File Coverage

blib/lib/Convert/Pluggable.pm

Criterion	Covered	Total	%
statement	18	181	9.9
branch	0	56	0.0
condition	0	20	0.0
subroutine	6	15	40.0
pod	6	8	75.0
total	30	280	10.7

package Convert::Pluggable;

use Moo;

use File::Slurp qw/read_file/;

use Data::Float qw/float_is_infinite float_is_nan/;
use Scalar::Util qw/looks_like_number/;

use JSON;
use Switch;

our @EXPORT_OK = qw(convert get_units);

our $VERSION           = '0.032';
our $DEFAULT_PRECISION = 3;

has data_file => ( is => 'lazy', );

has types => ( is => 'lazy', );

sub temperature_get_factor {
    my $convert = shift;

    switch ( $convert->{'from_unit'} ) {
        case /^(fahrenheit|f)$/i { return $convert->{'factor'}; }
        case /^(celsius|c)$/i {
            return ( $convert->{'factor'} * ( 9 / 5 ) ) + 32;
        }
        case /^(kelvin|k)$/i {
            return ( $convert->{'factor'} * ( 9 / 5 ) ) - 459.67;
        }
        case /^(rankine|r)$/i { return ( $convert->{'factor'} - 491.67 ) + 32; }
        case /^(reaumur|re)$/i {
            return ( $convert->{'factor'} * ( 9 / 4 ) ) + 32;
        }
        else { return undef; }
    }
}

sub convert_temperatures {
    my $convert = shift;

    # convert $from to fahrenheit:
    my $factor = temperature_get_factor($convert);

    # convert fahrenheit $to:
    switch ( $convert->{'to_unit'} ) {
        case /^(fahrenheit|f)$/i { return $factor; }
        case /^(celsius|c)$/i    { return ( $factor - 32 ) * ( 5 / 9 ); }
        case /^(kelvin|k)$/i     { return ( $factor + 459.67 ) * ( 5 / 9 ); }
        case /^(rankine|r)$/i    { return $factor + 459.67; }
        case /^(reaumur|re)$/i   { return ( $factor - 32 ) * ( 4 / 9 ); }
        else                     { return undef; }
    }
}

sub get_matches {
    my $self    = shift;
    my $matches = shift;

    my @matches = @{$matches};

    $matches[0] =~ s/"/inches/;
    $matches[0] =~ s/'/feet/;
    $matches[1] =~ s/"/inches/;
    $matches[1] =~ s/'/feet/;

    my @match_types     = ();
    my @factors         = ();
    my @units           = ();
    my @can_be_negative = ();

    my @types = @{ get_units() };

    foreach my $match (@matches) {
        foreach my $type ( @{ $self->types } ) {
            if ( lc $match eq $type->{'unit'}
                || grep { $_ eq lc $match } @{ $type->{'aliases'} } )
            {
                push( @match_types,     $type->{'type'} );
                push( @factors,         $type->{'factor'} );
                push( @units,           $type->{'unit'} );
                push( @can_be_negative, $type->{'can_be_negative'} || '0' );
            }
        }
    }

    return if scalar(@match_types) != 2;
    return if scalar(@factors) != 2;
    return if scalar(@units) != 2;
    return if scalar(@can_be_negative) != 2;

    my %matches = (
        'type_1'            => $match_types[0],
        'type_2'            => $match_types[1],
        'factor_1'          => $factors[0],
        'factor_2'          => $factors[1],
        'from_unit'         => $units[0],
        'to_unit'           => $units[1],
        'can_be_negative_1' => $can_be_negative[0],
        'can_be_negative_2' => $can_be_negative[1],
    );

    return \%matches;
}

sub convert {
    my $self = shift;

    my $conversion = shift;
    my $matches    = get_matches( $self,
        [ $conversion->{'from_unit'}, $conversion->{'to_unit'} ] );

    return
      if !( $matches->{'type_1'} && $matches->{'type_2'} );

    if ( looks_like_number( $conversion->{'factor'} ) ) {

        # looks_like_number thinks 'Inf' and 'NaN' are numbers:
        return
          if float_is_infinite( $conversion->{'factor'} )
          || float_is_nan( $conversion->{'factor'} );

        # if factor is < 0 and first thing can't be negative ...
        return
          if $conversion->{'factor'} < 0 && !$matches->{'can_be_negative_1'};
    }
    else {
     # if it doesn't look like a number, and it contains a number (e.g., '6^2'):
        $conversion->{'factor'} = parse_number( $conversion->{'factor'} );
    }

    return if $conversion->{'factor'} =~ /[[:alpha:]]/;

    # matches must be of the same type (e.g., can't convert mass to length):
    return if ( $matches->{'type_1'} ne $matches->{'type_2'} );

