NAME

   Short::URL - Encodes and Decodes short urls by using Bijection

SYNOPSIS

       use Short::URL;

       #use default alphabet
       my $su = Short::URL->new;

       my $encoded = $su->encode(10000);
       my $short_url = "http://www.example.com/$encoded";

       print "Encoded: $encoded\n"; #prints cP6
       print "Short url: $short_url\n"; #prints http://www.example.com/cP6

       my $decoded = $su->decode('cP6');

       print "Decoded: $decoded\n"; #prints 10000

       #set new alphabet
       $su->alphabet([qw/1 2 3 a b c/]);

       #or when you create the Short::URL object
       my $su = Short::URL->new(alphabet => [qw/1 2 3 a b c/]);

       #have an 'offset'. Meaning if you pass in integer $i, you get unique string for $i + offset
       $su->offset(10000);

       #or
       my $su = Short::URL->new(offset => 10000);

       my $encoded_with_offset = $su->encode(0);

       print "Encoded with offset: $encoded_with_offset\n"; #prints unique string for 10000, 'cP6'

       my $decoded_with_offset = $su->decode('cP6');

       print "Decoded with offset: $decoded_with_offset\n"; #prints 0

       #use shuffled alphabet
       $su->use_shuffled_alphabet(1);

       #or
       my $su = Short::URL->new(use_shuffled_alphabet => 1);

       my $encoded_with_shuffled_alphabet = $su->encode(10000);

       print "Encoded with shuffled alphabet: $encoded_with_shuffled_alphabet"; #prints 'dlu'

       my $decoded_with_shuffled_alphabet = $su->decode('dlu');

       print "Decoded with shuffled alphabet: $decoded_with_shuffled_alphabet"; #prints 10000

       #use no naughty words
       $su->no_vowels(1);

       #or
       my $su = Short::URL->new(no_vowels => 1);

       my $clean_encoded = $su->encode(7465182);

       print "My clean word: $clean_encoded\n"; #prints 'ccgZn', instead of 'F_ck', where '_' is replaced with 'u'


DESCRIPTION

   Short::URL can be used to help generate short, unique character string
   urls. It uses Bijection <http://en.wikipedia.org/wiki/Bijection> to
   create a one-to-one mapping from integers to strings over your
   alphabet, and from strings over your alphabet back to the original
   integer. An integer primary key in your database would be a good
   example of an integer you could use to generate a unique character
   string that maps uniquely to that row.

METHODS

alphabet

       $su->alphabet([qw/1 2 3 a b c/]);

   The alphabet that will be used for creating strings when mapping an
   integer to a string. The default alphabet is:

      [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 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 0 1 2 3 4 5 6 7 8 9/]

   All lower case letters, upper case letters, and digits 0-9.

encode

       my $encoded = $su->encode(1);

   Takes an integer and encodes it into a unique string over your
   alphabet.

decode

       my $decoded = $su->decode('b');

   Takes a string made from your alphabet and returns the corresponding
   integer that it maps to.

offset

       $su->offset(10000);
       my $encoded_with_offset = $su->encode(0);

       print "Encoded with offset: $encoded_with_offset\n"; #prints unique string for 10000, 'cP6' instead of 'a'

       my $decoded_with_offset = $su->decode('cP6');

       print "Decoded with offset: $decoded_with_offset\n"; #prints 0 instead of 10000

   "offset" allows you to shift all integers that you encode forward by a
   certain integer. Likewise, whenever you are decoding strings it will
   return the integer for that string by substracting your offset from
   what the original number would have been. Offset can be useful if you
   don't want people to know you have a small number of items by starting
   with a larger offset, or if you want them to have less of an idea what
   ids really correspond to what strings. When used in combination with
   "use_shuffled_alphabet", it is a lot harder to track what string would
   correspond to what id in your database, or how many ids you have in
   total.

use_shuffled_alphabet

       $su->use_shuffled_alphabet(1);

       my $encoded_with_shuffled_alphabet = $su->encode(10000);

       print "Encoded with shuffled alphabet: $encoded_with_shuffled_alphabet"; #prints 'dlu'

   Setting "use_shuffled_alphabet" to 1 means that instead of using the
   more common alphabet used for this algorithm that is stored in
   "alphabet", Short::URL will use a shuffled alphabet. Note, this
   shuffled alphabet will be the same every time, so encoding and decoding
   will work even with the use_shuffled_alphabet set to 1 even in
   different sessions of using Short::URL. This can be useful if for some
   reason you don't want people to know how many ids you have in your
   database. With the more standard alphabet it's clear when you are going
   up by one between strings, and thus also how many ids you have. When
   used in combination with "offset", it is a lot harder to track what
   string would correspond to what id in your databse, or how many ids you
   have in total. Below is the shuffled alphabet that is used:

       [qw/G w d A t H J 0 P o W C 6 3 y K 8 L u 7 X E O a e q 1 9 D c F x Z 5 M T N l z r i s j h B 4 b I f V Y Q g n S 2 m U k p v R/]

   This is just a shuffled version of "alphabet". The default for
   "use_shuffled_alphabet" is undef.

no_vowels

   As pointed out here
   <http://stackoverflow.com/questions/742013/how-to-code-a-url-shortener/742047#comment25208796_742047>,
   there is the possibility of creating naughty words. For instance:

       my $encoded = $su->encode(7465182);

       print "Encoded naughty: $encoded\n"; #prints F_ck, where '_' is replaced with 'u'

   If you want to avoid this, you can set "no_vowels" to 1:

       $su->no_vowels(1);

       #or
       my $su = Short::URL->new(no_vowels => 1);

   This uses a separate alphabet with no vowels in it (aeiou), so that no
   naughty words can be formed. If you also have "use_shuffled_alphabet"
   set to 1, that will still be respected. Short::URL will just use a
   clean version of the shuffled alphabet listed under
   "use_shuffled_alphabet". Below are the two clean alphabets:

       #clean_alphabet
       [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/]

       #clean_shuffled_alphabet
       [qw/G w d t H J 0 P W C 6 3 y K 8 L 7 X q 1 9 D c F x Z 5 M T N l z r s j h B 4 b f V Y Q g n S 2 m k p v R/]

croak_on_error

   This method sets whether you want Short::URL to Carp on an error.

       #enable
       $su->croak_on_error(1);

       #disable
       $su->croak_on_error(0);

   Default is 1. If "croak_on_error" is set to false and there is an
   error, then "encode" or "decode" will return a negative number.

AUTHOR

   Adam Hopkins <[email protected]>

COPYRIGHT

   Copyright 2019- Adam Hopkins

LICENSE

   This library is free software; you can redistribute it and/or modify it
   under the same terms as Perl itself.

SEE ALSO

     * http://stackoverflow.com/a/742047/834140

     * https://gist.github.com/zumbojo/1073996

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