From f5f900c433ee5247b0466d0e3efcd3f66ff664d9 Mon Sep 17 00:00:00 2001
From: Mischa POSLAWSKY <perl@shiar.org>
Date: Wed, 11 Nov 2009 16:01:27 +0100
Subject: [PATCH] +++: rangematch() fixes

---
 lib/List/Index.pm | 49 +++++++++++++++++++++++++++++++++--------------
 t/20-links.t      | 17 +++++++++-------
 2 files changed, 45 insertions(+), 21 deletions(-)

diff --git a/lib/List/Index.pm b/lib/List/Index.pm
index 89fdc75..9c86bc3 100644
--- a/lib/List/Index.pm
+++ b/lib/List/Index.pm
@@ -6,7 +6,7 @@ use warnings;
 
 use Exporter 'import';
 
-our $VERSION = '1.00';
+our $VERSION = '1.01';
 our @EXPORT_OK = qw(rangematch);
 
 sub new {
@@ -60,32 +60,49 @@ sub rangematch {
 
 	if (length $s1) {
 		my $prefix = '';
-		my $c1;
+		my $char;
 		for my $i (0 .. length($s1) - 1) {
-			$c1 = substr $s1, $i, 1;
-			my $c2 = length $s2 <= $i ? undef : substr $s2, $i, 1;
-			my $next = $i + 1 >= length($s1) ? $c1 : chr( ord($c1) + 1 );
-			my $last = defined $c2 && $i == 0 ? chr( ord($c2) - (length $s2 > 1) ) : 'z';
-			$next le $last or next if defined $c2;
+			$char = substr $s1, $i, 1;
+			my $next = $char;
+			$next = chr( ord($char) + 1 ) if length $s1 > $i + 1;
+			my $last = 'z';
+			if (length $s2 > $i) {
+				if ($s2 =~ /^\Q$prefix/) {
+					$last = substr $s2, $i, 1;
+					next if $char eq $last;
+					$last = chr( ord($last) - (length $s2 > 1) );
+					next if $next gt $last;
+				}
+			}
 			push @allow, $prefix."[$next-$last]";
 		}
 		continue {
-			$prefix .= $c1;
+			$prefix .= $char;
 		}
 	}
 
 	if (length $s2) {
 		my $prefix = '';
+		my $char;
 		for my $i (0 .. length($s2) - 1) {
-			my $c1 = length $s1 <= $i ? undef : substr $s1, $i, 1;
-			my $c2 = substr $s2, $i, 1;
+			$char = substr $s2, $i, 1;
 			my $last = 'z';
-			push @allow, "$prefix(?![$c2-$last])"
+			if (length $s1 > $i) {
+				my $c1 = substr $s1, $i, 1;
+				if ($s1 =~ /^\Q$prefix/) {
+					next if $c1 eq $char;
+				}
+			}
+			push @allow, $prefix."(?![$char-$last])"
 				if $i or $s1 eq '';
-			$prefix .= $c2;
 		}
+		continue {
+			$prefix .= $char;
+		}
+
 		push @allow, $prefix
-			unless length $s1 > length $s2 or length $s1 != 0 && length $s2 == 1; #TODO
+			if $s2 =~ /^\Q$prefix/ and $s1 le $s2
+			and not (length $s2 == 1 && length $s1 >= length $s2 && $s1 ne $s2);
 	}
 
 	my $match = sprintf @allow <= 1 ? '%s' : '(?:%s)', join('|', @allow);
@@ -105,7 +122,11 @@ List::Index - Paginate alphabetic entries by finding minimal prefixes
 	use List::Index;
 	my $index = List::Index->new(\@values);
 	my @pages = $index->ranges({pagesize => 50});
-	printf '<a href="?start=%s&amp;end=%s">%1$s</a> ', @$_ for @pages;
+	printf '<a href="?q=%s-%s">%1$s</a> ', @$_ for @pages;
+
+	use List::Index 'rangematch';
+	my $limit = rangematch('b-bmq');  # matches prefix like 'baa'..'bmq'
+	@results = grep { $limit } @results;
 
 =head1 DESCRIPTION
 
diff --git a/t/20-links.t b/t/20-links.t
index 6a09314..1180398 100644
--- a/t/20-links.t
+++ b/t/20-links.t
@@ -2,29 +2,32 @@
 use strict;
 use warnings;
 
-use Test::More tests => 18;
+use Test::More tests => 21;
 use Test::NoWarnings;
 use Data::Dump 'pp';
 
 BEGIN { use_ok('List::Index' => 'rangematch'); }
 
 for (
-	[   q      => 'q'],
-	['#foo.!$' => '\#foo\.\!\$'],
+	[   q      =>          'q'],
+	['#foo.!$' =>          '\#foo\.\!\$'],
 	[    -q    =>            '(?:(?![q-z])|q)'],
 	[    -qqq  =>            '(?:(?![q-z])|q(?![q-z])|qq(?![q-z])|qqq)'],
 	[  'q-'    =>    '[q-z]'],
 	['qqq-'    => '(?:[r-z]|q[r-z]|qq[q-z])'],
 	[  'q-x'   =>    '[q-x]'],
-	[  'q-q'   =>    '[q-q]'],
+	[  'q-q'   =>          'q'],
 	[ 'qq-qq'  =>                 'qq'],
-	[ 'qq-qqx' =>                                    'qq(?![x-z])|qqx'],
+	[ 'qq-qqx' =>                                 '(?:qq(?![x-z])|qqx)'],
 	[  'q-qx'  =>                      '(?:q(?![x-z])|qx)'],
 	['qqq-xxx' => '(?:[r-w]|q[r-z]|qq[q-z]|x(?![x-z])|xx(?![x-z])|xxx)'],
+	['qqq-xqq' => '(?:[r-w]|q[r-z]|qq[q-z]|x(?![q-z])|xq(?![q-z])|xqq)'],
+	['qqq-xq'  => '(?:[r-w]|q[r-z]|qq[q-z]|x(?![q-z])|xq)'],
+	[ 'qq-xqq' => '(?:[r-w]|q[q-z]|'   .  'x(?![q-z])|xq(?![q-z])|xqq)'],
+	[  'q-xxx' =>                '(?:[q-w]|x(?![x-z])|xx(?![x-z])|xxx)'],
 	['qqq-x'   => '(?:[r-x]|q[r-z]|qq[q-z])'],
+	['qaa-qb'  =>              '(?:qa[a-z]|qb)'],
 	['qqq-q'   =>       '(?:q[r-z]|qq[q-z])'],
-	['qaa-qb'  =>              '(?:qa[a-z]|q(?![b-z]))'],
-	[  'q-xxx' =>                '(?:[q-w]|x(?![x-z])|xx(?![x-z])|xxx)'],
 ) {
 	my ($in, $out) = @$_;
 	is(eval { rangematch($in) }, "(?i-xsm:^$out)", $in);
-- 
2.30.0