    # run the conversion:
    # temperatures don't have 1:1 conversions, so they get special treatment:
    my $factor;
    if ( $matches->{'type_1'} eq 'temperature' ) {
        $factor = convert_temperatures(
            {
                from_unit => $matches->{'from_unit'},
                to_unit   => $matches->{'to_unit'},
                factor    => $conversion->{'factor'},
            }
        );
    }
    else {
        $factor = $conversion->{'factor'} *
          ( $matches->{'factor_2'} / $matches->{'factor_1'} );
    }

    return if $factor < 0 && !( $matches->{'can_be_negative_2'} );

    $matches->{'result'} = precision(
        {
            factor    => $factor,
            precision => $conversion->{'precision'} || $DEFAULT_PRECISION,
        }
    );

    return $matches;
}

# thanks, @mwmiller!
sub parse_number {
    my $in = shift;

    my $out =
      ( $in =~ /^(-?\d*(?:\.?\d+))\^(-?\d*(?:\.?\d+))$/ ) ? $1**$2 : $in;

    return $in if $out =~ /[^\d]/;    # elo

    return 0 + $out;
}

sub _build_types {
    my $self = shift;

    return get_units( $self->{data_file} );
}

sub get_units {
    my $self = shift;

    #my $data_file = shift // 'NO_DATA_FILE';
    my $data_file = defined(shift) ? shift : 'NO_DATA_FILE';

    my $units;

    if ( $data_file eq 'NO_DATA_FILE' ) {

        $units = encode_json( old_get_units() );

    }
    else {
        $units = read_file($data_file);
    }

    return decode_json($units);
}

# does it make sense to return X if precision is > 1?
#   e.g., result = '0.999' with precision = '3' returns '1' atm
#   e.g., result = '1.000' with precision = '3' returns '1' atm
sub precision {
    my $precision = shift;

    if ( $precision->{'factor'} == 0 ) { return 0; }

    my $f = $precision->{'factor'} * ( 10**$precision->{'precision'} );

    my $r = int( $f + $f / abs( $f * 2 ) );

    return $r / ( 10**$precision->{'precision'} );
}

sub old_get_units {

    # metric ton is base unit for mass
    # known SI units and aliases / plurals
    my @mass = (
        {
            'unit'    => 'metric ton',
            'factor'  => '1',
            'aliases' => [
                'tonne',       't',      'mt', 'te',
                'metric tons', 'tonnes', 'ts', 'mts',
                'tes'
            ],
            'type' => 'mass',
        },
        {
            'unit'    => 'ounce',
            'factor'  => '35274',
            'aliases' => [ 'oz', 'ounces', 'ozs' ],
            'type'    => 'mass',
        },
        {
            'unit'    => 'pound',
            'factor'  => '2204.62',
            'aliases' => [
                'lb',  'lbm',  'pound mass', 'pounds',
                'lbs', 'lbms', 'pounds mass'
            ],
            'type' => 'mass',
        },
        {
            'unit'    => 'stone',
            'factor'  => '157.473',
            'aliases' => [ 'st', 'stones', 'sts' ],
            'type'    => 'mass',
        },
        {
            'unit'    => 'long ton',
            'factor'  => '0.984207',
            'aliases' => [
                'weight ton',
                'imperial ton',
                'long tons',
                'weight tons',
                'imperial tons'
            ],
            'type' => 'mass',
        },
        {
            'unit'    => 'microgram',
            'factor'  => 1_000_000_000_000,
            'aliases' => [ 'mcg', 'micrograms', 'mcgs' ],
            'type'    => 'mass',
        },
        {
            'unit'    => 'kilogram',
            'factor'  => 1000,
            'aliases' => [
                'kg',  'kilo',  'kilogramme', 'kilograms',
                'kgs', 'kilos', 'kilogrammes'
            ],
            'type' => 'mass',
        },
        {
            'unit'   => 'gram',
            'factor' => 1_000_000,
            'aliases' =>
              [ 'g', 'gm', 'gramme', 'grams', 'gs', 'gms', 'grammes' ],
            'type' => 'mass',
        },
        {
            'unit'    => 'milligram',
            'factor'  => 1_000_000_000,
            'aliases' => [ 'mg', 'milligrams', 'mgs' ],
            'type'    => 'mass',
        },
        {
            'unit'    => 'ton',
            'factor'  => '1.10231',
            'aliases' => [ 'short ton', 'short tons', 'tons' ],
            'type'    => 'mass',
        },
    );

