Sha256: d9f72392a6deaa5a9fe4a539e23a2d788b7cb9ecd064e1faa9119462c56347f4
Contents?: true
Size: 1.18 KB
Versions: 73
Compression:
Stored size: 1.18 KB
Contents
package Cipher;
use strict;
use warnings;
use List::Util qw(first);
sub new {
my ($class, $key) = @_;
if (defined $key and $key !~ /[a-z]/) {
die "ArgumentError: $key"
} else {
$key ||= "a";
}
return bless { keys => [ split '', $key ] };
}
sub encode {
my ($self, $plaintext) = @_;
my $cipher;
my @plain_chars = split '' => do { $plaintext = lc $plaintext; $plaintext =~ s/[^a-z]//g; $plaintext };
$cipher .= $self->_shift_char( $plain_chars[$_], $_ ) for 0..$#plain_chars;
return $cipher;
}
sub decode {
my ($self, $cipher) = @_;
my $plaintext;
my @cipher_chars = split '' => $cipher;
$plaintext .= $self->_shift_char( $cipher_chars[$_], $_ * -1) for 0..$#cipher_chars;
return $plaintext;
}
sub _shift_char {
my ($self, $plain, $index) = @_;
my $char_key = $self->{keys}->[abs($index)] || 'a';
my $shift_index = first { [('a'..'z')]->[$_] eq $char_key } (0..26);
my $plain_index = first { [('a'..'z')]->[$_] eq $plain } (0..26);
return [('a'..'z')]->[($plain_index - $shift_index) % 26] if ((caller(1))[3]) =~ /decode/;
return [('a'..'z')]->[($plain_index + $shift_index) % 26];
}
1;
Version data entries
73 entries across 73 versions & 1 rubygems