)

    elsif (/\G (-[rwxoRWXOezfdlpSbcugkTB] (?>(?:\s+ -[rwxoRWXOezfdlpSbcugkTB])+))
                                                             (?>\s*) (\") ((?:$qq_char)+?)             (\") /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_qq('',  $2,$4,$3) . ")"; }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) qq (?>\s*) (\#) ((?:$qq_char)+?)             (\#) /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_qq('qq',$2,$4,$3) . ")"; }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) qq (?>\s*) (\() ((?:$qq_paren)+?)            (\)) /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_qq('qq',$2,$4,$3) . ")"; }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) qq (?>\s*) (\{) ((?:$qq_brace)+?)            (\}) /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_qq('qq',$2,$4,$3) . ")"; }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) qq (?>\s*) (\[) ((?:$qq_bracket)+?)          (\]) /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_qq('qq',$2,$4,$3) . ")"; }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) qq (?>\s*) (\<) ((?:$qq_angle)+?)            (\>) /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_qq('qq',$2,$4,$3) . ")"; }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) qq (?>\s*) (\S) ((?:$qq_char)+?)             (\2) /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_qq('qq',$2,$4,$3) . ")"; }

    elsif (/\G (-[rwxoRWXOezfdlpSbcugkTB] (?>(?:\s+ -[rwxoRWXOezfdlpSbcugkTB])+))
                                                             (?>\s*) (\') ((?:\\\'|\\\\|$q_char)+?)    (\') /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_q ('',  $2,$4,$3) . ")"; }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) q  (?>\s*) (\#) ((?:\\\#|\\\\|$q_char)+?)    (\#) /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_q ('q', $2,$4,$3) . ")"; }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) q  (?>\s*) (\() ((?:\\\)|\\\\|$q_paren)+?)   (\)) /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_q ('q', $2,$4,$3) . ")"; }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) q  (?>\s*) (\{) ((?:\\\}|\\\\|$q_brace)+?)   (\}) /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_q ('q', $2,$4,$3) . ")"; }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) q  (?>\s*) (\[) ((?:\\\]|\\\\|$q_bracket)+?) (\]) /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_q ('q', $2,$4,$3) . ")"; }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) q  (?>\s*) (\<) ((?:\\\>|\\\\|$q_angle)+?)   (\>) /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_q ('q', $2,$4,$3) . ")"; }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) q  (?>\s*) (\S) ((?:\\\2|\\\\|$q_char)+?)    (\2) /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1)," . e_q ('q', $2,$4,$3) . ")"; }

    elsif (/\G (-[rwxoRWXOezfdlpSbcugkTB] (?>(?:\s+ -[rwxoRWXOezfdlpSbcugkTB])+)) (\$ (?> \w+ (?: ::\w+)* ) (?: (?: ->)? (?: [\$\@\%\&\*]\* | \$\#\* | \( (?:$qq_paren)*? \) | [\@\%\*]? \{ (?:$qq_brace)+? \} | [\@\%]? \[ (?:$qq_bracket)+? \] ) )*) /oxgc)
                                                                                                                   { $slash = 'm//'; return "Euhc::filetest(qw($1),$2)"; }
    elsif (/\G (-[rwxoRWXOezfdlpSbcugkTB] (?>(?:\s+ -[rwxoRWXOezfdlpSbcugkTB])+)) \( ((?:$qq_paren)*?) \)   /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1),$2)"; }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) (?= [a-z]+)                                       /oxgc) { $slash = 'm//'; return "Euhc::filetest qw($1),";    }
    elsif (/\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) ((?>\w+))                                         /oxgc) { $slash = 'm//'; return "Euhc::filetest(qw($1),$2)"; }

    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC])            (?>\s*) (\") ((?:$qq_char)+?)                (\") /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_qq('',  $2,$4,$3) . ")"; }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) qq (?>\s*) (\#) ((?:$qq_char)+?)                (\#) /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_qq('qq',$2,$4,$3) . ")"; }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) qq (?>\s*) (\() ((?:$qq_paren)+?)               (\)) /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_qq('qq',$2,$4,$3) . ")"; }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) qq (?>\s*) (\{) ((?:$qq_brace)+?)               (\}) /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_qq('qq',$2,$4,$3) . ")"; }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) qq (?>\s*) (\[) ((?:$qq_bracket)+?)             (\]) /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_qq('qq',$2,$4,$3) . ")"; }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) qq (?>\s*) (\<) ((?:$qq_angle)+?)               (\>) /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_qq('qq',$2,$4,$3) . ")"; }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) qq (?>\s*) (\S) ((?:$qq_char)+?)                (\2) /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_qq('qq',$2,$4,$3) . ")"; }

    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC])            (?>\s*) (\') ((?:\\\'|\\\\|$q_char)+?)       (\') /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_q ('',  $2,$4,$3) . ")"; }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) q  (?>\s*) (\#) ((?:\\\#|\\\\|$q_char)+?)       (\#) /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_q ('q', $2,$4,$3) . ")"; }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) q  (?>\s*) (\() ((?:\\\)|\\\\|$q_paren)+?)      (\)) /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_q ('q', $2,$4,$3) . ")"; }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) q  (?>\s*) (\{) ((?:\\\}|\\\\|$q_brace)+?)      (\}) /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_q ('q', $2,$4,$3) . ")"; }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) q  (?>\s*) (\[) ((?:\\\]|\\\\|$q_bracket)+?)    (\]) /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_q ('q', $2,$4,$3) . ")"; }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) q  (?>\s*) (\<) ((?:\\\>|\\\\|$q_angle)+?)      (\>) /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_q ('q', $2,$4,$3) . ")"; }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) q  (?>\s*) (\S) ((?:\\\2|\\\\|$q_char)+?)       (\2) /oxgc) { $slash = 'm//'; return "Euhc::$1(" . e_q ('q', $2,$4,$3) . ")"; }

    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s*) (\$ (?> \w+ (?: ::\w+)* ) (?: (?: ->)? (?: [\$\@\%\&\*]\* | \$\#\* | \( (?:$qq_paren)*? \) | [\@\%\*]? \{ (?:$qq_brace)+? \} | [\@\%]? \[ (?:$qq_bracket)+? \] ) )*) /oxgc)
                                                                                                                   { $slash = 'm//'; return "Euhc::$1($2)";             }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s*) \( ((?:$qq_paren)*?) \)                              /oxgc) { $slash = 'm//'; return "Euhc::$1($2)";             }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?= (?>\s+) [a-z]+)                                          /oxgc) { $slash = 'm//'; return "Euhc::$1";                 }
    elsif (/\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) ((?>\w+))                                            /oxgc) { $slash = 'm//'; return "Euhc::$1(::"."$2)";        }
    elsif (/\G -(t)                            (?>\s+) ((?>\w+))                                            /oxgc) { $slash = 'm//'; return "-t $2";                     }
    elsif (/\G \b lstat         (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(])                                /oxgc) { $slash = 'm//'; return 'Euhc::lstat';              }
    elsif (/\G \b stat          (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(])                                /oxgc) { $slash = 'm//'; return 'Euhc::stat';               }

    # "-s '' ..." means file test "-s 'filename' ..." (not means "- s/// ...")
    elsif (/\G -s                                          (?>\s*) (\") ((?:$qq_char)+?)               (\") /oxgc) { $slash = 'm//'; return '-s ' . e_qq('',  $1,$3,$2); }
    elsif (/\G -s                               (?>\s+) qq (?>\s*) (\#) ((?:$qq_char)+?)               (\#) /oxgc) { $slash = 'm//'; return '-s ' . e_qq('qq',$1,$3,$2); }
    elsif (/\G -s                               (?>\s+) qq (?>\s*) (\() ((?:$qq_paren)+?)              (\)) /oxgc) { $slash = 'm//'; return '-s ' . e_qq('qq',$1,$3,$2); }
    elsif (/\G -s                               (?>\s+) qq (?>\s*) (\{) ((?:$qq_brace)+?)              (\}) /oxgc) { $slash = 'm//'; return '-s ' . e_qq('qq',$1,$3,$2); }
    elsif (/\G -s                               (?>\s+) qq (?>\s*) (\[) ((?:$qq_bracket)+?)            (\]) /oxgc) { $slash = 'm//'; return '-s ' . e_qq('qq',$1,$3,$2); }
    elsif (/\G -s                               (?>\s+) qq (?>\s*) (\<) ((?:$qq_angle)+?)              (\>) /oxgc) { $slash = 'm//'; return '-s ' . e_qq('qq',$1,$3,$2); }
    elsif (/\G -s                               (?>\s+) qq (?>\s*) (\S) ((?:$qq_char)+?)               (\1) /oxgc) { $slash = 'm//'; return '-s ' . e_qq('qq',$1,$3,$2); }

    elsif (/\G -s                                          (?>\s*) (\') ((?:\\\'|\\\\|$q_char)+?)      (\') /oxgc) { $slash = 'm//'; return '-s ' . e_q ('',  $1,$3,$2); }
    elsif (/\G -s                               (?>\s+) q  (?>\s*) (\#) ((?:\\\#|\\\\|$q_char)+?)      (\#) /oxgc) { $slash = 'm//'; return '-s ' . e_q ('q', $1,$3,$2); }
    elsif (/\G -s                               (?>\s+) q  (?>\s*) (\() ((?:\\\)|\\\\|$q_paren)+?)     (\)) /oxgc) { $slash = 'm//'; return '-s ' . e_q ('q', $1,$3,$2); }
    elsif (/\G -s                               (?>\s+) q  (?>\s*) (\{) ((?:\\\}|\\\\|$q_brace)+?)     (\}) /oxgc) { $slash = 'm//'; return '-s ' . e_q ('q', $1,$3,$2); }
    elsif (/\G -s                               (?>\s+) q  (?>\s*) (\[) ((?:\\\]|\\\\|$q_bracket)+?)   (\]) /oxgc) { $slash = 'm//'; return '-s ' . e_q ('q', $1,$3,$2); }
    elsif (/\G -s                               (?>\s+) q  (?>\s*) (\<) ((?:\\\>|\\\\|$q_angle)+?)     (\>) /oxgc) { $slash = 'm//'; return '-s ' . e_q ('q', $1,$3,$2); }
    elsif (/\G -s                               (?>\s+) q  (?>\s*) (\S) ((?:\\\1|\\\\|$q_char)+?)      (\1) /oxgc) { $slash = 'm//'; return '-s ' . e_q ('q', $1,$3,$2); }

    elsif (/\G -s                               (?>\s*) (\$ (?> \w+ (?: ::\w+)* ) (?: (?: ->)? (?: [\$\@\%\&\*]\* | \$\#\* | \( (?:$qq_paren)*? \) | [\@\%\*]? \{ (?:$qq_brace)+? \} | [\@\%]? \[ (?:$qq_bracket)+? \] ) )*) /oxgc)
                                                                                                                   { $slash = 'm//'; return "-s $1";   }
    elsif (/\G -s                               (?>\s*) \( ((?:$qq_paren)*?) \)                             /oxgc) { $slash = 'm//'; return "-s ($1)"; }
    elsif (/\G -s                               (?= (?>\s+) [a-z]+)                                         /oxgc) { $slash = 'm//'; return '-s';      }
    elsif (/\G -s                               (?>\s+) ((?>\w+))                                           /oxgc) { $slash = 'm//'; return "-s $1";   }

    elsif (/\G \b bytes::length (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $slash = 'm//'; return 'length';                   }
    elsif (/\G \b bytes::chr    (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $slash = 'm//'; return 'chr';                      }
    elsif (/\G \b chr           (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $slash = 'm//'; return 'Euhc::chr';               }
    elsif (/\G \b bytes::ord    (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $slash = 'div'; return 'ord';                      }
    elsif (/\G \b ord           (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $slash = 'div'; return $function_ord;              }
    elsif (/\G \b glob          (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $slash = 'm//'; return 'Euhc::glob';              }
    elsif (/\G \b lc \b            (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return 'Euhc::lc_';               }
    elsif (/\G \b lcfirst \b       (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return 'Euhc::lcfirst_';          }
    elsif (/\G \b uc \b            (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return 'Euhc::uc_';               }
    elsif (/\G \b ucfirst \b       (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return 'Euhc::ucfirst_';          }
    elsif (/\G \b fc \b            (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return 'Euhc::fc_';               }
    elsif (/\G \b lstat \b         (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return 'Euhc::lstat_';            }
    elsif (/\G \b stat \b          (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return 'Euhc::stat_';             }
    elsif (/\G    (-[rwxoRWXOezfdlpSbcugkTB] (?>(?:\s+ -[rwxoRWXOezfdlpSbcugkTB])+))
                     \b            (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return "Euhc::filetest_(qw($1))"; }
    elsif (/\G    -([rwxoRWXOezsfdlpSbcugkTBMAC])
                     \b            (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return "Euhc::${1}_";             }

    elsif (/\G    -s \b            (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return '-s ';                      }

    elsif (/\G \b bytes::length \b (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return 'length';                   }
    elsif (/\G \b bytes::chr \b    (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return 'chr';                      }
    elsif (/\G \b chr \b           (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return 'Euhc::chr_';              }
    elsif (/\G \b bytes::ord \b    (?! (?>\s*) => )                          /oxgc) { $slash = 'div'; return 'ord';                      }
    elsif (/\G \b ord \b           (?! (?>\s*) => )                          /oxgc) { $slash = 'div'; return $function_ord_;             }
    elsif (/\G \b glob \b          (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return 'Euhc::glob_';             }
    elsif (/\G \b reverse \b       (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return $function_reverse;          }
    elsif (/\G \b getc \b          (?! (?>\s*) => )                          /oxgc) { $slash = 'm//'; return $function_getc;             }
    elsif (/\G \b opendir ((?>\s*) \( (?>\s*)) (?=[A-Za-z_])                 /oxgc) { $slash = 'm//'; return "Euhc::opendir$1*";        }
    elsif (/\G \b opendir ((?>\s+))            (?=[A-Za-z_])                 /oxgc) { $slash = 'm//'; return "Euhc::opendir$1*";        }
    elsif (/\G \b unlink \b       (?! (?>\s*) => )                           /oxgc) { $slash = 'm//'; return 'Euhc::unlink';            }

# chdir
    elsif (/\G \b (chdir) \b       (?! (?>\s*) => ) /oxgc) {
        $slash = 'm//';

        my $e = 'Euhc::chdir';

        while (/\G ( (?>\s+) | \( | \#.* ) /oxgc) {
            $e .= $1;
        }

# end of chdir
        if    (/\G (?= [,;\)\}\]] )          /oxgc) { return $e;                 }

# chdir scalar value
        elsif (/\G ( [\$\@\&\*] $qq_scalar ) /oxgc) { return $e . e_string($1);  }

# chdir qq//
        elsif (/\G \b (qq) \b /oxgc) {
            if (/\G (\#) ((?:$qq_char)*?) (\#) /oxgc)                        { return $e . e_chdir('qq',$1,$3,$2);   } # qq# #  --> qr # #
            else {
                while (not /\G \z/oxgc) {
                    if    (/\G ((?>\s+)|\#.*)                         /oxgc) { $e .= $1; }
                    elsif (/\G (\()          ((?:$qq_paren)*?)   (\)) /oxgc) { return $e . e_chdir('qq',$1,$3,$2);   } # qq ( ) --> qr ( )
                    elsif (/\G (\{)          ((?:$qq_brace)*?)   (\}) /oxgc) { return $e . e_chdir('qq',$1,$3,$2);   } # qq { } --> qr { }
                    elsif (/\G (\[)          ((?:$qq_bracket)*?) (\]) /oxgc) { return $e . e_chdir('qq',$1,$3,$2);   } # qq [ ] --> qr [ ]
                    elsif (/\G (\<)          ((?:$qq_angle)*?)   (\>) /oxgc) { return $e . e_chdir('qq',$1,$3,$2);   } # qq < > --> qr < >
                    elsif (/\G ([*\-:?\\^|]) ((?:$qq_char)*?)    (\1) /oxgc) { return $e . e_chdir('qq','{','}',$2); } # qq | | --> qr { }
                    elsif (/\G (\S)          ((?:$qq_char)*?)    (\1) /oxgc) { return $e . e_chdir('qq',$1,$3,$2);   } # qq * * --> qr * *
                }
                die __FILE__, ": Can't find string terminator anywhere before EOF\n";
            }
        }

# chdir q//
        elsif (/\G \b (q) \b /oxgc) {
            if (/\G (\#) ((?:\\\#|\\\\|$q_char)*?) (\#) /oxgc)                    { return $e . e_chdir_q('q',$1,$3,$2);   } # q# #  --> qr # #
            else {
                while (not /\G \z/oxgc) {
                    if    (/\G ((?>\s+)|\#.*)                              /oxgc) { $e .= $1; }
                    elsif (/\G (\() ((?:\\\\|\\\)|\\\(|$q_paren)*?)   (\)) /oxgc) { return $e . e_chdir_q('q',$1,$3,$2);   } # q ( ) --> qr ( )
                    elsif (/\G (\{) ((?:\\\\|\\\}|\\\{|$q_brace)*?)   (\}) /oxgc) { return $e . e_chdir_q('q',$1,$3,$2);   } # q { } --> qr { }
                    elsif (/\G (\[) ((?:\\\\|\\\]|\\\[|$q_bracket)*?) (\]) /oxgc) { return $e . e_chdir_q('q',$1,$3,$2);   } # q [ ] --> qr [ ]
                    elsif (/\G (\<) ((?:\\\\|\\\>|\\\<|$q_angle)*?)   (\>) /oxgc) { return $e . e_chdir_q('q',$1,$3,$2);   } # q < > --> qr < >
                    elsif (/\G ([*\-:?\\^|])       ((?:$q_char)*?)    (\1) /oxgc) { return $e . e_chdir_q('q','{','}',$2); } # q | | --> qr { }
                    elsif (/\G (\S) ((?:\\\\|\\\1|     $q_char)*?)    (\1) /oxgc) { return $e . e_chdir_q('q',$1,$3,$2);   } # q * * --> qr * *
                }
                die __FILE__, ": Can't find string terminator anywhere before EOF\n";
            }
        }

# chdir ''
        elsif (/\G (\') /oxgc) {
            my $q_string = '';
            while (not /\G \z/oxgc) {
                if    (/\G (\\\\)    /oxgc) { $q_string .= $1; }
                elsif (/\G (\\\')    /oxgc) { $q_string .= $1; }
                elsif (/\G \'        /oxgc)                                       { return $e . e_chdir_q('',"'","'",$q_string); }
                elsif (/\G ($q_char) /oxgc) { $q_string .= $1; }
            }
            die __FILE__, ": Can't find string terminator anywhere before EOF\n";
        }

# chdir ""
        elsif (/\G (\") /oxgc) {
            my $qq_string = '';
            while (not /\G \z/oxgc) {
                if    (/\G (\\\\)    /oxgc) { $qq_string .= $1; }
                elsif (/\G (\\\")    /oxgc) { $qq_string .= $1; }
                elsif (/\G \"        /oxgc)                                       { return $e . e_chdir('','"','"',$qq_string); }
                elsif (/\G ($q_char) /oxgc) { $qq_string .= $1; }
            }
            die __FILE__, ": Can't find string terminator anywhere before EOF\n";
        }
    }

# split
    elsif (/\G \b (split) \b (?! (?>\s*) => ) /oxgc) {
        $slash = 'm//';

        my $e = '';
        while (/\G ( (?>\s+) | \( | \#.* ) /oxgc) {
            $e .= $1;
        }

# end of split
        if    (/\G (?= [,;\)\}\]] )          /oxgc) { return 'Euhc::split' . $e;                 }

# split scalar value
        elsif (/\G ( [\$\@\&\*] $qq_scalar ) /oxgc) { return 'Euhc::split' . $e . e_string($1);  }

# split literal space
        elsif (/\G \b qq           (\#) [ ] (\#) /oxgc) { return 'Euhc::split' . $e . qq  {qq$1 $2}; }
        elsif (/\G \b qq ((?>\s*)) (\() [ ] (\)) /oxgc) { return 'Euhc::split' . $e . qq{$1qq$2 $3}; }
        elsif (/\G \b qq ((?>\s*)) (\{) [ ] (\}) /oxgc) { return 'Euhc::split' . $e . qq{$1qq$2 $3}; }
        elsif (/\G \b qq ((?>\s*)) (\[) [ ] (\]) /oxgc) { return 'Euhc::split' . $e . qq{$1qq$2 $3}; }
        elsif (/\G \b qq ((?>\s*)) (\<) [ ] (\>) /oxgc) { return 'Euhc::split' . $e . qq{$1qq$2 $3}; }
        elsif (/\G \b qq ((?>\s*)) (\S) [ ] (\2) /oxgc) { return 'Euhc::split' . $e . qq{$1qq$2 $3}; }
        elsif (/\G \b q            (\#) [ ] (\#) /oxgc) { return 'Euhc::split' . $e . qq   {q$1 $2}; }
        elsif (/\G \b q  ((?>\s*)) (\() [ ] (\)) /oxgc) { return 'Euhc::split' . $e . qq {$1q$2 $3}; }
        elsif (/\G \b q  ((?>\s*)) (\{) [ ] (\}) /oxgc) { return 'Euhc::split' . $e . qq {$1q$2 $3}; }
        elsif (/\G \b q  ((?>\s*)) (\[) [ ] (\]) /oxgc) { return 'Euhc::split' . $e . qq {$1q$2 $3}; }
        elsif (/\G \b q  ((?>\s*)) (\<) [ ] (\>) /oxgc) { return 'Euhc::split' . $e . qq {$1q$2 $3}; }
        elsif (/\G \b q  ((?>\s*)) (\S) [ ] (\2) /oxgc) { return 'Euhc::split' . $e . qq {$1q$2 $3}; }
        elsif (/\G                    ' [ ] '    /oxgc) { return 'Euhc::split' . $e . qq     {' '};  }
        elsif (/\G                    " [ ] "    /oxgc) { return 'Euhc::split' . $e . qq     {" "};  }

# split qq//
        elsif (/\G \b (qq) \b /oxgc) {
            if (/\G (\#) ((?:$qq_char)*?) (\#) /oxgc)                        { return e_split($e.'qr',$1,$3,$2,'');   } # qq# #  --> qr # #
            else {
                while (not /\G \z/oxgc) {
                    if    (/\G ((?>\s+)|\#.*)                         /oxgc) { $e .= $1; }
                    elsif (/\G (\()          ((?:$qq_paren)*?)   (\)) /oxgc) { return e_split($e.'qr',$1,$3,$2,'');   } # qq ( ) --> qr ( )
                    elsif (/\G (\{)          ((?:$qq_brace)*?)   (\}) /oxgc) { return e_split($e.'qr',$1,$3,$2,'');   } # qq { } --> qr { }
                    elsif (/\G (\[)          ((?:$qq_bracket)*?) (\]) /oxgc) { return e_split($e.'qr',$1,$3,$2,'');   } # qq [ ] --> qr [ ]
                    elsif (/\G (\<)          ((?:$qq_angle)*?)   (\>) /oxgc) { return e_split($e.'qr',$1,$3,$2,'');   } # qq < > --> qr < >
                    elsif (/\G ([*\-:?\\^|]) ((?:$qq_char)*?)    (\1) /oxgc) { return e_split($e.'qr','{','}',$2,''); } # qq | | --> qr { }
                    elsif (/\G (\S)          ((?:$qq_char)*?)    (\1) /oxgc) { return e_split($e.'qr',$1,$3,$2,'');   } # qq * * --> qr * *
                }
                die __FILE__, ": Can't find string terminator anywhere before EOF\n";
            }
        }

# split qr//
        elsif (/\G \b (qr) \b /oxgc) {
            if (/\G (\#) ((?:$qq_char)*?) (\#) ([imosxpadlunbB]*) /oxgc)                        { return e_split  ($e.'qr',$1,$3,$2,$4);   } # qr# #
            else {
                while (not /\G \z/oxgc) {
                    if    (/\G ((?>\s+)|\#.*)                                            /oxgc) { $e .= $1; }
                    elsif (/\G (\()          ((?:$qq_paren)*?)   (\)) ([imosxpadlunbB]*) /oxgc) { return e_split  ($e.'qr',$1, $3, $2,$4); } # qr ( )
                    elsif (/\G (\{)          ((?:$qq_brace)*?)   (\}) ([imosxpadlunbB]*) /oxgc) { return e_split  ($e.'qr',$1, $3, $2,$4); } # qr { }
                    elsif (/\G (\[)          ((?:$qq_bracket)*?) (\]) ([imosxpadlunbB]*) /oxgc) { return e_split  ($e.'qr',$1, $3, $2,$4); } # qr [ ]
                    elsif (/\G (\<)          ((?:$qq_angle)*?)   (\>) ([imosxpadlunbB]*) /oxgc) { return e_split  ($e.'qr',$1, $3, $2,$4); } # qr < >
                    elsif (/\G (\')          ((?:$qq_char)*?)    (\') ([imosxpadlunbB]*) /oxgc) { return e_split_q($e.'qr',$1, $3, $2,$4); } # qr ' '
                    elsif (/\G ([*\-:?\\^|]) ((?:$qq_char)*?)    (\1) ([imosxpadlunbB]*) /oxgc) { return e_split  ($e.'qr','{','}',$2,$4); } # qr | | --> qr { }
                    elsif (/\G (\S)          ((?:$qq_char)*?)    (\1) ([imosxpadlunbB]*) /oxgc) { return e_split  ($e.'qr',$1, $3, $2,$4); } # qr * *
                }
                die __FILE__, ": Can't find string terminator anywhere before EOF\n";
            }
        }

# split q//
        elsif (/\G \b (q) \b /oxgc) {
            if (/\G (\#) ((?:\\\#|\\\\|$q_char)*?) (\#) /oxgc)                    { return e_split_q($e.'qr',$1,$3,$2,'');   } # q# #  --> qr # #
            else {
                while (not /\G \z/oxgc) {
                    if    (/\G ((?>\s+)|\#.*)                              /oxgc) { $e .= $1; }
                    elsif (/\G (\() ((?:\\\\|\\\)|\\\(|$q_paren)*?)   (\)) /oxgc) { return e_split_q($e.'qr',$1,$3,$2,'');   } # q ( ) --> qr ( )
                    elsif (/\G (\{) ((?:\\\\|\\\}|\\\{|$q_brace)*?)   (\}) /oxgc) { return e_split_q($e.'qr',$1,$3,$2,'');   } # q { } --> qr { }
                    elsif (/\G (\[) ((?:\\\\|\\\]|\\\[|$q_bracket)*?) (\]) /oxgc) { return e_split_q($e.'qr',$1,$3,$2,'');   } # q [ ] --> qr [ ]
                    elsif (/\G (\<) ((?:\\\\|\\\>|\\\<|$q_angle)*?)   (\>) /oxgc) { return e_split_q($e.'qr',$1,$3,$2,'');   } # q < > --> qr < >
                    elsif (/\G ([*\-:?\\^|])       ((?:$q_char)*?)    (\1) /oxgc) { return e_split_q($e.'qr','{','}',$2,''); } # q | | --> qr { }
                    elsif (/\G (\S) ((?:\\\\|\\\1|     $q_char)*?)    (\1) /oxgc) { return e_split_q($e.'qr',$1,$3,$2,'');   } # q * * --> qr * *
                }
                die __FILE__, ": Can't find string terminator anywhere before EOF\n";
            }
        }

# split m//
        elsif (/\G \b (m) \b /oxgc) {
            if (/\G (\#) ((?:$qq_char)*?) (\#) ([cgimosxpadlunbB]*) /oxgc)                        { return e_split  ($e.'qr',$1,$3,$2,$4);   } # m# #  --> qr # #
            else {
                while (not /\G \z/oxgc) {
                    if    (/\G ((?>\s+)|\#.*)                                              /oxgc) { $e .= $1; }
                    elsif (/\G (\()          ((?:$qq_paren)*?)   (\)) ([cgimosxpadlunbB]*) /oxgc) { return e_split  ($e.'qr',$1, $3, $2,$4); } # m ( ) --> qr ( )
                    elsif (/\G (\{)          ((?:$qq_brace)*?)   (\}) ([cgimosxpadlunbB]*) /oxgc) { return e_split  ($e.'qr',$1, $3, $2,$4); } # m { } --> qr { }
                    elsif (/\G (\[)          ((?:$qq_bracket)*?) (\]) ([cgimosxpadlunbB]*) /oxgc) { return e_split  ($e.'qr',$1, $3, $2,$4); } # m [ ] --> qr [ ]
                    elsif (/\G (\<)          ((?:$qq_angle)*?)   (\>) ([cgimosxpadlunbB]*) /oxgc) { return e_split  ($e.'qr',$1, $3, $2,$4); } # m < > --> qr < >
                    elsif (/\G (\')          ((?:$qq_char)*?)    (\') ([cgimosxpadlunbB]*) /oxgc) { return e_split_q($e.'qr',$1, $3, $2,$4); } # m ' ' --> qr ' '
                    elsif (/\G ([*\-:?\\^|]) ((?:$qq_char)*?)    (\1) ([cgimosxpadlunbB]*) /oxgc) { return e_split  ($e.'qr','{','}',$2,$4); } # m | | --> qr { }
                    elsif (/\G (\S)          ((?:$qq_char)*?)    (\1) ([cgimosxpadlunbB]*) /oxgc) { return e_split  ($e.'qr',$1, $3, $2,$4); } # m * * --> qr * *
                }
                die __FILE__, ": Search pattern not terminated\n";
            }
        }

# split ''
        elsif (/\G (\') /oxgc) {
            my $q_string = '';
            while (not /\G \z/oxgc) {
                if    (/\G (\\\\)    /oxgc) { $q_string .= $1; }
                elsif (/\G (\\\')    /oxgc) { $q_string .= $1; }                               # splitqr'' --> split qr''
                elsif (/\G \'        /oxgc)                                                    { return e_split_q($e.q{ qr},"'","'",$q_string,''); } # ' ' --> qr ' '
                elsif (/\G ($q_char) /oxgc) { $q_string .= $1; }
            }
            die __FILE__, ": Can't find string terminator anywhere before EOF\n";
        }

# split ""
        elsif (/\G (\") /oxgc) {
            my $qq_string = '';
            while (not /\G \z/oxgc) {
                if    (/\G (\\\\)    /oxgc) { $qq_string .= $1; }
                elsif (/\G (\\\")    /oxgc) { $qq_string .= $1; }                              # splitqr"" --> split qr""
                elsif (/\G \"        /oxgc)                                                    { return e_split($e.q{ qr},'"','"',$qq_string,''); } # " " --> qr " "
                elsif (/\G ($q_char) /oxgc) { $qq_string .= $1; }
            }
            die __FILE__, ": Can't find string terminator anywhere before EOF\n";
        }

# split //
        elsif (/\G (\/) /oxgc) {
            my $regexp = '';
            while (not /\G \z/oxgc) {
                if    (/\G (\\\\)                  /oxgc) { $regexp .= $1; }
                elsif (/\G (\\\/)                  /oxgc) { $regexp .= $1; }                   # splitqr// --> split qr//
                elsif (/\G \/ ([cgimosxpadlunbB]*) /oxgc)                                      { return e_split($e.q{ qr}, '/','/',$regexp,$1); } # / / --> qr / /
                elsif (/\G ($q_char)               /oxgc) { $regexp .= $1; }
            }
            die __FILE__, ": Search pattern not terminated\n";
        }
    }