    # meter is the base unit for length
    # known SI units and aliases / plurals
    my @length = (
        {
            'unit'    => 'meter',
            'factor'  => '1',
            'aliases' => [ 'meters', 'metre', 'metres', 'm' ],
            'type'    => 'length',
        },
        {
            'unit'    => 'kilometer',
            'factor'  => '0.001',
            'aliases' => [
                'kilometers', 'kilometre', 'kilometres', 'km',
                'kms',        'klick',     'klicks'
            ],
            'type' => 'length',
        },
        {
            'unit'   => 'centimeter',
            'factor' => '100',
            'aliases' =>
              [ 'centimeters', 'centimetre', 'centimetres', 'cm', 'cms' ],
            'type' => 'length',
        },
        {
            'unit'   => 'millimeter',
            'factor' => '1000',
            'aliases' =>
              [ 'millimeters', 'millimetre', 'millimetres', 'mm', 'mms' ],
            'type' => 'length',
        },
        {
            'unit'    => 'mile',
            'factor'  => 1 / 1609.344,
            'aliases' => [
                'miles',
                'statute mile',
                'statute miles',
                'land mile',
                'land miles',
                'mi'
            ],
            'type' => 'length',
        },
        {
            'unit'    => 'yard',
            'factor'  => '1.0936133',
            'aliases' => [ 'yards', 'yd', 'yds', 'yrds', 'yrd' ],
            'type'    => 'length',
        },
        {
            'unit'    => 'foot',
            'factor'  => '3.28084',
            'aliases' => [
                'feet',
                'ft',
                'international foot',
                'international feet',
                'survey foot',
                'survey feet'
            ],
            'type' => 'length',
        },
        {
            'unit'    => 'inch',
            'factor'  => '39.3701',
            'aliases' => [ 'inches', 'in', 'ins' ],
            'type'    => 'length',
        },
        {
            'unit'   => 'nautical mile',
            'factor' => '0.000539957',
            'aliases' =>
              [ 'nautical miles', 'n', 'ns', 'nm', 'nms', 'nmi', 'nmis' ],
            'type' => 'length',
        },
        {
            'unit'    => 'furlong',
            'factor'  => ( 1 / 201.168 ),
            'aliases' => ['furlongs'],
            'type'    => 'length',
        },
        {
            'unit'    => 'chain',
            'factor'  => ( 1 / 20.1168 ),
            'aliases' => [ "gunter's chains", 'chains' ],
            'type'    => 'length',
        },
        {
            'unit'    => 'link',
            'factor'  => ( 1 / 0.201168 ),
            'aliases' => [ "gunter's links", 'links' ],
            'type'    => 'length',
        },
        {
            'unit'    => 'rod',
            'factor'  => 1 / (5.0292),
            'aliases' => ['rods'],
            'type'    => 'length',
        },
        {
            'unit'    => 'fathom',
            'factor'  => 1 / (1.853184),
            'aliases' => [ 'fathoms', 'ftm', 'ftms' ],
            'type'    => 'length',
        },
        {
            'unit'    => 'league',
            'factor'  => 1 / (4828.032),
            'aliases' => ['leagues'],
            'type'    => 'length',
        },
        {
            'unit'    => 'cable',
            'factor'  => 1 / (185.3184),
            'aliases' => ['cables'],
            'type'    => 'length',
        },
        {
            'unit'    => 'light year',
            'factor'  => ( 1 / 9460730472580800 ),
            'aliases' => [ 'light years', 'ly', 'lys' ],
            'type'    => 'length',
        },
        {
            'unit'    => 'parsec',
            'factor'  => ( 1 / 30856776376340067 ),
            'aliases' => [ 'parsecs', 'pc', 'pcs' ],
            'type'    => 'length',
        },
        {
            'unit'    => 'astronomical unit',
            'factor'  => ( 1 / 149597870700 ),
            'aliases' => [ 'astronomical units', 'au', 'aus' ],
            'type'    => 'length',
        },
    );

    # day is base unit for time
    # known SI units and aliases / plurals
    my @time = (
        {
            'unit'    => 'day',
            'factor'  => '1',
            'aliases' => [ 'days', 'dy', 'dys', 'd' ],
            'type'    => 'duration',
        },
        {
            'unit'    => 'second',
            'factor'  => '86400',
            'aliases' => [ 'seconds', 'sec', 's' ],
            'type'    => 'duration',
        },
        {
            'unit'    => 'millisecond',
            'factor'  => '86400000',
            'aliases' => [ 'milliseconds', 'millisec', 'millisecs', 'ms' ],
            'type'    => 'duration',
        },
        {
            'unit'    => 'microsecond',
            'factor'  => '86400000000',
            'aliases' => [ 'microseconds', 'microsec', 'microsecs', 'us' ],
            'type'    => 'duration',
        },
        {
            'unit'    => 'nanosecond',
            'factor'  => '86400000000000',
            'aliases' => [ 'nanoseconds', 'nanosec', 'nanosecs', 'ns' ],
            'type'    => 'duration',
        },
        {
            'unit'    => 'minute',
            'factor'  => '1440',
            'aliases' => [ 'minutes', 'min', 'mins' ],
            'type'    => 'duration',
        },
        {
            'unit'    => 'hour',
            'factor'  => '24',
            'aliases' => [ 'hours', 'hr', 'hrs', 'h' ],
            'type'    => 'duration',
        },
        {
            'unit'    => 'week',
            'factor'  => 1 / 7,
            'aliases' => [ 'weeks', 'wks', 'wk' ],
            'type'    => 'duration',
        },
        {
            'unit'    => 'fortnight',
            'factor'  => 1 / 14,
            'aliases' => [],
            'type'    => 'duration',
        },
        {
            'unit'    => 'month',
            'factor'  => 12 / 365,
            'aliases' => [ 'months', 'mons', 'mns', 'mn' ],
            'type'    => 'duration',
        },
        {
            'unit'    => 'year',
            'factor'  => 1 / 365,
            'aliases' => [ 'years', 'yr', 'yrs' ],
            'type'    => 'duration',
        },
        {
            'unit'    => 'leap year',
            'factor'  => 1 / 366,
            'aliases' => [ 'leap years', 'leapyear', 'leapyr', 'leapyrs' ],
            'type'    => 'duration',
        },
    );

