#!perl
# Copyright 2014 Jeffrey Kegler
# This file is part of Marpa::R2.  Marpa::R2 is free software: you can
# redistribute it and/or modify it under the terms of the GNU Lesser
# General Public License as published by the Free Software Foundation,
# either version 3 of the License, or (at your option) any later version.
#
# Marpa::R2 is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser
# General Public License along with Marpa::R2.  If not, see
# http://www.gnu.org/licenses/.

# the example grammar in Aycock/Horspool "Practical Earley Parsing",
# _The Computer Journal_, Vol. 45, No. 6, pp. 620-630,
# in its "NNF" form

use 5.010;
use strict;
use warnings;

use Test::More tests => 10;
use lib 'inc';
use Marpa::R2::Test;
use Marpa::R2;

## no critic (Subroutines::RequireArgUnpacking)

sub default_action {
    shift;
    my $v_count = scalar @_;
    return q{}   if $v_count <= 0;
    return $_[0] if $v_count == 1;
    return '(' . join( q{;}, @_ ) . ')';
} ## end sub default_action

## use critic

sub gen_grammar {
    my ($null_ranking) = @_;
    my $grammar = Marpa::R2::Grammar->new(
        {   start => 'S',
            rules => [
                {   lhs          => 'S',
                    rhs          => [qw/A A A A/],
                    null_ranking => $null_ranking
                },
                [ 'A', [qw/a/] ],
                ['A'],
            ],
            default_action     => 'main::default_action',
        }
    );
    $grammar->set( { terminals => ['a'], } );
    $grammar->precompute();
    return $grammar;
} ## end sub gen_grammar

my @maximal = ( q{}, qw[(a;;;) (a;a;;) (a;a;a;) (a;a;a;a)] );
my @minimal = ( q{}, qw[(;;;a) (;;a;a) (;a;a;a) (a;a;a;a)] );

for my $maximal ( 0, 1 ) {
    my $grammar = gen_grammar( $maximal ? 'low' : 'high' );
    my $recce = Marpa::R2::Recognizer->new(
        { grammar => $grammar, ranking_method => 'high_rule_only' } );

    my $input_length = 4;
    for ( 1 .. $input_length ) { $recce->read( 'a', 'a' ); }

    for my $i ( 0 .. $input_length ) {
        my $expected = $maximal ? \@maximal : \@minimal;
        my $name     = $maximal ? 'maximal' : 'minimal';
        $recce->reset_evaluation();
        $recce->set( { end => $i, } );
        my $result = $recce->value();
        Test::More::is( ${$result}, $expected->[$i],
            "$name parse, length=$i" );

    } ## end for my $i ( 0 .. $input_length )
} ## end for my $maximal ( 0, 1 )

1;    # In case used as "do" file

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