# tr/// or y///

    # about [cdsrbB]* (/B modifier)
    #
    # P.559 appendix C
    # of ISBN 4-89052-384-7 Programming perl
    # (Japanese title is: Perl puroguramingu)

    elsif (/\G \b ( tr | y ) \b /oxgc) {
        my $ope = $1;

        #        $1   $2               $3   $4               $5   $6
        if (/\G (\#) ((?:$qq_char)*?) (\#) ((?:$qq_char)*?) (\#) ([cdsrbB]*) /oxgc) { # tr# # #
            my @tr = ($tr_variable,$2);
            return e_tr(@tr,'',$4,$6);
        }
        else {
            my $e = '';
            while (not /\G \z/oxgc) {
                if    (/\G ((?>\s+)|\#.*)              /oxgc) { $e .= $1; }
                elsif (/\G (\() ((?:$qq_paren)*?) (\)) /oxgc) {
                    my @tr = ($tr_variable,$2);
                    while (not /\G \z/oxgc) {
                        if    (/\G ((?>\s+)|\#.*)                            /oxgc) { $e .= $1; }
                        elsif (/\G (\() ((?:$qq_paren)*?)   (\)) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr ( ) ( )
                        elsif (/\G (\{) ((?:$qq_brace)*?)   (\}) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr ( ) { }
                        elsif (/\G (\[) ((?:$qq_bracket)*?) (\]) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr ( ) [ ]
                        elsif (/\G (\<) ((?:$qq_angle)*?)   (\>) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr ( ) < >
                        elsif (/\G (\S) ((?:$qq_char)*?)    (\1) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr ( ) * *
                    }
                    die __FILE__, ": Transliteration replacement not terminated\n";
                }
                elsif (/\G (\{) ((?:$qq_brace)*?) (\}) /oxgc) {
                    my @tr = ($tr_variable,$2);
                    while (not /\G \z/oxgc) {
                        if    (/\G ((?>\s+)|\#.*)                            /oxgc) { $e .= $1; }
                        elsif (/\G (\() ((?:$qq_paren)*?)   (\)) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr { } ( )
                        elsif (/\G (\{) ((?:$qq_brace)*?)   (\}) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr { } { }
                        elsif (/\G (\[) ((?:$qq_bracket)*?) (\]) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr { } [ ]
                        elsif (/\G (\<) ((?:$qq_angle)*?)   (\>) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr { } < >
                        elsif (/\G (\S) ((?:$qq_char)*?)    (\1) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr { } * *
                    }
                    die __FILE__, ": Transliteration replacement not terminated\n";
                }
                elsif (/\G (\[) ((?:$qq_bracket)*?) (\]) /oxgc) {
                    my @tr = ($tr_variable,$2);
                    while (not /\G \z/oxgc) {
                        if    (/\G ((?>\s+)|\#.*)                            /oxgc) { $e .= $1; }
                        elsif (/\G (\() ((?:$qq_paren)*?)   (\)) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr [ ] ( )
                        elsif (/\G (\{) ((?:$qq_brace)*?)   (\}) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr [ ] { }
                        elsif (/\G (\[) ((?:$qq_bracket)*?) (\]) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr [ ] [ ]
                        elsif (/\G (\<) ((?:$qq_angle)*?)   (\>) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr [ ] < >
                        elsif (/\G (\S) ((?:$qq_char)*?)    (\1) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr [ ] * *
                    }
                    die __FILE__, ": Transliteration replacement not terminated\n";
                }
                elsif (/\G (\<) ((?:$qq_angle)*?) (\>) /oxgc) {
                    my @tr = ($tr_variable,$2);
                    while (not /\G \z/oxgc) {
                        if    (/\G ((?>\s+)|\#.*)                            /oxgc) { $e .= $1; }
                        elsif (/\G (\() ((?:$qq_paren)*?)   (\)) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr < > ( )
                        elsif (/\G (\{) ((?:$qq_brace)*?)   (\}) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr < > { }
                        elsif (/\G (\[) ((?:$qq_bracket)*?) (\]) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr < > [ ]
                        elsif (/\G (\<) ((?:$qq_angle)*?)   (\>) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr < > < >
                        elsif (/\G (\S) ((?:$qq_char)*?)    (\1) ([cdsrbB]*) /oxgc) { return e_tr(@tr,$e,$2,$4); } # tr < > * *
                    }
                    die __FILE__, ": Transliteration replacement not terminated\n";
                }
                #           $1   $2               $3   $4               $5   $6
                elsif (/\G (\S) ((?:$qq_char)*?) (\1) ((?:$qq_char)*?) (\1) ([cdsrbB]*) /oxgc) { # tr * * *
                    my @tr = ($tr_variable,$2);
                    return e_tr(@tr,'',$4,$6);
                }
            }
            die __FILE__, ": Transliteration pattern not terminated\n";
        }
    }

# qq//
    elsif (/\G \b (qq) \b /oxgc) {
        my $ope = $1;

#       if (/\G (\#) ((?:$qq_char)*?) (\#) /oxgc) { return e_qq($ope,$1,$3,$2); } # qq# #
        if (/\G (\#) /oxgc) {                                                     # qq# #
            my $qq_string = '';
            while (not /\G \z/oxgc) {
                if    (/\G (\\\\)     /oxgc) { $qq_string .= $1;                     }
                elsif (/\G (\\\#)     /oxgc) { $qq_string .= $1;                     }
                elsif (/\G (\#)       /oxgc) { return e_qq($ope,'#','#',$qq_string); }
                elsif (/\G ($qq_char) /oxgc) { $qq_string .= $1;                     }
            }
            die __FILE__, ": Can't find string terminator anywhere before EOF\n";
        }

        else {
            my $e = '';
            while (not /\G \z/oxgc) {
                if    (/\G ((?>\s+)|\#.*)              /oxgc) { $e .= $1; }

#               elsif (/\G (\() ((?:$qq_paren)*?) (\)) /oxgc) { return $e . e_qq($ope,$1,$3,$2); } # qq ( )
                elsif (/\G (\() /oxgc) {                                                           # qq ( )
                    my $qq_string = '';
                    local $nest = 1;
                    while (not /\G \z/oxgc) {
                        if    (/\G (\\\\)     /oxgc) { $qq_string .= $1;                          }
                        elsif (/\G (\\\))     /oxgc) { $qq_string .= $1;                          }
                        elsif (/\G (\()       /oxgc) { $qq_string .= $1; $nest++;                 }
                        elsif (/\G (\))       /oxgc) {
                            if (--$nest == 0)        { return $e . e_qq($ope,'(',')',$qq_string); }
                            else                     { $qq_string .= $1;                          }
                        }
                        elsif (/\G ($qq_char) /oxgc) { $qq_string .= $1;                          }
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }

#               elsif (/\G (\{) ((?:$qq_brace)*?) (\}) /oxgc) { return $e . e_qq($ope,$1,$3,$2); } # qq { }
                elsif (/\G (\{) /oxgc) {                                                           # qq { }
                    my $qq_string = '';
                    local $nest = 1;
                    while (not /\G \z/oxgc) {
                        if    (/\G (\\\\)     /oxgc) { $qq_string .= $1;                          }
                        elsif (/\G (\\\})     /oxgc) { $qq_string .= $1;                          }
                        elsif (/\G (\{)       /oxgc) { $qq_string .= $1; $nest++;                 }
                        elsif (/\G (\})       /oxgc) {
                            if (--$nest == 0)        { return $e . e_qq($ope,'{','}',$qq_string); }
                            else                     { $qq_string .= $1;                          }
                        }
                        elsif (/\G ($qq_char) /oxgc) { $qq_string .= $1;                          }
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }

#               elsif (/\G (\[) ((?:$qq_bracket)*?) (\]) /oxgc) { return $e . e_qq($ope,$1,$3,$2); } # qq [ ]
                elsif (/\G (\[) /oxgc) {                                                             # qq [ ]
                    my $qq_string = '';
                    local $nest = 1;
                    while (not /\G \z/oxgc) {
                        if    (/\G (\\\\)     /oxgc) { $qq_string .= $1;                          }
                        elsif (/\G (\\\])     /oxgc) { $qq_string .= $1;                          }
                        elsif (/\G (\[)       /oxgc) { $qq_string .= $1; $nest++;                 }
                        elsif (/\G (\])       /oxgc) {
                            if (--$nest == 0)        { return $e . e_qq($ope,'[',']',$qq_string); }
                            else                     { $qq_string .= $1;                          }
                        }
                        elsif (/\G ($qq_char) /oxgc) { $qq_string .= $1;                          }
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }

#               elsif (/\G (\<) ((?:$qq_angle)*?) (\>) /oxgc) { return $e . e_qq($ope,$1,$3,$2); } # qq < >
                elsif (/\G (\<) /oxgc) {                                                           # qq < >
                    my $qq_string = '';
                    local $nest = 1;
                    while (not /\G \z/oxgc) {
                        if    (/\G (\\\\)     /oxgc) { $qq_string .= $1;                          }
                        elsif (/\G (\\\>)     /oxgc) { $qq_string .= $1;                          }
                        elsif (/\G (\<)       /oxgc) { $qq_string .= $1; $nest++;                 }
                        elsif (/\G (\>)       /oxgc) {
                            if (--$nest == 0)        { return $e . e_qq($ope,'<','>',$qq_string); }
                            else                     { $qq_string .= $1;                          }
                        }
                        elsif (/\G ($qq_char) /oxgc) { $qq_string .= $1;                          }
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }

#               elsif (/\G (\S) ((?:$qq_char)*?) (\1) /oxgc) { return $e . e_qq($ope,$1,$3,$2); } # qq * *
                elsif (/\G (\S) /oxgc) {                                                          # qq * *
                    my $delimiter = $1;
                    my $qq_string = '';
                    while (not /\G \z/oxgc) {
                        if    (/\G (\\\\)             /oxgc) { $qq_string .= $1;                                        }
                        elsif (/\G (\\\Q$delimiter\E) /oxgc) { $qq_string .= $1;                                        }
                        elsif (/\G (\Q$delimiter\E)   /oxgc) { return $e . e_qq($ope,$delimiter,$delimiter,$qq_string); }
                        elsif (/\G ($qq_char)         /oxgc) { $qq_string .= $1;                                        }
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }
            }
            die __FILE__, ": Can't find string terminator anywhere before EOF\n";
        }
    }

# qr//
    elsif (/\G \b (qr) \b /oxgc) {
        my $ope = $1;
        if (/\G (\#) ((?:$qq_char)*?) (\#) ([imosxpadlunbB]*) /oxgc) { # qr# # #
            return e_qr($ope,$1,$3,$2,$4);
        }
        else {
            my $e = '';
            while (not /\G \z/oxgc) {
                if    (/\G ((?>\s+)|\#.*)                                            /oxgc) { $e .= $1; }
                elsif (/\G (\()          ((?:$qq_paren)*?)   (\)) ([imosxpadlunbB]*) /oxgc) { return $e . e_qr  ($ope,$1, $3, $2,$4); } # qr ( )
                elsif (/\G (\{)          ((?:$qq_brace)*?)   (\}) ([imosxpadlunbB]*) /oxgc) { return $e . e_qr  ($ope,$1, $3, $2,$4); } # qr { }
                elsif (/\G (\[)          ((?:$qq_bracket)*?) (\]) ([imosxpadlunbB]*) /oxgc) { return $e . e_qr  ($ope,$1, $3, $2,$4); } # qr [ ]
                elsif (/\G (\<)          ((?:$qq_angle)*?)   (\>) ([imosxpadlunbB]*) /oxgc) { return $e . e_qr  ($ope,$1, $3, $2,$4); } # qr < >
                elsif (/\G (\')          ((?:$qq_char)*?)    (\') ([imosxpadlunbB]*) /oxgc) { return $e . e_qr_q($ope,$1, $3, $2,$4); } # qr ' '
                elsif (/\G ([*\-:?\\^|]) ((?:$qq_char)*?)    (\1) ([imosxpadlunbB]*) /oxgc) { return $e . e_qr  ($ope,'{','}',$2,$4); } # qr | | --> qr { }
                elsif (/\G (\S)          ((?:$qq_char)*?)    (\1) ([imosxpadlunbB]*) /oxgc) { return $e . e_qr  ($ope,$1, $3, $2,$4); } # qr * *
            }
            die __FILE__, ": Can't find string terminator anywhere before EOF\n";
        }
    }

# qw//
    elsif (/\G \b (qw) \b /oxgc) {
        my $ope = $1;
        if (/\G (\#) (.*?) (\#) /oxmsgc) { # qw# #
            return e_qw($ope,$1,$3,$2);
        }
        else {
            my $e = '';
            while (not /\G \z/oxgc) {
                if    (/\G ((?>\s+)|\#.*)                        /oxgc)   { $e .= $1; }

                elsif (/\G (\()          ([^(]*?)           (\)) /oxmsgc) { return $e . e_qw($ope,$1,$3,$2); } # qw ( )
                elsif (/\G (\()          ((?:$q_paren)*?)   (\)) /oxmsgc) { return $e . e_qw($ope,$1,$3,$2); } # qw ( )

                elsif (/\G (\{)          ([^{]*?)           (\}) /oxmsgc) { return $e . e_qw($ope,$1,$3,$2); } # qw { }
                elsif (/\G (\{)          ((?:$q_brace)*?)   (\}) /oxmsgc) { return $e . e_qw($ope,$1,$3,$2); } # qw { }

                elsif (/\G (\[)          ([^[]*?)           (\]) /oxmsgc) { return $e . e_qw($ope,$1,$3,$2); } # qw [ ]
                elsif (/\G (\[)          ((?:$q_bracket)*?) (\]) /oxmsgc) { return $e . e_qw($ope,$1,$3,$2); } # qw [ ]

                elsif (/\G (\<)          ([^<]*?)           (\>) /oxmsgc) { return $e . e_qw($ope,$1,$3,$2); } # qw < >
                elsif (/\G (\<)          ((?:$q_angle)*?)   (\>) /oxmsgc) { return $e . e_qw($ope,$1,$3,$2); } # qw < >

                elsif (/\G ([\x21-\x3F]) (.*?)              (\1) /oxmsgc) { return $e . e_qw($ope,$1,$3,$2); } # qw * *
                elsif (/\G (\S)          ((?:$q_char)*?)    (\1) /oxmsgc) { return $e . e_qw($ope,$1,$3,$2); } # qw * *
            }
            die __FILE__, ": Can't find string terminator anywhere before EOF\n";
        }
    }

# qx//
    elsif (/\G \b (qx) \b /oxgc) {
        my $ope = $1;
        if (/\G (\#) ((?:$qq_char)*?) (\#) /oxgc) { # qx# #
            return e_qq($ope,$1,$3,$2);
        }
        else {
            my $e = '';
            while (not /\G \z/oxgc) {
                if    (/\G ((?>\s+)|\#.*)                /oxgc) { $e .= $1; }
                elsif (/\G (\() ((?:$qq_paren)*?)   (\)) /oxgc) { return $e . e_qq($ope,$1,$3,$2); } # qx ( )
                elsif (/\G (\{) ((?:$qq_brace)*?)   (\}) /oxgc) { return $e . e_qq($ope,$1,$3,$2); } # qx { }
                elsif (/\G (\[) ((?:$qq_bracket)*?) (\]) /oxgc) { return $e . e_qq($ope,$1,$3,$2); } # qx [ ]
                elsif (/\G (\<) ((?:$qq_angle)*?)   (\>) /oxgc) { return $e . e_qq($ope,$1,$3,$2); } # qx < >
                elsif (/\G (\') ((?:$qq_char)*?)    (\') /oxgc) { return $e . e_q ($ope,$1,$3,$2); } # qx ' '
                elsif (/\G (\S) ((?:$qq_char)*?)    (\1) /oxgc) { return $e . e_qq($ope,$1,$3,$2); } # qx * *
            }
            die __FILE__, ": Can't find string terminator anywhere before EOF\n";
        }
    }

# q//
    elsif (/\G \b (q) \b /oxgc) {
        my $ope = $1;

#       if (/\G (\#) ((?:\\\#|\\\\|$q_char)*?) (\#) /oxgc) { return e_q($ope,$1,$3,$2); } # q# #

        # avoid "Error: Runtime exception" of perl version 5.005_03
        # (and so on)

        if (/\G (\#) /oxgc) {                                                             # q# #
            my $q_string = '';
            while (not /\G \z/oxgc) {
                if    (/\G (\\\\)    /oxgc) { $q_string .= $1;                    }
                elsif (/\G (\\\#)    /oxgc) { $q_string .= $1;                    }
                elsif (/\G (\#)      /oxgc) { return e_q($ope,'#','#',$q_string); }
                elsif (/\G ($q_char) /oxgc) { $q_string .= $1;                    }
            }
            die __FILE__, ": Can't find string terminator anywhere before EOF\n";
        }

        else {
            my $e = '';
            while (not /\G \z/oxgc) {
                if    (/\G ((?>\s+)|\#.*)                       /oxgc) { $e .= $1; }

#               elsif (/\G (\() ((?:\\\)|\\\\|$q_paren)*?) (\)) /oxgc) { return $e . e_q($ope,$1,$3,$2); } # q ( )
                elsif (/\G (\() /oxgc) {                                                                   # q ( )
                    my $q_string = '';
                    local $nest = 1;
                    while (not /\G \z/oxgc) {
                        if    (/\G (\\\\)    /oxgc) { $q_string .= $1;                         }
                        elsif (/\G (\\\))    /oxgc) { $q_string .= $1;                         }
                        elsif (/\G (\\\()    /oxgc) { $q_string .= $1;                         }
                        elsif (/\G (\()      /oxgc) { $q_string .= $1; $nest++;                }
                        elsif (/\G (\))      /oxgc) {
                            if (--$nest == 0)       { return $e . e_q($ope,'(',')',$q_string); }
                            else                    { $q_string .= $1;                         }
                        }
                        elsif (/\G ($q_char) /oxgc) { $q_string .= $1;                         }
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }

#               elsif (/\G (\{) ((?:\\\}|\\\\|$q_brace)*?) (\}) /oxgc) { return $e . e_q($ope,$1,$3,$2); } # q { }
                elsif (/\G (\{) /oxgc) {                                                                   # q { }
                    my $q_string = '';
                    local $nest = 1;
                    while (not /\G \z/oxgc) {
                        if    (/\G (\\\\)    /oxgc) { $q_string .= $1;                         }
                        elsif (/\G (\\\})    /oxgc) { $q_string .= $1;                         }
                        elsif (/\G (\\\{)    /oxgc) { $q_string .= $1;                         }
                        elsif (/\G (\{)      /oxgc) { $q_string .= $1; $nest++;                }
                        elsif (/\G (\})      /oxgc) {
                            if (--$nest == 0)       { return $e . e_q($ope,'{','}',$q_string); }
                            else                    { $q_string .= $1;                         }
                        }
                        elsif (/\G ($q_char) /oxgc) { $q_string .= $1;                         }
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }

#               elsif (/\G (\[) ((?:\\\]|\\\\|$q_bracket)*?) (\]) /oxgc) { return $e . e_q($ope,$1,$3,$2); } # q [ ]
                elsif (/\G (\[) /oxgc) {                                                                     # q [ ]
                    my $q_string = '';
                    local $nest = 1;
                    while (not /\G \z/oxgc) {
                        if    (/\G (\\\\)    /oxgc) { $q_string .= $1;                         }
                        elsif (/\G (\\\])    /oxgc) { $q_string .= $1;                         }
                        elsif (/\G (\\\[)    /oxgc) { $q_string .= $1;                         }
                        elsif (/\G (\[)      /oxgc) { $q_string .= $1; $nest++;                }
                        elsif (/\G (\])      /oxgc) {
                            if (--$nest == 0)       { return $e . e_q($ope,'[',']',$q_string); }
                            else                    { $q_string .= $1;                         }
                        }
                        elsif (/\G ($q_char) /oxgc) { $q_string .= $1;                         }
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }

#               elsif (/\G (\<) ((?:\\\>|\\\\|$q_angle)*?) (\>) /oxgc) { return $e . e_q($ope,$1,$3,$2); } # q < >
                elsif (/\G (\<) /oxgc) {                                                                   # q < >
                    my $q_string = '';
                    local $nest = 1;
                    while (not /\G \z/oxgc) {
                        if    (/\G (\\\\)    /oxgc) { $q_string .= $1;                         }
                        elsif (/\G (\\\>)    /oxgc) { $q_string .= $1;                         }
                        elsif (/\G (\\\<)    /oxgc) { $q_string .= $1;                         }
                        elsif (/\G (\<)      /oxgc) { $q_string .= $1; $nest++;                }
                        elsif (/\G (\>)      /oxgc) {
                            if (--$nest == 0)       { return $e . e_q($ope,'<','>',$q_string); }
                            else                    { $q_string .= $1;                         }
                        }
                        elsif (/\G ($q_char) /oxgc) { $q_string .= $1;                         }
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }

#               elsif (/\G (\S) ((?:\\\1|\\\\|$q_char)*?) (\1) /oxgc) { return $e . e_q($ope,$1,$3,$2); } # q * *
                elsif (/\G (\S) /oxgc) {                                                                  # q * *
                    my $delimiter = $1;
                    my $q_string = '';
                    while (not /\G \z/oxgc) {
                        if    (/\G (\\\\)             /oxgc) { $q_string .= $1;                                       }
                        elsif (/\G (\\\Q$delimiter\E) /oxgc) { $q_string .= $1;                                       }
                        elsif (/\G (\Q$delimiter\E)   /oxgc) { return $e . e_q($ope,$delimiter,$delimiter,$q_string); }
                        elsif (/\G ($q_char)          /oxgc) { $q_string .= $1;                                       }
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }
            }
            die __FILE__, ": Can't find string terminator anywhere before EOF\n";
        }
    }

# m//
    elsif (/\G \b (m) \b /oxgc) {
        my $ope = $1;
        if (/\G (\#) ((?:$qq_char)*?) (\#) ([cgimosxpadlunbB]*) /oxgc) { # m# #
            return e_qr($ope,$1,$3,$2,$4);
        }
        else {
            my $e = '';
            while (not /\G \z/oxgc) {
                if    (/\G ((?>\s+)|\#.*)                                             /oxgc) { $e .= $1; }
                elsif (/\G (\()         ((?:$qq_paren)*?)   (\)) ([cgimosxpadlunbB]*) /oxgc) { return $e . e_qr  ($ope,$1, $3, $2,$4); } # m ( )
                elsif (/\G (\{)         ((?:$qq_brace)*?)   (\}) ([cgimosxpadlunbB]*) /oxgc) { return $e . e_qr  ($ope,$1, $3, $2,$4); } # m { }
                elsif (/\G (\[)         ((?:$qq_bracket)*?) (\]) ([cgimosxpadlunbB]*) /oxgc) { return $e . e_qr  ($ope,$1, $3, $2,$4); } # m [ ]
                elsif (/\G (\<)         ((?:$qq_angle)*?)   (\>) ([cgimosxpadlunbB]*) /oxgc) { return $e . e_qr  ($ope,$1, $3, $2,$4); } # m < >
                elsif (/\G (\?)         ((?:$qq_char)*?)    (\?) ([cgimosxpadlunbB]*) /oxgc) { return $e . e_qr  ($ope,$1, $3, $2,$4); } # m ? ?
                elsif (/\G (\')         ((?:$qq_char)*?)    (\') ([cgimosxpadlunbB]*) /oxgc) { return $e . e_qr_q($ope,$1, $3, $2,$4); } # m ' '
                elsif (/\G ([*\-:\\^|]) ((?:$qq_char)*?)    (\1) ([cgimosxpadlunbB]*) /oxgc) { return $e . e_qr  ($ope,'{','}',$2,$4); } # m | | --> m { }
                elsif (/\G (\S)         ((?:$qq_char)*?)    (\1) ([cgimosxpadlunbB]*) /oxgc) { return $e . e_qr  ($ope,$1, $3, $2,$4); } # m * *
            }
            die __FILE__, ": Search pattern not terminated\n";
        }
    }

# s///

    # about [cegimosxpradlunbB]* (/cg modifier)
    #
    # P.67 Pattern-Matching Operators
    # of ISBN 0-596-00241-6 Perl in a Nutshell, Second Edition.

    elsif (/\G \b (s) \b /oxgc) {
        my $ope = $1;

        #        $1   $2               $3   $4               $5   $6
        if (/\G (\#) ((?:$qq_char)*?) (\#) ((?:$qq_char)*?) (\#) ([cegimosxpradlunbB]*) /oxgc) { # s# # #
            return e_sub($sub_variable,$1,$2,$3,$3,$4,$5,$6);
        }
        else {
            my $e = '';
            while (not /\G \z/oxgc) {
                if (/\G ((?>\s+)|\#.*) /oxgc) { $e .= $1; }
                elsif (/\G (\() ((?:$qq_paren)*?) (\)) /oxgc) {
                    my @s = ($1,$2,$3);
                    while (not /\G \z/oxgc) {
                        if    (/\G ((?>\s+)|\#.*)                                       /oxgc) { $e .= $1; }
                        #           $1   $2                  $3   $4
                        elsif (/\G (\() ((?:$qq_paren)*?)   (\)) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\{) ((?:$qq_brace)*?)   (\}) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\[) ((?:$qq_bracket)*?) (\]) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\<) ((?:$qq_angle)*?)   (\>) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\') ((?:$qq_char)*?)    (\') ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\$) ((?:$qq_char)*?)    (\$) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\:) ((?:$qq_char)*?)    (\:) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\@) ((?:$qq_char)*?)    (\@) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\S) ((?:$qq_char)*?)    (\1) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                    }
                    die __FILE__, ": Substitution replacement not terminated\n";
                }
                elsif (/\G (\{) ((?:$qq_brace)*?) (\}) /oxgc) {
                    my @s = ($1,$2,$3);
                    while (not /\G \z/oxgc) {
                        if    (/\G ((?>\s+)|\#.*)                                       /oxgc) { $e .= $1; }
                        #           $1   $2                  $3   $4
                        elsif (/\G (\() ((?:$qq_paren)*?)   (\)) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\{) ((?:$qq_brace)*?)   (\}) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\[) ((?:$qq_bracket)*?) (\]) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\<) ((?:$qq_angle)*?)   (\>) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\') ((?:$qq_char)*?)    (\') ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\$) ((?:$qq_char)*?)    (\$) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\:) ((?:$qq_char)*?)    (\:) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\@) ((?:$qq_char)*?)    (\@) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\S) ((?:$qq_char)*?)    (\1) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                    }
                    die __FILE__, ": Substitution replacement not terminated\n";
                }
                elsif (/\G (\[) ((?:$qq_bracket)*?) (\]) /oxgc) {
                    my @s = ($1,$2,$3);
                    while (not /\G \z/oxgc) {
                        if    (/\G ((?>\s+)|\#.*)                                       /oxgc) { $e .= $1; }
                        #           $1   $2                  $3   $4
                        elsif (/\G (\() ((?:$qq_paren)*?)   (\)) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\{) ((?:$qq_brace)*?)   (\}) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\[) ((?:$qq_bracket)*?) (\]) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\<) ((?:$qq_angle)*?)   (\>) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\') ((?:$qq_char)*?)    (\') ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\$) ((?:$qq_char)*?)    (\$) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\S) ((?:$qq_char)*?)    (\1) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                    }
                    die __FILE__, ": Substitution replacement not terminated\n";
                }
                elsif (/\G (\<) ((?:$qq_angle)*?) (\>) /oxgc) {
                    my @s = ($1,$2,$3);
                    while (not /\G \z/oxgc) {
                        if    (/\G ((?>\s+)|\#.*)                                       /oxgc) { $e .= $1; }
                        #           $1   $2                  $3   $4
                        elsif (/\G (\() ((?:$qq_paren)*?)   (\)) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\{) ((?:$qq_brace)*?)   (\}) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\[) ((?:$qq_bracket)*?) (\]) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\<) ((?:$qq_angle)*?)   (\>) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\') ((?:$qq_char)*?)    (\') ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\$) ((?:$qq_char)*?)    (\$) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\:) ((?:$qq_char)*?)    (\:) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\@) ((?:$qq_char)*?)    (\@) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                        elsif (/\G (\S) ((?:$qq_char)*?)    (\1) ([cegimosxpradlunbB]*) /oxgc) { return e_sub($sub_variable,@s,$1,$2,$3,$4); }
                    }
                    die __FILE__, ": Substitution replacement not terminated\n";
                }
                #           $1   $2               $3   $4               $5   $6
                elsif (/\G (\') ((?:$qq_char)*?) (\') ((?:$qq_char)*?) (\') ([cegimosxpradlunbB]*) /oxgc) {
                    return e_sub($sub_variable,$1,$2,$3,$3,$4,$5,$6);
                }
                #           $1            $2               $3   $4               $5   $6
                elsif (/\G ([*\-:?\\^|]) ((?:$qq_char)*?) (\1) ((?:$qq_char)*?) (\1) ([cegimosxpradlunbB]*) /oxgc) {
                    return e_sub($sub_variable,'{',$2,'}','{',$4,'}',$6); # s | | | --> s { } { }
                }
                #           $1   $2               $3   $4               $5   $6
                elsif (/\G (\$) ((?:$qq_char)*?) (\1) ((?:$qq_char)*?) (\1) ([cegimosxpradlunbB]*) /oxgc) {
                    return e_sub($sub_variable,$1,$2,$3,$3,$4,$5,$6);
                }
                #           $1   $2               $3   $4               $5   $6
                elsif (/\G (\S) ((?:$qq_char)*?) (\1) ((?:$qq_char)*?) (\1) ([cegimosxpradlunbB]*) /oxgc) {
                    return e_sub($sub_variable,$1,$2,$3,$3,$4,$5,$6);
                }
            }
            die __FILE__, ": Substitution pattern not terminated\n";
        }
    }

# do
    elsif (/\G \b do (?= (?>\s*) \{ )                                                         /oxmsgc) { return 'do';                }
    elsif (/\G \b do (?= (?>\s+) (?: q | qq | qx ) \b)                                        /oxmsgc) { return 'Euhc::do';         }
    elsif (/\G \b do (?= (?>\s+) (?>\w+))                                                     /oxmsgc) { return 'do';                }
    elsif (/\G \b do (?= (?>\s*) \$ (?> \w+ (?: ::\w+)* ) \( )                                /oxmsgc) { return 'do';                }
    elsif (/\G \b do \b                                                                       /oxmsgc) { return 'Euhc::do';         }

# require ignore module
    elsif (/\G \b require ((?>\s+) (?:$ignore_modules) .*? ;) ([ \t]* [#\n])                  /oxmsgc) { return "# require$1$2";     }
    elsif (/\G \b require ((?>\s+) (?:$ignore_modules) .*? ;) ([ \t]* [^\x81-\xFE#]) /oxmsgc) { return "# require$1\n$2";   }
    elsif (/\G \b require ((?>\s+) (?:$ignore_modules)) \b                                    /oxmsgc) { return "# require$1";       }

# require version number
    elsif (/\G \b require (?>\s+) ((?>0[0-7_]*))                    (?>\s*) ;                 /oxmsgc) { return "require $1;";       }
    elsif (/\G \b require (?>\s+) ((?>[1-9][0-9_]*(?:\.[0-9_]+)*))  (?>\s*) ;                 /oxmsgc) { return "require $1;";       }
    elsif (/\G \b require (?>\s+) ((?>v[0-9][0-9_]*(?:\.[0-9_]+)*)) (?>\s*) ;                 /oxmsgc) { return "require $1;";       }

