X-Git-Url: http://git.shiar.net/perl/list-index.git/blobdiff_plain/d6c30ef4ef400982bc1b08e9b7bf93993ea29be5..20b084d596ff3d71a76dbc55a9f458911b4b8415:/lib/List/Index.pm

diff --git a/lib/List/Index.pm b/lib/List/Index.pm
index c42db44..574613e 100644
--- a/lib/List/Index.pm
+++ b/lib/List/Index.pm
@@ -28,12 +28,15 @@ sub ranges {
 	while ($offset < @$self) {
 		my $link = substr $self->[$offset], 0, $length;
 		if ($context) {
+			# 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;
-			my $before = $offset > $context ? $self->[$offset - $context] : '';
 			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;
 		}
 
@@ -43,11 +46,13 @@ sub ranges {
 
 	for my $i (0 .. $#links - 1) {
 		my ($link, $lastchar) = $links[$i + 1]->[0] =~ /(.*)(.)/;
-		$link .= $lastchar eq '.' ? 'a' : chr( ord($lastchar) - 1 )
-			unless $lastchar eq 'a';
+		$link .= $lastchar eq 'a' ? '.' : chr( ord($lastchar) - 1 )
+			unless $lastchar eq '.';
+		next if $link eq $links[$i]->[0] and $i;
 		$links[$i]->[1] = $link;
 	}
 	$links[-1]->[1] = '';
+	$links[0]->[0] = '';
 
 	return \@links;
 }