NAME

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 <[email protected]>

COPYRIGHT AND LICENSE
This software is copyright (c) 2017, 2015, 2014 by [email protected].

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