1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
|
#!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/.
use 5.010001;
use strict;
use warnings;
use English qw( -no_match_vars );
use List::Util qw(min);
use Test::More tests => 7;
use lib 'inc';
use Marpa::R2::Test;
use Marpa::R2;
sub find_match {
my ($s) = @_;
my $grammar_args = {
start => 'S',
rules => [
[ S => [qw(prefix first_balanced endmark )] ],
{ lhs => 'S',
rhs => [qw(prefix first_balanced )]
},
{ lhs => 'prefix', rhs => [qw(prefix_char)], min => 0 },
{ lhs => 'prefix_char', rhs => [qw(xlparen)] },
{ lhs => 'prefix_char', rhs => [qw(rparen)] },
{ lhs => 'lparen', rhs => [qw(xlparen)] },
{ lhs => 'lparen', rhs => [qw(ilparen)] },
{ lhs => 'first_balanced',
rhs => [qw(xlparen balanced_sequence rparen)],
},
{ lhs => 'balanced',
rhs => [qw(lparen balanced_sequence rparen)],
},
{ lhs => 'balanced_sequence',
rhs => [qw(balanced)],
min => 0,
},
],
};
my $grammar = Marpa::R2::Grammar->new($grammar_args);
$grammar->precompute();
my ($first_balanced_rule) =
grep { ( $grammar->rule($_) )[0] eq 'first_balanced' }
$grammar->rule_ids();
my $recce = Marpa::R2::Recognizer->new( { grammar => $grammar } );
# Marpa::R2::Display
# name: Recognizer expected_symbol_event_set() Synopsis
$recce->expected_symbol_event_set( 'endmark', 1 );
# Marpa::R2::Display::End
my $location = 0;
my $string_length = length $s;
my $end_of_match;
# find the match which ends first -- the one which starts
# first must start at or before it does
CHAR: while ( $location < $string_length ) {
my $value = substr $s, $location, 1;
my $event_count;
if ( $value eq '(' ) {
# say "Adding xlparen at $location";
$event_count = $recce->read('xlparen');
}
else {
# say "Adding rparen at $location";
$event_count = $recce->read('rparen');
}
if ( $event_count
and grep { $_->[0] eq 'SYMBOL_EXPECTED' } @{ $recce->events() } )
{
$end_of_match = $location + 1;
last CHAR;
} ## end if ( $event_count and grep { $_->[0] eq 'SYMBOL_EXPECTED'...})
$location++;
} ## end CHAR: while ( $location < $string_length )
if ( not defined $end_of_match ) {
say "No balanced parens";
return 0;
}
CHAR: while ( ++$location < $string_length ) {
my $value = substr $s, $location, 1;
my $token = $value eq '(' ? 'ilparen' : 'rparen';
# say "Adding $token at $location";
my $event_count = $recce->read($token);
last CHAR if not defined $event_count;
if ( $event_count
and grep { $_->[0] eq 'SYMBOL_EXPECTED' } @{ $recce->events() } )
{
$end_of_match = $location + 1;
}
} ## end CHAR: while ( ++$location < $string_length )
my $report = $recce->progress($end_of_match);
# say Dumper($report);
my $start_of_match = List::Util::min map { $_->[2] }
grep { $_->[1] < 0 && $_->[0] == $first_balanced_rule } @{$report};
return "$start_of_match-$end_of_match";
} ## end sub find_match
my $base_string = '(' x 40;
my $target = '(()())';
for my $pos (
0, 1, 2,
-( 2 + length $target ),
-( 1 + length $target ),
-( length $target )
)
{
my $test_string = $base_string;
substr $test_string, $pos, ( length $target ), $target;
my ( $expected_start, $expected_end );
if ( $pos >= 0 ) {
$expected_start = $pos;
$expected_end = $pos + length $target;
}
else {
$expected_start = $pos + 40;
$expected_end = $pos + 40 + length $target;
}
my $expected = $expected_start . q{-} . $expected_end;
Marpa::R2::Test::is( find_match($test_string),
$expected, "target at pos $pos" );
} ## end for my $pos ( 0, 1, 2, -( 2 + length $target ), -( 1 ...))
my $test_string = '(' x 20 . ')' x 20;
Marpa::R2::Test::is( find_match($test_string), '0-40', 'Middle target' );
|
