X-Git-Url: http://git.shiar.net/gitweb.cgi/perl/list-index.git/blobdiff_plain/0433a4eb785409f46a2d61e668fda84bd87c3148..ab9917512865cf7070b364a1b0f07f32a3b49e3f:/lib/List/Index.pm

diff --git a/lib/List/Index.pm b/lib/List/Index.pm
index 7214ced..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];
@@ -43,11 +63,13 @@ sub ranges {
 
 	for my $i (0 .. $#links - 1) {
 		my ($link, $lastchar) = $links[$i + 1]->[0] =~ /(.*)(.)/;
-		$link .= $lastchar eq '.' ? 'z' : chr( ord($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;
 }
@@ -59,6 +81,10 @@ sub rangematch {
 	my @allow;
 
 	if (length $s1) {
+		if (length $s2) {
+			$s1 le $s2 or $s1 =~ /^\Q$s2/ or return undef;
+		}
+
 		my $prefix = '';
 		my $char;
 		for my $i (0 .. length($s1) - 1) {