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#!perl
# Copyright 2022 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 from p. 166 of Leo's paper,
# augmented to test Leo prediction items.
#
use 5.010001;
use strict;
use warnings;
use Test::More tests => 2;
use lib 'inc';
use Marpa::R2::Test;
use Marpa::R2;
## no critic (Subroutines::RequireArgUnpacking)
sub main::default_action {
shift;
return ( join q{}, grep {defined} @_ );
}
## use critic
my $grammar = Marpa::R2::Scanless::G->new(
{
default_action => 'main::default_action',
source => \(<<'END_OF_DSL'),
:start ::= S
S ::= 'a' A
A ::= B
B ::= C
C ::= S
S ::=
event A = completed <A>
event C = completed <C>
event S = completed <S>
event 'A[]' = nulled <A>
event 'C[]' = nulled <C>
event 'S[]' = nulled <S>
END_OF_DSL
}
);
my $recce = Marpa::R2::Scanless::R->new( { grammar => $grammar } );
my $input = 'aaa';
my $event_history = q{};
my $pos = $recce->read( \$input );
READ: while (1) {
my @event_names;
for ( my $ix = 0; my $event = $recce->event($ix); $ix++ ) {
push @event_names, @{$event};
}
$event_history .= join q{ }, $pos, sort @event_names;
$event_history .= "\n";
last READ if $pos >= length $input;
$pos = $recce->resume();
} ## end READ: while (1)
my $value_ref = $recce->value();
my $value = $value_ref ? ${$value_ref} : 'No parse';
Marpa::R2::Test::is( $value, 'aaa', 'Leo SLIF parse' );
Marpa::R2::Test::is( $event_history, <<'END_OF_TEXT', 'Event history' );
0 S[]
1 A[] C[] S S[]
2 A A[] C C[] S S[]
3 A A[] C C[] S S[]
END_OF_TEXT
# vim: expandtab shiftwidth=4:
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