/ 
MarpaX-Simple-0.07
River stage one • 6 direct dependents • 9 total dependents
/ MarpaX::Simple

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.