NAME

GraphViz2::Marpa::Lexer::DFA - A Perl lexer for Graphviz dot files

Synopsis

This module is called from GraphViz2::Marpa::Lexer.

Description

GraphViz2::Marpa::Lexer::DFA provides a Set:FA::Element-based lexer for Graphviz (dot) graph definitions.

Demo lexer/parser output: http://savage.net.au/Perl-modules/html/graphviz2.marpa/index.html.

State Transition Table: http://savage.net.au/Perl-modules/html/graphviz2.marpa/default.stt.html.

Command line options and object attributes: http://savage.net.au/Perl-modules/html/graphviz2.marpa/code.attributes.html.

My article on this set of modules: http://www.perl.com/pub/2012/10/an-overview-of-lexing-and-parsing.html.

The Marpa grammar as an image: http://savage.net.au/Ron/html/graphviz2.marpa/Marpa.Grammar.svg. This image was created with Graphviz via GraphViz2.

Installation

Install GraphViz2::Marpa as you would for any Perl module:

Run:

        cpanm GraphViz2::Marpa

or run:

        sudo cpan GraphViz2::Marpa

or unpack the distro, and then either:

        perl Build.PL
        ./Build
        ./Build test
        sudo ./Build install

or:

        perl Makefile.PL
        make (or dmake or nmake)
        make test
        make install

Constructor and Initialization

new() is called as my($dfa) = GraphViz2::Marpa::Lexer::DFA -> new(k1 => v1, k2 => v2, ...).

It returns a new object of type GraphViz2::Marpa::Lexer::DFA.

Key-value pairs accepted in the parameter list (see corresponding methods for details [e.g. graph_text()]):

o graph_text => $string

Specify a string for the Graphviz (dot) graph definition.

Default: ''.

o logger => $logger

Specify a logger object to use.

Default: ''.

o report_stt => $Boolean

Log the State Transition Table.

Default: 0.

o start => $start_state_name

Specify the name of the start state.

There is no default. The code dies if a value is not supplied.

o state => $state_hashref

Specify the State Transition Table.

There is no default. The code dies if a value is not supplied.

o verbose => $Boolean

Specify the verbosity level in the call to Set::FA::Element.

The value is only used by the latter module when a logger is not passed to it from the current module.

Default: 0.

Methods

graph_text([$graph])

The [] indicate an optional parameter.

Get or set the Graphviz (dot) graph definition.

'graph_text' is a parameter to "new()". See "Constructor and Initialization" for details.

items()

Returns a object of type Set::Array, which is an arrayref of items output by the DFA.

These items are not the same as the arrayref of items returned by the items() method in GraphViz2::Marpa::Parser, but they are the same as in GraphViz2::Marpa::Lexer.

Each element is a hashref with these keys:

o count => $integer

Just counts the items as 1 .. N.

o name => $string

Not used. Always ''.

o type => $string

The type of the token.

The range of values is documented in the lexer's FAQ item: How is the lexed graph stored in RAM?.

o value => $string

The value of the token from the input stream.

Usage:

        my(@items) = @{$dfa -> items};

log($level, $s)

Calls $self -> logger -> $level($s) if ($self -> logger).

logger([$logger_object])

Here, the [] indicate an optional parameter.

Get or set the logger object.

new()

See "Constructor and Initialization" for details on the parameters accepted by "new()".

report_stt([$Boolean])

The [] indicate an optional parameter.

Get or set the value which determines whether or not to log the parsed state transition table (STT).

Calls "report()" in Set::FA::Element. Set min and max log levels to 'info' for this.

'report_stt' is a parameter to "new()". See "Constructor and Initialization" for details.

run()

Runs the state machine.

Afterwards, you call "items()" to retrieve the arrayref of results.

start([$start_state_name])

The [] indicate an optional parameter.

Get or set the name of the state in which the STT starts.

'start' is a parameter to "new()". See "Constructor and Initialization" for details.

state([\%state_hashref])

The [] indicate an optional parameter.

Get or set the hashref defining the STT.

'state' is a parameter to "new()". See "Constructor and Initialization" for details.

verbose([$Boolean])

The [] indicate an optional parameter.

Get or set the verbosity level when calling Set::FA::Element.

'verbose' is a parameter to "new()". See "Constructor and Initialization" for details.

Machine-Readable Change Log

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

Version Numbers

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

Support

Email the author, or log a bug on RT:

https://rt.cpan.org/Public/Dist/Display.html?Name=GraphViz2::Marpa.

Author

GraphViz2::Marpa was written by Ron Savage <ron@savage.net.au> in 2012.

Home page: http://savage.net.au/index.html.

Copyright

Australian copyright (c) 2012, 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 Artistic License, a copy of which is available at:
        http://www.opensource.org/licenses/index.html

cpanm GraphViz2::Marpa

perl -MCPAN -e shell
install GraphViz2::Marpa