    # pascal is base unit for pressure
    # known SI units and aliases / plurals
    my @pressure = (
        {
            'unit'    => 'pascal',
            'factor'  => 1,
            'aliases' => [ 'pascals', 'pa', 'pas' ],
            'type'    => 'pressure',
        },
        {
            'unit'    => 'kilopascal',
            'factor'  => ( 1 / 1000 ),
            'aliases' => [ 'kilopascals', 'kpa', 'kpas' ],
            'type'    => 'pressure',
        },
        {
            'unit'    => 'megapascal',
            'factor'  => ( 1 / 1_000_000 ),
            'aliases' => [ 'megapascals', 'megapa', 'megapas' ],
            'type'    => 'pressure',
        },
        {
            'unit'    => 'gigapascal',
            'factor'  => ( 1 / 1_000_000_000 ),
            'aliases' => [ 'gigapascals', 'gpa', 'gpas' ],
            'type'    => 'pressure',
        },
        {
            'unit'    => 'bar',
            'factor'  => 1 / (100_000),
            'aliases' => [ 'bars', 'pa', 'pas' ],
            'type'    => 'pressure',
        },
        {
            'unit'    => 'atmosphere',
            'factor'  => 1 / (101_325),
            'aliases' => [ 'atmospheres', 'atm', 'atms' ],
            'type'    => 'pressure',
        },
        {
            'unit'    => 'pounds per square inch',
            'factor'  => 1 / 6894.8,
            'aliases' => [ 'psis', 'psi', 'lbs/inch^2', 'p.s.i.', 'p.s.i' ],
            'type'    => 'pressure',
        },
    );

    # joule is base unit for energy
    # known SI units and aliases / plurals
    my @energy = (
        {
            'unit'    => 'joule',
            'factor'  => 1,
            'aliases' => [ 'joules', 'j', 'js' ],
            'type'    => 'energy',
        },
        {
            'unit'    => 'watt-second',
            'factor'  => (1),
            'aliases' => [ 'watt second', 'watt seconds', 'ws' ],
            'type'    => 'energy',
        },
        {
            'unit'    => 'watt-hour',
            'factor'  => ( 1 / 3600 ),
            'aliases' => [ 'watt hour', 'watt hours', 'wh' ],
            'type'    => 'energy',
        },
        {
            'unit'    => 'kilowatt-hour',
            'factor'  => ( 1 / 3_600_000 ),
            'aliases' => [ 'kilowatt hour', 'kilowatt hours', 'kwh' ],
            'type'    => 'energy',
        },
        {
            'unit'    => 'erg',
            'factor'  => ( 1 / 10_000_000 ),
            'aliases' => [ 'ergon', 'ergs', 'ergons' ],
            'type'    => 'energy',
        },
        {
            'unit'    => 'electron volt',
            'factor'  => (6.2415096e+18),
            'aliases' => [ 'electronvolt', 'electron volts', 'ev', 'evs' ],
            'type'    => 'energy',
        },
        {
            'unit'    => 'thermochemical gram calorie',
            'factor'  => ( 1 / 4.184 ),
            'aliases' => [
                'small calories',
                'thermochemical gram calories',
                'chemical calorie',
                'chemical calories'
            ],
            'type' => 'energy',
        },
        {
            'unit'    => 'large calorie',
            'factor'  => ( 1 / 4184 ),
            'aliases' => [
                'large calories',
                'food calorie',
                'food calories',
                'kcals',
                'kcal'
            ],
            'type' => 'energy',
        },
        {
            'unit'    => 'british thermal unit',
            'factor'  => ( 1 / 1054.5 ),
            'aliases' => [ 'british thermal units', 'btu', 'btus' ],
            'type'    => 'energy',
        },
        {
            'unit'   => 'ton of TNT',
            'factor' => ( 1 / 4.184e+9 ),
            'aliases' =>
              [ 'tnt equivilent', 'tonnes of tnt', 'tnt', 'tons of tnt' ],
            'type' => 'energy',
        }
    );

