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.IX Title "GraphViz::Regex 3"
.TH GraphViz::Regex 3 2024-09-01 "perl v5.40.0" "User Contributed Perl Documentation"
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.SH NAME
GraphViz::Regex \- Visualise a regular expression
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\&  use GraphViz::Regex;
\&
\&  my $regex = \*(Aq(([abcd0\-9])|(foo))\*(Aq;
\&
\&  my $graph = GraphViz::Regex\->new($regex);
\&  print $graph\->as_png;
.Ve
.SH DESCRIPTION
.IX Header "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.
.PP
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 \f(CW$1\fR, \f(CW$2\fR, etc.) are represented by a 'START \f(CW$1\fR' .. 'END \f(CW$1\fR' node
pair.
.PP
This uses the GraphViz module to draw the graph.
.SH METHODS
.IX Header "METHODS"
.SS new
.IX Subsection "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.
.PP
.Vb 1
\&  my $graph = GraphViz::Regex\->new($regex);
.Ve
.SS as_*
.IX Subsection "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:
.PP
.Vb 2
\&  # Print out a PNG\-format file
\&  print $g\->as_png;
\&
\&  # Print out a PostScript\-format file
\&  print $g\->as_ps;
.Ve
.SH BUGS
.IX Header "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.
.SH AUTHOR
.IX Header "AUTHOR"
Leon Brocard <\fIacme@astray.com\fR>
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright (C) 2000\-1, Leon Brocard
.PP
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/>.