# require bare package name
    elsif (/\G \b require (?>\s+) ((?>[A-Za-z_]\w* (?: :: [A-Za-z_]\w*)*)) (?>\s*) ;          /oxmsgc) { return "require $1;";       }

# require else
    elsif (/\G \b require                                       (?>\s*) ;                     /oxmsgc) { return 'Euhc::require;';   }
    elsif (/\G \b require \b                                                                  /oxmsgc) { return 'Euhc::require';    }

# use strict; --> use strict; no strict qw(refs);
    elsif (/\G \b use ((?>\s+) strict .*? ;) ([ \t]* [#\n])                                   /oxmsgc) { return "use$1 no strict qw(refs);$2";   }
    elsif (/\G \b use ((?>\s+) strict .*? ;) ([ \t]* [^\x81-\xFE#])                  /oxmsgc) { return "use$1 no strict qw(refs);\n$2"; }
    elsif (/\G \b use ((?>\s+) strict) \b                                                     /oxmsgc) { return "use$1; no strict qw(refs)";     }

# use 5.12.0; --> use 5.12.0; no strict qw(refs);
    elsif (/\G \b use (?>\s+) ((?>([1-9][0-9_]*)(?:\.([0-9_]+))*))  (?>\s*) ; /oxmsgc) {
        if (($2 >= 6) or (($2 == 5) and ($3 ge '012'))) {
            return "use $1; no strict qw(refs);";
        }
        else {
            return "use $1;";
        }
    }
    elsif (/\G \b use (?>\s+) ((?>v([0-9][0-9_]*)(?:\.([0-9_]+))*)) (?>\s*) ; /oxmsgc) {
        if (($2 >= 6) or (($2 == 5) and ($3 >= 12))) {
            return "use $1; no strict qw(refs);";
        }
        else {
            return "use $1;";
        }
    }

# ignore use module
    elsif (/\G \b use ((?>\s+) (?:$ignore_modules) .*? ;) ([ \t]* [#\n])                  /oxmsgc) { return "# use$1$2";         }
    elsif (/\G \b use ((?>\s+) (?:$ignore_modules) .*? ;) ([ \t]* [^\x81-\xFE#]) /oxmsgc) { return "# use$1\n$2";       }
    elsif (/\G \b use ((?>\s+) (?:$ignore_modules)) \b                                    /oxmsgc) { return "# use$1";           }

# ignore no module
    elsif (/\G \b no  ((?>\s+) (?:$ignore_modules) .*? ;) ([ \t]* [#\n])                  /oxmsgc) { return "# no$1$2";          }
    elsif (/\G \b no  ((?>\s+) (?:$ignore_modules) .*? ;) ([ \t]* [^\x81-\xFE#]) /oxmsgc) { return "# no$1\n$2";        }
    elsif (/\G \b no  ((?>\s+) (?:$ignore_modules)) \b                                    /oxmsgc) { return "# no$1";            }

# use without import
    elsif (/\G \b use (?>\s+) ((?>0[0-7_]*))                                                        (?>\s*) ; /oxmsgc) { return "use $1;";           }
    elsif (/\G \b use (?>\s+) ((?>[1-9][0-9_]*(?:\.[0-9_]+)*))                                      (?>\s*) ; /oxmsgc) { return "use $1;";           }
    elsif (/\G \b use (?>\s+) ((?>v[0-9][0-9_]*(?:\.[0-9_]+)*))                                     (?>\s*) ; /oxmsgc) { return "use $1;";           }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s*)            (\()          (?>\s*) \) (?>\s*) ; /oxmsgc) { return e_use_noimport($1);  }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) qw (?>\s*) (\()          (?>\s*) \) (?>\s*) ; /oxmsgc) { return e_use_noimport($1);  }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) qw (?>\s*) (\{)          (?>\s*) \} (?>\s*) ; /oxmsgc) { return e_use_noimport($1);  }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) qw (?>\s*) (\[)          (?>\s*) \] (?>\s*) ; /oxmsgc) { return e_use_noimport($1);  }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) qw (?>\s*) (\<)          (?>\s*) \> (?>\s*) ; /oxmsgc) { return e_use_noimport($1);  }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) qw (?>\s*) ([\x21-\x3F]) (?>\s*) \2 (?>\s*) ; /oxmsgc) { return e_use_noimport($1);  }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) qw (?>\s*) (\S)          (?>\s*) \2 (?>\s*) ; /oxmsgc) { return e_use_noimport($1);  }

# use with import no parameter
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*))                                             (?>\s*) ; /oxmsgc) { return e_use_noparam($1);   }

# use with import parameters
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s*) (                          (\()    [^\x81-\xFE)]* \)) (?>\s*) ; /oxmsgc) { return e_use($1,$2); }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s*) (                          (\')    [^\x81-\xFE']* \') (?>\s*) ; /oxmsgc) { return e_use($1,$2); }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s*) (                          (\")    [^\x81-\xFE"]* \") (?>\s*) ; /oxmsgc) { return e_use($1,$2); }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) ((?: q | qq | qw ) (?>\s*) (\()    [^\x81-\xFE)]* \)) (?>\s*) ; /oxmsgc) { return e_use($1,$2); }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) ((?: q | qq | qw ) (?>\s*) (\{)    (?:$q_char)*?           \}) (?>\s*) ; /oxmsgc) { return e_use($1,$2); }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) ((?: q | qq | qw ) (?>\s*) (\[)    (?:$q_char)*?           \]) (?>\s*) ; /oxmsgc) { return e_use($1,$2); }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) ((?: q | qq | qw ) (?>\s*) (\<)    [^\x81-\xFE>]* \>) (?>\s*) ; /oxmsgc) { return e_use($1,$2); }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) ((?: q | qq | qw ) (?>\s*) ([\x21-\x3F]) .*?               \3) (?>\s*) ; /oxmsgc) { return e_use($1,$2); }
    elsif (/\G \b use (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) ((?: q | qq | qw ) (?>\s*) (\S)    (?:$q_char)*?           \3) (?>\s*) ; /oxmsgc) { return e_use($1,$2); }

# no without unimport
    elsif (/\G \b no  (?>\s+) ((?>0[0-7_]*))                                                        (?>\s*) ; /oxmsgc) { return "no $1;";            }
    elsif (/\G \b no  (?>\s+) ((?>[1-9][0-9_]*(?:\.[0-9_]+)*))                                      (?>\s*) ; /oxmsgc) { return "no $1;";            }
    elsif (/\G \b no  (?>\s+) ((?>v[0-9][0-9_]*(?:\.[0-9_]+)*))                                     (?>\s*) ; /oxmsgc) { return "no $1;";            }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s*)            (\()          (?>\s*) \) (?>\s*) ; /oxmsgc) { return e_no_nounimport($1); }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) qw (?>\s*) (\()          (?>\s*) \) (?>\s*) ; /oxmsgc) { return e_no_nounimport($1); }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) qw (?>\s*) (\{)          (?>\s*) \} (?>\s*) ; /oxmsgc) { return e_no_nounimport($1); }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) qw (?>\s*) (\[)          (?>\s*) \] (?>\s*) ; /oxmsgc) { return e_no_nounimport($1); }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) qw (?>\s*) (\<)          (?>\s*) \> (?>\s*) ; /oxmsgc) { return e_no_nounimport($1); }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) qw (?>\s*) ([\x21-\x3F]) (?>\s*) \2 (?>\s*) ; /oxmsgc) { return e_no_nounimport($1); }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) qw (?>\s*) (\S)          (?>\s*) \2 (?>\s*) ; /oxmsgc) { return e_no_nounimport($1); }

# no with unimport no parameter
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*))                                             (?>\s*) ; /oxmsgc) { return e_no_noparam($1);    }

# no with unimport parameters
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s*) (                          (\()    [^\x81-\xFE)]* \)) (?>\s*) ; /oxmsgc) { return e_no($1,$2);  }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s*) (                          (\')    [^\x81-\xFE']* \') (?>\s*) ; /oxmsgc) { return e_no($1,$2);  }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s*) (                          (\")    [^\x81-\xFE"]* \") (?>\s*) ; /oxmsgc) { return e_no($1,$2);  }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) ((?: q | qq | qw ) (?>\s*) (\()    [^\x81-\xFE)]* \)) (?>\s*) ; /oxmsgc) { return e_no($1,$2);  }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) ((?: q | qq | qw ) (?>\s*) (\{)    (?:$q_char)*?           \}) (?>\s*) ; /oxmsgc) { return e_no($1,$2);  }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) ((?: q | qq | qw ) (?>\s*) (\[)    (?:$q_char)*?           \]) (?>\s*) ; /oxmsgc) { return e_no($1,$2);  }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) ((?: q | qq | qw ) (?>\s*) (\<)    [^\x81-\xFE>]* \>) (?>\s*) ; /oxmsgc) { return e_no($1,$2);  }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) ((?: q | qq | qw ) (?>\s*) ([\x21-\x3F]) .*?               \3) (?>\s*) ; /oxmsgc) { return e_no($1,$2);  }
    elsif (/\G \b no  (?>\s+) ((?>[A-Z]\w*(?: ::\w+)*)) (?>\s+) ((?: q | qq | qw ) (?>\s*) (\S)    (?:$q_char)*?           \3) (?>\s*) ; /oxmsgc) { return e_no($1,$2);  }

# use else
    elsif (/\G \b use \b /oxmsgc) { return "use"; }

# use else
    elsif (/\G \b no  \b /oxmsgc) { return "no";  }

# ''
    elsif (/\G (?
        my $q_string = '';
        while (not /\G \z/oxgc) {
            if    (/\G (\\\\)                  /oxgc) { $q_string .= $1;                   }
            elsif (/\G (\\\')                  /oxgc) { $q_string .= $1;                   }
            elsif (/\G \'                      /oxgc) { return e_q('', "'","'",$q_string); }
            elsif (/\G ($q_char)               /oxgc) { $q_string .= $1;                   }
        }
        die __FILE__, ": Can't find string terminator anywhere before EOF\n";
    }

# ""
    elsif (/\G (\") /oxgc) {
        my $qq_string = '';
        while (not /\G \z/oxgc) {
            if    (/\G (\\\\)                  /oxgc) { $qq_string .= $1;                    }
            elsif (/\G (\\\")                  /oxgc) { $qq_string .= $1;                    }
            elsif (/\G \"                      /oxgc) { return e_qq('', '"','"',$qq_string); }
            elsif (/\G ($q_char)               /oxgc) { $qq_string .= $1;                    }
        }
        die __FILE__, ": Can't find string terminator anywhere before EOF\n";
    }

# ``
    elsif (/\G (\`) /oxgc) {
        my $qx_string = '';
        while (not /\G \z/oxgc) {
            if    (/\G (\\\\)                  /oxgc) { $qx_string .= $1;                    }
            elsif (/\G (\\\`)                  /oxgc) { $qx_string .= $1;                    }
            elsif (/\G \`                      /oxgc) { return e_qq('', '`','`',$qx_string); }
            elsif (/\G ($q_char)               /oxgc) { $qx_string .= $1;                    }
        }
        die __FILE__, ": Can't find string terminator anywhere before EOF\n";
    }

# //   --- not divide operator (num / num), not defined-or
    elsif (($slash eq 'm//') and /\G (\/) /oxgc) {
        my $regexp = '';
        while (not /\G \z/oxgc) {
            if    (/\G (\\\\)                  /oxgc) { $regexp .= $1;                       }
            elsif (/\G (\\\/)                  /oxgc) { $regexp .= $1;                       }
            elsif (/\G \/ ([cgimosxpadlunbB]*) /oxgc) { return e_qr('', '/','/',$regexp,$1); }
            elsif (/\G ($q_char)               /oxgc) { $regexp .= $1;                       }
        }
        die __FILE__, ": Search pattern not terminated\n";
    }

# ??   --- not conditional operator (condition ? then : else)
    elsif (($slash eq 'm//') and /\G (\?) /oxgc) {
        my $regexp = '';
        while (not /\G \z/oxgc) {
            if    (/\G (\\\\)                  /oxgc) { $regexp .= $1;                       }
            elsif (/\G (\\\?)                  /oxgc) { $regexp .= $1;                       }
            elsif (/\G \? ([cgimosxpadlunbB]*) /oxgc) { return e_qr('m','?','?',$regexp,$1); }
            elsif (/\G ($q_char)               /oxgc) { $regexp .= $1;                       }
        }
        die __FILE__, ": Search pattern not terminated\n";
    }

# <<>> (a safer ARGV)
    elsif (/\G ( <<>> ) /oxgc)                         { $slash = 'm//'; return $1;          }

# << (bit shift)   --- not here document
    elsif (/\G ( << (?>\s*) ) (?= [0-9\$\@\&] ) /oxgc) { $slash = 'm//'; return $1;          }

# <<~'HEREDOC'
    elsif (/\G ( <<~ [\t ]* '([a-zA-Z_0-9]*)' ) /oxgc) {
        $slash = 'm//';
        my $here_quote = $1;
        my $delimiter  = $2;

        # get here document
        if ($here_script eq '') {
            $here_script = CORE::substr $_, pos $_;
            $here_script =~ s/.*?\n//oxm;
        }
        if ($here_script =~ s/\A (.*?) \n ([\t ]*) $delimiter \n //xms) {
            my $heredoc = $1;
            my $indent  = $2;
            $heredoc =~ s{^$indent}{}msg; # no /ox
            push @heredoc, $heredoc . qq{\n$delimiter\n};
            push @heredoc_delimiter, qq{\\s*$delimiter};
        }
        else {
            die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
        }
        return qq{<<'$delimiter'};
    }

# <<~\HEREDOC

    # P.66 2.6.6. "Here" Documents
    # in Chapter 2: Bits and Pieces
    # of ISBN 0-596-00027-8 Programming Perl Third Edition.

    # P.73 "Here" Documents
    # in Chapter 2: Bits and Pieces
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    elsif (/\G ( <<~ \\([a-zA-Z_0-9]+) ) /oxgc) {
        $slash = 'm//';
        my $here_quote = $1;
        my $delimiter  = $2;

        # get here document
        if ($here_script eq '') {
            $here_script = CORE::substr $_, pos $_;
            $here_script =~ s/.*?\n//oxm;
        }
        if ($here_script =~ s/\A (.*?) \n ([\t ]*) $delimiter \n //xms) {
            my $heredoc = $1;
            my $indent  = $2;
            $heredoc =~ s{^$indent}{}msg; # no /ox
            push @heredoc, $heredoc . qq{\n$delimiter\n};
            push @heredoc_delimiter, qq{\\s*$delimiter};
        }
        else {
            die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
        }
        return qq{<<\\$delimiter};
    }

# <<~"HEREDOC"
    elsif (/\G ( <<~ [\t ]* "([a-zA-Z_0-9]*)" ) /oxgc) {
        $slash = 'm//';
        my $here_quote = $1;
        my $delimiter  = $2;

        # get here document
        if ($here_script eq '') {
            $here_script = CORE::substr $_, pos $_;
            $here_script =~ s/.*?\n//oxm;
        }
        if ($here_script =~ s/\A (.*?) \n ([\t ]*) $delimiter \n //xms) {
            my $heredoc = $1;
            my $indent  = $2;
            $heredoc =~ s{^$indent}{}msg; # no /ox
            push @heredoc, e_heredoc($heredoc) . qq{\n$delimiter\n};
            push @heredoc_delimiter, qq{\\s*$delimiter};
        }
        else {
            die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
        }
        return qq{<<"$delimiter"};
    }

# <<~HEREDOC
    elsif (/\G ( <<~ ([a-zA-Z_0-9]+) ) /oxgc) {
        $slash = 'm//';
        my $here_quote = $1;
        my $delimiter  = $2;

        # get here document
        if ($here_script eq '') {
            $here_script = CORE::substr $_, pos $_;
            $here_script =~ s/.*?\n//oxm;
        }
        if ($here_script =~ s/\A (.*?) \n ([\t ]*) $delimiter \n //xms) {
            my $heredoc = $1;
            my $indent  = $2;
            $heredoc =~ s{^$indent}{}msg; # no /ox
            push @heredoc, e_heredoc($heredoc) . qq{\n$delimiter\n};
            push @heredoc_delimiter, qq{\\s*$delimiter};
        }
        else {
            die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
        }
        return qq{<<$delimiter};
    }

# <<~`HEREDOC`
    elsif (/\G ( <<~ [\t ]* `([a-zA-Z_0-9]*)` ) /oxgc) {
        $slash = 'm//';
        my $here_quote = $1;
        my $delimiter  = $2;

        # get here document
        if ($here_script eq '') {
            $here_script = CORE::substr $_, pos $_;
            $here_script =~ s/.*?\n//oxm;
        }
        if ($here_script =~ s/\A (.*?) \n ([\t ]*) $delimiter \n //xms) {
            my $heredoc = $1;
            my $indent  = $2;
            $heredoc =~ s{^$indent}{}msg; # no /ox
            push @heredoc, e_heredoc($heredoc) . qq{\n$delimiter\n};
            push @heredoc_delimiter, qq{\\s*$delimiter};
        }
        else {
            die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
        }
        return qq{<<`$delimiter`};
    }

# <<'HEREDOC'
    elsif (/\G ( << '([a-zA-Z_0-9]*)' ) /oxgc) {
        $slash = 'm//';
        my $here_quote = $1;
        my $delimiter  = $2;

        # get here document
        if ($here_script eq '') {
            $here_script = CORE::substr $_, pos $_;
            $here_script =~ s/.*?\n//oxm;
        }
        if ($here_script =~ s/\A (.*?) \n $delimiter \n //xms) {
            push @heredoc, $1 . qq{\n$delimiter\n};
            push @heredoc_delimiter, $delimiter;
        }
        else {
            die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
        }
        return $here_quote;
    }

# <<\HEREDOC

    # P.66 2.6.6. "Here" Documents
    # in Chapter 2: Bits and Pieces
    # of ISBN 0-596-00027-8 Programming Perl Third Edition.

    # P.73 "Here" Documents
    # in Chapter 2: Bits and Pieces
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    elsif (/\G ( << \\([a-zA-Z_0-9]+) ) /oxgc) {
        $slash = 'm//';
        my $here_quote = $1;
        my $delimiter  = $2;

        # get here document
        if ($here_script eq '') {
            $here_script = CORE::substr $_, pos $_;
            $here_script =~ s/.*?\n//oxm;
        }
        if ($here_script =~ s/\A (.*?) \n $delimiter \n //xms) {
            push @heredoc, $1 . qq{\n$delimiter\n};
            push @heredoc_delimiter, $delimiter;
        }
        else {
            die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
        }
        return $here_quote;
    }

# <<"HEREDOC"
    elsif (/\G ( << "([a-zA-Z_0-9]*)" ) /oxgc) {
        $slash = 'm//';
        my $here_quote = $1;
        my $delimiter  = $2;

        # get here document
        if ($here_script eq '') {
            $here_script = CORE::substr $_, pos $_;
            $here_script =~ s/.*?\n//oxm;
        }
        if ($here_script =~ s/\A (.*?) \n $delimiter \n //xms) {
            push @heredoc, e_heredoc($1) . qq{\n$delimiter\n};
            push @heredoc_delimiter, $delimiter;
        }
        else {
            die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
        }
        return $here_quote;
    }

# <
    elsif (/\G ( << ([a-zA-Z_0-9]+) ) /oxgc) {
        $slash = 'm//';
        my $here_quote = $1;
        my $delimiter  = $2;

        # get here document
        if ($here_script eq '') {
            $here_script = CORE::substr $_, pos $_;
            $here_script =~ s/.*?\n//oxm;
        }
        if ($here_script =~ s/\A (.*?) \n $delimiter \n //xms) {
            push @heredoc, e_heredoc($1) . qq{\n$delimiter\n};
            push @heredoc_delimiter, $delimiter;
        }
        else {
            die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
        }
        return $here_quote;
    }

# <<`HEREDOC`
    elsif (/\G ( << `([a-zA-Z_0-9]*)` ) /oxgc) {
        $slash = 'm//';
        my $here_quote = $1;
        my $delimiter  = $2;

        # get here document
        if ($here_script eq '') {
            $here_script = CORE::substr $_, pos $_;
            $here_script =~ s/.*?\n//oxm;
        }
        if ($here_script =~ s/\A (.*?) \n $delimiter \n //xms) {
            push @heredoc, e_heredoc($1) . qq{\n$delimiter\n};
            push @heredoc_delimiter, $delimiter;
        }
        else {
            die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
        }
        return $here_quote;
    }

# <<= <=> <= < operator
    elsif (/\G ( <<= | <=> | <= | < ) (?= (?>\s*) [A-Za-z_0-9'"`\$\@\&\*\(\+\-] )/oxgc) {
        return $1;
    }

#
    elsif (/\G (<[\$]?[A-Za-z_][A-Za-z_0-9]*>) /oxgc) {
        return $1;
    }

#  --- glob

    # avoid "Error: Runtime exception" of perl version 5.005_03

    elsif (/\G < ((?:[^\x81-\xFE>\0\a\e\f\n\r\t]|[\x81-\xFE][\x00-\xFF])+?) > /oxgc) {
        return 'Euhc::glob("' . $1 . '")';
    }

# __DATA__
    elsif (/\G ^ ( __DATA__ \n .*) \z /oxmsgc) { return $1; }

# __END__
    elsif (/\G ^ ( __END__  \n .*) \z /oxmsgc) { return $1; }

# \cD Control-D

    # P.68 2.6.8. Other Literal Tokens
    # in Chapter 2: Bits and Pieces
    # of ISBN 0-596-00027-8 Programming Perl Third Edition.

    # P.76 Other Literal Tokens
    # in Chapter 2: Bits and Pieces
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    elsif (/\G   ( \cD         .*) \z /oxmsgc) { return $1; }

# \cZ Control-Z
    elsif (/\G   ( \cZ         .*) \z /oxmsgc) { return $1; }

    # any operator before div
    elsif (/\G (
            -- | \+\+ |
            [\)\}\]]

            ) /oxgc) { $slash = 'div'; return $1; }

    # yada-yada or triple-dot operator
    elsif (/\G (
            \.\.\.

            ) /oxgc) { $slash = 'm//'; return q{die('Unimplemented')}; }

    # any operator before m//

    # //, //= (defined-or)

    # P.164 Logical Operators
    # in Chapter 10: More Control Structures
    # of ISBN 978-0-596-52010-6 Learning Perl, Fifth Edition

    # P.119 C-Style Logical (Short-Circuit) Operators
    # in Chapter 3: Unary and Binary Operators
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    # (and so on)

    # ~~

    # P.221 The Smart Match Operator
    # in Chapter 15: Smart Matching and given-when
    # of ISBN 978-0-596-52010-6 Learning Perl, Fifth Edition

    # P.112 Smartmatch Operator
    # in Chapter 3: Unary and Binary Operators
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    # (and so on)

    elsif (/\G ((?>

            !~~ | !~ | != | ! |
            %= | % |
            &&= | && | &= | &\.= | &\. | & |
            -= | -> | - |
            :(?>\s*)= |
            : |
            <<>> |
            <<= | <=> | <= | < |
            == | => | =~ | = |
            >>= | >> | >= | > |
            \*\*= | \*\* | \*= | \* |
            \+= | \+ |
            \.\. | \.= | \. |
            \/\/= | \/\/ |
            \/= | \/ |
            \? |
            \\ |
            \^= | \^\.= | \^\. | \^ |
            \b x= |
            \|\|= | \|\| | \|= | \|\.= | \|\. | \| |
            ~~ | ~\. | ~ |
            \b(?: and | cmp | eq | ge | gt | le | lt | ne | not | or | xor | x )\b |
            \b(?: print )\b |

            [,;\(\{\[]

            )) /oxgc) { $slash = 'm//'; return $1; }

    # other any character
    elsif (/\G ($q_char) /oxgc) { $slash = 'div'; return $1; }

    # system error
    else {
        die __FILE__, ": Oops, this shouldn't happen!\n";
    }
}

# escape UHC string
sub e_string {
    my($string) = @_;
    my $e_string = '';

    local $slash = 'm//';

    # P.1024 Appendix W.10 Multibyte Processing
    # of ISBN 1-56592-224-7 CJKV Information Processing
    # (and so on)

    my @char = $string =~ / \G (?>[^\x81-\xFE\\]|\\$q_char|$q_char) /oxmsg;

    # without { ... }
    if (not (grep(/\A \{ \z/xms, @char) and grep(/\A \} \z/xms, @char))) {
        if ($string !~ /<
            return $string;
        }
    }

E_STRING_LOOP:
    while ($string !~ /\G \z/oxgc) {
        if (0) {
        }

# $`, ${`}, $PREMATCH, ${PREMATCH}, ${^PREMATCH} --> @{[Euhc::PREMATCH()]}
        elsif ($string =~ /\G ( \$` | \$\{`\} | \$ (?>\s*) PREMATCH  \b | \$ (?>\s*) \{ (?>\s*) PREMATCH  (?>\s*) \} | \$ (?>\s*) \{\^PREMATCH\}  ) /oxmsgc) {
            $e_string .= q{Euhc::PREMATCH()};
            $slash = 'div';
        }

# $&, ${&}, $MATCH, ${MATCH}, ${^MATCH} --> @{[Euhc::MATCH()]}
        elsif ($string =~ /\G ( \$& | \$\{&\} | \$ (?>\s*) MATCH     \b | \$ (?>\s*) \{ (?>\s*) MATCH     (?>\s*) \} | \$ (?>\s*) \{\^MATCH\}     ) /oxmsgc) {
            $e_string .= q{Euhc::MATCH()};
            $slash = 'div';
        }

# $', ${'} --> $', ${'}
        elsif ($string =~ /\G ( \$' | \$\{'\}                                                                                                     ) /oxmsgc) {
            $e_string .= $1;
            $slash = 'div';
        }

# $POSTMATCH, ${POSTMATCH}, ${^POSTMATCH} --> @{[Euhc::POSTMATCH()]}
        elsif ($string =~ /\G (                 \$ (?>\s*) POSTMATCH \b | \$ (?>\s*) \{ (?>\s*) POSTMATCH (?>\s*) \} | \$ (?>\s*) \{\^POSTMATCH\} ) /oxmsgc) {
            $e_string .= q{Euhc::POSTMATCH()};
            $slash = 'div';
        }

# bareword
        elsif ($string =~ /\G ( \{ (?>\s*) (?: tr | index | rindex | reverse ) (?>\s*) \} ) /oxmsgc) {
            $e_string .= $1;
            $slash = 'div';
        }

# $0 --> $0
        elsif ($string =~ /\G ( \$ 0 ) /oxmsgc) {
            $e_string .= $1;
            $slash = 'div';
        }
        elsif ($string =~ /\G ( \$ \{ (?>\s*) 0 (?>\s*) \} ) /oxmsgc) {
            $e_string .= $1;
            $slash = 'div';
        }

# $$ --> $$
        elsif ($string =~ /\G ( \$ \$ ) (?![\w\{]) /oxmsgc) {
            $e_string .= $1;
            $slash = 'div';
        }

# $1, $2, $3 --> $2, $3, $4 after s/// with multibyte anchoring
# $1, $2, $3 --> $1, $2, $3 otherwise
        elsif ($string =~ /\G \$ ((?>[1-9][0-9]*)) /oxmsgc) {
            $e_string .= e_capture($1);
            $slash = 'div';
        }
        elsif ($string =~ /\G \$ \{ (?>\s*) ((?>[1-9][0-9]*)) (?>\s*) \} /oxmsgc) {
            $e_string .= e_capture($1);
            $slash = 'div';
        }

# $$foo[ ... ] --> $ $foo->[ ... ]
        elsif ($string =~ /\G \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \[ .+? \] ) /oxmsgc) {
            $e_string .= e_capture($1.'->'.$2);
            $slash = 'div';
        }

# $$foo{ ... } --> $ $foo->{ ... }
        elsif ($string =~ /\G \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \{ .+? \} ) /oxmsgc) {
            $e_string .= e_capture($1.'->'.$2);
            $slash = 'div';
        }

# $$foo
        elsif ($string =~ /\G \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) /oxmsgc) {
            $e_string .= e_capture($1);
            $slash = 'div';
        }

# ${ foo }
        elsif ($string =~ /\G \$ (?>\s*) \{ ((?> \s* [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* \s* )) \} /oxmsgc) {
            $e_string .= '${' . $1 . '}';
            $slash = 'div';
        }

# ${ ... }
        elsif ($string =~ /\G \$ (?>\s*) \{ (?>\s*) ( $qq_brace ) (?>\s*) \} /oxmsgc) {
            $e_string .= e_capture($1);
            $slash = 'div';
        }

# variable or function
        #                             $ @ % & *     $ #
        elsif ($string =~ /\G ( (?: [\$\@\%\&\*] | \$\# | -> | \b sub \b) (?>\s*) (?: split | chop | index | rindex | lc | uc | fc | chr | ord | reverse | getc | tr | y | q | qq | qx | qw | m | s | qr | glob | lstat | opendir | stat | unlink | chdir ) ) \b /oxmsgc) {
            $e_string .= $1;
            $slash = 'div';
        }
        #                           $ $ $ $ $ $ $ $ $ $ $ $ $ $
        #                           $ @ # \ ' " / ? ( ) [ ] < >
        elsif ($string =~ /\G ( \$[\$\@\#\\\'\"\/\?\(\)\[\]\<\>] ) /oxmsgc) {
            $e_string .= $1;
            $slash = 'div';
        }

