Pegex::Grammar (3)

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NAME

Pegex::Grammar - Pegex Grammar Base Class

SYNOPSIS

Define a Pegex grammar (for the Foo syntax):

    package Pegex::Foo::Grammar;
    use base 'Pegex::Base';
    extends 'Pegex::Grammar';

    has text => q{
    foo: bar baz
    ... rest of Foo grammar ...
    };

then use it to parse some Foo:

    use Pegex::Parser;
    my $parse_tree = Pegex::Parser->new(
        grammar => 'Pegex::Foo::Grammar',
        receiver => 'Pegex::Tree',
    )->parse('my/file.foo');

DESCRIPTION

Pegex::Grammar is a base class for defining your own Pegex grammar classes. You just need to provide the grammar view the "text" or the "file" attributes.

When Pegex::Parser uses your grammar, it will want it in the tree (compiled) form, so Pegex::Grammar provides automatic compilation support.

PROPERTIES AND METHODS

tree

This is the data structure containing the compiled grammar for your syntax. It is usually produced by "Pegex::Compiler". You can inline it in the "tree" method, or else the "make_tree" method will be called to produce it.

The "make_tree" method will call on Pegex::Compiler to compile the "text" property by default. You can define your own "make_tree" method to do override this behavior.

Often times you will want to generate your own Pegex::Grammar subclasses in an automated fashion. The Pegex and TestML modules do this to be performant. This also allows you to keep your grammar text in a separate file, and often in a separate repository, so it can be shared by multiple programming language's module implementations.

See <github.com/ingydotnet/pegex-pgx> and <github.com/ingydotnet/pegex-pm/blob/master/lib/Pegex/Pegex/Grammar.pm>.

text

This is simply the text of your grammar, if you define this, you should (probably) not define the "tree" property. This grammar text will be automatically compiled when the "tree" is required.

file

This is the file where your Pegex grammar lives. It is usually used when you are making a Pegex module. The path is relative to your top level module directory.

make_tree

This method is called when the grammar needs the compiled version.

AUTHOR

Ingy döt Net <ingy@cpan.org>

COPYRIGHT AND LICENSE

Copyright 2010-2017. Ingy döt Net.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

See <www.perl.com/perl/misc/Artistic.html>