    # watt is base unit for power
    # known SI units and aliases / plurals
    my @power = (
        {
            'unit'    => 'watt',
            'factor'  => 1,
            'aliases' => [ 'watts', 'w' ],
            'type'    => 'power',
        },
        {
            'unit'    => 'kilowatt',
            'factor'  => 1 / 1000,
            'aliases' => [ 'kilowatts', 'kw' ],
            'type'    => 'power',
        },
        {
            'unit'    => 'megawatt',
            'factor'  => 1 / 1_000_000,
            'aliases' => [ 'megawatts', 'mw' ],
            'type'    => 'power',
        },
        {
            'unit'    => 'gigawatt',
            'factor'  => 1 / 1_000_000_000,
            'aliases' => [ 'gigawatts', 'jiggawatts', 'gw' ],
            'type'    => 'power',
        },
        {
            'unit'    => 'terawatt',
            'factor'  => 1 / 1_000_000_000_000,
            'aliases' => [ 'terawatts', 'tw' ],
            'type'    => 'power',
        },
        {
            'unit'    => 'petawatt',
            'factor'  => 1 / 1_000_000_000_000_000,
            'aliases' => [ 'petawatts', 'pw' ],
            'type'    => 'power',
        },
        {
            'unit'    => 'milliwatt',
            'factor'  => 1000,
            'aliases' => ['milliwatts'],
            'type'    => 'power',
        },
        {
            'unit'    => 'microwatt',
            'factor'  => 1_000_000,
            'aliases' => ['microwatts'],
            'type'    => 'power',
        },
        {
            'unit'    => 'nanowatt',
            'factor'  => 1_000_000_000,
            'aliases' => [ 'nanowatts', 'nw' ],
            'type'    => 'power',
        },
        {
            'unit'    => 'picowatt',
            'factor'  => 1_000_000_000_000,
            'aliases' => [ 'picowatts', 'pw' ],
            'type'    => 'power',
        },
        {
            'unit'    => 'metric horsepower',
            'factor'  => ( 1 / 735.49875 ),
            'aliases' => [
                'metric horsepowers',
                'mhp', 'hp', 'ps', 'cv', 'hk', 'ks', 'ch'
            ],
            'type' => 'power',
        },
        {
            'unit'   => 'horsepower',
            'factor' => ( 1 / 745.69987158227022 ),
            'aliases' =>
              [ 'mechnical horsepower', 'horsepower', 'hp', 'hp', 'bhp' ],
            'type' => 'power',
        },
        {
            'unit'    => 'electical horsepower',
            'factor'  => ( 1 / 746 ),
            'aliases' => [ 'electical horsepowers', 'hp', 'hp' ],
            'type'    => 'power',
        },
    );

    # degree is base unit for angles
    # known SI units and aliases / plurals
    my @angle = (
        {
            'unit'    => 'degree',
            'factor'  => 1,
            'aliases' => [ 'degrees', 'deg', 'degs' ],
            'type'    => 'angle',
        },
        {
            'unit'    => 'radian',
            'factor'  => 3.14159265358979323 / 180,
            'aliases' => [ 'radians', 'rad', 'rads' ],
            'type'    => 'angle',
        },
        {
            'unit'   => 'gradian',
            'factor' => 10 / 9,
            'aliases' =>
              [ 'gradians', 'grad', 'grads', 'gon', 'gons', 'grade', 'grades' ],
            'type' => 'angle',
        },
        {
            'unit'    => 'quadrant',
            'factor'  => 1 / 90,
            'aliases' => [ 'quadrants', 'quads', 'quad' ],
            'type'    => 'angle',
        },
        {
            'unit'    => 'semi-circle',
            'factor'  => 1 / 180,
            'aliases' => [
                'semi circle', 'semicircle', 'semi circles', 'semicircles',
                'semi-circles'
            ],
            'type' => 'angle',
        },
        {
            'unit'    => 'revolution',
            'factor'  => 1 / 360,
            'aliases' => [ 'revolutions', 'circle', 'circles', 'revs' ],
            'type'    => 'angle',
        },
    );