# subroutines of package Euhc
        elsif ($string =~ /\G \b (CORE:: | ->(>?\s*) (?: atan2 | [a-z]{2,})) \b       /oxgc) { $e_string .= $1;                  $slash = 'm//'; }
        elsif ($string =~ /\G \b Char::eval       (?= (?>\s*) \{ )                    /oxgc) { $e_string .= 'eval';              $slash = 'm//'; }
        elsif ($string =~ /\G \b UHC::eval       (?= (?>\s*) \{ )                    /oxgc) { $e_string .= 'eval';              $slash = 'm//'; }
        elsif ($string =~ /\G \b Char::eval \b                                        /oxgc) { $e_string .= 'eval Char::escape'; $slash = 'm//'; }
        elsif ($string =~ /\G \b UHC::eval \b                                        /oxgc) { $e_string .= 'eval UHC::escape'; $slash = 'm//'; }
        elsif ($string =~ /\G \b bytes::substr \b                                     /oxgc) { $e_string .= 'substr';            $slash = 'm//'; }
        elsif ($string =~ /\G \b chop \b                                              /oxgc) { $e_string .= 'Euhc::chop';       $slash = 'm//'; }
        elsif ($string =~ /\G \b bytes::index \b                                      /oxgc) { $e_string .= 'index';             $slash = 'm//'; }
        elsif ($string =~ /\G \b Char::index \b                                       /oxgc) { $e_string .= 'Char::index';       $slash = 'm//'; }
        elsif ($string =~ /\G \b UHC::index \b                                       /oxgc) { $e_string .= 'UHC::index';       $slash = 'm//'; }
        elsif ($string =~ /\G \b index \b                                             /oxgc) { $e_string .= 'Euhc::index';      $slash = 'm//'; }
        elsif ($string =~ /\G \b bytes::rindex \b                                     /oxgc) { $e_string .= 'rindex';            $slash = 'm//'; }
        elsif ($string =~ /\G \b Char::rindex \b                                      /oxgc) { $e_string .= 'Char::rindex';      $slash = 'm//'; }
        elsif ($string =~ /\G \b UHC::rindex \b                                      /oxgc) { $e_string .= 'UHC::rindex';      $slash = 'm//'; }
        elsif ($string =~ /\G \b rindex \b                                            /oxgc) { $e_string .= 'Euhc::rindex';     $slash = 'm//'; }
        elsif ($string =~ /\G \b lc      (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $e_string .= 'Euhc::lc';         $slash = 'm//'; }
        elsif ($string =~ /\G \b lcfirst (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $e_string .= 'Euhc::lcfirst';    $slash = 'm//'; }
        elsif ($string =~ /\G \b uc      (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $e_string .= 'Euhc::uc';         $slash = 'm//'; }
        elsif ($string =~ /\G \b ucfirst (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $e_string .= 'Euhc::ucfirst';    $slash = 'm//'; }
        elsif ($string =~ /\G \b fc      (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $e_string .= 'Euhc::fc';         $slash = 'm//'; }
        elsif ($string =~ /\G (-[rwxoRWXOezfdlpSbcugkTB] (?>(?:\s+ -[rwxoRWXOezfdlpSbcugkTB])+))
                                                                            (?>\s*) (\") ((?:$qq_char)+?)             (\") /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_qq('',  $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) qq (?>\s*) (\#) ((?:$qq_char)+?)             (\#) /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_qq('qq',$2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) qq (?>\s*) (\() ((?:$qq_paren)+?)            (\)) /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_qq('qq',$2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) qq (?>\s*) (\{) ((?:$qq_brace)+?)            (\}) /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_qq('qq',$2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) qq (?>\s*) (\[) ((?:$qq_bracket)+?)          (\]) /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_qq('qq',$2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) qq (?>\s*) (\<) ((?:$qq_angle)+?)            (\>) /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_qq('qq',$2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) qq (?>\s*) (\S) ((?:$qq_char)+?)             (\2) /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_qq('qq',$2,$4,$3) . ")"; $slash = 'm//'; }

        elsif ($string =~ /\G (-[rwxoRWXOezfdlpSbcugkTB] (?>(?:\s+ -[rwxoRWXOezfdlpSbcugkTB])+))
                                                                            (?>\s*) (\') ((?:\\\'|\\\\|$q_char)+?)    (\') /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_q ('',  $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) q  (?>\s*) (\#) ((?:\\\#|\\\\|$q_char)+?)    (\#) /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_q ('q', $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) q  (?>\s*) (\() ((?:\\\)|\\\\|$q_paren)+?)   (\)) /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_q ('q', $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) q  (?>\s*) (\{) ((?:\\\}|\\\\|$q_brace)+?)   (\}) /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_q ('q', $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) q  (?>\s*) (\[) ((?:\\\]|\\\\|$q_bracket)+?) (\]) /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_q ('q', $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) q  (?>\s*) (\<) ((?:\\\>|\\\\|$q_angle)+?)   (\>) /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_q ('q', $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) q  (?>\s*) (\S) ((?:\\\2|\\\\|$q_char)+?)    (\2) /oxgc) { $e_string .= "Euhc::filetest(qw($1)," . e_q ('q', $2,$4,$3) . ")"; $slash = 'm//'; }

        elsif ($string =~ /\G (-[rwxoRWXOezfdlpSbcugkTB] (?>(?:\s+ -[rwxoRWXOezfdlpSbcugkTB])+)) (\$ (?> \w+ (?: ::\w+)*) (?: (?: ->)? (?: [\$\@\%\&\*]\* | \$\#\* | \( (?:$qq_paren)*? \) | [\@\%\*]? \{ (?:$qq_brace)+? \} | [\@\%]? \[ (?:$qq_bracket)+? \] ) )*) /oxgc)
                                                                                                                                  { $e_string .= "Euhc::filetest(qw($1),$2)"; $slash = 'm//'; }
        elsif ($string =~ /\G (-[rwxoRWXOezfdlpSbcugkTB] (?>(?:\s+ -[rwxoRWXOezfdlpSbcugkTB])+)) \( ((?:$qq_paren)*?) \)   /oxgc) { $e_string .= "Euhc::filetest(qw($1),$2)"; $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) (?= [a-z]+)                                       /oxgc) { $e_string .= "Euhc::filetest qw($1),";    $slash = 'm//'; }
        elsif ($string =~ /\G ((?:-[rwxoRWXOezfdlpSbcugkTB](?>\s+)){2,}) ((?>\w+))                                         /oxgc) { $e_string .= "Euhc::filetest(qw($1),$2)"; $slash = 'm//'; }

        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC])            (?>\s*) (\") ((?:$qq_char)+?)                (\") /oxgc) { $e_string .= "Euhc::$1(" . e_qq('',  $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) qq (?>\s*) (\#) ((?:$qq_char)+?)                (\#) /oxgc) { $e_string .= "Euhc::$1(" . e_qq('qq',$2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) qq (?>\s*) (\() ((?:$qq_paren)+?)               (\)) /oxgc) { $e_string .= "Euhc::$1(" . e_qq('qq',$2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) qq (?>\s*) (\{) ((?:$qq_brace)+?)               (\}) /oxgc) { $e_string .= "Euhc::$1(" . e_qq('qq',$2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) qq (?>\s*) (\[) ((?:$qq_bracket)+?)             (\]) /oxgc) { $e_string .= "Euhc::$1(" . e_qq('qq',$2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) qq (?>\s*) (\<) ((?:$qq_angle)+?)               (\>) /oxgc) { $e_string .= "Euhc::$1(" . e_qq('qq',$2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) qq (?>\s*) (\S) ((?:$qq_char)+?)                (\2) /oxgc) { $e_string .= "Euhc::$1(" . e_qq('qq',$2,$4,$3) . ")"; $slash = 'm//'; }

        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC])            (?>\s*) (\') ((?:\\\'|\\\\|$q_char)+?)       (\') /oxgc) { $e_string .= "Euhc::$1(" . e_q ('',  $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) q  (?>\s*) (\#) ((?:\\\#|\\\\|$q_char)+?)       (\#) /oxgc) { $e_string .= "Euhc::$1(" . e_q ('q', $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) q  (?>\s*) (\() ((?:\\\)|\\\\|$q_paren)+?)      (\)) /oxgc) { $e_string .= "Euhc::$1(" . e_q ('q', $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) q  (?>\s*) (\{) ((?:\\\}|\\\\|$q_brace)+?)      (\}) /oxgc) { $e_string .= "Euhc::$1(" . e_q ('q', $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) q  (?>\s*) (\[) ((?:\\\]|\\\\|$q_bracket)+?)    (\]) /oxgc) { $e_string .= "Euhc::$1(" . e_q ('q', $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) q  (?>\s*) (\<) ((?:\\\>|\\\\|$q_angle)+?)      (\>) /oxgc) { $e_string .= "Euhc::$1(" . e_q ('q', $2,$4,$3) . ")"; $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) q  (?>\s*) (\S) ((?:\\\2|\\\\|$q_char)+?)       (\2) /oxgc) { $e_string .= "Euhc::$1(" . e_q ('q', $2,$4,$3) . ")"; $slash = 'm//'; }

        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s*) (\$ (?> \w+ (?: ::\w+)*) (?: (?: ->)? (?: [\$\@\%\&\*]\* | \$\#\* | \( (?:$qq_paren)*? \) | [\@\%\*]? \{ (?:$qq_brace)+? \} | [\@\%]? \[ (?:$qq_bracket)+? \] ) )*) /oxgc)
                                                                                                                                  { $e_string .= "Euhc::$1($2)";      $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s*) \( ((?:$qq_paren)*?) \)                              /oxgc) { $e_string .= "Euhc::$1($2)";      $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?= (?>\s+) [a-z]+)                                          /oxgc) { $e_string .= "Euhc::$1";          $slash = 'm//'; }
        elsif ($string =~ /\G -([rwxoRWXOezsfdlpSbcugkTBMAC]) (?>\s+) ((?>\w+))                                            /oxgc) { $e_string .= "Euhc::$1(::"."$2)"; $slash = 'm//'; }
        elsif ($string =~ /\G -(t)                            (?>\s+) ((?>\w+))                                            /oxgc) { $e_string .= "-t $2";              $slash = 'm//'; }
        elsif ($string =~ /\G \b lstat         (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(])                                /oxgc) { $e_string .= 'Euhc::lstat';       $slash = 'm//'; }
        elsif ($string =~ /\G \b stat          (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(])                                /oxgc) { $e_string .= 'Euhc::stat';        $slash = 'm//'; }

        # "-s '' ..." means file test "-s 'filename' ..." (not means "- s/// ...")
        elsif ($string =~ /\G -s                                         (?>\s*) (\") ((?:$qq_char)+?)                (\") /oxgc) { $e_string .= '-s ' . e_qq('',  $1,$3,$2); $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s+) qq (?>\s*) (\#) ((?:$qq_char)+?)                (\#) /oxgc) { $e_string .= '-s ' . e_qq('qq',$1,$3,$2); $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s+) qq (?>\s*) (\() ((?:$qq_paren)+?)               (\)) /oxgc) { $e_string .= '-s ' . e_qq('qq',$1,$3,$2); $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s+) qq (?>\s*) (\{) ((?:$qq_brace)+?)               (\}) /oxgc) { $e_string .= '-s ' . e_qq('qq',$1,$3,$2); $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s+) qq (?>\s*) (\[) ((?:$qq_bracket)+?)             (\]) /oxgc) { $e_string .= '-s ' . e_qq('qq',$1,$3,$2); $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s+) qq (?>\s*) (\<) ((?:$qq_angle)+?)               (\>) /oxgc) { $e_string .= '-s ' . e_qq('qq',$1,$3,$2); $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s+) qq (?>\s*) (\S) ((?:$qq_char)+?)                (\1) /oxgc) { $e_string .= '-s ' . e_qq('qq',$1,$3,$2); $slash = 'm//'; }

        elsif ($string =~ /\G -s                                         (?>\s*) (\') ((?:\\\'|\\\\|$q_char)+?)       (\') /oxgc) { $e_string .= '-s ' . e_q ('',  $1,$3,$2); $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s+) q  (?>\s*) (\#) ((?:\\\#|\\\\|$q_char)+?)       (\#) /oxgc) { $e_string .= '-s ' . e_q ('q', $1,$3,$2); $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s+) q  (?>\s*) (\() ((?:\\\)|\\\\|$q_paren)+?)      (\)) /oxgc) { $e_string .= '-s ' . e_q ('q', $1,$3,$2); $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s+) q  (?>\s*) (\{) ((?:\\\}|\\\\|$q_brace)+?)      (\}) /oxgc) { $e_string .= '-s ' . e_q ('q', $1,$3,$2); $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s+) q  (?>\s*) (\[) ((?:\\\]|\\\\|$q_bracket)+?)    (\]) /oxgc) { $e_string .= '-s ' . e_q ('q', $1,$3,$2); $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s+) q  (?>\s*) (\<) ((?:\\\>|\\\\|$q_angle)+?)      (\>) /oxgc) { $e_string .= '-s ' . e_q ('q', $1,$3,$2); $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s+) q  (?>\s*) (\S) ((?:\\\1|\\\\|$q_char)+?)       (\1) /oxgc) { $e_string .= '-s ' . e_q ('q', $1,$3,$2); $slash = 'm//'; }

        elsif ($string =~ /\G -s                              (?>\s*) (\$ (?> \w+ (?: ::\w+)*) (?: (?: ->)? (?: [\$\@\%\&\*]\* | \$\#\* | \( (?:$qq_paren)*? \) | [\@\%\*]? \{ (?:$qq_brace)+? \} | [\@\%]? \[ (?:$qq_bracket)+? \] ))*) /oxgc)
                                                                                                                                  { $e_string .= "-s $1";   $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s*) \( ((?:$qq_paren)*?) \)                              /oxgc) { $e_string .= "-s ($1)"; $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?= (?>\s+) [a-z]+)                                          /oxgc) { $e_string .= '-s';      $slash = 'm//'; }
        elsif ($string =~ /\G -s                              (?>\s+) ((?>\w+))                                            /oxgc) { $e_string .= "-s $1";   $slash = 'm//'; }

        elsif ($string =~ /\G \b bytes::length (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $e_string .= 'length';               $slash = 'm//'; }
        elsif ($string =~ /\G \b bytes::chr    (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $e_string .= 'chr';                  $slash = 'm//'; }
        elsif ($string =~ /\G \b chr           (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $e_string .= 'Euhc::chr';           $slash = 'm//'; }
        elsif ($string =~ /\G \b bytes::ord    (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $e_string .= 'ord';                  $slash = 'div'; }
        elsif ($string =~ /\G \b ord           (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $e_string .= $function_ord;          $slash = 'div'; }
        elsif ($string =~ /\G \b glob          (?= (?>\s+)[A-Za-z_]|(?>\s*)['"`\$\@\&\*\(]) /oxgc) { $e_string .= 'Euhc::glob';          $slash = 'm//'; }
        elsif ($string =~ /\G \b lc \b                                                      /oxgc) { $e_string .= 'Euhc::lc_';               $slash = 'm//'; }
        elsif ($string =~ /\G \b lcfirst \b                                                 /oxgc) { $e_string .= 'Euhc::lcfirst_';          $slash = 'm//'; }
        elsif ($string =~ /\G \b uc \b                                                      /oxgc) { $e_string .= 'Euhc::uc_';               $slash = 'm//'; }
        elsif ($string =~ /\G \b ucfirst \b                                                 /oxgc) { $e_string .= 'Euhc::ucfirst_';          $slash = 'm//'; }
        elsif ($string =~ /\G \b fc \b                                                      /oxgc) { $e_string .= 'Euhc::fc_';               $slash = 'm//'; }
        elsif ($string =~ /\G \b lstat \b                                                   /oxgc) { $e_string .= 'Euhc::lstat_';            $slash = 'm//'; }
        elsif ($string =~ /\G \b stat \b                                                    /oxgc) { $e_string .= 'Euhc::stat_';             $slash = 'm//'; }
        elsif ($string =~ /\G    (-[rwxoRWXOezfdlpSbcugkTB] (?>(?:\s+ -[rwxoRWXOezfdlpSbcugkTB])+))
                                                                 \b                         /oxgc) { $e_string .= "Euhc::filetest_(qw($1))"; $slash = 'm//'; }
        elsif ($string =~ /\G    -([rwxoRWXOezsfdlpSbcugkTBMAC]) \b                         /oxgc) { $e_string .= "Euhc::${1}_";             $slash = 'm//'; }
        elsif ($string =~ /\G    -s                              \b                         /oxgc) { $e_string .= '-s ';                      $slash = 'm//'; }

        elsif ($string =~ /\G \b bytes::length \b                                           /oxgc) { $e_string .= 'length';                   $slash = 'm//'; }
        elsif ($string =~ /\G \b bytes::chr \b                                              /oxgc) { $e_string .= 'chr';                      $slash = 'm//'; }
        elsif ($string =~ /\G \b chr \b                                                     /oxgc) { $e_string .= 'Euhc::chr_';              $slash = 'm//'; }
        elsif ($string =~ /\G \b bytes::ord \b                                              /oxgc) { $e_string .= 'ord';                      $slash = 'div'; }
        elsif ($string =~ /\G \b ord \b                                                     /oxgc) { $e_string .= $function_ord_;             $slash = 'div'; }
        elsif ($string =~ /\G \b glob \b                                                    /oxgc) { $e_string .= 'Euhc::glob_';             $slash = 'm//'; }
        elsif ($string =~ /\G \b reverse \b                                                 /oxgc) { $e_string .= $function_reverse;          $slash = 'm//'; }
        elsif ($string =~ /\G \b getc \b                                                    /oxgc) { $e_string .= $function_getc;             $slash = 'm//'; }
        elsif ($string =~ /\G \b opendir ((?>\s*) \( (?>\s*)) (?=[A-Za-z_])                 /oxgc) { $e_string .= "Euhc::opendir$1*";        $slash = 'm//'; }
        elsif ($string =~ /\G \b opendir ((?>\s+))            (?=[A-Za-z_])                 /oxgc) { $e_string .= "Euhc::opendir$1*";        $slash = 'm//'; }
        elsif ($string =~ /\G \b unlink \b                                                  /oxgc) { $e_string .= 'Euhc::unlink';            $slash = 'm//'; }

# chdir
        elsif ($string =~ /\G \b (chdir) \b (?! (?>\s*) => ) /oxgc) {
            $slash = 'm//';

            $e_string .= 'Euhc::chdir';

            while ($string =~ /\G ( (?>\s+) | \( | \#.* ) /oxgc) {
                $e_string .= $1;
            }

# end of chdir
            if    ($string =~ /\G (?= [,;\)\}\]] )          /oxgc) { return $e_string;                               }

# chdir scalar value
            elsif ($string =~ /\G ( [\$\@\&\*] $qq_scalar ) /oxgc) { $e_string .= e_string($1);  next E_STRING_LOOP; }

# chdir qq//
            elsif ($string =~ /\G \b (qq) \b /oxgc) {
                if ($string =~ /\G (\#) ((?:$qq_char)*?) (\#) /oxgc)                             { $e_string .= e_chdir('qq',$1,$3,$2);   next E_STRING_LOOP; } # qq# #  --> qr # #
                else {
                    while ($string !~ /\G \z/oxgc) {
                        if    ($string =~ /\G ((?>\s+)|\#.*)                              /oxgc) { $e_string .= $1; }
                        elsif ($string =~ /\G (\()          ((?:$qq_paren)*?)   (\))      /oxgc) { $e_string .= e_chdir('qq',$1,$3,$2);   next E_STRING_LOOP; } # qq ( ) --> qr ( )
                        elsif ($string =~ /\G (\{)          ((?:$qq_brace)*?)   (\})      /oxgc) { $e_string .= e_chdir('qq',$1,$3,$2);   next E_STRING_LOOP; } # qq { } --> qr { }
                        elsif ($string =~ /\G (\[)          ((?:$qq_bracket)*?) (\])      /oxgc) { $e_string .= e_chdir('qq',$1,$3,$2);   next E_STRING_LOOP; } # qq [ ] --> qr [ ]
                        elsif ($string =~ /\G (\<)          ((?:$qq_angle)*?)   (\>)      /oxgc) { $e_string .= e_chdir('qq',$1,$3,$2);   next E_STRING_LOOP; } # qq < > --> qr < >
                        elsif ($string =~ /\G ([*\-:?\\^|]) ((?:$qq_char)*?)    (\1)      /oxgc) { $e_string .= e_chdir('qq','{','}',$2); next E_STRING_LOOP; } # qq | | --> qr { }
                        elsif ($string =~ /\G (\S)          ((?:$qq_char)*?)    (\1)      /oxgc) { $e_string .= e_chdir('qq',$1,$3,$2);   next E_STRING_LOOP; } # qq * * --> qr * *
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }
            }

# chdir q//
            elsif ($string =~ /\G \b (q) \b /oxgc) {
                if ($string =~ /\G (\#) ((?:\\\#|\\\\|$q_char)*?) (\#) /oxgc)                    { $e_string .= e_chdir_q('q',$1,$3,$2);   next E_STRING_LOOP; } # q# #  --> qr # #
                else {
                    while ($string !~ /\G \z/oxgc) {
                        if    ($string =~ /\G ((?>\s+)|\#.*)                              /oxgc) { $e_string .= $1; }
                        elsif ($string =~ /\G (\() ((?:\\\\|\\\)|\\\(|$q_paren)*?)   (\)) /oxgc) { $e_string .= e_chdir_q('q',$1,$3,$2);   next E_STRING_LOOP; } # q ( ) --> qr ( )
                        elsif ($string =~ /\G (\{) ((?:\\\\|\\\}|\\\{|$q_brace)*?)   (\}) /oxgc) { $e_string .= e_chdir_q('q',$1,$3,$2);   next E_STRING_LOOP; } # q { } --> qr { }
                        elsif ($string =~ /\G (\[) ((?:\\\\|\\\]|\\\[|$q_bracket)*?) (\]) /oxgc) { $e_string .= e_chdir_q('q',$1,$3,$2);   next E_STRING_LOOP; } # q [ ] --> qr [ ]
                        elsif ($string =~ /\G (\<) ((?:\\\\|\\\>|\\\<|$q_angle)*?)   (\>) /oxgc) { $e_string .= e_chdir_q('q',$1,$3,$2);   next E_STRING_LOOP; } # q < > --> qr < >
                        elsif ($string =~ /\G ([*\-:?\\^|])       ((?:$q_char)*?)    (\1) /oxgc) { $e_string .= e_chdir_q('q','{','}',$2); next E_STRING_LOOP; } # q | | --> qr { }
                        elsif ($string =~ /\G (\S) ((?:\\\\|\\\1|     $q_char)*?)    (\1) /oxgc) { $e_string .= e_chdir_q('q',$1,$3,$2);   next E_STRING_LOOP; } # q * * --> qr * *
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }
            }

# chdir ''
            elsif ($string =~ /\G (\') /oxgc) {
                my $q_string = '';
                while ($string !~ /\G \z/oxgc) {
                    if    ($string =~ /\G (\\\\)    /oxgc) { $q_string .= $1; }
                    elsif ($string =~ /\G (\\\')    /oxgc) { $q_string .= $1; }
                    elsif ($string =~ /\G \'        /oxgc)                                       { $e_string .= e_chdir_q('',"'","'",$q_string); next E_STRING_LOOP; }
                    elsif ($string =~ /\G ($q_char) /oxgc) { $q_string .= $1; }
                }
                die __FILE__, ": Can't find string terminator anywhere before EOF\n";
            }

# chdir ""
            elsif ($string =~ /\G (\") /oxgc) {
                my $qq_string = '';
                while ($string !~ /\G \z/oxgc) {
                    if    ($string =~ /\G (\\\\)    /oxgc) { $qq_string .= $1; }
                    elsif ($string =~ /\G (\\\")    /oxgc) { $qq_string .= $1; }
                    elsif ($string =~ /\G \"        /oxgc)                                       { $e_string .= e_chdir('','"','"',$qq_string); next E_STRING_LOOP; }
                    elsif ($string =~ /\G ($q_char) /oxgc) { $qq_string .= $1; }
                }
                die __FILE__, ": Can't find string terminator anywhere before EOF\n";
            }
        }

# split
        elsif ($string =~ /\G \b (split) \b (?! (?>\s*) => ) /oxgc) {
            $slash = 'm//';

            my $e = '';
            while ($string =~ /\G ( (?>\s+) | \( | \#.* ) /oxgc) {
                $e .= $1;
            }

# end of split
            if    ($string =~ /\G (?= [,;\)\}\]] )          /oxgc) { return 'Euhc::split' . $e;                                           }

# split scalar value
            elsif ($string =~ /\G ( [\$\@\&\*] $qq_scalar ) /oxgc) { $e_string .= 'Euhc::split' . $e . e_string($1);  next E_STRING_LOOP; }

# split literal space
            elsif ($string =~ /\G \b qq           (\#) [ ] (\#) /oxgc) { $e_string .= 'Euhc::split' . $e . qq  {qq$1 $2}; next E_STRING_LOOP; }
            elsif ($string =~ /\G \b qq ((?>\s*)) (\() [ ] (\)) /oxgc) { $e_string .= 'Euhc::split' . $e . qq{$1qq$2 $3}; next E_STRING_LOOP; }
            elsif ($string =~ /\G \b qq ((?>\s*)) (\{) [ ] (\}) /oxgc) { $e_string .= 'Euhc::split' . $e . qq{$1qq$2 $3}; next E_STRING_LOOP; }
            elsif ($string =~ /\G \b qq ((?>\s*)) (\[) [ ] (\]) /oxgc) { $e_string .= 'Euhc::split' . $e . qq{$1qq$2 $3}; next E_STRING_LOOP; }
            elsif ($string =~ /\G \b qq ((?>\s*)) (\<) [ ] (\>) /oxgc) { $e_string .= 'Euhc::split' . $e . qq{$1qq$2 $3}; next E_STRING_LOOP; }
            elsif ($string =~ /\G \b qq ((?>\s*)) (\S) [ ] (\2) /oxgc) { $e_string .= 'Euhc::split' . $e . qq{$1qq$2 $3}; next E_STRING_LOOP; }
            elsif ($string =~ /\G \b q            (\#) [ ] (\#) /oxgc) { $e_string .= 'Euhc::split' . $e . qq   {q$1 $2}; next E_STRING_LOOP; }
            elsif ($string =~ /\G \b q  ((?>\s*)) (\() [ ] (\)) /oxgc) { $e_string .= 'Euhc::split' . $e . qq {$1q$2 $3}; next E_STRING_LOOP; }
            elsif ($string =~ /\G \b q  ((?>\s*)) (\{) [ ] (\}) /oxgc) { $e_string .= 'Euhc::split' . $e . qq {$1q$2 $3}; next E_STRING_LOOP; }
            elsif ($string =~ /\G \b q  ((?>\s*)) (\[) [ ] (\]) /oxgc) { $e_string .= 'Euhc::split' . $e . qq {$1q$2 $3}; next E_STRING_LOOP; }
            elsif ($string =~ /\G \b q  ((?>\s*)) (\<) [ ] (\>) /oxgc) { $e_string .= 'Euhc::split' . $e . qq {$1q$2 $3}; next E_STRING_LOOP; }
            elsif ($string =~ /\G \b q  ((?>\s*)) (\S) [ ] (\2) /oxgc) { $e_string .= 'Euhc::split' . $e . qq {$1q$2 $3}; next E_STRING_LOOP; }
            elsif ($string =~ /\G                    ' [ ] '    /oxgc) { $e_string .= 'Euhc::split' . $e . qq     {' '};  next E_STRING_LOOP; }
            elsif ($string =~ /\G                    " [ ] "    /oxgc) { $e_string .= 'Euhc::split' . $e . qq     {" "};  next E_STRING_LOOP; }

# split qq//
            elsif ($string =~ /\G \b (qq) \b /oxgc) {
                if ($string =~ /\G (\#) ((?:$qq_char)*?) (\#) /oxgc)                        { $e_string .= e_split($e.'qr',$1,$3,$2,'');   next E_STRING_LOOP; } # qq# #  --> qr # #
                else {
                    while ($string !~ /\G \z/oxgc) {
                        if    ($string =~ /\G ((?>\s+)|\#.*)                         /oxgc) { $e_string .= $e . $1; }
                        elsif ($string =~ /\G (\()          ((?:$qq_paren)*?)   (\)) /oxgc) { $e_string .= e_split($e.'qr',$1,$3,$2,'');   next E_STRING_LOOP; } # qq ( ) --> qr ( )
                        elsif ($string =~ /\G (\{)          ((?:$qq_brace)*?)   (\}) /oxgc) { $e_string .= e_split($e.'qr',$1,$3,$2,'');   next E_STRING_LOOP; } # qq { } --> qr { }
                        elsif ($string =~ /\G (\[)          ((?:$qq_bracket)*?) (\]) /oxgc) { $e_string .= e_split($e.'qr',$1,$3,$2,'');   next E_STRING_LOOP; } # qq [ ] --> qr [ ]
                        elsif ($string =~ /\G (\<)          ((?:$qq_angle)*?)   (\>) /oxgc) { $e_string .= e_split($e.'qr',$1,$3,$2,'');   next E_STRING_LOOP; } # qq < > --> qr < >
                        elsif ($string =~ /\G ([*\-:?\\^|]) ((?:$qq_char)*?)    (\1) /oxgc) { $e_string .= e_split($e.'qr','{','}',$2,''); next E_STRING_LOOP; } # qq | | --> qr { }
                        elsif ($string =~ /\G (\S)          ((?:$qq_char)*?)    (\1) /oxgc) { $e_string .= e_split($e.'qr',$1,$3,$2,'');   next E_STRING_LOOP; } # qq * * --> qr * *
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }
            }

# split qr//
            elsif ($string =~ /\G \b (qr) \b /oxgc) {
                if ($string =~ /\G (\#) ((?:$qq_char)*?) (\#) ([imosxpadlunbB]*) /oxgc)                        { $e_string .= e_split  ($e.'qr',$1,$3,$2,$4);   next E_STRING_LOOP; } # qr# #
                else {
                    while ($string !~ /\G \z/oxgc) {
                        if    ($string =~ /\G ((?>\s+)|\#.*)                                            /oxgc) { $e_string .= $e . $1; }
                        elsif ($string =~ /\G (\()          ((?:$qq_paren)*?)   (\)) ([imosxpadlunbB]*) /oxgc) { $e_string .= e_split  ($e.'qr',$1, $3, $2,$4); next E_STRING_LOOP; } # qr ( )
                        elsif ($string =~ /\G (\{)          ((?:$qq_brace)*?)   (\}) ([imosxpadlunbB]*) /oxgc) { $e_string .= e_split  ($e.'qr',$1, $3, $2,$4); next E_STRING_LOOP; } # qr { }
                        elsif ($string =~ /\G (\[)          ((?:$qq_bracket)*?) (\]) ([imosxpadlunbB]*) /oxgc) { $e_string .= e_split  ($e.'qr',$1, $3, $2,$4); next E_STRING_LOOP; } # qr [ ]
                        elsif ($string =~ /\G (\<)          ((?:$qq_angle)*?)   (\>) ([imosxpadlunbB]*) /oxgc) { $e_string .= e_split  ($e.'qr',$1, $3, $2,$4); next E_STRING_LOOP; } # qr < >
                        elsif ($string =~ /\G (\')          ((?:$qq_char)*?)    (\') ([imosxpadlunbB]*) /oxgc) { $e_string .= e_split_q($e.'qr',$1, $3, $2,$4); next E_STRING_LOOP; } # qr ' '
                        elsif ($string =~ /\G ([*\-:?\\^|]) ((?:$qq_char)*?)    (\1) ([imosxpadlunbB]*) /oxgc) { $e_string .= e_split  ($e.'qr','{','}',$2,$4); next E_STRING_LOOP; } # qr | | --> qr { }
                        elsif ($string =~ /\G (\S)          ((?:$qq_char)*?)    (\1) ([imosxpadlunbB]*) /oxgc) { $e_string .= e_split  ($e.'qr',$1, $3, $2,$4); next E_STRING_LOOP; } # qr * *
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }
            }

# split q//
            elsif ($string =~ /\G \b (q) \b /oxgc) {
                if ($string =~ /\G (\#) ((?:\\\#|\\\\|$q_char)*?) (\#) /oxgc)                    { $e_string .= e_split_q($e.'qr',$1,$3,$2,'');   next E_STRING_LOOP; } # q# #  --> qr # #
                else {
                    while ($string !~ /\G \z/oxgc) {
                        if    ($string =~ /\G ((?>\s+)|\#.*)                              /oxgc) { $e_string .= $e . $1; }
                        elsif ($string =~ /\G (\() ((?:\\\\|\\\)|\\\(|$q_paren)*?)   (\)) /oxgc) { $e_string .= e_split_q($e.'qr',$1,$3,$2,'');   next E_STRING_LOOP; } # q ( ) --> qr ( )
                        elsif ($string =~ /\G (\{) ((?:\\\\|\\\}|\\\{|$q_brace)*?)   (\}) /oxgc) { $e_string .= e_split_q($e.'qr',$1,$3,$2,'');   next E_STRING_LOOP; } # q { } --> qr { }
                        elsif ($string =~ /\G (\[) ((?:\\\\|\\\]|\\\[|$q_bracket)*?) (\]) /oxgc) { $e_string .= e_split_q($e.'qr',$1,$3,$2,'');   next E_STRING_LOOP; } # q [ ] --> qr [ ]
                        elsif ($string =~ /\G (\<) ((?:\\\\|\\\>|\\\<|$q_angle)*?)   (\>) /oxgc) { $e_string .= e_split_q($e.'qr',$1,$3,$2,'');   next E_STRING_LOOP; } # q < > --> qr < >
                        elsif ($string =~ /\G ([*\-:?\\^|])       ((?:$q_char)*?)    (\1) /oxgc) { $e_string .= e_split_q($e.'qr','{','}',$2,''); next E_STRING_LOOP; } # q | | --> qr { }
                        elsif ($string =~ /\G (\S) ((?:\\\\|\\\1|     $q_char)*?)    (\1) /oxgc) { $e_string .= e_split_q($e.'qr',$1,$3,$2,'');   next E_STRING_LOOP; } # q * * --> qr * *
                    }
                    die __FILE__, ": Can't find string terminator anywhere before EOF\n";
                }
            }

