NAME
    MarpaX::Simple - Generate Marpa-based parser

VERSION
    This document describes version 0.07 of MarpaX::Simple (from Perl
    distribution MarpaX-Simple), released on 2017-07-10.

SYNOPSIS
     use MarpaX::Simple qw(gen_parser);

     my $parser = gen_parser(
         grammar => <<'EOG',
     :start     ::= expr
     expr       ::= num
                  | num '+' num    action => do_add
     num        ~ [\d]+
     :discard   ~ whitespace
     whitespace ~ [\s]+
     EOG
         actions => {
             do_add => sub { shift; $_[0] + $_[2] }
         },
     );

     print $parser->('3 + 4'); # -> 7
     print $parser->('3 + ');  # dies with parse error

    which is a shortcut for roughly this:

     no strict 'refs';
     use Marpa::R2;
     my $slif = Marpa::R2::Scanless::G->new({source => \$args{grammar}});
     my $pkg = "MarpaX::Simple::gen" . some_random_value();
     my $actions = $args{actions};
     for (keys %$actions) {
         ${"$pkg\::$_"} = $actions->{$_};
     }
     my $parser = sub {
         my $input = shift;
         my $recce = Marpa::R2::Scanless::R->new({
             grammar => $slif,
             semantics_package => $pkg,
         });
     };

DESCRIPTION
    This module tries to simplify the incantation of producing a parser
    using Marpa::R2 (the scanless interface) by reducing the process to a
    single function call: "gen_parser".

FUNCTIONS
  gen_parser
    Usage:

     gen_parser(%args) -> code

    Generate Marpa-based parser.

    One of "slif_grammar", "grammar_class_file", "grammar_module_file",
    "grammar_file", "grammar" must be specified for the input grammar. The
    arguments will be checked in that order. The simplest would be to use
    grammar text inlined in your source code ("grammar"), but for larger
    grammar it might be more convenient to put it in a separate file (the
    "grammar_*file" arguments) so you can check line numbers from error
    messages more easily. The "slif_grammar" has the lowest overhead since
    you specify SLIF grammar that are already instantiated. See also the
    related Dist::Zilla plugin
    "Dist::Zilla::Plugin::InsertMarpaSLIFGrammar".

    This function is not exported by default, but exportable.

    Arguments ('*' denotes required arguments):

    *   actions => *hash*

        Supply code for actions specified in the grammar.

    *   grammar => *str*

        Marpa BNF input grammar text.

    *   grammar_class_file => *str*

        Marpa BNF input grammar file, resolved using File::ShareDir's
        class_file().

    *   grammar_file => *str*

        Marpa BNF input grammar file.

    *   grammar_module_file => *str*

        Marpa BNF input grammar file, resolved using File::ShareDir's
        module_file().

    *   slif_grammar => *obj*

        SLIF input grammar.

        This input-grammar argument is checked first because it is the most
        ready-to-use form and has the least overhead. The other
        input-grammar arguments require creating the
        "Marpa::R2::Scanless::G" object first from the Marpa BNF DSL
        grammar.

    *   too_many_earley_items => *int*

        Will be passed to recognizer's constructor.

    *   trace_terminals => *bool*

        Will be passed to recognizer's constructor.

    *   trace_values => *bool*

        Will be passed to recognizer's constructor.

    Return value: (code)

HOMEPAGE
    Please visit the project's homepage at
    <https://metacpan.org/release/MarpaX-Simple>.

SOURCE
    Source repository is at
    <https://github.com/perlancar/perl-MarpaX-Simple>.

BUGS
    Please report any bugs or feature requests on the bugtracker website
    <https://rt.cpan.org/Public/Dist/Display.html?Name=MarpaX-Simple>

    When submitting a bug or request, please include a test-file or a patch
    to an existing test-file that illustrates the bug or desired feature.

SEE ALSO
    Marpa::R2

AUTHOR
    perlancar <perlancar@cpan.org>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2017, 2015, 2014 by perlancar@cpan.org.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.