    # newton is base unit for force
    # known SI units and aliases / plurals
    my @force = (
        {
            'unit'    => 'newton',
            'factor'  => 1,
            'aliases' => [ 'newtons', 'n' ],
            'type'    => 'force',
        },
        {
            'unit'    => 'kilonewton',
            'factor'  => 1 / 1000,
            'aliases' => [ 'kilonewtons', 'kn' ],
            'type'    => 'force',
        },
        {
            'unit'    => 'meganewton',
            'factor'  => 1 / 1_000_000,
            'aliases' => [ 'meganewtons', 'mn' ],
            'type'    => 'force',
        },
        {
            'unit'    => 'giganewton',
            'factor'  => 1 / 1_000_000_000,
            'aliases' => [ 'giganewtons', 'gn' ],
            'type'    => 'force',
        },
        {
            'unit'    => 'dyne',
            'factor'  => 1 / 100000,
            'aliases' => ['dynes'],
            'type'    => 'force',
        },
        {
            'unit'    => 'kilodyne',
            'factor'  => 1 / 100,
            'aliases' => ['kilodynes'],
            'type'    => 'force',
        },
        {
            'unit'    => 'megadyne',
            'factor'  => 10,
            'aliases' => ['megadynes'],
            'type'    => 'force',
        },
        {
            'unit'    => 'pounds force',
            'factor'  => 1 / 4.4482216152605,
            'aliases' => [ 'lbs force', 'pounds force' ],
            'type'    => 'force',
        },
        {
            'unit'    => 'poundal',
            'factor'  => 1 / 0.138254954376,
            'aliases' => [ 'poundals', 'pdl' ],
            'type'    => 'force',
        },
    );

    # fahrenheit is base unit for temperature
    # known SI units and aliases / plurals
    my @temperature = (
        {
            'unit'            => 'fahrenheit',
            'factor'          => 1,               # all '1' because un-used
            'aliases'         => ['f'],
            'type'            => 'temperature',
            'can_be_negative' => 1,
        },
        {
            'unit'            => 'celsius',
            'factor'          => 1,
            'aliases'         => ['c'],
            'type'            => 'temperature',
            'can_be_negative' => 1,
        },
        {
            'unit'    => 'kelvin',
            'factor'  => 1,
            'aliases' => ['k'],      # be careful ... other units could use 'K'
            'type' => 'temperature',
        },
        {
            'unit'    => 'rankine',
            'factor'  => 1,
            'aliases' => ['r'],
            'type'    => 'temperature',
        },
        {
            'unit'    => 'reaumur',
            'factor'  => 1,
            'aliases' => ['re']
            ,    # also can be 'R', but that's being used for rankine
            'type'            => 'temperature',
            'can_be_negative' => 1,
        },
    );

