NAME

       GraphViz::Regex - Visualise a regular expression

SYNOPSIS

         use GraphViz::Regex;

         my $regex = '(([abcd0-9])|(foo))';

         my $graph = GraphViz::Regex->new($regex);
         print $graph->as_png;

DESCRIPTION

       This module attempts to visualise a Perl regular expression. Understanding regular
       expressions is tricky at the best of times, and regexess almost always evolve in ways
       unforseen at the start. This module aims to visualise a regex as a graph in order to make
       the structure clear and aid in understanding the regex.

       The graph visualises how the Perl regular expression engine attempts to match the regex.
       Simple text matches or character classes are represented by.box-shaped nodes. Alternations
       are represented by a diamond-shaped node which points to the alternations. Repetitions are
       represented by self-edges with a label of the repetition type (the nodes being repeated
       are pointed to be a full edge, a dotted edge points to what to match after the
       repetition). Matched patterns (such as $1, $2, etc.) are represented by a 'START $1' ..
       'END $1' node pair.

       This uses the GraphViz module to draw the graph.

METHODS

   new
       This is the constructor. It takes one mandatory argument, which is a string of the regular
       expression to be visualised. A GraphViz object is returned.

         my $graph = GraphViz::Regex->new($regex);

   as_*
       The regex can be visualised in a number of different graphical formats. Methods include
       as_ps, as_hpgl, as_pcl, as_mif, as_pic, as_gd, as_gd2, as_gif, as_jpeg, as_png, as_wbmp,
       as_ismap, as_imap, as_vrml, as_vtx, as_mp, as_fig, as_svg. See the GraphViz documentation
       for more information. The two most common methods are:

         # Print out a PNG-format file
         print $g->as_png;

         # Print out a PostScript-format file
         print $g->as_ps;

BUGS

       Note that this module relies on debugging information provided by Perl, and is known to
       fail on at least two versions of Perl: 5.005_03 and 5.7.1. Sorry about that - please use a
       more recent version of Perl if you want to use this module.

AUTHOR

       Leon Brocard <acme@astray.com>

COPYRIGHT

       Copyright (C) 2000-1, Leon Brocard

       This module is free software; you can redistribute it or modify it under the Perl License,
       a copy of which is available at <http://dev.perl.org/licenses/>.