=encoding utf8

=head1 NAME

Pegex::Regex - Use Pegex Like a Regex

=head1 SYNOPSIS

    {
        # Turn on Pegex regular expressions in lexical scope.
        use Pegex::Regex;
        my $grammar = qr{$grammar_text}x;
        $text =~ $grammar;
        my $data = \%/;

        # Turn off Pegex in this scope.
        no Pegex::Regex;
    }

=head1 DESCRIPTION

This is a trivial sugar module that lets you use Pegex parser grammars like
regular expressions, if you're into that kind of thing.

This is basically a clone of Damian Conway's L<Regexp::Grammars> module API.
You put a grammar into a C<qr{...}x> and apply it the input string you want to
parse. If the parse is successful, you get a data structure of the content in
C<%/>.

IMHO, building a recursive decscent parser entirely inside of a regular
expression, is not the clearest way to code. But, of course, TMTOWTDI. :)

=head1 TMTOWTDI

Here's a Pegex::Regex code snippet:

    use Pegex::Regex;
    $text =~ qr{path/to/grammar_file.pgx};
    print $/{foo};

And the equivalent Pegex code:

    use Pegex;
    my $data = pegex('path/to/grammar_file.pgx')->parse($text);
    print $data->{foo};

And the more explicit Pegex solution:

    use Pegex::Grammar;
    my $grammar = Pegex::Grammar->new(
        text => 'path/to/grammar_file.pgx',
    );
    my $data = $grammar->parse($input);
    print $data->{foo};

And even more explicit yet:

    use Pegex::Grammar;
    use Pegex::Compiler;
    use Pegex::Parser;
    use Pegex::Receiver;
    use Pegex::Input;
    my $parser = Pegex::Grammar->new(
        grammar => Pegex::Grammar->new(
            tree => Pegex::Compile->compile(
                Pegex::Input->new(
                    file => 'path/to/grammar_file.pgx',
                )
            )->tree,
        ),
        parser => 'Pegex::Parser',
        receiver => 'Pegex::Receiver',
    );
    $parser->parse(Pegex::Input->new(string => $input));
    print $parser->receiver->data->{foo};

In the last example there are 5 components/classes, all of which you can
subclass to make your perfect parser.

Pegex::Regex is just a gateway drug. :)

=head1 INPUT OPTIONS

There are different ways to input a grammar into a Pegex::Regex:

    qr{
        grammar: <as> <text>
    }x;
    qr{$grammar_in_a_variable}x;
    qr{path/to/grammar-file.pgx};

Make sure to use the C<x> modifier if you are specifying the grammar as a
literal string or in a variable.

=head WARNING

This gateway drug, er, module, technically should not even work.

It turns your "grammar inside a regexp" into a Pegex::Grammar using qr{}
overloading, and then turns your regexp itself into a shim that calls the
parse method for you. This is highly magical and technically makes a reentrant
call to the regex engine, which is not supported yet.  Use at your own risk.

Better yet, do yourself a favor and learn how to use the Pegex toolset without
this ::Regex sugar.  C<:-)>

=head1 SEE ALSO

=over

=item *

L<Pegex>

=item *

L<Regexp::Grammars>

=back

=head1 AUTHOR

Ingy döt Net <ingy@cpan.org>

=head1 COPYRIGHT AND LICENSE

Copyright (c) 2011. 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

=cut