    # bit is base unit for digital
    # while not absolutely correct, a byte is defined as 8 bits herein.
    # known SI units and aliases / plurals
    my @digital = (
        {
            'unit'    => 'bit',
            'factor'  => 1,
            'aliases' => ['bits'],
            'type'    => 'digital',
        },
        {
            'unit'    => 'kilobit',
            'factor'  => 1 / 1_000,
            'aliases' => [ 'kbit', 'kbits', 'kilobits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'megabit',
            'factor'  => 1 / 1_000_000,
            'aliases' => [ 'mbit', 'mbits', 'megabits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'gigabit',
            'factor'  => 1 / 1_000_000_000,
            'aliases' => [ 'gbit', 'gigabits', 'gbits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'terabit',
            'factor'  => 1 / 1_000_000_000_000,
            'aliases' => [ 'tbit', 'tbits', 'terabits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'petabit',
            'factor'  => 1 / 1_000_000_000_000_000,
            'aliases' => [ 'pbit', 'pbits', 'petabits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'exabit',
            'factor'  => 1 / 1_000_000_000_000_000_000,
            'aliases' => [ 'ebit', 'ebits', 'exabits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'zettabit',
            'factor'  => 1 / 1_000_000_000_000_000_000_000,
            'aliases' => [ 'zbit', 'zbits', 'zettabits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'yottabit',
            'factor'  => 1 / 1_000_000_000_000_000_000_000_000,
            'aliases' => [ 'ybit', 'ybits', 'yottabits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'kibibit',
            'factor'  => 1 / 1024,
            'aliases' => [ 'kibit', 'kibits', 'kibibits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'mebibit',
            'factor'  => 1 / 1024**2,
            'aliases' => [ 'mibit', 'mibits', 'mebibits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'gibibit',
            'factor'  => 1 / 1024**3,
            'aliases' => [ 'gibit', 'gibits', 'gibibits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'tebibit',
            'factor'  => 1 / 1024**4,
            'aliases' => [ 'tibit', 'tibits', 'tebibits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'pebibit',
            'factor'  => 1 / 1024**5,
            'aliases' => [ 'pibit', 'pibits', 'pebibits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'exbibit',
            'factor'  => 1 / 1024**6,
            'aliases' => [ 'eibit', 'eibits', 'exbibits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'zebibit',
            'factor'  => 1 / 1024**7,
            'aliases' => [ 'zibit', 'zibits', 'zebibits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'yobibit',
            'factor'  => 1 / 1024**8,
            'aliases' => [ 'yibit', 'yibits', 'yobibits' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'byte',
            'factor'  => 1 / 8,
            'aliases' => ['bytes'],
            'type'    => 'digital',
        },
        {
            'unit'    => 'kilobyte',
            'factor'  => 1 / 8_000,
            'aliases' => [ 'kb', 'kbs', 'kilobytes' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'megabyte',
            'factor'  => 1 / 8_000_000,
            'aliases' => [ 'mb', 'mbs', 'megabytes' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'gigabyte',
            'factor'  => 1 / 8_000_000_000,
            'aliases' => [ 'gb', 'gbs', 'gigabytes' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'terabyte',
            'factor'  => 1 / 8_000_000_000_000,
            'aliases' => [ 'tb', 'tbs', 'terabytes' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'petabyte',
            'factor'  => 1 / 8_000_000_000_000_000,
            'aliases' => [ 'pb', 'pbs', 'petabytes' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'exabyte',
            'factor'  => 1 / 8_000_000_000_000_000_000,
            'aliases' => [ 'eb', 'ebs', 'exabytes' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'zettabyte',
            'factor'  => 1 / 8_000_000_000_000_000_000_000,
            'aliases' => [ 'zb', 'zbs', 'zettabytes' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'yottabyte',
            'factor'  => 1 / 8_000_000_000_000_000_000_000_000,
            'aliases' => [ 'yb', 'ybs', 'yottabytes' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'kibibyte',
            'factor'  => 1 / 8192,
            'aliases' => [ 'kib', 'kibs', 'kibibytes' ],    # KB
            'type'    => 'digital',
        },
        {
            'unit'    => 'mebibyte',
            'factor'  => 1 / 8388608,
            'aliases' => [ 'mib', 'mibs', 'mebibytes' ],    # MB
            'type'    => 'digital',
        },
        {
            'unit'    => 'gibibyte',
            'factor'  => 1 / 8589934592,                    # 1/8*1024**3 ...
            'aliases' => [ 'gib', 'gibs', 'gibibytes' ],    # GB ...
            'type'    => 'digital',
        },
        {
            'unit'    => 'tebibyte',
            'factor'  => 1 / 8796093022208,
            'aliases' => [ 'tib', 'tibs', 'tebibytes' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'pebibyte',
            'factor'  => 1 / 9007199254740992,              # 1/8*1024**5 ...
            'aliases' => [ 'pib', 'pibs', 'pebibytes' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'exbibyte',
            'factor'  => 1 / 9.22337203685478e+18,
            'aliases' => [ 'eib', 'eibs', 'exbibytes' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'zebibyte',
            'factor'  => 1 / 9.44473296573929e+21,
            'aliases' => [ 'zib', 'zibs', 'zebibytes' ],
            'type'    => 'digital',
        },
        {
            'unit'    => 'yobibyte',
            'factor'  => 1 / 9.67140655691703e+24,
            'aliases' => [ 'yib', 'yibs', 'yobibytes' ],
            'type'    => 'digital',
        },
    );

    # hectare is base unit for area
    my @area = (
        {
            'unit'    => 'hectare',
            'factor'  => 1,
            'aliases' => [ 'hectares', 'ha' ],
            'type'    => 'area',
        },
        {
            'unit'    => 'acre',
            'factor'  => 2.4710439,
            'aliases' => ['acres'],
            'type'    => 'area',
        },
        {
            'unit'    => 'square meter',
            'factor'  => 10_000,
            'aliases' => [
                'square meters', 'metre^2',
                'meter^2',       'metres^2',
                'meters^2',      'square metre',
                'square metres', 'm^2'
            ],
            'type' => 'area',
        },
        {
            'unit'    => 'square kilometer',
            'factor'  => 0.01,
            'aliases' => [
                'square kilometers',
                'square kilometre',
                'square kilometres',
                'km^2'
            ],
            'type' => 'area',
        },
        {
            'unit'    => 'square centimeter',
            'factor'  => 100_000_000,
            'aliases' => [
                'square centimeters',
                'square centimetre',
                'square centimetres',
                'cm^2'
            ],
            'type' => 'area',
        },
        {
            'unit'    => 'square millimeter',
            'factor'  => 10_000_000_000,
            'aliases' => [
                'square millimeters',
                'square millimetre',
                'square millimetres',
                'mm^2'
            ],
            'type' => 'area',
        },
        {
            'unit'    => 'square mile',
            'factor'  => 1 / 258.99881,
            'aliases' => [
                'square miles',
                'square statute mile',
                'square statute miles',
                'square land mile',
                'square land miles',
                'miles^2',
                'sq mi'
            ],
            'type' => 'area',
        },
        {
            'unit'   => 'square yard',
            'factor' => 11959.9,
            'aliases' =>
              [ 'square yards', 'yard^2', 'yards^2', 'yd^2', 'yrd^2' ],
            'type' => 'area',
        },
        {
            'unit'    => 'square foot',
            'factor'  => 107639.1,
            'aliases' => [ 'square feet', 'feet^2', 'foot^2', 'foot', 'ft^2' ],
            'type'    => 'area',
        },
        {
            'unit'   => 'square inch',
            'factor' => 15500031,
            'aliases' =>
              [ 'square inches', 'inch^2', 'inches^2', 'squinch', 'in^2' ],
            'type' => 'area',
        },
        {
            'unit'    => 'tsubo',
            'factor'  => 3024.9863876,
            'aliases' => ['tsubos'],
            'type'    => 'area',
        }
    );

