GraphViz2::Parse::RecDescent - Visualize a Parse::RecDescent grammar as a graph


        #!/usr/bin/env perl

        use strict;
        use warnings;

        use File::Spec;

        use GraphViz2;
        use GraphViz2::Parse::RecDescent;

        use Parse::RecDescent;

        use File::Slurp; # For read_file().

        my($graph) = GraphViz2 -> new
                 edge   => {color => 'grey'},
                 global => {directed => 1},
                 graph  => {rankdir => 'TB'},
                 node   => {color => 'blue', shape => 'oval'},
        my($g)      = GraphViz2::Parse::RecDescent -> new(graph => $graph);
        my $grammar = read_file(File::Spec -> catfile('t', 'sample.recdescent.1.dat') );
        my($parser) = Parse::RecDescent -> new($grammar);

        $g -> create(name => 'Grammar', grammar => $parser);

        my($format)      = shift || 'svg';
        my($output_file) = shift || File::Spec -> catfile('html', "parse.recdescent.$format");

        $graph -> run(format => $format, output_file => $output_file);

See scripts/ ("Scripts Shipped with this Module" in GraphViz2).


Takes a Parse::RecDescent grammar and converts it into a graph.

You can write the result in any format supported by Graphviz.

Here is the list of output formats.

Constructor and Initialization

Calling new()

new() is called as my($obj) = GraphViz2::Parse::RecDescent -> new(k1 => v1, k2 => v2, ...).

It returns a new object of type GraphViz2::Parse::RecDescent.

Key-value pairs accepted in the parameter list:

o graph => $graphviz_object

This option specifies the GraphViz2 object to use. This allows you to configure it as desired.

The default is GraphViz2->new. The default attributes are the same as in the synopsis, above.

This key is optional.


create(name => $name, grammar => $grammar)

Creates the graph, which is accessible via the graph() method, or via the graph object you passed to new().

Returns $self for method chaining.

$name is the string which will be placed in the root node of the tree.

$grammar is either a Parse::RecDescent object or a grammar. If it's a grammar, the code will fabricate an object of type Parse::RecDescent.


Returns the graph object, either the one supplied to new() or the one created during the call to new().

Scripts Shipped with this Module


Demonstrates graphing a Parse::RecDescent-style grammar.

Inputs from t/sample.recdescent.1.dat and outputs to ./html/parse.recdescent.svg by default.

The input grammar was extracted from t/basics.t in Parse::RecDescent V 1.965001.

You can patch the *.pl to read from t/sample.recdescent.2.dat, which was copied from a V 2 bug report.


Many thanks are due to the people who chose to make Graphviz Open Source.

And thanks to Leon Brocard, who wrote GraphViz, and kindly gave me co-maint of the module.

Version Numbers

Version numbers < 1.00 represent development versions. From 1.00 up, they are production versions.

Machine-Readable Change Log

The file Changes was converted into Changelog.ini by Module::Metadata::Changes.


Email the author, or log a bug on RT:


GraphViz2 was written by Ron Savage <> in 2011.

Home page:


Australian copyright (c) 2011, Ron Savage.

        All Programs of mine are 'OSI Certified Open Source Software';
        you can redistribute them and/or modify them under the terms of
        The Perl License, a copy of which is available at: