NAME

       Pegex::Compiler - Pegex Compiler

SYNOPSIS

           use Pegex::Compiler;
           my $grammar_text = '... grammar text ...';
           my $pegex_compiler = Pegex::Compiler->new();
           my $grammar_tree = $pegex_compiler->compile($grammar_text)->tree;

       or:

           perl -Ilib -MYourGrammarModule=compile

DESCRIPTION

       The Pegex::Compiler transforms a Pegex grammar string (or file) into a compiled form. The
       compiled form is known as a grammar tree, which is simply a nested data structure.

       The grammar tree can be serialized to YAML, JSON, Perl, or any other programming language.
       This makes it extremely portable. Pegex::Grammar has methods for serializing to all these
       forms.

       NOTE: Unless you are developing Pegex based modules, you can safely ignore
             this module. Even if you are you probably won't use it directly. See [In
             Place Compilation] below.

METHODS

       The following public methods are available:

       "$compiler = Pegex::Compiler->new();"
           Return a new Pegex::Compiler object.

       "$grammar_tree = $compiler->compile($grammar_input);"
           Compile a grammar text into a grammar tree that can be used by a Pegex::Parser. This
           method is calls the "parse" and "combinate" methods and returns the resulting tree.

           Input can be a string, a string ref, a file path, a file handle, or a Pegex::Input
           object. Return $self so you can chain it to other methods.

       "$compiler->parse($grammar_text)"
           The first step of a "compile" is "parse". This applies the Pegex language grammar to
           your grammar text and produces an unoptimized tree.

           This method returns $self so you can chain it to other methods.

       "$compiler->combinate()"
           Before a Pegex grammar tree can be used to parse things, it needs to be combinated.
           This process turns the regex tokens into real regexes. It also combines some rules
           together and eliminates rules that are not needed or have been combinated. The result
           is a Pegex grammar tree that can be used by a Pegex::Parser.

           NOTE: While the parse phase of a compile is always the same for various
                 programming languages, the combinate phase takes into consideration and
                 special needs of the target language. Pegex::Compiler only combinates
                 for Perl, although this is often sufficient in similar languages like
                 Ruby or Python (PCRE based regexes). Languages like Java probably need
                 to use their own combinators.

       "$compiler->tree()"
           Return the current state of the grammar tree (as a hash ref).

       "$compiler->to_yaml()"
           Serialize the current grammar tree to YAML.

       "$compiler->to_json()"
           Serialize the current grammar tree to JSON.

       "$compiler->to_perl()"
           Serialize the current grammar tree to Perl.

IN PLACE COMPILATION

       When you write a Pegex based module you will want to precompile your grammar into Perl so
       that it has no load penalty. Pegex::Grammar provides a special mechanism for this. Say you
       have a class like this:

           package MyThing::Grammar;
           use Pegex::Base;
           extends 'Pegex::Grammar';

           use constant file => '../mything-grammar-repo/mything.pgx';
           sub make_tree {
           }

       Simply use this command:

           perl -Ilib -MMyThing::Grammar=compile

       and Pegex::Grammar will call Pegex::Compile to put your compiled grammar inside your
       "make_tree" subroutine. It will actually write the text into your module. This makes it
       trivial to update your grammar module after making changes to the grammar file.

       See Pegex::JSON for an example.

AUTHOR

       Ingy döt Net <ingy@cpan.org>

COPYRIGHT AND LICENSE

       Copyright 2010-2020. Ingy döt Net.

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

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