    # litre is the base unit for volume
    my @volume = (
        {
            'unit'   => 'litre',
            'factor' => 1,
            'aliases' =>
              [ 'liter', 'litres', 'liters', 'l', 'litter', 'litters' ],
            'type' => 'volume',
        },
        {
            'unit'    => 'millilitre',
            'factor'  => 1000,
            'aliases' => [ 'milliliter', 'millilitres', 'milliliters', 'ml' ],
            'type'    => 'volume',
        },
        {
            'unit'   => 'cubic metre',
            'factor' => 1 / 1000,
            'aliases' =>
              [ 'metre^3', 'meter^3', 'metres^3', 'meters^3', 'm^3' ],
            'type' => 'volume',
        },
        {
            'unit'    => 'cubic centimetre',
            'factor'  => 1000,
            'aliases' => [
                'centimetre^3',  'centimeter^3',
                'centimetres^3', 'centimeters^3',
                'cm^3'
            ],
            'type' => 'volume',
        },
        {
            'unit'    => 'cubic millimetre',
            'factor'  => 1_000_000,
            'aliases' => [
                'millimetre^3',  'millimeter^3',
                'millimetres^3', 'millimeters^3',
                'mm^3'
            ],
            'type' => 'volume',
        },
        {
            'unit'    => 'liquid pint',
            'factor'  => 1000 / 473.176473,
            'aliases' => [
                'liquid pints',
                'us pints',
                'us liquid pint',
                'us liquid pints'
            ],
            'type' => 'volume',
        },
        {
            'unit'    => 'dry pint',
            'factor'  => 1000 / 550.6104713575,
            'aliases' => ['dry pints'],
            'type'    => 'volume',
        },
        {
            'unit'    => 'imperial pint',
            'factor'  => 1000 / 568.26125,
            'aliases' => [
                'pints',        'pint', 'imperial pints', 'uk pint',
                'british pint', 'pts'
            ],
            'type' => 'volume',
        },
        {
            'unit'    => 'imperial gallon',
            'factor'  => 1 / 4.54609,
            'aliases' => [
                'imperial gallon',
                'uk gallon',
                'british gallon',
                'british gallons',
                'uk gallons'
            ],
            'type' => 'volume',
        },
        {
            'unit'    => 'us gallon',
            'factor'  => 1 / 3.78541178,
            'aliases' => [
                'fluid gallon',
                'us fluid gallon',
                'fluid gallons',
                'us gallons',
                'gallon',
                'gallons'
            ],
            'type' => 'volume',
        },
        {
            'unit'    => 'quart',
            'factor'  => 1 / 0.946352946,
            'aliases' => [
                'liquid quart',
                'us quart',
                'us quarts',
                'quarts',
                'liquid quarts'
            ],
            'type' => 'volume',
        },
        {
            'unit'   => 'imperial quart',
            'factor' => 4 * 1000 / 568.26125,
            'aliases' =>
              [ 'imperial quarts', 'british quarts', 'british quart' ],
            'type' => 'volume',
        },
        {
            'unit'    => 'imperial fluid ounce',
            'factor'  => 16 * 1000 / 568.26125,
            'aliases' => [
                'imperial fluid ounces',
                'imperial fl oz',
                'imperial fluid oz',
            ],
            'type' => 'volume',
        },
        {
            'unit'   => 'us fluid ounce',
            'factor' => 16 * 1000 / 473.176473,
            'aliases' =>
              [ 'us fluid ounces', 'us fl oz', 'fl oz', 'fl. oz', 'fluid oz' ],
            'type' => 'volume',
        },
        {
            'unit'    => 'us cup',
            'factor'  => 4.2267528,
            'aliases' => [ 'us cups', 'cups', 'cup' ],
            'type'    => 'volume',
        },
        {
            'unit'    => 'metric cup',
            'factor'  => 4,
            'aliases' => ['metric cups'],
            'type'    => 'volume',
        },
    );

    # unit types available for conversion
    my @types = (
        @mass,  @length,   @area,        @volume,
        @time,  @pressure, @energy,      @power,
        @angle, @force,    @temperature, @digital
    );

    return \@types;
}

1;

__END__