# split m//
            elsif ($string =~ /\G \b (m) \b /oxgc) {
                if ($string =~ /\G (\#) ((?:$qq_char)*?) (\#) ([cgimosxpadlunbB]*) /oxgc)                        { $e_string .= e_split  ($e.'qr',$1,$3,$2,$4);   next E_STRING_LOOP; } # m# #  --> qr # #
                else {
                    while ($string !~ /\G \z/oxgc) {
                        if    ($string =~ /\G ((?>\s+)|\#.*)                                              /oxgc) { $e_string .= $e . $1; }
                        elsif ($string =~ /\G (\()          ((?:$qq_paren)*?)   (\)) ([cgimosxpadlunbB]*) /oxgc) { $e_string .= e_split  ($e.'qr',$1, $3, $2,$4); next E_STRING_LOOP; } # m ( ) --> qr ( )
                        elsif ($string =~ /\G (\{)          ((?:$qq_brace)*?)   (\}) ([cgimosxpadlunbB]*) /oxgc) { $e_string .= e_split  ($e.'qr',$1, $3, $2,$4); next E_STRING_LOOP; } # m { } --> qr { }
                        elsif ($string =~ /\G (\[)          ((?:$qq_bracket)*?) (\]) ([cgimosxpadlunbB]*) /oxgc) { $e_string .= e_split  ($e.'qr',$1, $3, $2,$4); next E_STRING_LOOP; } # m [ ] --> qr [ ]
                        elsif ($string =~ /\G (\<)          ((?:$qq_angle)*?)   (\>) ([cgimosxpadlunbB]*) /oxgc) { $e_string .= e_split  ($e.'qr',$1, $3, $2,$4); next E_STRING_LOOP; } # m < > --> qr < >
                        elsif ($string =~ /\G (\')          ((?:$qq_char)*?)    (\') ([cgimosxpadlunbB]*) /oxgc) { $e_string .= e_split_q($e.'qr',$1, $3, $2,$4); next E_STRING_LOOP; } # m ' ' --> qr ' '
                        elsif ($string =~ /\G ([*\-:?\\^|]) ((?:$qq_char)*?)    (\1) ([cgimosxpadlunbB]*) /oxgc) { $e_string .= e_split  ($e.'qr','{','}',$2,$4); next E_STRING_LOOP; } # m | | --> qr { }
                        elsif ($string =~ /\G (\S)          ((?:$qq_char)*?)    (\1) ([cgimosxpadlunbB]*) /oxgc) { $e_string .= e_split  ($e.'qr',$1, $3, $2,$4); next E_STRING_LOOP; } # m * * --> qr * *
                    }
                    die __FILE__, ": Search pattern not terminated\n";
                }
            }

# split ''
            elsif ($string =~ /\G (\') /oxgc) {
                my $q_string = '';
                while ($string !~ /\G \z/oxgc) {
                    if    ($string =~ /\G (\\\\)    /oxgc) { $q_string .= $1; }
                    elsif ($string =~ /\G (\\\')    /oxgc) { $q_string .= $1; } # splitqr'' --> split qr''
                    elsif ($string =~ /\G \'        /oxgc)                      { $e_string .= e_split_q($e.q{ qr},"'","'",$q_string,''); next E_STRING_LOOP; } # ' ' --> qr ' '
                    elsif ($string =~ /\G ($q_char) /oxgc) { $q_string .= $1; }
                }
                die __FILE__, ": Can't find string terminator anywhere before EOF\n";
            }

# split ""
            elsif ($string =~ /\G (\") /oxgc) {
                my $qq_string = '';
                while ($string !~ /\G \z/oxgc) {
                    if    ($string =~ /\G (\\\\)    /oxgc) { $qq_string .= $1; }
                    elsif ($string =~ /\G (\\\")    /oxgc) { $qq_string .= $1; } # splitqr"" --> split qr""
                    elsif ($string =~ /\G \"        /oxgc)                       { $e_string .= e_split($e.q{ qr},'"','"',$qq_string,''); next E_STRING_LOOP; } # " " --> qr " "
                    elsif ($string =~ /\G ($q_char) /oxgc) { $qq_string .= $1; }
                }
                die __FILE__, ": Can't find string terminator anywhere before EOF\n";
            }

# split //
            elsif ($string =~ /\G (\/) /oxgc) {
                my $regexp = '';
                while ($string !~ /\G \z/oxgc) {
                    if    ($string =~ /\G (\\\\)                  /oxgc) { $regexp .= $1; }
                    elsif ($string =~ /\G (\\\/)                  /oxgc) { $regexp .= $1; } # splitqr// --> split qr//
                    elsif ($string =~ /\G \/ ([cgimosxpadlunbB]*) /oxgc)                    { $e_string .= e_split($e.q{ qr}, '/','/',$regexp,$1); next E_STRING_LOOP; } # / / --> qr / /
                    elsif ($string =~ /\G ($q_char)               /oxgc) { $regexp .= $1; }
                }
                die __FILE__, ": Search pattern not terminated\n";
            }
        }

# qq//
        elsif ($string =~ /\G \b (qq) \b /oxgc) {
            my $ope = $1;
            if ($string =~ /\G (\#) ((?:$qq_char)*?) (\#) /oxgc) { # qq# #
                $e_string .= e_qq($ope,$1,$3,$2);
            }
            else {
                my $e = '';
                while ($string !~ /\G \z/oxgc) {
                    if    ($string =~ /\G ((?>\s+)|\#.*)                /oxgc) { $e .= $1; }
                    elsif ($string =~ /\G (\() ((?:$qq_paren)*?)   (\)) /oxgc) { $e_string .= $e . e_qq($ope,$1,$3,$2); next E_STRING_LOOP; } # qq ( )
                    elsif ($string =~ /\G (\{) ((?:$qq_brace)*?)   (\}) /oxgc) { $e_string .= $e . e_qq($ope,$1,$3,$2); next E_STRING_LOOP; } # qq { }
                    elsif ($string =~ /\G (\[) ((?:$qq_bracket)*?) (\]) /oxgc) { $e_string .= $e . e_qq($ope,$1,$3,$2); next E_STRING_LOOP; } # qq [ ]
                    elsif ($string =~ /\G (\<) ((?:$qq_angle)*?)   (\>) /oxgc) { $e_string .= $e . e_qq($ope,$1,$3,$2); next E_STRING_LOOP; } # qq < >
                    elsif ($string =~ /\G (\S) ((?:$qq_char)*?)    (\1) /oxgc) { $e_string .= $e . e_qq($ope,$1,$3,$2); next E_STRING_LOOP; } # qq * *
                }
                die __FILE__, ": Can't find string terminator anywhere before EOF\n";
            }
        }

# qx//
        elsif ($string =~ /\G \b (qx) \b /oxgc) {
            my $ope = $1;
            if ($string =~ /\G (\#) ((?:$qq_char)*?) (\#) /oxgc) { # qx# #
                $e_string .= e_qq($ope,$1,$3,$2);
            }
            else {
                my $e = '';
                while ($string !~ /\G \z/oxgc) {
                    if    ($string =~ /\G ((?>\s+)|\#.*)                /oxgc) { $e .= $1; }
                    elsif ($string =~ /\G (\() ((?:$qq_paren)*?)   (\)) /oxgc) { $e_string .= $e . e_qq($ope,$1,$3,$2); next E_STRING_LOOP; } # qx ( )
                    elsif ($string =~ /\G (\{) ((?:$qq_brace)*?)   (\}) /oxgc) { $e_string .= $e . e_qq($ope,$1,$3,$2); next E_STRING_LOOP; } # qx { }
                    elsif ($string =~ /\G (\[) ((?:$qq_bracket)*?) (\]) /oxgc) { $e_string .= $e . e_qq($ope,$1,$3,$2); next E_STRING_LOOP; } # qx [ ]
                    elsif ($string =~ /\G (\<) ((?:$qq_angle)*?)   (\>) /oxgc) { $e_string .= $e . e_qq($ope,$1,$3,$2); next E_STRING_LOOP; } # qx < >
                    elsif ($string =~ /\G (\') ((?:$qq_char)*?)    (\') /oxgc) { $e_string .= $e . e_q ($ope,$1,$3,$2); next E_STRING_LOOP; } # qx ' '
                    elsif ($string =~ /\G (\S) ((?:$qq_char)*?)    (\1) /oxgc) { $e_string .= $e . e_qq($ope,$1,$3,$2); next E_STRING_LOOP; } # qx * *
                }
                die __FILE__, ": Can't find string terminator anywhere before EOF\n";
            }
        }

# q//
        elsif ($string =~ /\G \b (q) \b /oxgc) {
            my $ope = $1;
            if ($string =~ /\G (\#) ((?:\\\#|\\\\|$q_char)*?) (\#) /oxgc) { # q# #
                $e_string .= e_q($ope,$1,$3,$2);
            }
            else {
                my $e = '';
                while ($string !~ /\G \z/oxgc) {
                    if    ($string =~ /\G ((?>\s+)|\#.*)                              /oxgc) { $e .= $1; }
                    elsif ($string =~ /\G (\() ((?:\\\\|\\\)|\\\(|$q_paren)*?)   (\)) /oxgc) { $e_string .= $e . e_q($ope,$1,$3,$2); next E_STRING_LOOP; } # q ( )
                    elsif ($string =~ /\G (\{) ((?:\\\\|\\\}|\\\{|$q_brace)*?)   (\}) /oxgc) { $e_string .= $e . e_q($ope,$1,$3,$2); next E_STRING_LOOP; } # q { }
                    elsif ($string =~ /\G (\[) ((?:\\\\|\\\]|\\\[|$q_bracket)*?) (\]) /oxgc) { $e_string .= $e . e_q($ope,$1,$3,$2); next E_STRING_LOOP; } # q [ ]
                    elsif ($string =~ /\G (\<) ((?:\\\\|\\\>|\\\<|$q_angle)*?)   (\>) /oxgc) { $e_string .= $e . e_q($ope,$1,$3,$2); next E_STRING_LOOP; } # q < >
                    elsif ($string =~ /\G (\S) ((?:\\\\|\\\1|     $q_char)*?)    (\1) /oxgc) { $e_string .= $e . e_q($ope,$1,$3,$2); next E_STRING_LOOP; } # q * *
                }
                die __FILE__, ": Can't find string terminator anywhere before EOF\n";
            }
        }

# ''
        elsif ($string =~ /\G (?

# ""
        elsif ($string =~ /\G (\") ((?:$qq_char)*?) (\")                                        /oxgc) { $e_string .= e_qq('',$1,$3,$2); }

# ``
        elsif ($string =~ /\G (\`) ((?:$qq_char)*?) (\`)                                        /oxgc) { $e_string .= e_qq('',$1,$3,$2); }

# <<>> (a safer ARGV)
        elsif ($string =~ /\G ( <<>> )                                                          /oxgc) { $e_string .= $1;                }

# <<= <=> <= < operator
        elsif ($string =~ /\G ( <<= | <=> | <= | < ) (?= (?>\s*) [A-Za-z_0-9'"`\$\@\&\*\(\+\-] )/oxgc) { $e_string .= $1;                }

#
        elsif ($string =~ /\G (<[\$]?[A-Za-z_][A-Za-z_0-9]*>)                                   /oxgc) { $e_string .= $1;                }

#    --- glob
        elsif ($string =~ /\G < ((?:$q_char)+?) > /oxgc) {
            $e_string .= 'Euhc::glob("' . $1 . '")';
        }

# << (bit shift)   --- not here document
        elsif ($string =~ /\G ( << (?>\s*) ) (?= [0-9\$\@\&] ) /oxgc) {
            $slash = 'm//';
            $e_string .= $1;
        }

# <<~'HEREDOC'
        elsif ($string =~ /\G ( <<~ [\t ]* '([a-zA-Z_0-9]*)' ) /oxgc) {
            $slash = 'm//';
            my $here_quote = $1;
            my $delimiter  = $2;

            # get here document
            if ($here_script eq '') {
                $here_script = CORE::substr $_, pos $_;
                $here_script =~ s/.*?\n//oxm;
            }
            if ($here_script =~ s/\A (.*?) \n ([\t ]*) $delimiter \n //xms) {
                my $heredoc = $1;
                my $indent  = $2;
                $heredoc =~ s{^$indent}{}msg; # no /ox
                push @heredoc, $heredoc . qq{\n$delimiter\n};
                push @heredoc_delimiter, qq{\\s*$delimiter};
            }
            else {
                die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
            }
            $e_string .= qq{<<'$delimiter'};
        }

# <<~\HEREDOC
        elsif ($string =~ /\G ( <<~ \\([a-zA-Z_0-9]+) ) /oxgc) {
            $slash = 'm//';
            my $here_quote = $1;
            my $delimiter  = $2;

            # get here document
            if ($here_script eq '') {
                $here_script = CORE::substr $_, pos $_;
                $here_script =~ s/.*?\n//oxm;
            }
            if ($here_script =~ s/\A (.*?) \n ([\t ]*) $delimiter \n //xms) {
                my $heredoc = $1;
                my $indent  = $2;
                $heredoc =~ s{^$indent}{}msg; # no /ox
                push @heredoc, $heredoc . qq{\n$delimiter\n};
                push @heredoc_delimiter, qq{\\s*$delimiter};
            }
            else {
                die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
            }
            $e_string .= qq{<<\\$delimiter};
        }

# <<~"HEREDOC"
        elsif ($string =~ /\G ( <<~ [\t ]* "([a-zA-Z_0-9]*)" ) /oxgc) {
            $slash = 'm//';
            my $here_quote = $1;
            my $delimiter  = $2;

            # get here document
            if ($here_script eq '') {
                $here_script = CORE::substr $_, pos $_;
                $here_script =~ s/.*?\n//oxm;
            }
            if ($here_script =~ s/\A (.*?) \n ([\t ]*) $delimiter \n //xms) {
                my $heredoc = $1;
                my $indent  = $2;
                $heredoc =~ s{^$indent}{}msg; # no /ox
                push @heredoc, e_heredoc($heredoc) . qq{\n$delimiter\n};
                push @heredoc_delimiter, qq{\\s*$delimiter};
            }
            else {
                die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
            }
            $e_string .= qq{<<"$delimiter"};
        }

# <<~HEREDOC
        elsif ($string =~ /\G ( <<~ ([a-zA-Z_0-9]+) ) /oxgc) {
            $slash = 'm//';
            my $here_quote = $1;
            my $delimiter  = $2;

            # get here document
            if ($here_script eq '') {
                $here_script = CORE::substr $_, pos $_;
                $here_script =~ s/.*?\n//oxm;
            }
            if ($here_script =~ s/\A (.*?) \n ([\t ]*) $delimiter \n //xms) {
                my $heredoc = $1;
                my $indent  = $2;
                $heredoc =~ s{^$indent}{}msg; # no /ox
                push @heredoc, e_heredoc($heredoc) . qq{\n$delimiter\n};
                push @heredoc_delimiter, qq{\\s*$delimiter};
            }
            else {
                die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
            }
            $e_string .= qq{<<$delimiter};
        }

# <<~`HEREDOC`
        elsif ($string =~ /\G ( <<~ [\t ]* `([a-zA-Z_0-9]*)` ) /oxgc) {
            $slash = 'm//';
            my $here_quote = $1;
            my $delimiter  = $2;

            # get here document
            if ($here_script eq '') {
                $here_script = CORE::substr $_, pos $_;
                $here_script =~ s/.*?\n//oxm;
            }
            if ($here_script =~ s/\A (.*?) \n ([\t ]*) $delimiter \n //xms) {
                my $heredoc = $1;
                my $indent  = $2;
                $heredoc =~ s{^$indent}{}msg; # no /ox
                push @heredoc, e_heredoc($heredoc) . qq{\n$delimiter\n};
                push @heredoc_delimiter, qq{\\s*$delimiter};
            }
            else {
                die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
            }
            $e_string .= qq{<<`$delimiter`};
        }

# <<'HEREDOC'
        elsif ($string =~ /\G ( << '([a-zA-Z_0-9]*)' ) /oxgc) {
            $slash = 'm//';
            my $here_quote = $1;
            my $delimiter  = $2;

            # get here document
            if ($here_script eq '') {
                $here_script = CORE::substr $_, pos $_;
                $here_script =~ s/.*?\n//oxm;
            }
            if ($here_script =~ s/\A (.*?) \n $delimiter \n //xms) {
                push @heredoc, $1 . qq{\n$delimiter\n};
                push @heredoc_delimiter, $delimiter;
            }
            else {
                die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
            }
            $e_string .= $here_quote;
        }

# <<\HEREDOC
        elsif ($string =~ /\G ( << \\([a-zA-Z_0-9]+) ) /oxgc) {
            $slash = 'm//';
            my $here_quote = $1;
            my $delimiter  = $2;

            # get here document
            if ($here_script eq '') {
                $here_script = CORE::substr $_, pos $_;
                $here_script =~ s/.*?\n//oxm;
            }
            if ($here_script =~ s/\A (.*?) \n $delimiter \n //xms) {
                push @heredoc, $1 . qq{\n$delimiter\n};
                push @heredoc_delimiter, $delimiter;
            }
            else {
                die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
            }
            $e_string .= $here_quote;
        }

# <<"HEREDOC"
        elsif ($string =~ /\G ( << "([a-zA-Z_0-9]*)" ) /oxgc) {
            $slash = 'm//';
            my $here_quote = $1;
            my $delimiter  = $2;

            # get here document
            if ($here_script eq '') {
                $here_script = CORE::substr $_, pos $_;
                $here_script =~ s/.*?\n//oxm;
            }
            if ($here_script =~ s/\A (.*?) \n $delimiter \n //xms) {
                push @heredoc, e_heredoc($1) . qq{\n$delimiter\n};
                push @heredoc_delimiter, $delimiter;
            }
            else {
                die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
            }
            $e_string .= $here_quote;
        }

# <
        elsif ($string =~ /\G ( << ([a-zA-Z_0-9]+) ) /oxgc) {
            $slash = 'm//';
            my $here_quote = $1;
            my $delimiter  = $2;

            # get here document
            if ($here_script eq '') {
                $here_script = CORE::substr $_, pos $_;
                $here_script =~ s/.*?\n//oxm;
            }
            if ($here_script =~ s/\A (.*?) \n $delimiter \n //xms) {
                push @heredoc, e_heredoc($1) . qq{\n$delimiter\n};
                push @heredoc_delimiter, $delimiter;
            }
            else {
                die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
            }
            $e_string .= $here_quote;
        }

# <<`HEREDOC`
        elsif ($string =~ /\G ( << `([a-zA-Z_0-9]*)` ) /oxgc) {
            $slash = 'm//';
            my $here_quote = $1;
            my $delimiter  = $2;

            # get here document
            if ($here_script eq '') {
                $here_script = CORE::substr $_, pos $_;
                $here_script =~ s/.*?\n//oxm;
            }
            if ($here_script =~ s/\A (.*?) \n $delimiter \n //xms) {
                push @heredoc, e_heredoc($1) . qq{\n$delimiter\n};
                push @heredoc_delimiter, $delimiter;
            }
            else {
                die __FILE__, ": Can't find string terminator $delimiter anywhere before EOF\n";
            }
            $e_string .= $here_quote;
        }

        # any operator before div
        elsif ($string =~ /\G (
            -- | \+\+ |
            [\)\}\]]

            ) /oxgc) { $slash = 'div'; $e_string .= $1; }

        # yada-yada or triple-dot operator
        elsif ($string =~ /\G (
            \.\.\.

            ) /oxgc) { $slash = 'm//'; $e_string .= q{die('Unimplemented')}; }

        # any operator before m//
        elsif ($string =~ /\G ((?>

            !~~ | !~ | != | ! |
            %= | % |
            &&= | && | &= | &\.= | &\. | & |
            -= | -> | - |
            :(?>\s*)= |
            : |
            <<>> |
            <<= | <=> | <= | < |
            == | => | =~ | = |
            >>= | >> | >= | > |
            \*\*= | \*\* | \*= | \* |
            \+= | \+ |
            \.\. | \.= | \. |
            \/\/= | \/\/ |
            \/= | \/ |
            \? |
            \\ |
            \^= | \^\.= | \^\. | \^ |
            \b x= |
            \|\|= | \|\| | \|= | \|\.= | \|\. | \| |
            ~~ | ~\. | ~ |
            \b(?: and | cmp | eq | ge | gt | le | lt | ne | not | or | xor | x )\b |
            \b(?: print )\b |

            [,;\(\{\[]

            )) /oxgc) { $slash = 'm//'; $e_string .= $1; }

        # other any character
        elsif ($string =~ /\G ($q_char) /oxgc) { $e_string .= $1; }

        # system error
        else {
            die __FILE__, ": Oops, this shouldn't happen!\n";
        }
    }

    return $e_string;
}

#
# character class
#
sub character_class {
    my($char,$modifier) = @_;

    if ($char eq '.') {
        if ($modifier =~ /s/) {
            return '${Euhc::dot_s}';
        }
        else {
            return '${Euhc::dot}';
        }
    }
    else {
        return Euhc::classic_character_class($char);
    }
}

#
# escape capture ($1, $2, $3, ...)
#
sub e_capture {

    return join '', '${Euhc::capture(', $_[0], ')}';
    return join '', '${',                $_[0],  '}';
}

#
# escape transliteration (tr/// or y///)
#
sub e_tr {
    my($variable,$charclass,$e,$charclass2,$modifier) = @_;
    my $e_tr = '';
    $modifier ||= '';

    $slash = 'div';

    # quote character class 1
    $charclass  = q_tr($charclass);

    # quote character class 2
    $charclass2 = q_tr($charclass2);

    # /b /B modifier
    if ($modifier =~ tr/bB//d) {
        if ($variable eq '') {
            $e_tr = qq{tr$charclass$e$charclass2$modifier};
        }
        else {
            $e_tr = qq{$variable${bind_operator}tr$charclass$e$charclass2$modifier};
        }
    }
    else {
        if ($variable eq '') {
            $e_tr = qq{Euhc::tr(\$_,' =~ ',$charclass,$e$charclass2,'$modifier')};
        }
        else {
            $e_tr = qq{Euhc::tr($variable,'$bind_operator',$charclass,$e$charclass2,'$modifier')};
        }
    }

    # clear tr/// variable
    $tr_variable = '';
    $bind_operator = '';

    return $e_tr;
}

#
# quote for escape transliteration (tr/// or y///)
#
sub q_tr {
    my($charclass) = @_;

    # quote character class
    if ($charclass !~ /'/oxms) {
        return e_q('',  "'", "'", $charclass); # --> q' '
    }
    elsif ($charclass !~ /\//oxms) {
        return e_q('q',  '/', '/', $charclass); # --> q/ /
    }
    elsif ($charclass !~ /\#/oxms) {
        return e_q('q',  '#', '#', $charclass); # --> q# #
    }
    elsif ($charclass !~ /[\<\>]/oxms) {
        return e_q('q', '<', '>', $charclass); # --> q< >
    }
    elsif ($charclass !~ /[\(\)]/oxms) {
        return e_q('q', '(', ')', $charclass); # --> q( )
    }
    elsif ($charclass !~ /[\{\}]/oxms) {
        return e_q('q', '{', '}', $charclass); # --> q{ }
    }
    else {
        for my $char (qw( ! " $ % & * + . : = ? @ ^ ` | ~ ), "\x00".."\x1F", "\x7F", "\xFF") {
            if ($charclass !~ /\Q$char\E/xms) {
                return e_q('q', $char, $char, $charclass);
            }
        }
    }

    return e_q('q', '{', '}', $charclass);
}

#
# escape q string (q//, '')
#
sub e_q {
    my($ope,$delimiter,$end_delimiter,$string) = @_;

    $slash = 'div';

    my @char = $string =~ / \G (?>$q_char) /oxmsg;
    for (my $i=0; $i <= $#char; $i++) {

        # escape last octet of multiple-octet
        if ($char[$i] =~ /\A ([\x80-\xFF].*) (\Q$delimiter\E|\Q$end_delimiter\E) \z/xms) {
            $char[$i] = $1 . '\\' . $2;
        }
        elsif (defined($char[$i+1]) and ($char[$i+1] eq '\\') and ($char[$i] =~ /\A ([\x80-\xFF].*) (\\) \z/xms)) {
            $char[$i] = $1 . '\\' . $2;
        }
    }
    if (defined($char[-1]) and ($char[-1] =~ /\A ([\x80-\xFF].*) (\\) \z/xms)) {
        $char[-1] = $1 . '\\' . $2;
    }

    return join '', $ope, $delimiter, @char,   $end_delimiter;
    return join '', $ope, $delimiter, $string, $end_delimiter;
}

#
# escape qq string (qq//, "", qx//, ``)
#
sub e_qq {
    my($ope,$delimiter,$end_delimiter,$string) = @_;

    $slash = 'div';

    my $left_e  = 0;
    my $right_e = 0;

    # split regexp
    my @char = $string =~ /\G((?>
        [^\x81-\xFE\\\$]|[\x81-\xFE][\x00-\xFF] |
        \\x\{ (?>[0-9A-Fa-f]+) \}            |
        \\o\{ (?>[0-7]+)       \}            |
        \\N\{ (?>[^\x81-\xFE0-9\}][^\x81-\xFE\}]*) \} |
        \\ $q_char                           |
        \$` | \$\{`\} | \$ (?>\s*) PREMATCH  | \$ (?>\s*) \{ (?>\s*) PREMATCH  (?>\s*) \} | \$ (?>\s*) \{\^PREMATCH\}  |
        \$& | \$\{&\} | \$ (?>\s*) MATCH     | \$ (?>\s*) \{ (?>\s*) MATCH     (?>\s*) \} | \$ (?>\s*) \{\^MATCH\}     |
                        \$ (?>\s*) POSTMATCH | \$ (?>\s*) \{ (?>\s*) POSTMATCH (?>\s*) \} | \$ (?>\s*) \{\^POSTMATCH\} |
        \$ (?>\s* [0-9]+)                    |
        \$ (?>\s*) \{ (?>\s* [0-9]+ \s*) \}  |
        \$ \$ (?![\w\{])                     |
        \$ (?>\s*) \$ (?>\s*) $qq_variable   |
           $q_char
    ))/oxmsg;

    for (my $i=0; $i <= $#char; $i++) {

        # "\L\u" --> "\u\L"
        if (($char[$i] eq '\L') and ($char[$i+1] eq '\u')) {
            @char[$i,$i+1] = @char[$i+1,$i];
        }

        # "\U\l" --> "\l\U"
        elsif (($char[$i] eq '\U') and ($char[$i+1] eq '\l')) {
            @char[$i,$i+1] = @char[$i+1,$i];
        }

        # octal escape sequence
        elsif ($char[$i] =~ /\A \\o \{ ([0-7]+) \} \z/oxms) {
            $char[$i] = Euhc::octchr($1);
        }

        # hexadecimal escape sequence
        elsif ($char[$i] =~ /\A \\x \{ ([0-9A-Fa-f]+) \} \z/oxms) {
            $char[$i] = Euhc::hexchr($1);
        }

        # \N{CHARNAME} --> N{CHARNAME}
        elsif ($char[$i] =~ /\A \\ ( N\{ ([^\x81-\xFE0-9\}][^\x81-\xFE\}]*) \} ) \z/oxms) {
            $char[$i] = $1;
        }

        if (0) {
        }

        # escape last octet of multiple-octet
        # my $metachar = qr/[\@\\\|]/oxms; # '|' is for qx//, ``, open(), and system()
        # variable $delimiter and $end_delimiter can be ''
        elsif ($char[$i] =~ /\A ([\x80-\xFF].*) ([\@\\\|$delimiter$end_delimiter]) \z/xms) {
            $char[$i] = $1 . '\\' . $2;
        }

        # \F
        #
        # P.69 Table 2-6. Translation escapes
        # in Chapter 2: Bits and Pieces
        # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.
        # (and so on)

        # \u \l \U \L \F \Q \E
        elsif ($char[$i] =~ /\A ([<>]) \z/oxms) {
            if ($right_e < $left_e) {
                $char[$i] = '\\' . $char[$i];
            }
        }
        elsif ($char[$i] eq '\u') {

            # "STRING @{[ LIST EXPR ]} MORE STRING"

            # P.257 Other Tricks You Can Do with Hard References
            # in Chapter 8: References
            # of ISBN 0-596-00027-8 Programming Perl Third Edition.

