GraphViz::Regex(3) User Contributed Perl Documentation GraphViz::Regex(3)NAMEGraphViz::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 same terms as Perl itself.
perl v5.14.3 2012-11-09 GraphViz::Regex(3)
