/ 
Graph-Easy-0.22
River stage two • 24 direct dependents • 27 total dependents
/ Graph::Easy::Parser

NAME

Graph::Easy::Parser - Parse graph from textual description

SYNOPSIS

# creating a graph from a textual description
use Graph::Easy::Parser;
my $parser = Graph::Easy::Parser->new();

my $graph = $parser->from_text(
        '[ Bonn ] => [ Berlin ]'.
        '[ Berlin ] => [ Rostock ]'.
);
print $graph->as_ascii( );

DESCRIPTION

Graph::Easy::Parser lets you parse simple textual descriptions of graphs, and constructs a Graph::Easy object from them.

The resulting object can than be used to layout and output the graph.

Input

The input consists of text describing the graph.

[ Bonn ]      --> [ Berlin ]
[ Frankfurt ] <=> [ Dresden ]
[ Bonn ]      --> [ Frankfurt ]
[ Bonn ]      ==> [ Frankfurt ]

See Output for how this will be rendered in ASCII art.

The edges between the nodes can have the following styles:

-->		solid
==>		double
..>		dotted
- >		dashed
~~>		wave
.->		dot-dash
..->		dot-dot-dash

In additon the following three directions are possible:

 -->		connect the node on the left to the node on the right
<-->		the direction between the nodes
		goes into both directions at once
<--		connect the node on the right to the node on the left

Of course you can combine all three directions with all styles.

Output

The output will be a Graph::Easy object, see there for what you can do with it.

EXAMPLES

See Graph::Easy for an extensive list of examples.

METHODS

Graph::Easy::Parser supports the following methods:

new()

use Graph::Easy::Parser;
my $parser = Graph::Easy::Parser->new();

Creates a new parser object.

reset()

$parser->reset();

Reset the status of the parser, clear errors etc.

from_text()

my $graph = $parser->from_text( $text );

Create a Graph::Easy object from the textual description in $text.

Returns undef for error, you can find out what the error was with error().

This method will reset any previous error, and thus the $parser object can be re-used to parse different texts by just calling from_text() multiple times.

from_file()

my $graph = $parser->from_file( $filename );
my $graph = Graph::Easy::Parser->from_file( $filename );

Creates a Graph::Easy object from the textual description in the file $filename.

The second calling style will create a temporary Graph::Easy::Parser object, parse the file and return the resulting Graph::Easy object.

Returns undef for error, you can find out what the error was with error() when using the first calling style.

error()

my $error = $parser->error();

Returns the last error, or the empty string if no error occured.

parse_error()

$parser->parse_error( $msg_nr, @params);

Sets an error message from a message number and replaces embedded templates like ##param1## with the passed parameters.

valid_attribute()

my $val = $parser->valid_attribute ($name, $value);

Checkc that the given name/value pair is an valid attribute, and returns the new value or undef for invalid attributes.

The returned attribute value might differ from what you pass in as:

my $val =
  $parser->valid_attribute ('color', 'red');
print $val;					# prints '#ff0000'

_parse_attributes()

	my $attributes = $parser->_parse_attributes( $txt );

Internal usage only. Takes a text like this:

attribute: value;  attribute2 : value2;

and returns a hash with the attributes.

EXPORT

Exports nothing.

SEE ALSO

Graph::Easy.

AUTHOR

Copyright (C) 2004 - 2005 by Tels http://bloodgate.com

See the LICENSE file for information.