            # P.353 Other Tricks You Can Do with Hard References
            # in Chapter 8: References
            # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

            # (and so on)

            $char[$i] = '@{[Euhc::ucfirst qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\l') {
            $char[$i] = '@{[Euhc::lcfirst qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\U') {
            $char[$i] = '@{[Euhc::uc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\L') {
            $char[$i] = '@{[Euhc::lc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\F') {
            $char[$i] = '@{[Euhc::fc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\Q') {
            $char[$i] = '@{[CORE::quotemeta qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\E') {
            if ($right_e < $left_e) {
                $char[$i] = '>]}';
                $right_e++;
            }
            else {
                $char[$i] = '';
            }
        }
        elsif ($char[$i] eq '\Q') {
            while (1) {
                if (++$i > $#char) {
                    last;
                }
                if ($char[$i] eq '\E') {
                    last;
                }
            }
        }
        elsif ($char[$i] eq '\E') {
        }

        # $0 --> $0
        elsif ($char[$i] =~ /\A \$ 0 \z/oxms) {
        }
        elsif ($char[$i] =~ /\A \$ \{ (?>\s*) 0 (?>\s*) \} \z/oxms) {
        }

        # $$ --> $$
        elsif ($char[$i] =~ /\A \$\$ \z/oxms) {
        }

        # $1, $2, $3 --> $2, $3, $4 after s/// with multibyte anchoring
        # $1, $2, $3 --> $1, $2, $3 otherwise
        elsif ($char[$i] =~ /\A \$ ((?>[1-9][0-9]*)) \z/oxms) {
            $char[$i] = e_capture($1);
        }
        elsif ($char[$i] =~ /\A \$ \{ (?>\s*) ((?>[1-9][0-9]*)) (?>\s*) \} \z/oxms) {
            $char[$i] = e_capture($1);
        }

        # $$foo[ ... ] --> $ $foo->[ ... ]
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \[ (?:$qq_bracket)*? \] ) \z/oxms) {
            $char[$i] = e_capture($1.'->'.$2);
        }

        # $$foo{ ... } --> $ $foo->{ ... }
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \{ (?:$qq_brace)*? \} ) \z/oxms) {
            $char[$i] = e_capture($1.'->'.$2);
        }

        # $$foo
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) \z/oxms) {
            $char[$i] = e_capture($1);
        }

        # $`, ${`}, $PREMATCH, ${PREMATCH}, ${^PREMATCH} --> Euhc::PREMATCH()
        elsif ($char[$i] =~ /\A ( \$` | \$\{`\} | \$ (?>\s*) PREMATCH  | \$ (?>\s*) \{ (?>\s*) PREMATCH (?>\s*) \}  | \$ (?>\s*) \{\^PREMATCH\}  ) \z/oxmsgc) {
            $char[$i] = '@{[Euhc::PREMATCH()]}';
        }

        # $&, ${&}, $MATCH, ${MATCH}, ${^MATCH} --> Euhc::MATCH()
        elsif ($char[$i] =~ /\A ( \$& | \$\{&\} | \$ (?>\s*) MATCH     | \$ (?>\s*) \{ (?>\s*) MATCH     (?>\s*) \} | \$ (?>\s*) \{\^MATCH\}     ) \z/oxmsgc) {
            $char[$i] = '@{[Euhc::MATCH()]}';
        }

        # $POSTMATCH, ${POSTMATCH}, ${^POSTMATCH} --> Euhc::POSTMATCH()
        elsif ($char[$i] =~ /\A (                 \$ (?>\s*) POSTMATCH | \$ (?>\s*) \{ (?>\s*) POSTMATCH (?>\s*) \} | \$ (?>\s*) \{\^POSTMATCH\} ) \z/oxmsgc) {
            $char[$i] = '@{[Euhc::POSTMATCH()]}';
        }

        # ${ foo } --> ${ foo }
        elsif ($char[$i] =~ /\A \$ (?>\s*) \{ (?> \s* [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* \s* ) \}                                \z/oxms) {
        }

        # ${ ... }
        elsif ($char[$i] =~ /\A \$ (?>\s*) \{ ( .+ ) \} \z/oxms) {
            $char[$i] = e_capture($1);
        }
    }

    # return string
    if ($left_e > $right_e) {
        return join '', $ope, $delimiter, @char, '>]}' x ($left_e - $right_e), $end_delimiter;
    }
    return     join '', $ope, $delimiter, @char,                               $end_delimiter;
}

#
# escape qw string (qw//)
#
sub e_qw {
    my($ope,$delimiter,$end_delimiter,$string) = @_;

    $slash = 'div';

    # choice again delimiter
    my %octet = map {$_ => 1} ($string =~ /\G ([\x00-\xFF]) /oxmsg);
    if (not $octet{$end_delimiter}) {
        return join '', $ope, $delimiter, $string, $end_delimiter;
    }
    elsif (not $octet{')'}) {
        return join '', $ope, '(',        $string, ')';
    }
    elsif (not $octet{'}'}) {
        return join '', $ope, '{',        $string, '}';
    }
    elsif (not $octet{']'}) {
        return join '', $ope, '[',        $string, ']';
    }
    elsif (not $octet{'>'}) {
        return join '', $ope, '<',        $string, '>';
    }
    else {
        for my $char (qw( ! " $ % & * + - . / : = ? @ ^ ` | ~ ), "\x00".."\x1F", "\x7F", "\xFF") {
            if (not $octet{$char}) {
                return join '', $ope,      $char, $string, $char;
            }
        }
    }

    # qw/AAA BBB C'CC/ --> ('AAA', 'BBB', 'C\'CC')
    my @string = CORE::split(/\s+/, $string);
    for my $string (@string) {
        my @octet = $string =~ /\G ([\x00-\xFF]) /oxmsg;
        for my $octet (@octet) {
            if ($octet =~ /\A (['\\]) \z/oxms) {
                $octet = '\\' . $1;
            }
        }
        $string = join '', @octet;
    }
    return join '', '(', (join ', ', map { "'$_'" } @string), ')';
}

#
# escape here document (<<"HEREDOC", <
#
sub e_heredoc {
    my($string) = @_;

    $slash = 'm//';

    my $metachar = qr/[\@\\|]/oxms; # '|' is for <<`HEREDOC`

    my $left_e  = 0;
    my $right_e = 0;

    # split regexp
    my @char = $string =~ /\G((?>
        [^\x81-\xFE\\\$]|[\x81-\xFE][\x00-\xFF] |
        \\x\{ (?>[0-9A-Fa-f]+) \}            |
        \\o\{ (?>[0-7]+)       \}            |
        \\N\{ (?>[^\x81-\xFE0-9\}][^\x81-\xFE\}]*) \} |
        \\ $q_char                           |
        \$` | \$\{`\} | \$ (?>\s*) PREMATCH  | \$ (?>\s*) \{ (?>\s*) PREMATCH  (?>\s*) \} | \$ (?>\s*) \{\^PREMATCH\}  |
        \$& | \$\{&\} | \$ (?>\s*) MATCH     | \$ (?>\s*) \{ (?>\s*) MATCH     (?>\s*) \} | \$ (?>\s*) \{\^MATCH\}     |
                        \$ (?>\s*) POSTMATCH | \$ (?>\s*) \{ (?>\s*) POSTMATCH (?>\s*) \} | \$ (?>\s*) \{\^POSTMATCH\} |
        \$ (?>\s* [0-9]+)                    |
        \$ (?>\s*) \{ (?>\s* [0-9]+ \s*) \}  |
        \$ \$ (?![\w\{])                     |
        \$ (?>\s*) \$ (?>\s*) $qq_variable   |
           $q_char
    ))/oxmsg;

    for (my $i=0; $i <= $#char; $i++) {

        # "\L\u" --> "\u\L"
        if (($char[$i] eq '\L') and ($char[$i+1] eq '\u')) {
            @char[$i,$i+1] = @char[$i+1,$i];
        }

        # "\U\l" --> "\l\U"
        elsif (($char[$i] eq '\U') and ($char[$i+1] eq '\l')) {
            @char[$i,$i+1] = @char[$i+1,$i];
        }

        # octal escape sequence
        elsif ($char[$i] =~ /\A \\o \{ ([0-7]+) \} \z/oxms) {
            $char[$i] = Euhc::octchr($1);
        }

        # hexadecimal escape sequence
        elsif ($char[$i] =~ /\A \\x \{ ([0-9A-Fa-f]+) \} \z/oxms) {
            $char[$i] = Euhc::hexchr($1);
        }

        # \N{CHARNAME} --> N{CHARNAME}
        elsif ($char[$i] =~ /\A \\ ( N\{ ([^\x81-\xFE0-9\}][^\x81-\xFE\}]*) \} ) \z/oxms) {
            $char[$i] = $1;
        }

        if (0) {
        }

        # escape character
        elsif ($char[$i] =~ /\A ([\x80-\xFF].*) ($metachar) \z/oxms) {
            $char[$i] = $1 . '\\' . $2;
        }

        # \u \l \U \L \F \Q \E
        elsif ($char[$i] =~ /\A ([<>]) \z/oxms) {
            if ($right_e < $left_e) {
                $char[$i] = '\\' . $char[$i];
            }
        }
        elsif ($char[$i] eq '\u') {
            $char[$i] = '@{[Euhc::ucfirst qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\l') {
            $char[$i] = '@{[Euhc::lcfirst qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\U') {
            $char[$i] = '@{[Euhc::uc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\L') {
            $char[$i] = '@{[Euhc::lc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\F') {
            $char[$i] = '@{[Euhc::fc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\Q') {
            $char[$i] = '@{[CORE::quotemeta qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\E') {
            if ($right_e < $left_e) {
                $char[$i] = '>]}';
                $right_e++;
            }
            else {
                $char[$i] = '';
            }
        }
        elsif ($char[$i] eq '\Q') {
            while (1) {
                if (++$i > $#char) {
                    last;
                }
                if ($char[$i] eq '\E') {
                    last;
                }
            }
        }
        elsif ($char[$i] eq '\E') {
        }

        # $0 --> $0
        elsif ($char[$i] =~ /\A \$ 0 \z/oxms) {
        }
        elsif ($char[$i] =~ /\A \$ \{ (?>\s*) 0 (?>\s*) \} \z/oxms) {
        }

        # $$ --> $$
        elsif ($char[$i] =~ /\A \$\$ \z/oxms) {
        }

        # $1, $2, $3 --> $2, $3, $4 after s/// with multibyte anchoring
        # $1, $2, $3 --> $1, $2, $3 otherwise
        elsif ($char[$i] =~ /\A \$ ((?>[1-9][0-9]*)) \z/oxms) {
            $char[$i] = e_capture($1);
        }
        elsif ($char[$i] =~ /\A \$ \{ (?>\s*) ((?>[1-9][0-9]*)) (?>\s*) \} \z/oxms) {
            $char[$i] = e_capture($1);
        }

        # $$foo[ ... ] --> $ $foo->[ ... ]
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \[ (?:$qq_bracket)*? \] ) \z/oxms) {
            $char[$i] = e_capture($1.'->'.$2);
        }

        # $$foo{ ... } --> $ $foo->{ ... }
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \{ (?:$qq_brace)*? \} ) \z/oxms) {
            $char[$i] = e_capture($1.'->'.$2);
        }

        # $$foo
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) \z/oxms) {
            $char[$i] = e_capture($1);
        }

        # $`, ${`}, $PREMATCH, ${PREMATCH}, ${^PREMATCH} --> Euhc::PREMATCH()
        elsif ($char[$i] =~ /\A ( \$` | \$\{`\} | \$ (?>\s*) PREMATCH  | \$ (?>\s*) \{ (?>\s*) PREMATCH  (?>\s*) \} | \$ (?>\s*) \{\^PREMATCH\}  ) \z/oxmsgc) {
            $char[$i] = '@{[Euhc::PREMATCH()]}';
        }

        # $&, ${&}, $MATCH, ${MATCH}, ${^MATCH} --> Euhc::MATCH()
        elsif ($char[$i] =~ /\A ( \$& | \$\{&\} | \$ (?>\s*) MATCH     | \$ (?>\s*) \{ (?>\s*) MATCH     (?>\s*) \} | \$ (?>\s*) \{\^MATCH\}     ) \z/oxmsgc) {
            $char[$i] = '@{[Euhc::MATCH()]}';
        }

        # $POSTMATCH, ${POSTMATCH}, ${^POSTMATCH} --> Euhc::POSTMATCH()
        elsif ($char[$i] =~ /\A (                 \$ (?>\s*) POSTMATCH | \$ (?>\s*) \{ (?>\s*) POSTMATCH (?>\s*) \} | \$ (?>\s*) \{\^POSTMATCH\} ) \z/oxmsgc) {
            $char[$i] = '@{[Euhc::POSTMATCH()]}';
        }

        # ${ foo } --> ${ foo }
        elsif ($char[$i] =~ /\A \$ (?>\s*) \{ (?> \s* [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* \s* ) \}                                \z/oxms) {
        }

        # ${ ... }
        elsif ($char[$i] =~ /\A \$ (?>\s*) \{ ( .+ ) \} \z/oxms) {
            $char[$i] = e_capture($1);
        }
    }

    # return string
    if ($left_e > $right_e) {
        return join '', @char, '>]}' x ($left_e - $right_e);
    }
    return     join '', @char;
}

#
# escape regexp (m//, qr//)
#
sub e_qr {
    my($ope,$delimiter,$end_delimiter,$string,$modifier) = @_;
    $modifier ||= '';

    $modifier =~ tr/p//d;
    if ($modifier =~ /([adlu])/oxms) {
        my $line = 0;
        for (my $i=0; my($package,$filename,$use_line,$subroutine) = caller($i); $i++) {
            if ($filename ne __FILE__) {
                $line = $use_line + (CORE::substr($_,0,pos($_)) =~ tr/\n//) + 1;
                last;
            }
        }
        die qq{Unsupported modifier "$1" used at line $line.\n};
    }

    $slash = 'div';

    # literal null string pattern
    if ($string eq '') {
        $modifier =~ tr/bB//d;
        $modifier =~ tr/i//d;
        return join '', $ope, $delimiter, $end_delimiter, $modifier;
    }

    # /b /B modifier
    elsif ($modifier =~ tr/bB//d) {

        # choice again delimiter
        if ($delimiter =~ / [\@:] /oxms) {
            my @char = $string =~ /\G ([\x00-\xFF]) /oxmsg;
            my %octet = map {$_ => 1} @char;
            if (not $octet{')'}) {
                $delimiter     = '(';
                $end_delimiter = ')';
            }
            elsif (not $octet{'}'}) {
                $delimiter     = '{';
                $end_delimiter = '}';
            }
            elsif (not $octet{']'}) {
                $delimiter     = '[';
                $end_delimiter = ']';
            }
            elsif (not $octet{'>'}) {
                $delimiter     = '<';
                $end_delimiter = '>';
            }
            else {
                for my $char (qw( ! " $ % & * + - . / = ? ^ ` | ~ ), "\x00".."\x1F", "\x7F", "\xFF") {
                    if (not $octet{$char}) {
                        $delimiter     = $char;
                        $end_delimiter = $char;
                        last;
                    }
                }
            }
        }

        if (($ope =~ /\A m? \z/oxms) and ($delimiter eq '?')) {
            return join '', $ope, $delimiter,        $string,      $matched, $end_delimiter, $modifier;
        }
        else {
            return join '', $ope, $delimiter, '(?:', $string, ')', $matched, $end_delimiter, $modifier;
        }
    }

    my $ignorecase = ($modifier =~ /i/oxms) ? 1 : 0;
    my $metachar = qr/[\@\\|[\]{^]/oxms;

    # split regexp
    my @char = $string =~ /\G((?>
        [^\x81-\xFE\\\$\@\[\(]|[\x81-\xFE][\x00-\xFF] |
        \\x   (?>[0-9A-Fa-f]{1,2}) |
        \\    (?>[0-7]{2,3})       |
        \\c   [\x40-\x5F]          |
        \\x\{ (?>[0-9A-Fa-f]+) \}  |
        \\o\{ (?>[0-7]+)       \}  |
        \\[bBNpP]\{ (?>[^\x81-\xFE0-9\}][^\x81-\xFE\}]*) \} |
        \\  $q_char                |
        \$` | \$\{`\} | \$ (?>\s*) PREMATCH  | \$ (?>\s*) \{ (?>\s*) PREMATCH  (?>\s*) \} | \$ (?>\s*) \{\^PREMATCH\}  |
        \$& | \$\{&\} | \$ (?>\s*) MATCH     | \$ (?>\s*) \{ (?>\s*) MATCH     (?>\s*) \} | \$ (?>\s*) \{\^MATCH\}     |
                        \$ (?>\s*) POSTMATCH | \$ (?>\s*) \{ (?>\s*) POSTMATCH (?>\s*) \} | \$ (?>\s*) \{\^POSTMATCH\} |
        [\$\@] $qq_variable        |
        \$ (?>\s* [0-9]+)          |
        \$ (?>\s*) \{ (?>\s* [0-9]+ \s*) \}  |
        \$ \$ (?![\w\{])           |
        \$ (?>\s*) \$ (?>\s*) $qq_variable   |
        \[\^                       |
        \[\:   (?>[a-z]+) :\]      |
        \[\:\^ (?>[a-z]+) :\]      |
        \(\?                       |
            $q_char
    ))/oxmsg;

    # choice again delimiter
    if ($delimiter =~ / [\@:] /oxms) {
        my %octet = map {$_ => 1} @char;
        if (not $octet{')'}) {
            $delimiter     = '(';
            $end_delimiter = ')';
        }
        elsif (not $octet{'}'}) {
            $delimiter     = '{';
            $end_delimiter = '}';
        }
        elsif (not $octet{']'}) {
            $delimiter     = '[';
            $end_delimiter = ']';
        }
        elsif (not $octet{'>'}) {
            $delimiter     = '<';
            $end_delimiter = '>';
        }
        else {
            for my $char (qw( ! " $ % & * + - . / = ? ^ ` | ~ ), "\x00".."\x1F", "\x7F", "\xFF") {
                if (not $octet{$char}) {
                    $delimiter     = $char;
                    $end_delimiter = $char;
                    last;
                }
            }
        }
    }

    my $left_e  = 0;
    my $right_e = 0;
    for (my $i=0; $i <= $#char; $i++) {

        # "\L\u" --> "\u\L"
        if (($char[$i] eq '\L') and ($char[$i+1] eq '\u')) {
            @char[$i,$i+1] = @char[$i+1,$i];
        }

        # "\U\l" --> "\l\U"
        elsif (($char[$i] eq '\U') and ($char[$i+1] eq '\l')) {
            @char[$i,$i+1] = @char[$i+1,$i];
        }

        # octal escape sequence
        elsif ($char[$i] =~ /\A \\o \{ ([0-7]+) \} \z/oxms) {
            $char[$i] = Euhc::octchr($1);
        }

        # hexadecimal escape sequence
        elsif ($char[$i] =~ /\A \\x \{ ([0-9A-Fa-f]+) \} \z/oxms) {
            $char[$i] = Euhc::hexchr($1);
        }

        # \b{...}      --> b\{...}
        # \B{...}      --> B\{...}
        # \N{CHARNAME} --> N\{CHARNAME}
        # \p{PROPERTY} --> p\{PROPERTY}
        # \P{PROPERTY} --> P\{PROPERTY}
        elsif ($char[$i] =~ /\A \\ ([bBNpP]) ( \{ ([^\x81-\xFE0-9\}][^\x81-\xFE\}]*) \} ) \z/oxms) {
            $char[$i] = $1 . '\\' . $2;
        }

        # \p, \P, \X --> p, P, X
        elsif ($char[$i] =~ /\A \\ ( [pPX] ) \z/oxms) {
            $char[$i] = $1;
        }

        if (0) {
        }

        # escape last octet of multiple-octet
        elsif ($char[$i] =~ /\A \\? ([\x80-\xFF].*) ($metachar|\Q$delimiter\E|\Q$end_delimiter\E) \z/xms) {
            $char[$i] = $1 . '\\' . $2;
        }

        # join separated multiple-octet
        elsif ($char[$i] =~ /\A (?: \\ [0-7]{2,3} | \\x [0-9A-Fa-f]{1,2}) \z/oxms) {
            if (   ($i+3 <= $#char) and (grep(/\A (?: \\ [0-7]{2,3} | \\x [0-9A-Fa-f]{1,2}) \z/oxms, @char[$i+1..$i+3]) == 3) and (CORE::eval(sprintf '"%s%s%s%s"', @char[$i..$i+3]) =~ /\A $q_char \z/oxms)) {
                $char[$i] .= join '', splice @char, $i+1, 3;
            }
            elsif (($i+2 <= $#char) and (grep(/\A (?: \\ [0-7]{2,3} | \\x [0-9A-Fa-f]{1,2}) \z/oxms, @char[$i+1..$i+2]) == 2) and (CORE::eval(sprintf '"%s%s%s"',   @char[$i..$i+2]) =~ /\A $q_char \z/oxms)) {
                $char[$i] .= join '', splice @char, $i+1, 2;
            }
            elsif (($i+1 <= $#char) and (grep(/\A (?: \\ [0-7]{2,3} | \\x [0-9A-Fa-f]{1,2}) \z/oxms, $char[$i+1      ]) == 1) and (CORE::eval(sprintf '"%s%s"',     @char[$i..$i+1]) =~ /\A $q_char \z/oxms)) {
                $char[$i] .= join '', splice @char, $i+1, 1;
            }
        }

        # open character class [...]
        elsif ($char[$i] eq '[') {
            my $left = $i;

            # [] make die "Unmatched [] in regexp ...\n"
            # (and so on)

            if ($char[$i+1] eq ']') {
                $i++;
            }

            while (1) {
                if (++$i > $#char) {
                    die __FILE__, ": Unmatched [] in regexp\n";
                }
                if ($char[$i] eq ']') {
                    my $right = $i;

                    # [...]
                    if (grep(/\A [\$\@]/oxms,@char[$left+1..$right-1]) >= 1) {
                        splice @char, $left, $right-$left+1, sprintf(q{@{[Euhc::charlist_qr(%s,'%s')]}}, join(',', map {qq_stuff($delimiter,$end_delimiter,$_)} @char[$left+1..$right-1]), $modifier);
                    }
                    else {
                        splice @char, $left, $right-$left+1, Euhc::charlist_qr(@char[$left+1..$right-1], $modifier);
                    }

                    $i = $left;
                    last;
                }
            }
        }

        # open character class [^...]
        elsif ($char[$i] eq '[^') {
            my $left = $i;

            # [^] make die "Unmatched [] in regexp ...\n"
            # (and so on)

            if ($char[$i+1] eq ']') {
                $i++;
            }

            while (1) {
                if (++$i > $#char) {
                    die __FILE__, ": Unmatched [] in regexp\n";
                }
                if ($char[$i] eq ']') {
                    my $right = $i;

                    # [^...]
                    if (grep(/\A [\$\@]/oxms,@char[$left+1..$right-1]) >= 1) {
                        splice @char, $left, $right-$left+1, sprintf(q{@{[Euhc::charlist_not_qr(%s,'%s')]}}, join(',', map {qq_stuff($delimiter,$end_delimiter,$_)} @char[$left+1..$right-1]), $modifier);
                    }
                    else {
                        splice @char, $left, $right-$left+1, Euhc::charlist_not_qr(@char[$left+1..$right-1], $modifier);
                    }

                    $i = $left;
                    last;
                }
            }
        }

        # rewrite character class or escape character
        elsif (my $char = character_class($char[$i],$modifier)) {
            $char[$i] = $char;
        }

        # /i modifier
        elsif ($ignorecase and ($char[$i] =~ /\A [\x00-\xFF] \z/oxms) and (Euhc::uc($char[$i]) ne Euhc::fc($char[$i]))) {
            if (CORE::length(Euhc::fc($char[$i])) == 1) {
                $char[$i] = '['   . Euhc::uc($char[$i])       . Euhc::fc($char[$i]) . ']';
            }
            else {
                $char[$i] = '(?:' . Euhc::uc($char[$i]) . '|' . Euhc::fc($char[$i]) . ')';
            }
        }

        # \u \l \U \L \F \Q \E
        elsif ($char[$i] =~ /\A [<>] \z/oxms) {
            if ($right_e < $left_e) {
                $char[$i] = '\\' . $char[$i];
            }
        }
        elsif ($char[$i] eq '\u') {
            $char[$i] = '@{[Euhc::ucfirst qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\l') {
            $char[$i] = '@{[Euhc::lcfirst qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\U') {
            $char[$i] = '@{[Euhc::uc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\L') {
            $char[$i] = '@{[Euhc::lc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\F') {
            $char[$i] = '@{[Euhc::fc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\Q') {
            $char[$i] = '@{[CORE::quotemeta qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\E') {
            if ($right_e < $left_e) {
                $char[$i] = '>]}';
                $right_e++;
            }
            else {
                $char[$i] = '';
            }
        }
        elsif ($char[$i] eq '\Q') {
            while (1) {
                if (++$i > $#char) {
                    last;
                }
                if ($char[$i] eq '\E') {
                    last;
                }
            }
        }
        elsif ($char[$i] eq '\E') {
        }

        # $0 --> $0
        elsif ($char[$i] =~ /\A \$ 0 \z/oxms) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }
        elsif ($char[$i] =~ /\A \$ \{ (?>\s*) 0 (?>\s*) \} \z/oxms) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $$ --> $$
        elsif ($char[$i] =~ /\A \$\$ \z/oxms) {
        }

        # $1, $2, $3 --> $2, $3, $4 after s/// with multibyte anchoring
        # $1, $2, $3 --> $1, $2, $3 otherwise
        elsif ($char[$i] =~ /\A \$ ((?>[1-9][0-9]*)) \z/oxms) {
            $char[$i] = e_capture($1);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }
        elsif ($char[$i] =~ /\A \$ \{ (?>\s*) ((?>[1-9][0-9]*)) (?>\s*) \} \z/oxms) {
            $char[$i] = e_capture($1);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $$foo[ ... ] --> $ $foo->[ ... ]
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \[ (?:$qq_bracket)*? \] ) \z/oxms) {
            $char[$i] = e_capture($1.'->'.$2);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $$foo{ ... } --> $ $foo->{ ... }
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \{ (?:$qq_brace)*? \} ) \z/oxms) {
            $char[$i] = e_capture($1.'->'.$2);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $$foo
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) \z/oxms) {
            $char[$i] = e_capture($1);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $`, ${`}, $PREMATCH, ${PREMATCH}, ${^PREMATCH} --> Euhc::PREMATCH()
        elsif ($char[$i] =~ /\A ( \$` | \$\{`\} | \$ (?>\s*) PREMATCH  | \$ (?>\s*) \{ (?>\s*) PREMATCH  (?>\s*) \} | \$ (?>\s*) \{\^PREMATCH\}  ) \z/oxmsgc) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(Euhc::PREMATCH())]}';
            }
            else {
                $char[$i] = '@{[Euhc::PREMATCH()]}';
            }
        }

        # $&, ${&}, $MATCH, ${MATCH}, ${^MATCH} --> Euhc::MATCH()
        elsif ($char[$i] =~ /\A ( \$& | \$\{&\} | \$ (?>\s*) MATCH     | \$ (?>\s*) \{ (?>\s*) MATCH     (?>\s*) \} | \$ (?>\s*) \{\^MATCH\}     ) \z/oxmsgc) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(Euhc::MATCH())]}';
            }
            else {
                $char[$i] = '@{[Euhc::MATCH()]}';
            }
        }

        # $POSTMATCH, ${POSTMATCH}, ${^POSTMATCH} --> Euhc::POSTMATCH()
        elsif ($char[$i] =~ /\A (                 \$ (?>\s*) POSTMATCH | \$ (?>\s*) \{ (?>\s*) POSTMATCH (?>\s*) \} | \$ (?>\s*) \{\^POSTMATCH\} ) \z/oxmsgc) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(Euhc::POSTMATCH())]}';
            }
            else {
                $char[$i] = '@{[Euhc::POSTMATCH()]}';
            }
        }

        # ${ foo }
        elsif ($char[$i] =~ /\A \$ (?>\s*) \{ ((?> \s* [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* \s* )) \}                              \z/oxms) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # ${ ... }
        elsif ($char[$i] =~ /\A \$ (?>\s*) \{ ( .+ ) \} \z/oxms) {
            $char[$i] = e_capture($1);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $scalar or @array
        elsif ($char[$i] =~ /\A [\$\@].+ /oxms) {
            $char[$i] = e_string($char[$i]);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # quote character before ? + * {
        elsif (($i >= 1) and ($char[$i] =~ /\A [\?\+\*\{] \z/oxms)) {
            if ($char[$i-1] =~ /\A (?:[\x00-\xFF]|\\[0-7]{2,3}|\\x[0-9-A-Fa-f]{1,2}) \z/oxms) {
            }
            elsif (($ope =~ /\A m? \z/oxms) and ($delimiter eq '?')) {
                my $char = $char[$i-1];
                if ($char[$i] eq '{') {
                    die __FILE__, qq{: "MULTIBYTE{n}" should be "(MULTIBYTE){n}" in m?? (and shift \$1,\$2,\$3,...) ($char){n}\n};
                }
                else {
                    die __FILE__, qq{: "MULTIBYTE$char[$i]" should be "(MULTIBYTE)$char[$i]" in m?? (and shift \$1,\$2,\$3,...) ($char)$char[$i]\n};
                }
            }
            else {
                $char[$i-1] = '(?:' . $char[$i-1] . ')';
            }
        }
    }

    # make regexp string
    $modifier =~ tr/i//d;
    if ($left_e > $right_e) {
        if (($ope =~ /\A m? \z/oxms) and ($delimiter eq '?')) {
            return join '', $ope, $delimiter, $anchor,        @char, '>]}' x ($left_e - $right_e),      $matched, $end_delimiter, $modifier;
        }
        else {
            return join '', $ope, $delimiter, $anchor, '(?:', @char, '>]}' x ($left_e - $right_e), ')', $matched, $end_delimiter, $modifier;
        }
    }
    if (($ope =~ /\A m? \z/oxms) and ($delimiter eq '?')) {
        return     join '', $ope, $delimiter, $anchor,        @char,                                    $matched, $end_delimiter, $modifier;
    }
    else {
        return     join '', $ope, $delimiter, $anchor, '(?:', @char,                               ')', $matched, $end_delimiter, $modifier;
    }
}

#
# double quote stuff
#
sub qq_stuff {
    my($delimiter,$end_delimiter,$stuff) = @_;

    # scalar variable or array variable
    if ($stuff =~ /\A [\$\@] /oxms) {
        return $stuff;
    }

    # quote by delimiter
    my %octet = map {$_ => 1} ($stuff =~ /\G ([\x00-\xFF]) /oxmsg);
    for my $char (qw( ! " $ % & * + - . / : = ? @ ^ ` | ~ ), "\x00".."\x1F", "\x7F", "\xFF") {
        next if $char eq $delimiter;
        next if $char eq $end_delimiter;
        if (not $octet{$char}) {
            return join '', 'qq', $char, $stuff, $char;
        }
    }
    return join '', 'qq', '<', $stuff, '>';
}

#
# escape regexp (m'', qr'', and m''b, qr''b)
#
sub e_qr_q {
    my($ope,$delimiter,$end_delimiter,$string,$modifier) = @_;
    $modifier ||= '';

    $modifier =~ tr/p//d;
    if ($modifier =~ /([adlu])/oxms) {
        my $line = 0;
        for (my $i=0; my($package,$filename,$use_line,$subroutine) = caller($i); $i++) {
            if ($filename ne __FILE__) {
                $line = $use_line + (CORE::substr($_,0,pos($_)) =~ tr/\n//) + 1;
                last;
            }
        }
        die qq{Unsupported modifier "$1" used at line $line.\n};
    }

    $slash = 'div';

    # literal null string pattern
    if ($string eq '') {
        $modifier =~ tr/bB//d;
        $modifier =~ tr/i//d;
        return join '', $ope, $delimiter, $end_delimiter, $modifier;
    }

    # with /b /B modifier
    elsif ($modifier =~ tr/bB//d) {
        return e_qr_qb($ope,$delimiter,$end_delimiter,$string,$modifier);
    }

    # without /b /B modifier
    else {
        return e_qr_qt($ope,$delimiter,$end_delimiter,$string,$modifier);
    }
}

#
# escape regexp (m'', qr'')
#
sub e_qr_qt {
    my($ope,$delimiter,$end_delimiter,$string,$modifier) = @_;

    my $ignorecase = ($modifier =~ /i/oxms) ? 1 : 0;

    # split regexp
    my @char = $string =~ /\G((?>
        [^\x81-\xFE\\\[\$\@\/] |
        [\x81-\xFE][\x00-\xFF] |
        \[\^                            |
        \[\:   (?>[a-z]+) \:\]          |
        \[\:\^ (?>[a-z]+) \:\]          |
        [\$\@\/]                        |
        \\     (?:$q_char)              |
               (?:$q_char)
    ))/oxmsg;

    # unescape character
    for (my $i=0; $i <= $#char; $i++) {
        if (0) {
        }

        # escape last octet of multiple-octet
        elsif ($char[$i] =~ /\A ([\x80-\xFF].*) ([\\|\[\{\^]|\Q$delimiter\E|\Q$end_delimiter\E) \z/xms) {
            $char[$i] = $1 . '\\' . $2;
        }

