From b6d480274eff8424a5ee22894a96bba261d3d4ae Mon Sep 17 00:00:00 2001
From: Mischa POSLAWSKY <perl@shiar.org>
Date: Fri, 13 Nov 2009 17:00:38 +0100
Subject: [PATCH] lookbehind penalty

---
 lib/List/Index.pm | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/List/Index.pm b/lib/List/Index.pm
index 4a21189..06c2727 100644
--- a/lib/List/Index.pm
+++ b/lib/List/Index.pm
@@ -24,13 +24,14 @@ sub ranges {
 
 	$pagesize = @$self / $pages;
 	my $offset = $pagesize + .5;
+	my $penalty = 0;
 	my @links = ('');
 	while ($offset < @$self) {
 		my $link = substr $self->[$offset], 0, $length;
 		if ($context) {
-			if ($offset > $context - 1) {
+			if ($offset > $context - 1 + $penalty) {
 				# take a value slightly before the current offset
-				my $before = $self->[$offset - $context - 1];
+				my $before = $self->[$offset - $context - 1 + $penalty];
 				# see how much of it matches the current link
 				my $trim = 1;
 				for my $match (split //, $before) {
@@ -41,6 +42,7 @@ sub ranges {
 				substr($link, $trim) = '' unless $trim > length $link;
 			}
 
+			$penalty = 0;
 			if ($offset + $context < $#$self) {
 				# take a value after the current offset
 				my $after = $self->[$offset + $context];
@@ -53,6 +55,9 @@ sub ranges {
 				# use this link if it's shorter
 				if ($trim < length $link) {
 					$link = substr $after, 0, $trim;
+#					$offset += $context + 1;
+					$self->[$offset + ++$penalty] =~ /^\Q$link/
+						while $offset + $penalty < $#$self;
 				}
 			}
 		}
-- 
2.30.0