File Coverage

blib/lib/Bijection.pm

Criterion	Covered	Total	%
statement	34	34	100.0
branch	6	6	100.0
condition			n/a
subroutine	11	11	100.0
pod	4	4	100.0
total	55	55	100.0

package Bijection;
use 5.006; use strict; use warnings; our $VERSION = '1.00';
use Import::Export; use base qw/Import::Export/;
use Carp qw/croak/;
our %EX = (biject => [qw/all main/], inverse => [qw/all main/], bijection_set => [qw/all set/], offset_set => [qw/all set/]);

our (@ALPHA, $OFFSET, $COUNT, %INDEX);
BEGIN {
	sub bijection_set {
		@ALPHA = @_;
		$ALPHA[0] =~ m/^[1-9](?!$)\d+$/ ? offset_set(shift @ALPHA) : offset_set(scalar @ALPHA);
		$COUNT = @ALPHA;
		my $index = -1;
		%INDEX = map +( $_ => ++$index ), @ALPHA;
	}
	sub offset_set {
		$OFFSET = shift;
	}
	bijection_set(qw/b c d f g h j k l m n p q r s t v w x y z B C D F G H J K L M N P Q R S T V W X Y Z 0 1 2 3 4 5 6 7 8 9/);
}

sub biject {
	my ($id, $out) = @_;
	croak "id to encode must be an integer and non-negative: $id" unless ($id =~ m/^\d+$/);
	$id += $OFFSET;
	do { $out .= $ALPHA[($id % $COUNT)]; $id = int($id/$COUNT); } while ($id > 0);
	reverse $out;
}

sub inverse {
	my ($out, $id) = (@_, 0);
	$id = exists $INDEX{$_}
		? $id * $COUNT + $INDEX{$_}
		: croak "invalid character $_ in $out"
	for (split //, $out);
	$id - $OFFSET;
}

1;

__END__