        # open character class [...]
        elsif ($char[$i] eq '[') {
            my $left = $i;
            if ($char[$i+1] eq ']') {
                $i++;
            }
            while (1) {
                if (++$i > $#char) {
                    die __FILE__, ": Unmatched [] in regexp\n";
                }
                if ($char[$i] eq ']') {
                    my $right = $i;

                    # [...]
                    splice @char, $left, $right-$left+1, Euhc::charlist_qr(@char[$left+1..$right-1], $modifier);

                    $i = $left;
                    last;
                }
            }
        }

        # open character class [^...]
        elsif ($char[$i] eq '[^') {
            my $left = $i;
            if ($char[$i+1] eq ']') {
                $i++;
            }
            while (1) {
                if (++$i > $#char) {
                    die __FILE__, ": Unmatched [] in regexp\n";
                }
                if ($char[$i] eq ']') {
                    my $right = $i;

                    # [^...]
                    splice @char, $left, $right-$left+1, Euhc::charlist_not_qr(@char[$left+1..$right-1], $modifier);

                    $i = $left;
                    last;
                }
            }
        }

        # escape $ @ / and \
        elsif ($char[$i] =~ /\A [\$\@\/\\] \z/oxms) {
            $char[$i] = '\\' . $char[$i];
        }

        # rewrite character class or escape character
        elsif (my $char = character_class($char[$i],$modifier)) {
            $char[$i] = $char;
        }

        # /i modifier
        elsif ($ignorecase and ($char[$i] =~ /\A [\x00-\xFF] \z/oxms) and (Euhc::uc($char[$i]) ne Euhc::fc($char[$i]))) {
            if (CORE::length(Euhc::fc($char[$i])) == 1) {
                $char[$i] = '['   . Euhc::uc($char[$i])       . Euhc::fc($char[$i]) . ']';
            }
            else {
                $char[$i] = '(?:' . Euhc::uc($char[$i]) . '|' . Euhc::fc($char[$i]) . ')';
            }
        }

        # quote character before ? + * {
        elsif (($i >= 1) and ($char[$i] =~ /\A [\?\+\*\{] \z/oxms)) {
            if ($char[$i-1] =~ /\A [\x00-\xFF] \z/oxms) {
            }
            else {
                $char[$i-1] = '(?:' . $char[$i-1] . ')';
            }
        }
    }

    $delimiter     = '/';
    $end_delimiter = '/';

    $modifier =~ tr/i//d;
    return join '', $ope, $delimiter, $anchor, '(?:', @char, ')', $matched, $end_delimiter, $modifier;
}

#
# escape regexp (m''b, qr''b)
#
sub e_qr_qb {
    my($ope,$delimiter,$end_delimiter,$string,$modifier) = @_;

    # split regexp
    my @char = $string =~ /\G ((?>[^\\]|\\\\|[\x00-\xFF])) /oxmsg;

    # unescape character
    for (my $i=0; $i <= $#char; $i++) {
        if (0) {
        }

        # remain \\
        elsif ($char[$i] eq '\\\\') {
        }

        # escape $ @ / and \
        elsif ($char[$i] =~ /\A [\$\@\/\\] \z/oxms) {
            $char[$i] = '\\' . $char[$i];
        }
    }

    $delimiter     = '/';
    $end_delimiter = '/';
    return join '', $ope, $delimiter, '(?:', @char, ')', $matched, $end_delimiter, $modifier;
}

#
# escape regexp (s/here//)
#
sub e_s1 {
    my($ope,$delimiter,$end_delimiter,$string,$modifier) = @_;
    $modifier ||= '';

    $modifier =~ tr/p//d;
    if ($modifier =~ /([adlu])/oxms) {
        my $line = 0;
        for (my $i=0; my($package,$filename,$use_line,$subroutine) = caller($i); $i++) {
            if ($filename ne __FILE__) {
                $line = $use_line + (CORE::substr($_,0,pos($_)) =~ tr/\n//) + 1;
                last;
            }
        }
        die qq{Unsupported modifier "$1" used at line $line.\n};
    }

    $slash = 'div';

    # literal null string pattern
    if ($string eq '') {
        $modifier =~ tr/bB//d;
        $modifier =~ tr/i//d;
        return join '', $ope, $delimiter, $end_delimiter, $modifier;
    }

    # /b /B modifier
    elsif ($modifier =~ tr/bB//d) {

        # choice again delimiter
        if ($delimiter =~ / [\@:] /oxms) {
            my @char = $string =~ /\G ([\x00-\xFF]) /oxmsg;
            my %octet = map {$_ => 1} @char;
            if (not $octet{')'}) {
                $delimiter     = '(';
                $end_delimiter = ')';
            }
            elsif (not $octet{'}'}) {
                $delimiter     = '{';
                $end_delimiter = '}';
            }
            elsif (not $octet{']'}) {
                $delimiter     = '[';
                $end_delimiter = ']';
            }
            elsif (not $octet{'>'}) {
                $delimiter     = '<';
                $end_delimiter = '>';
            }
            else {
                for my $char (qw( ! " $ % & * + - . / = ? ^ ` | ~ ), "\x00".."\x1F", "\x7F", "\xFF") {
                    if (not $octet{$char}) {
                        $delimiter     = $char;
                        $end_delimiter = $char;
                        last;
                    }
                }
            }
        }

        my $prematch = '';
        $prematch = q{(\G[\x00-\xFF]*?)};
        return join '', $ope, $delimiter, $prematch, '(?:', $string, ')', $matched, $end_delimiter, $modifier;
    }

    my $ignorecase = ($modifier =~ /i/oxms) ? 1 : 0;
    my $metachar = qr/[\@\\|[\]{^]/oxms;

    # split regexp
    my @char = $string =~ /\G((?>
        [^\x81-\xFE\\\$\@\[\(]|[\x81-\xFE][\x00-\xFF] |
        \\                               (?>[1-9][0-9]*)            |
        \\g (?>\s*)                      (?>[1-9][0-9]*)            |
        \\g (?>\s*) \{ (?>\s*)           (?>[1-9][0-9]*) (?>\s*) \} |
        \\g (?>\s*) \{ (?>\s*) - (?>\s*) (?>[1-9][0-9]*) (?>\s*) \} |
        \\x                              (?>[0-9A-Fa-f]{1,2})       |
        \\                               (?>[0-7]{2,3})             |
        \\c                              [\x40-\x5F]                |
        \\x\{                            (?>[0-9A-Fa-f]+)        \} |
        \\o\{                            (?>[0-7]+)              \} |
        \\[bBNpP]\{                      (?>[^\x81-\xFE0-9\}][^\x81-\xFE\}]*) \} |
        \\ $q_char                           |
        \$` | \$\{`\} | \$ (?>\s*) PREMATCH  | \$ (?>\s*) \{ (?>\s*) PREMATCH  (?>\s*) \} | \$ (?>\s*) \{\^PREMATCH\}  |
        \$& | \$\{&\} | \$ (?>\s*) MATCH     | \$ (?>\s*) \{ (?>\s*) MATCH     (?>\s*) \} | \$ (?>\s*) \{\^MATCH\}     |
                        \$ (?>\s*) POSTMATCH | \$ (?>\s*) \{ (?>\s*) POSTMATCH (?>\s*) \} | \$ (?>\s*) \{\^POSTMATCH\} |
        [\$\@] $qq_variable                  |
        \$ (?>\s* [0-9]+)                    |
        \$ (?>\s*) \{ (?>\s* [0-9]+ \s*) \}  |
        \$ \$ (?![\w\{])                     |
        \$ (?>\s*) \$ (?>\s*) $qq_variable   |
        \[\^                                 |
        \[\:   (?>[a-z]+) :\]                |
        \[\:\^ (?>[a-z]+) :\]                |
        \(\?                                 |
            $q_char
    ))/oxmsg;

    # choice again delimiter
    if ($delimiter =~ / [\@:] /oxms) {
        my %octet = map {$_ => 1} @char;
        if (not $octet{')'}) {
            $delimiter     = '(';
            $end_delimiter = ')';
        }
        elsif (not $octet{'}'}) {
            $delimiter     = '{';
            $end_delimiter = '}';
        }
        elsif (not $octet{']'}) {
            $delimiter     = '[';
            $end_delimiter = ']';
        }
        elsif (not $octet{'>'}) {
            $delimiter     = '<';
            $end_delimiter = '>';
        }
        else {
            for my $char (qw( ! " $ % & * + - . / = ? ^ ` | ~ ), "\x00".."\x1F", "\x7F", "\xFF") {
                if (not $octet{$char}) {
                    $delimiter     = $char;
                    $end_delimiter = $char;
                    last;
                }
            }
        }
    }

    # count '('
    my $parens = grep { $_ eq '(' } @char;

    my $left_e  = 0;
    my $right_e = 0;
    for (my $i=0; $i <= $#char; $i++) {

        # "\L\u" --> "\u\L"
        if (($char[$i] eq '\L') and ($char[$i+1] eq '\u')) {
            @char[$i,$i+1] = @char[$i+1,$i];
        }

        # "\U\l" --> "\l\U"
        elsif (($char[$i] eq '\U') and ($char[$i+1] eq '\l')) {
            @char[$i,$i+1] = @char[$i+1,$i];
        }

        # octal escape sequence
        elsif ($char[$i] =~ /\A \\o \{ ([0-7]+) \} \z/oxms) {
            $char[$i] = Euhc::octchr($1);
        }

        # hexadecimal escape sequence
        elsif ($char[$i] =~ /\A \\x \{ ([0-9A-Fa-f]+) \} \z/oxms) {
            $char[$i] = Euhc::hexchr($1);
        }

        # \b{...}      --> b\{...}
        # \B{...}      --> B\{...}
        # \N{CHARNAME} --> N\{CHARNAME}
        # \p{PROPERTY} --> p\{PROPERTY}
        # \P{PROPERTY} --> P\{PROPERTY}
        elsif ($char[$i] =~ /\A \\ ([bBNpP]) ( \{ ([^\x81-\xFE0-9\}][^\x81-\xFE\}]*) \} ) \z/oxms) {
            $char[$i] = $1 . '\\' . $2;
        }

        # \p, \P, \X --> p, P, X
        elsif ($char[$i] =~ /\A \\ ( [pPX] ) \z/oxms) {
            $char[$i] = $1;
        }

        if (0) {
        }

        # escape last octet of multiple-octet
        elsif ($char[$i] =~ /\A \\? ([\x80-\xFF].*) ($metachar|\Q$delimiter\E|\Q$end_delimiter\E) \z/xms) {
            $char[$i] = $1 . '\\' . $2;
        }

        # join separated multiple-octet
        elsif ($char[$i] =~ /\A (?: \\ [0-7]{2,3} | \\x [0-9A-Fa-f]{1,2}) \z/oxms) {
            if (   ($i+3 <= $#char) and (grep(/\A (?: \\ [0-7]{2,3} | \\x [0-9A-Fa-f]{1,2}) \z/oxms, @char[$i+1..$i+3]) == 3) and (CORE::eval(sprintf '"%s%s%s%s"', @char[$i..$i+3]) =~ /\A $q_char \z/oxms)) {
                $char[$i] .= join '', splice @char, $i+1, 3;
            }
            elsif (($i+2 <= $#char) and (grep(/\A (?: \\ [0-7]{2,3} | \\x [0-9A-Fa-f]{1,2}) \z/oxms, @char[$i+1..$i+2]) == 2) and (CORE::eval(sprintf '"%s%s%s"',   @char[$i..$i+2]) =~ /\A $q_char \z/oxms)) {
                $char[$i] .= join '', splice @char, $i+1, 2;
            }
            elsif (($i+1 <= $#char) and (grep(/\A (?: \\ [0-7]{2,3} | \\x [0-9A-Fa-f]{1,2}) \z/oxms, $char[$i+1      ]) == 1) and (CORE::eval(sprintf '"%s%s"',     @char[$i..$i+1]) =~ /\A $q_char \z/oxms)) {
                $char[$i] .= join '', splice @char, $i+1, 1;
            }
        }

        # open character class [...]
        elsif ($char[$i] eq '[') {
            my $left = $i;
            if ($char[$i+1] eq ']') {
                $i++;
            }
            while (1) {
                if (++$i > $#char) {
                    die __FILE__, ": Unmatched [] in regexp\n";
                }
                if ($char[$i] eq ']') {
                    my $right = $i;

                    # [...]
                    if (grep(/\A [\$\@]/oxms,@char[$left+1..$right-1]) >= 1) {
                        splice @char, $left, $right-$left+1, sprintf(q{@{[Euhc::charlist_qr(%s,'%s')]}}, join(',', map {qq_stuff($delimiter,$end_delimiter,$_)} @char[$left+1..$right-1]), $modifier);
                    }
                    else {
                        splice @char, $left, $right-$left+1, Euhc::charlist_qr(@char[$left+1..$right-1], $modifier);
                    }

                    $i = $left;
                    last;
                }
            }
        }

        # open character class [^...]
        elsif ($char[$i] eq '[^') {
            my $left = $i;
            if ($char[$i+1] eq ']') {
                $i++;
            }
            while (1) {
                if (++$i > $#char) {
                    die __FILE__, ": Unmatched [] in regexp\n";
                }
                if ($char[$i] eq ']') {
                    my $right = $i;

                    # [^...]
                    if (grep(/\A [\$\@]/oxms,@char[$left+1..$right-1]) >= 1) {
                        splice @char, $left, $right-$left+1, sprintf(q{@{[Euhc::charlist_not_qr(%s,'%s')]}}, join(',', map {qq_stuff($delimiter,$end_delimiter,$_)} @char[$left+1..$right-1]), $modifier);
                    }
                    else {
                        splice @char, $left, $right-$left+1, Euhc::charlist_not_qr(@char[$left+1..$right-1], $modifier);
                    }

                    $i = $left;
                    last;
                }
            }
        }

        # rewrite character class or escape character
        elsif (my $char = character_class($char[$i],$modifier)) {
            $char[$i] = $char;
        }

        # /i modifier
        elsif ($ignorecase and ($char[$i] =~ /\A [\x00-\xFF] \z/oxms) and (Euhc::uc($char[$i]) ne Euhc::fc($char[$i]))) {
            if (CORE::length(Euhc::fc($char[$i])) == 1) {
                $char[$i] = '['   . Euhc::uc($char[$i])       . Euhc::fc($char[$i]) . ']';
            }
            else {
                $char[$i] = '(?:' . Euhc::uc($char[$i]) . '|' . Euhc::fc($char[$i]) . ')';
            }
        }

        # \u \l \U \L \F \Q \E
        elsif ($char[$i] =~ /\A [<>] \z/oxms) {
            if ($right_e < $left_e) {
                $char[$i] = '\\' . $char[$i];
            }
        }
        elsif ($char[$i] eq '\u') {
            $char[$i] = '@{[Euhc::ucfirst qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\l') {
            $char[$i] = '@{[Euhc::lcfirst qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\U') {
            $char[$i] = '@{[Euhc::uc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\L') {
            $char[$i] = '@{[Euhc::lc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\F') {
            $char[$i] = '@{[Euhc::fc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\Q') {
            $char[$i] = '@{[CORE::quotemeta qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\E') {
            if ($right_e < $left_e) {
                $char[$i] = '>]}';
                $right_e++;
            }
            else {
                $char[$i] = '';
            }
        }
        elsif ($char[$i] eq '\Q') {
            while (1) {
                if (++$i > $#char) {
                    last;
                }
                if ($char[$i] eq '\E') {
                    last;
                }
            }
        }
        elsif ($char[$i] eq '\E') {
        }

        # \0 --> \0
        elsif ($char[$i] =~ /\A \\ (?>\s*) 0 \z/oxms) {
        }

        # \g{N}, \g{-N}

        # P.108 Using Simple Patterns
        # in Chapter 7: In the World of Regular Expressions
        # of ISBN 978-0-596-52010-6 Learning Perl, Fifth Edition

        # P.221 Capturing
        # in Chapter 5: Pattern Matching
        # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

        # \g{-1}, \g{-2}, \g{-3} --> \g{-1}, \g{-2}, \g{-3}
        elsif ($char[$i] =~ /\A \\g (?>\s*) \{ (?>\s*) - (?>\s*) ((?>[1-9][0-9]*)) (?>\s*) \} \z/oxms) {
        }

        # \g{1}, \g{2}, \g{3} --> \g{2}, \g{3}, \g{4} (only when multibyte anchoring is enable)
        elsif ($char[$i] =~ /\A \\g (?>\s*) \{ (?>\s*) ((?>[1-9][0-9]*)) (?>\s*) \} \z/oxms) {
            if ($1 <= $parens) {
                $char[$i] = '\\g{' . ($1 + 1) . '}';
            }
        }

        # \g1, \g2, \g3 --> \g2, \g3, \g4 (only when multibyte anchoring is enable)
        elsif ($char[$i] =~ /\A \\g (?>\s*) ((?>[1-9][0-9]*)) \z/oxms) {
            if ($1 <= $parens) {
                $char[$i] = '\\g' . ($1 + 1);
            }
        }

        # \1, \2, \3 --> \2, \3, \4 (only when multibyte anchoring is enable)
        elsif ($char[$i] =~ /\A \\ (?>\s*) ((?>[1-9][0-9]*)) \z/oxms) {
            if ($1 <= $parens) {
                $char[$i] = '\\' . ($1 + 1);
            }
        }

        # $0 --> $0
        elsif ($char[$i] =~ /\A \$ 0 \z/oxms) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }
        elsif ($char[$i] =~ /\A \$ \{ (?>\s*) 0 (?>\s*) \} \z/oxms) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $$ --> $$
        elsif ($char[$i] =~ /\A \$\$ \z/oxms) {
        }

        # $1, $2, $3 --> $2, $3, $4 after s/// with multibyte anchoring
        # $1, $2, $3 --> $1, $2, $3 otherwise
        elsif ($char[$i] =~ /\A \$ ((?>[1-9][0-9]*)) \z/oxms) {
            $char[$i] = e_capture($1);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }
        elsif ($char[$i] =~ /\A \$ \{ (?>\s*) ((?>[1-9][0-9]*)) (?>\s*) \} \z/oxms) {
            $char[$i] = e_capture($1);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $$foo[ ... ] --> $ $foo->[ ... ]
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \[ (?:$qq_bracket)*? \] ) \z/oxms) {
            $char[$i] = e_capture($1.'->'.$2);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $$foo{ ... } --> $ $foo->{ ... }
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \{ (?:$qq_brace)*? \} ) \z/oxms) {
            $char[$i] = e_capture($1.'->'.$2);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $$foo
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) \z/oxms) {
            $char[$i] = e_capture($1);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $`, ${`}, $PREMATCH, ${PREMATCH}, ${^PREMATCH} --> Euhc::PREMATCH()
        elsif ($char[$i] =~ /\A ( \$` | \$\{`\} | \$ (?>\s*) PREMATCH  | \$ (?>\s*) \{ (?>\s*) PREMATCH  (?>\s*) \} | \$ (?>\s*) \{\^PREMATCH\}  ) \z/oxmsgc) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(Euhc::PREMATCH())]}';
            }
            else {
                $char[$i] = '@{[Euhc::PREMATCH()]}';
            }
        }

        # $&, ${&}, $MATCH, ${MATCH}, ${^MATCH} --> Euhc::MATCH()
        elsif ($char[$i] =~ /\A ( \$& | \$\{&\} | \$ (?>\s*) MATCH     | \$ (?>\s*) \{ (?>\s*) MATCH     (?>\s*) \} | \$ (?>\s*) \{\^MATCH\}     ) \z/oxmsgc) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(Euhc::MATCH())]}';
            }
            else {
                $char[$i] = '@{[Euhc::MATCH()]}';
            }
        }

        # $POSTMATCH, ${POSTMATCH}, ${^POSTMATCH} --> Euhc::POSTMATCH()
        elsif ($char[$i] =~ /\A (                 \$ (?>\s*) POSTMATCH | \$ (?>\s*) \{ (?>\s*) POSTMATCH (?>\s*) \} | \$ (?>\s*) \{\^POSTMATCH\} ) \z/oxmsgc) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(Euhc::POSTMATCH())]}';
            }
            else {
                $char[$i] = '@{[Euhc::POSTMATCH()]}';
            }
        }

        # ${ foo }
        elsif ($char[$i] =~ /\A \$ (?>\s*) \{ ((?> \s* [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* \s* )) \}                              \z/oxms) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # ${ ... }
        elsif ($char[$i] =~ /\A \$ (?>\s*) \{ ( .+ ) \} \z/oxms) {
            $char[$i] = e_capture($1);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $scalar or @array
        elsif ($char[$i] =~ /\A [\$\@].+ /oxms) {
            $char[$i] = e_string($char[$i]);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # quote character before ? + * {
        elsif (($i >= 1) and ($char[$i] =~ /\A [\?\+\*\{] \z/oxms)) {
            if ($char[$i-1] =~ /\A (?:[\x00-\xFF]|\\[0-7]{2,3}|\\x[0-9-A-Fa-f]{1,2}) \z/oxms) {
            }
            else {
                $char[$i-1] = '(?:' . $char[$i-1] . ')';
            }
        }
    }

    # make regexp string
    my $prematch = '';
    $prematch = "($anchor)";
    $modifier =~ tr/i//d;
    if ($left_e > $right_e) {
        return join '', $ope, $delimiter, $prematch, '(?:', @char, '>]}' x ($left_e - $right_e), ')', $matched, $end_delimiter, $modifier;
    }
    return     join '', $ope, $delimiter, $prematch, '(?:', @char,                               ')', $matched, $end_delimiter, $modifier;
}

#
# escape regexp (s'here'' or s'here''b)
#
sub e_s1_q {
    my($ope,$delimiter,$end_delimiter,$string,$modifier) = @_;
    $modifier ||= '';

    $modifier =~ tr/p//d;
    if ($modifier =~ /([adlu])/oxms) {
        my $line = 0;
        for (my $i=0; my($package,$filename,$use_line,$subroutine) = caller($i); $i++) {
            if ($filename ne __FILE__) {
                $line = $use_line + (CORE::substr($_,0,pos($_)) =~ tr/\n//) + 1;
                last;
            }
        }
        die qq{Unsupported modifier "$1" used at line $line.\n};
    }

    $slash = 'div';

    # literal null string pattern
    if ($string eq '') {
        $modifier =~ tr/bB//d;
        $modifier =~ tr/i//d;
        return join '', $ope, $delimiter, $end_delimiter, $modifier;
    }

    # with /b /B modifier
    elsif ($modifier =~ tr/bB//d) {
        return e_s1_qb($ope,$delimiter,$end_delimiter,$string,$modifier);
    }

    # without /b /B modifier
    else {
        return e_s1_qt($ope,$delimiter,$end_delimiter,$string,$modifier);
    }
}

#
# escape regexp (s'here'')
#
sub e_s1_qt {
    my($ope,$delimiter,$end_delimiter,$string,$modifier) = @_;

    my $ignorecase = ($modifier =~ /i/oxms) ? 1 : 0;

    # split regexp
    my @char = $string =~ /\G((?>
        [^\x81-\xFE\\\[\$\@\/] |
        [\x81-\xFE][\x00-\xFF] |
        \[\^                            |
        \[\:   (?>[a-z]+) \:\]          |
        \[\:\^ (?>[a-z]+) \:\]          |
        [\$\@\/]                        |
        \\     (?:$q_char)              |
               (?:$q_char)
    ))/oxmsg;

    # unescape character
    for (my $i=0; $i <= $#char; $i++) {
        if (0) {
        }

        # escape last octet of multiple-octet
        elsif ($char[$i] =~ /\A ([\x80-\xFF].*) ([\\|\[\{\^]|\Q$delimiter\E|\Q$end_delimiter\E) \z/xms) {
            $char[$i] = $1 . '\\' . $2;
        }

        # open character class [...]
        elsif ($char[$i] eq '[') {
            my $left = $i;
            if ($char[$i+1] eq ']') {
                $i++;
            }
            while (1) {
                if (++$i > $#char) {
                    die __FILE__, ": Unmatched [] in regexp\n";
                }
                if ($char[$i] eq ']') {
                    my $right = $i;

                    # [...]
                    splice @char, $left, $right-$left+1, Euhc::charlist_qr(@char[$left+1..$right-1], $modifier);

                    $i = $left;
                    last;
                }
            }
        }

        # open character class [^...]
        elsif ($char[$i] eq '[^') {
            my $left = $i;
            if ($char[$i+1] eq ']') {
                $i++;
            }
            while (1) {
                if (++$i > $#char) {
                    die __FILE__, ": Unmatched [] in regexp\n";
                }
                if ($char[$i] eq ']') {
                    my $right = $i;

                    # [^...]
                    splice @char, $left, $right-$left+1, Euhc::charlist_not_qr(@char[$left+1..$right-1], $modifier);

                    $i = $left;
                    last;
                }
            }
        }

        # escape $ @ / and \
        elsif ($char[$i] =~ /\A [\$\@\/\\] \z/oxms) {
            $char[$i] = '\\' . $char[$i];
        }

        # rewrite character class or escape character
        elsif (my $char = character_class($char[$i],$modifier)) {
            $char[$i] = $char;
        }

        # /i modifier
        elsif ($ignorecase and ($char[$i] =~ /\A [\x00-\xFF] \z/oxms) and (Euhc::uc($char[$i]) ne Euhc::fc($char[$i]))) {
            if (CORE::length(Euhc::fc($char[$i])) == 1) {
                $char[$i] = '['   . Euhc::uc($char[$i])       . Euhc::fc($char[$i]) . ']';
            }
            else {
                $char[$i] = '(?:' . Euhc::uc($char[$i]) . '|' . Euhc::fc($char[$i]) . ')';
            }
        }

        # quote character before ? + * {
        elsif (($i >= 1) and ($char[$i] =~ /\A [\?\+\*\{] \z/oxms)) {
            if ($char[$i-1] =~ /\A [\x00-\xFF] \z/oxms) {
            }
            else {
                $char[$i-1] = '(?:' . $char[$i-1] . ')';
            }
        }
    }

    $modifier =~ tr/i//d;
    $delimiter     = '/';
    $end_delimiter = '/';
    my $prematch = '';
    $prematch = "($anchor)";
    return join '', $ope, $delimiter, $prematch, '(?:', @char, ')', $matched, $end_delimiter, $modifier;
}

#
# escape regexp (s'here''b)
#
sub e_s1_qb {
    my($ope,$delimiter,$end_delimiter,$string,$modifier) = @_;

    # split regexp
    my @char = $string =~ /\G (?>[^\\]|\\\\|[\x00-\xFF]) /oxmsg;

    # unescape character
    for (my $i=0; $i <= $#char; $i++) {
        if (0) {
        }

        # remain \\
        elsif ($char[$i] eq '\\\\') {
        }

        # escape $ @ / and \
        elsif ($char[$i] =~ /\A [\$\@\/\\] \z/oxms) {
            $char[$i] = '\\' . $char[$i];
        }
    }

    $delimiter     = '/';
    $end_delimiter = '/';
    my $prematch = '';
    $prematch = q{(\G[\x00-\xFF]*?)};
    return join '', $ope, $delimiter, $prematch, '(?:', @char, ')', $matched, $end_delimiter, $modifier;
}

#
# escape regexp (s''here')
#
sub e_s2_q {
    my($ope,$delimiter,$end_delimiter,$string) = @_;

    $slash = 'div';

    my @char = $string =~ / \G (?>[^\x81-\xFE\\]|\\\\|$q_char) /oxmsg;
    for (my $i=0; $i <= $#char; $i++) {
        if (0) {
        }

        # escape last octet of multiple-octet
        elsif ($char[$i] =~ /\A ([\x80-\xFF].*) (\Q$delimiter\E|\Q$end_delimiter\E) \z/xms) {
            $char[$i] = $1 . '\\' . $2;
        }
        elsif (defined($char[$i+1]) and ($char[$i+1] eq '\\') and ($char[$i] =~ /\A ([\x80-\xFF].*) (\\) \z/xms)) {
            $char[$i] = $1 . '\\' . $2;
        }

        # not escape \\
        elsif ($char[$i] =~ /\A \\\\ \z/oxms) {
        }

        # escape $ @ / and \
        elsif ($char[$i] =~ /\A [\$\@\/\\] \z/oxms) {
            $char[$i] = '\\' . $char[$i];
        }
    }
    if (defined($char[-1]) and ($char[-1] =~ /\A ([\x80-\xFF].*) (\\) \z/xms)) {
        $char[-1] = $1 . '\\' . $2;
    }

    return join '', $ope, $delimiter, @char,   $end_delimiter;
}

#
# escape regexp (s/here/and here/modifier)
#
sub e_sub {
    my($variable,$delimiter1,$pattern,$end_delimiter1,$delimiter2,$replacement,$end_delimiter2,$modifier) = @_;
    $modifier ||= '';

    $modifier =~ tr/p//d;
    if ($modifier =~ /([adlu])/oxms) {
        my $line = 0;
        for (my $i=0; my($package,$filename,$use_line,$subroutine) = caller($i); $i++) {
            if ($filename ne __FILE__) {
                $line = $use_line + (CORE::substr($_,0,pos($_)) =~ tr/\n//) + 1;
                last;
            }
        }
        die qq{Unsupported modifier "$1" used at line $line.\n};
    }

    if ($variable eq '') {
        $variable      = '$_';
        $bind_operator = ' =~ ';
    }

    $slash = 'div';

    # P.128 Start of match (or end of previous match): \G
    # P.130 Advanced Use of \G with Perl
    # in Chapter 3: Overview of Regular Expression Features and Flavors
    # P.312 Iterative Matching: Scalar Context, with /g
    # in Chapter 7: Perl
    # of ISBN 0-596-00289-0 Mastering Regular Expressions, Second edition

    # P.181 Where You Left Off: The \G Assertion
    # in Chapter 5: Pattern Matching
    # of ISBN 0-596-00027-8 Programming Perl Third Edition.

