X-Git-Url: http://git.shiar.net/gitweb.cgi/perl/list-index.git/blobdiff_plain/319dd675faee700a9fa0485863889a661ef9dc53..ab9917512865cf7070b364a1b0f07f32a3b49e3f:/lib/List/Index.pm?ds=sidebyside

diff --git a/lib/List/Index.pm b/lib/List/Index.pm
index 00f2bdb..47ef0da 100644
--- a/lib/List/Index.pm
+++ b/lib/List/Index.pm
@@ -28,13 +28,33 @@ sub ranges {
 	while ($offset < @$self) {
 		my $link = substr $self->[$offset], 0, $length;
 		if ($context) {
-			my $trim = 1;
-			my $before = $offset > $context ? $self->[$offset - $context] : '.';
-			for my $match (split //, $before) {
-				scalar $link =~ /\G\Q$match/g or last;
-				$trim++;
+			{
+				# take a value slightly before the current offset
+				my $before = $offset > $context ? $self->[$offset - $context] : '.';
+				# see how much of it matches the current link
+				my $trim = 1;
+				for my $match (split //, $before) {
+					scalar $link =~ /\G\Q$match/g or last;
+					$trim++;
+				}
+				# truncate link upto where the earlier value starts to differ
+				substr($link, $trim) = '' unless $trim > length $link;
+			}
+
+			if ($offset + $context < $#$self) {
+				# take a value after the current offset
+				my $after = $self->[$offset + $context];
+				# see how much of it matches the current link
+				my $trim = 1;
+				for my $match (split //, $after) {
+					scalar $link =~ /\G\Q$match/g or last;
+					$trim++;
+				}
+				# use this link if it's shorter
+				if ($trim < length $link) {
+					$link = substr $after, 0, $trim;
+				}
 			}
-			substr($link, $trim) = '' unless $trim > length $link;
 		}
 
 		push @links, [$link];
@@ -45,10 +65,11 @@ sub ranges {
 		my ($link, $lastchar) = $links[$i + 1]->[0] =~ /(.*)(.)/;
 		$link .= $lastchar eq 'a' ? '.' : chr( ord($lastchar) - 1 )
 			unless $lastchar eq '.';
-		next if $link eq $links[$i]->[0];
+		next if $link eq $links[$i]->[0] and $i;
 		$links[$i]->[1] = $link;
 	}
 	$links[-1]->[1] = '';
+	$links[0]->[0] = '';
 
 	return \@links;
 }