Small example for Marpa::R2 issue #233

small233.pl

use strict;
use warnings;

use Test::More;

use Data::Dumper;
$Data::Dumper::Indent = 1;
$Data::Dumper::Terse = 1;
$Data::Dumper::Deepcopy = 1;

use Carp::Always; # force stack trace

use Marpa::R2;

my $input = q{a b};

my $grammar = '';
while (<DATA>) { $grammar .= $_ }

my $slg = Marpa::R2::Scanless::G->new({ source => \$grammar });

# no ranking
my $slr_ranking_none = Marpa::R2::Scanless::R->new({
    grammar => $slg,
    ranking_method => 'none',
} );

$slr_ranking_none->read(\$input);

ok $slr_ranking_none->ambiguous() ne '', "No ranking, many parses, ambiguous status isn't empty";
ok $slr_ranking_none->ambiguity_metric() > 1, "No ranking, many parses, ambiguity metric > 1";

# high_rule_only
my $slr_ranking_high_rule = Marpa::R2::Scanless::R->new({
    grammar => $slg,
    ranking_method => 'high_rule_only',
} );

$slr_ranking_high_rule->read(\$input);

# count parses
my $parse_count = 0;
while (defined $slr_ranking_high_rule->value()) { ++$parse_count }
$slr_ranking_high_rule->series_restart();

is $parse_count, 1, "high_rule_only ranking, single parse";
is $slr_ranking_high_rule->ambiguous(), '', "high_rule_only ranking, single parse, ambiguous status is empty";
is $slr_ranking_high_rule->ambiguity_metric(), 1, "high_rule_only ranking, single parse ambiguity metric is 1";

done_testing();

__END__
lexeme default = latm => 1

top ::= unchoice rank => 1
top ::= choice
unchoice ::= choice1
choice ::= choice1 | choice2
choice1 ::= A1 B1
choice2 ::= A2 B2
A1 ~ 'a'
A2 ~ 'a'
B1 ~ 'b'
B2 ~ 'b'

:discard ~ ws
ws ~ [\s]+