    # P.220 Where You Left Off: The \G Assertion
    # in Chapter 5: Pattern Matching
    # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

    my $e_modifier = $modifier =~ tr/e//d;
    my $r_modifier = $modifier =~ tr/r//d;

    my $my = '';
    if ($variable =~ s/\A \( (?>\s*) ( (?>(?: local \b | my \b | our \b | state \b )?) .+ ) \) \z/$1/oxms) {
        $my = $variable;
        $variable =~ s/ (?: local \b | my \b | our \b | state \b ) (?>\s*) //oxms;
        $variable =~ s/ = .+ \z//oxms;
    }

    (my $variable_basename = $variable) =~ s/ [\[\{].* \z//oxms;
    $variable_basename =~ s/ \s+ \z//oxms;

    # quote replacement string
    my $e_replacement = '';
    if ($e_modifier >= 1) {
        $e_replacement = e_qq('', '', '', $replacement);
        $e_modifier--;
    }
    else {
        if ($delimiter2 eq "'") {
            $e_replacement = e_s2_q('qq', '/',         '/',             $replacement);
        }
        else {
            $e_replacement = e_qq  ('qq', $delimiter2, $end_delimiter2, $replacement);
        }
    }

    my $sub = '';

    # with /r
    if ($r_modifier) {
        if (0) {
        }

        # s///gr with multibyte anchoring
        elsif ($modifier =~ /g/oxms) {
            $sub = sprintf(
                #                               1                                                2   3                                  4   5
                q,

                $variable,                                                       #  1
                ($delimiter1 eq "'") ?                                           #  2
                e_s1_q('m', $delimiter1, $end_delimiter1, $pattern, $modifier) : #  :
                e_s1  ('m', $delimiter1, $end_delimiter1, $pattern, $modifier),  #  :
                $s_matched,                                                      #  3
                $e_replacement,                                                  #  4
                '$Euhc::re_r=CORE::eval $Euhc::re_r; ' x $e_modifier,          #  5
            );
        }

        # s///gr without multibyte anchoring
        elsif ($modifier =~ /g/oxms) {
            $sub = sprintf(
                #                               1                         2   3                                  4   5
                q,

                $variable,                                                       #  1
                ($delimiter1 eq "'") ?                                           #  2
                e_s1_q('m', $delimiter1, $end_delimiter1, $pattern, $modifier) : #  :
                e_s1  ('m', $delimiter1, $end_delimiter1, $pattern, $modifier),  #  :
                $s_matched,                                                      #  3
                $e_replacement,                                                  #  4
                '$Euhc::re_r=CORE::eval $Euhc::re_r; ' x $e_modifier,          #  5
            );
        }

        # s///r
        else {

            my $prematch = q{$`};
            $prematch = q{${1}};

            $sub = sprintf(
                #  1     2                3                                  4   5  6                     7
                q<(%s =~ %s) ? CORE::eval{%s local $^W=0; local $Euhc::re_r=%s; %s"%s$Euhc::re_r$'" } : %s>,

                $variable,                                                       #  1
                ($delimiter1 eq "'") ?                                           #  2
                e_s1_q('m', $delimiter1, $end_delimiter1, $pattern, $modifier) : #  :
                e_s1  ('m', $delimiter1, $end_delimiter1, $pattern, $modifier),  #  :
                $s_matched,                                                      #  3
                $e_replacement,                                                  #  4
                '$Euhc::re_r=CORE::eval $Euhc::re_r; ' x $e_modifier,          #  5
                $prematch,                                                       #  6
                $variable,                                                       #  7
            );
        }

        # $var !~ s///r doesn't make sense
        if ($bind_operator =~ / !~ /oxms) {
            $sub = q{die("$0: Using !~ with s///r doesn't make sense"), } . $sub;
        }
    }

    # without /r
    else {
        if (0) {
        }

        # s///g with multibyte anchoring
        elsif ($modifier =~ /g/oxms) {
            $sub = sprintf(
                #                                                               1     2   3                                  4   5 6                                        7                                                              8        9                            10
                q,

                $variable,                                                       #  1
                ($delimiter1 eq "'") ?                                           #  2
                e_s1_q('m', $delimiter1, $end_delimiter1, $pattern, $modifier) : #  :
                e_s1  ('m', $delimiter1, $end_delimiter1, $pattern, $modifier),  #  :
                $s_matched,                                                      #  3
                $e_replacement,                                                  #  4
                '$Euhc::re_r=CORE::eval $Euhc::re_r; ' x $e_modifier,          #  5
                $variable,                                                       #  6
                $variable,                                                       #  7
                $variable,                                                       #  8
                $variable,                                                       #  9

# Binary "!~" is just like "=~" except the return value is negated in the logical sense.
# It returns false if the match succeeds, and true if it fails.
# (and so on)

                ($bind_operator =~ / !~ /oxms) ? '!' : '',                       # 10
            );
        }

        # s///g without multibyte anchoring
        elsif ($modifier =~ /g/oxms) {
            $sub = sprintf(
                #                                        1     2   3                                  4   5 6                          7                                                   8
                q,

                $variable,                                                       #  1
                ($delimiter1 eq "'") ?                                           #  2
                e_s1_q('m', $delimiter1, $end_delimiter1, $pattern, $modifier) : #  :
                e_s1  ('m', $delimiter1, $end_delimiter1, $pattern, $modifier),  #  :
                $s_matched,                                                      #  3
                $e_replacement,                                                  #  4
                '$Euhc::re_r=CORE::eval $Euhc::re_r; ' x $e_modifier,          #  5
                $variable,                                                       #  6
                $variable,                                                       #  7
                ($bind_operator =~ / !~ /oxms) ? '!' : '',                       #  8
            );
        }

        # s///
        else {

            my $prematch = q{$`};
            $prematch = q{${1}};

            $sub = sprintf(

                ($bind_operator =~ / =~ /oxms) ?

                #  1 2 3                4                                  5   6 7   8
                q<(%s%s%s) ? CORE::eval{%s local $^W=0; local $Euhc::re_r=%s; %s%s="%s$Euhc::re_r$'"; 1 } : undef> :

                #  1 2 3                    4                                  5   6 7   8
                q<(%s%s%s) ? 1 : CORE::eval{%s local $^W=0; local $Euhc::re_r=%s; %s%s="%s$Euhc::re_r$'"; undef }>,

                $variable,                                                       #  1
                $bind_operator,                                                  #  2
                ($delimiter1 eq "'") ?                                           #  3
                e_s1_q('m', $delimiter1, $end_delimiter1, $pattern, $modifier) : #  :
                e_s1  ('m', $delimiter1, $end_delimiter1, $pattern, $modifier),  #  :
                $s_matched,                                                      #  4
                $e_replacement,                                                  #  5
                '$Euhc::re_r=CORE::eval $Euhc::re_r; ' x $e_modifier,          #  6
                $variable,                                                       #  7
                $prematch,                                                       #  8
            );
        }
    }

    # (my $foo = $bar) =~ s///   -->   (my $foo = $bar, CORE::eval { ... })[1]
    if ($my ne '') {
        $sub = "($my, $sub)[1]";
    }

    # clear s/// variable
    $sub_variable = '';
    $bind_operator = '';

    return $sub;
}

#
# escape chdir (qq//, "")
#
sub e_chdir {
    my($ope,$delimiter,$end_delimiter,$string) = @_;

    if ($^W) {
        if (Euhc::_MSWin32_5Cended_path($string)) {
            if ($] !~ /^5\.005/oxms) {
                warn <
@{[__FILE__]}: Can't chdir to '$string'

chdir does not work with chr(0x5C) at end of path
http://bugs.activestate.com/show_bug.cgi?id=81839
END
            }
        }
    }

    return e_qq($ope,$delimiter,$end_delimiter,$string);
}

#
# escape chdir (q//, '')
#
sub e_chdir_q {
    my($ope,$delimiter,$end_delimiter,$string) = @_;

    if ($^W) {
        if (Euhc::_MSWin32_5Cended_path($string)) {
            if ($] !~ /^5\.005/oxms) {
                warn <
@{[__FILE__]}: Can't chdir to '$string'

chdir does not work with chr(0x5C) at end of path
http://bugs.activestate.com/show_bug.cgi?id=81839
END
            }
        }
    }

    return e_q($ope,$delimiter,$end_delimiter,$string);
}

#
# escape regexp of split qr//
#
sub e_split {
    my($ope,$delimiter,$end_delimiter,$string,$modifier) = @_;
    $modifier ||= '';

    $modifier =~ tr/p//d;
    if ($modifier =~ /([adlu])/oxms) {
        my $line = 0;
        for (my $i=0; my($package,$filename,$use_line,$subroutine) = caller($i); $i++) {
            if ($filename ne __FILE__) {
                $line = $use_line + (CORE::substr($_,0,pos($_)) =~ tr/\n//) + 1;
                last;
            }
        }
        die qq{Unsupported modifier "$1" used at line $line.\n};
    }

    $slash = 'div';

    # /b /B modifier
    if ($modifier =~ tr/bB//d) {
        return join '', 'split', $ope, $delimiter, $string, $end_delimiter, $modifier;
    }

    my $ignorecase = ($modifier =~ /i/oxms) ? 1 : 0;
    my $metachar = qr/[\@\\|[\]{^]/oxms;

    # split regexp
    my @char = $string =~ /\G((?>
        [^\x81-\xFE\\\$\@\[\(]|[\x81-\xFE][\x00-\xFF] |
        \\x   (?>[0-9A-Fa-f]{1,2}) |
        \\    (?>[0-7]{2,3})       |
        \\c   [\x40-\x5F]          |
        \\x\{ (?>[0-9A-Fa-f]+) \}  |
        \\o\{ (?>[0-7]+)       \}  |
        \\[bBNpP]\{ (?>[^\x81-\xFE0-9\}][^\x81-\xFE\}]*) \} |
        \\  $q_char                |
        \$` | \$\{`\} | \$ (?>\s*) PREMATCH  | \$ (?>\s*) \{ (?>\s*) PREMATCH  (?>\s*) \} | \$ (?>\s*) \{\^PREMATCH\}  |
        \$& | \$\{&\} | \$ (?>\s*) MATCH     | \$ (?>\s*) \{ (?>\s*) MATCH     (?>\s*) \} | \$ (?>\s*) \{\^MATCH\}     |
                        \$ (?>\s*) POSTMATCH | \$ (?>\s*) \{ (?>\s*) POSTMATCH (?>\s*) \} | \$ (?>\s*) \{\^POSTMATCH\} |
        [\$\@] $qq_variable        |
        \$ (?>\s* [0-9]+)          |
        \$ (?>\s*) \{ (?>\s* [0-9]+ \s*) \}  |
        \$ \$ (?![\w\{])           |
        \$ (?>\s*) \$ (?>\s*) $qq_variable   |
        \[\^                       |
        \[\:   (?>[a-z]+) :\]      |
        \[\:\^ (?>[a-z]+) :\]      |
        \(\?                       |
            $q_char
    ))/oxmsg;

    my $left_e  = 0;
    my $right_e = 0;
    for (my $i=0; $i <= $#char; $i++) {

        # "\L\u" --> "\u\L"
        if (($char[$i] eq '\L') and ($char[$i+1] eq '\u')) {
            @char[$i,$i+1] = @char[$i+1,$i];
        }

        # "\U\l" --> "\l\U"
        elsif (($char[$i] eq '\U') and ($char[$i+1] eq '\l')) {
            @char[$i,$i+1] = @char[$i+1,$i];
        }

        # octal escape sequence
        elsif ($char[$i] =~ /\A \\o \{ ([0-7]+) \} \z/oxms) {
            $char[$i] = Euhc::octchr($1);
        }

        # hexadecimal escape sequence
        elsif ($char[$i] =~ /\A \\x \{ ([0-9A-Fa-f]+) \} \z/oxms) {
            $char[$i] = Euhc::hexchr($1);
        }

        # \b{...}      --> b\{...}
        # \B{...}      --> B\{...}
        # \N{CHARNAME} --> N\{CHARNAME}
        # \p{PROPERTY} --> p\{PROPERTY}
        # \P{PROPERTY} --> P\{PROPERTY}
        elsif ($char[$i] =~ /\A \\ ([bBNpP]) ( \{ ([^\x81-\xFE0-9\}][^\x81-\xFE\}]*) \} ) \z/oxms) {
            $char[$i] = $1 . '\\' . $2;
        }

        # \p, \P, \X --> p, P, X
        elsif ($char[$i] =~ /\A \\ ( [pPX] ) \z/oxms) {
            $char[$i] = $1;
        }

        if (0) {
        }

        # escape last octet of multiple-octet
        elsif ($char[$i] =~ /\A \\? ([\x80-\xFF].*) ($metachar|\Q$delimiter\E|\Q$end_delimiter\E) \z/xms) {
            $char[$i] = $1 . '\\' . $2;
        }

        # join separated multiple-octet
        elsif ($char[$i] =~ /\A (?: \\ [0-7]{2,3} | \\x [0-9A-Fa-f]{1,2}) \z/oxms) {
            if (   ($i+3 <= $#char) and (grep(/\A (?: \\ [0-7]{2,3} | \\x [0-9A-Fa-f]{1,2}) \z/oxms, @char[$i+1..$i+3]) == 3) and (CORE::eval(sprintf '"%s%s%s%s"', @char[$i..$i+3]) =~ /\A $q_char \z/oxms)) {
                $char[$i] .= join '', splice @char, $i+1, 3;
            }
            elsif (($i+2 <= $#char) and (grep(/\A (?: \\ [0-7]{2,3} | \\x [0-9A-Fa-f]{1,2}) \z/oxms, @char[$i+1..$i+2]) == 2) and (CORE::eval(sprintf '"%s%s%s"',   @char[$i..$i+2]) =~ /\A $q_char \z/oxms)) {
                $char[$i] .= join '', splice @char, $i+1, 2;
            }
            elsif (($i+1 <= $#char) and (grep(/\A (?: \\ [0-7]{2,3} | \\x [0-9A-Fa-f]{1,2}) \z/oxms, $char[$i+1      ]) == 1) and (CORE::eval(sprintf '"%s%s"',     @char[$i..$i+1]) =~ /\A $q_char \z/oxms)) {
                $char[$i] .= join '', splice @char, $i+1, 1;
            }
        }

        # open character class [...]
        elsif ($char[$i] eq '[') {
            my $left = $i;
            if ($char[$i+1] eq ']') {
                $i++;
            }
            while (1) {
                if (++$i > $#char) {
                    die __FILE__, ": Unmatched [] in regexp\n";
                }
                if ($char[$i] eq ']') {
                    my $right = $i;

                    # [...]
                    if (grep(/\A [\$\@]/oxms,@char[$left+1..$right-1]) >= 1) {
                        splice @char, $left, $right-$left+1, sprintf(q{@{[Euhc::charlist_qr(%s,'%s')]}}, join(',', map {qq_stuff($delimiter,$end_delimiter,$_)} @char[$left+1..$right-1]), $modifier);
                    }
                    else {
                        splice @char, $left, $right-$left+1, Euhc::charlist_qr(@char[$left+1..$right-1], $modifier);
                    }

                    $i = $left;
                    last;
                }
            }
        }

        # open character class [^...]
        elsif ($char[$i] eq '[^') {
            my $left = $i;
            if ($char[$i+1] eq ']') {
                $i++;
            }
            while (1) {
                if (++$i > $#char) {
                    die __FILE__, ": Unmatched [] in regexp\n";
                }
                if ($char[$i] eq ']') {
                    my $right = $i;

                    # [^...]
                    if (grep(/\A [\$\@]/oxms,@char[$left+1..$right-1]) >= 1) {
                        splice @char, $left, $right-$left+1, sprintf(q{@{[Euhc::charlist_not_qr(%s,'%s')]}}, join(',', map {qq_stuff($delimiter,$end_delimiter,$_)} @char[$left+1..$right-1]), $modifier);
                    }
                    else {
                        splice @char, $left, $right-$left+1, Euhc::charlist_not_qr(@char[$left+1..$right-1], $modifier);
                    }

                    $i = $left;
                    last;
                }
            }
        }

        # rewrite character class or escape character
        elsif (my $char = character_class($char[$i],$modifier)) {
            $char[$i] = $char;
        }

        # P.794 29.2.161. split
        # in Chapter 29: Functions
        # of ISBN 0-596-00027-8 Programming Perl Third Edition.

        # P.951 split
        # in Chapter 27: Functions
        # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

        # said "The //m modifier is assumed when you split on the pattern /^/",
        # but perl5.008 is not so. Therefore, this software adds //m.
        # (and so on)

        # split(m/^/) --> split(m/^/m)
        elsif (($char[$i] eq '^') and ($modifier !~ /m/oxms)) {
            $modifier .= 'm';
        }

        # /i modifier
        elsif ($ignorecase and ($char[$i] =~ /\A [\x00-\xFF] \z/oxms) and (Euhc::uc($char[$i]) ne Euhc::fc($char[$i]))) {
            if (CORE::length(Euhc::fc($char[$i])) == 1) {
                $char[$i] = '['   . Euhc::uc($char[$i])       . Euhc::fc($char[$i]) . ']';
            }
            else {
                $char[$i] = '(?:' . Euhc::uc($char[$i]) . '|' . Euhc::fc($char[$i]) . ')';
            }
        }

        # \u \l \U \L \F \Q \E
        elsif ($char[$i] =~ /\A ([<>]) \z/oxms) {
            if ($right_e < $left_e) {
                $char[$i] = '\\' . $char[$i];
            }
        }
        elsif ($char[$i] eq '\u') {
            $char[$i] = '@{[Euhc::ucfirst qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\l') {
            $char[$i] = '@{[Euhc::lcfirst qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\U') {
            $char[$i] = '@{[Euhc::uc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\L') {
            $char[$i] = '@{[Euhc::lc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\F') {
            $char[$i] = '@{[Euhc::fc qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\Q') {
            $char[$i] = '@{[CORE::quotemeta qq<';
            $left_e++;
        }
        elsif ($char[$i] eq '\E') {
            if ($right_e < $left_e) {
                $char[$i] = '>]}';
                $right_e++;
            }
            else {
                $char[$i] = '';
            }
        }
        elsif ($char[$i] eq '\Q') {
            while (1) {
                if (++$i > $#char) {
                    last;
                }
                if ($char[$i] eq '\E') {
                    last;
                }
            }
        }
        elsif ($char[$i] eq '\E') {
        }

        # $0 --> $0
        elsif ($char[$i] =~ /\A \$ 0 \z/oxms) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }
        elsif ($char[$i] =~ /\A \$ \{ (?>\s*) 0 (?>\s*) \} \z/oxms) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $$ --> $$
        elsif ($char[$i] =~ /\A \$\$ \z/oxms) {
        }

        # $1, $2, $3 --> $2, $3, $4 after s/// with multibyte anchoring
        # $1, $2, $3 --> $1, $2, $3 otherwise
        elsif ($char[$i] =~ /\A \$ ((?>[1-9][0-9]*)) \z/oxms) {
            $char[$i] = e_capture($1);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }
        elsif ($char[$i] =~ /\A \$ \{ (?>\s*) ((?>[1-9][0-9]*)) (?>\s*) \} \z/oxms) {
            $char[$i] = e_capture($1);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $$foo[ ... ] --> $ $foo->[ ... ]
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \[ (?:$qq_bracket)*? \] ) \z/oxms) {
            $char[$i] = e_capture($1.'->'.$2);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $$foo{ ... } --> $ $foo->{ ... }
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) ( \{ (?:$qq_brace)*? \} ) \z/oxms) {
            $char[$i] = e_capture($1.'->'.$2);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $$foo
        elsif ($char[$i] =~ /\A \$ ((?> \$ [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* )) \z/oxms) {
            $char[$i] = e_capture($1);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $`, ${`}, $PREMATCH, ${PREMATCH}, ${^PREMATCH} --> Euhc::PREMATCH()
        elsif ($char[$i] =~ /\A ( \$` | \$\{`\} | \$ (?>\s*) PREMATCH  | \$ (?>\s*) \{ (?>\s*) PREMATCH  (?>\s*) \} | \$ (?>\s*) \{\^PREMATCH\}  ) \z/oxmsgc) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(Euhc::PREMATCH())]}';
            }
            else {
                $char[$i] = '@{[Euhc::PREMATCH()]}';
            }
        }

        # $&, ${&}, $MATCH, ${MATCH}, ${^MATCH} --> Euhc::MATCH()
        elsif ($char[$i] =~ /\A ( \$& | \$\{&\} | \$ (?>\s*) MATCH     | \$ (?>\s*) \{ (?>\s*) MATCH     (?>\s*) \} | \$ (?>\s*) \{\^MATCH\}     ) \z/oxmsgc) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(Euhc::MATCH())]}';
            }
            else {
                $char[$i] = '@{[Euhc::MATCH()]}';
            }
        }

        # $POSTMATCH, ${POSTMATCH}, ${^POSTMATCH} --> Euhc::POSTMATCH()
        elsif ($char[$i] =~ /\A (                 \$ (?>\s*) POSTMATCH | \$ (?>\s*) \{ (?>\s*) POSTMATCH (?>\s*) \} | \$ (?>\s*) \{\^POSTMATCH\} ) \z/oxmsgc) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(Euhc::POSTMATCH())]}';
            }
            else {
                $char[$i] = '@{[Euhc::POSTMATCH()]}';
            }
        }

        # ${ foo }
        elsif ($char[$i] =~ /\A \$ (?>\s*) \{ ((?> \s* [A-Za-z_][A-Za-z0-9_]*(?: ::[A-Za-z_][A-Za-z0-9_]*)* \s* )) \}                            \z/oxms) {
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $1 . ')]}';
            }
        }

        # ${ ... }
        elsif ($char[$i] =~ /\A \$ (?>\s*) \{ ( .+ ) \} \z/oxms) {
            $char[$i] = e_capture($1);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # $scalar or @array
        elsif ($char[$i] =~ /\A [\$\@].+ /oxms) {
            $char[$i] = e_string($char[$i]);
            if ($ignorecase) {
                $char[$i] = '@{[Euhc::ignorecase(' . $char[$i] . ')]}';
            }
        }

        # quote character before ? + * {
        elsif (($i >= 1) and ($char[$i] =~ /\A [\?\+\*\{] \z/oxms)) {
            if ($char[$i-1] =~ /\A (?:[\x00-\xFF]|\\[0-7]{2,3}|\\x[0-9-A-Fa-f]{1,2}) \z/oxms) {
            }
            else {
                $char[$i-1] = '(?:' . $char[$i-1] . ')';
            }
        }
    }

    # make regexp string
    $modifier =~ tr/i//d;
    if ($left_e > $right_e) {
        return join '', 'Euhc::split', $ope, $delimiter, @char, '>]}' x ($left_e - $right_e), $end_delimiter, $modifier;
    }
    return     join '', 'Euhc::split', $ope, $delimiter, @char,                               $end_delimiter, $modifier;
}

#
# escape regexp of split qr''
#
sub e_split_q {
    my($ope,$delimiter,$end_delimiter,$string,$modifier) = @_;
    $modifier ||= '';

    $modifier =~ tr/p//d;
    if ($modifier =~ /([adlu])/oxms) {
        my $line = 0;
        for (my $i=0; my($package,$filename,$use_line,$subroutine) = caller($i); $i++) {
            if ($filename ne __FILE__) {
                $line = $use_line + (CORE::substr($_,0,pos($_)) =~ tr/\n//) + 1;
                last;
            }
        }
        die qq{Unsupported modifier "$1" used at line $line.\n};
    }

    $slash = 'div';

    # /b /B modifier
    if ($modifier =~ tr/bB//d) {
        return join '', 'split', $ope, $delimiter, $string, $end_delimiter, $modifier;
    }

    my $ignorecase = ($modifier =~ /i/oxms) ? 1 : 0;

    # split regexp
    my @char = $string =~ /\G((?>
        [^\x81-\xFE\\\[]       |
        [\x81-\xFE][\x00-\xFF] |
        \[\^                            |
        \[\:   (?>[a-z]+) \:\]          |
        \[\:\^ (?>[a-z]+) \:\]          |
        \\     (?:$q_char)              |
               (?:$q_char)
    ))/oxmsg;

    # unescape character
    for (my $i=0; $i <= $#char; $i++) {
        if (0) {
        }

        # escape last octet of multiple-octet
        elsif ($char[$i] =~ /\A ([\x80-\xFF].*) ([\\|\[\{\^]|\Q$delimiter\E|\Q$end_delimiter\E) \z/xms) {
            $char[$i] = $1 . '\\' . $2;
        }

        # open character class [...]
        elsif ($char[$i] eq '[') {
            my $left = $i;
            if ($char[$i+1] eq ']') {
                $i++;
            }
            while (1) {
                if (++$i > $#char) {
                    die __FILE__, ": Unmatched [] in regexp\n";
                }
                if ($char[$i] eq ']') {
                    my $right = $i;

                    # [...]
                    splice @char, $left, $right-$left+1, Euhc::charlist_qr(@char[$left+1..$right-1], $modifier);

                    $i = $left;
                    last;
                }
            }
        }

        # open character class [^...]
        elsif ($char[$i] eq '[^') {
            my $left = $i;
            if ($char[$i+1] eq ']') {
                $i++;
            }
            while (1) {
                if (++$i > $#char) {
                    die __FILE__, ": Unmatched [] in regexp\n";
                }
                if ($char[$i] eq ']') {
                    my $right = $i;

                    # [^...]
                    splice @char, $left, $right-$left+1, Euhc::charlist_not_qr(@char[$left+1..$right-1], $modifier);

                    $i = $left;
                    last;
                }
            }
        }

        # rewrite character class or escape character
        elsif (my $char = character_class($char[$i],$modifier)) {
            $char[$i] = $char;
        }

        # split(m/^/) --> split(m/^/m)
        elsif (($char[$i] eq '^') and ($modifier !~ /m/oxms)) {
            $modifier .= 'm';
        }

        # /i modifier
        elsif ($ignorecase and ($char[$i] =~ /\A [\x00-\xFF] \z/oxms) and (Euhc::uc($char[$i]) ne Euhc::fc($char[$i]))) {
            if (CORE::length(Euhc::fc($char[$i])) == 1) {
                $char[$i] = '['   . Euhc::uc($char[$i])       . Euhc::fc($char[$i]) . ']';
            }
            else {
                $char[$i] = '(?:' . Euhc::uc($char[$i]) . '|' . Euhc::fc($char[$i]) . ')';
            }
        }

        # quote character before ? + * {
        elsif (($i >= 1) and ($char[$i] =~ /\A [\?\+\*\{] \z/oxms)) {
            if ($char[$i-1] =~ /\A [\x00-\xFF] \z/oxms) {
            }
            else {
                $char[$i-1] = '(?:' . $char[$i-1] . ')';
            }
        }
    }

    $modifier =~ tr/i//d;
    return join '', 'Euhc::split', $ope, $delimiter, @char, $end_delimiter, $modifier;
}

#
# escape use without import
#
sub e_use_noimport {
    my($module) = @_;

    my $expr = _pathof($module);

    my $fh = gensym();
    for my $realfilename (_realfilename($expr)) {

        if (Euhc::_open_r($fh, $realfilename)) {
            local $/ = undef; # slurp mode
            my $script = <$fh>;
            close($fh) or die "Can't close file: $realfilename: $!";

            if ($script =~ /^ (?>\s*) use (?>\s+) UHC (?>\s*) ([^\x81-\xFE;]*) ; (?>\s*) \n? $/oxms) {
                return qq;
            }
            last;
        }
    }

    return qq;
}

#
# escape no without unimport
#
sub e_no_nounimport {
    my($module) = @_;

    my $expr = _pathof($module);

    my $fh = gensym();
    for my $realfilename (_realfilename($expr)) {

        if (Euhc::_open_r($fh, $realfilename)) {
            local $/ = undef; # slurp mode
            my $script = <$fh>;
            close($fh) or die "Can't close file: $realfilename: $!";

            if ($script =~ /^ (?>\s*) use (?>\s+) UHC (?>\s*) ([^\x81-\xFE;]*) ; (?>\s*) \n? $/oxms) {
                return qq;
            }
            last;
        }
    }

    return qq;
}

#
# escape use with import no parameter
#
sub e_use_noparam {
    my($module) = @_;

    my $expr = _pathof($module);

    my $fh = gensym();
    for my $realfilename (_realfilename($expr)) {

        if (Euhc::_open_r($fh, $realfilename)) {
            local $/ = undef; # slurp mode
            my $script = <$fh>;
            close($fh) or die "Can't close file: $realfilename: $!";

            if ($script =~ /^ (?>\s*) use (?>\s+) UHC (?>\s*) ([^\x81-\xFE;]*) ; (?>\s*) \n? $/oxms) {

                # P.326 UNIVERSAL: The Ultimate Ancestor Class
                # in Chapter 12: Objects
                # of ISBN 0-596-00027-8 Programming Perl Third Edition.

                # P.435 UNIVERSAL: The Ultimate Ancestor Class
                # in Chapter 12: Objects
                # of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

                # (and so on)

                return qq[BEGIN { Euhc::require '$expr'; $module->import() if $module->can('import'); }];
            }
            last;
        }
    }

    return qq;
}

#
# escape no with unimport no parameter
#
sub e_no_noparam {
    my($module) = @_;

    my $expr = _pathof($module);

    my $fh = gensym();
    for my $realfilename (_realfilename($expr)) {

        if (Euhc::_open_r($fh, $realfilename)) {
            local $/ = undef; # slurp mode
            my $script = <$fh>;
            close($fh) or die "Can't close file: $realfilename: $!";

            if ($script =~ /^ (?>\s*) use (?>\s+) UHC (?>\s*) ([^\x81-\xFE;]*) ; (?>\s*) \n? $/oxms) {
                return qq[BEGIN { Euhc::require '$expr'; $module->unimport() if $module->can('unimport'); }];
            }
            last;
        }
    }

    return qq;
}

#
# escape use with import parameters
#
sub e_use {
    my($module,$list) = @_;

    my $expr = _pathof($module);

    my $fh = gensym();
    for my $realfilename (_realfilename($expr)) {

        if (Euhc::_open_r($fh, $realfilename)) {
            local $/ = undef; # slurp mode
            my $script = <$fh>;
            close($fh) or die "Can't close file: $realfilename: $!";

            if ($script =~ /^ (?>\s*) use (?>\s+) UHC (?>\s*) ([^\x81-\xFE;]*) ; (?>\s*) \n? $/oxms) {
                return qq[BEGIN { Euhc::require '$expr'; $module->import($list) if $module->can('import'); }];
            }
            last;
        }
    }

    return qq;
}

#
# escape no with unimport parameters
#
sub e_no {
    my($module,$list) = @_;

    my $expr = _pathof($module);

    my $fh = gensym();
    for my $realfilename (_realfilename($expr)) {

        if (Euhc::_open_r($fh, $realfilename)) {
            local $/ = undef; # slurp mode
            my $script = <$fh>;
            close($fh) or die "Can't close file: $realfilename: $!";

            if ($script =~ /^ (?>\s*) use (?>\s+) UHC (?>\s*) ([^\x81-\xFE;]*) ; (?>\s*) \n? $/oxms) {
                return qq[BEGIN { Euhc::require '$expr'; $module->unimport($list) if $module->can('unimport'); }];
            }
            last;
        }
    }

    return qq;
}

#
# file path of module
#
sub _pathof {
    my($expr) = @_;

    if ($^O eq 'MacOS') {
        $expr =~ s#::#:#g;
    }
    else {
        $expr =~ s#::#/#g;
    }
    $expr .= '.pm' if $expr !~ / \.pm \z/oxmsi;

    return $expr;
}

#
# real file name of module
#
sub _realfilename {
    my($expr) = @_;

    if ($^O eq 'MacOS') {
        return map {"$_$expr"} @INC;
    }
    else {
        return map {"$_/$expr"} @INC;
    }
}

#
# instead of Carp::carp
#
sub carp {
    my($package,$filename,$line) = caller(1);
    print STDERR "@_ at $filename line $line.\n";
}

#
# instead of Carp::croak
#
sub croak {
    my($package,$filename,$line) = caller(1);
    print STDERR "@_ at $filename line $line.\n";
    die "\n";
}

#
# instead of Carp::cluck
#
sub cluck {
    my $i = 0;
    my @cluck = ();
    while (my($package,$filename,$line,$subroutine) = caller($i)) {
        push @cluck, "[$i] $filename($line) $package::$subroutine\n";
        $i++;
    }
    print STDERR CORE::reverse @cluck;
    print STDERR "\n";
    print STDERR @_;
}

#
# instead of Carp::confess
#
sub confess {
    my $i = 0;
    my @confess = ();
    while (my($package,$filename,$line,$subroutine) = caller($i)) {
        push @confess, "[$i] $filename($line) $package::$subroutine\n";
        $i++;
    }
    print STDERR CORE::reverse @confess;
    print STDERR "\n";
    print STDERR @_;
    die "\n";
}

1;

__END__