X-Git-Url: http://git.shiar.net/perl/list-index.git/blobdiff_plain/20b084d596ff3d71a76dbc55a9f458911b4b8415..0f46a9fa54c9ecca0f0c3180b51f7c3079d048a8:/lib/List/Index.pm

diff --git a/lib/List/Index.pm b/lib/List/Index.pm
index 574613e..ea7b433 100644
--- a/lib/List/Index.pm
+++ b/lib/List/Index.pm
@@ -23,36 +23,53 @@ sub ranges {
 	my $pages    = $options->{pages   } || 1 + int $#$self / $pagesize;
 
 	$pagesize = @$self / $pages;
-	my $offset = 0;
-	my @links;
+	my $offset = $pagesize;
+	my @links = ('');
 	while ($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;
-			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, $trim;
+				}
 			}
-			# truncate link upto where the earlier value starts to differ
-			substr($link, $trim) = '' unless $trim > length $link;
 		}
 
-		push @links, [$link];
+		push @links, $link;
 		$offset += $pagesize;
 	}
 
+	use List::MoreUtils 'uniq';
+	@links = uniq @links;
 	for my $i (0 .. $#links - 1) {
-		my ($link, $lastchar) = $links[$i + 1]->[0] =~ /(.*)(.)/;
-		$link .= $lastchar eq 'a' ? '.' : chr( ord($lastchar) - 1 )
-			unless $lastchar eq '.';
-		next if $link eq $links[$i]->[0] and $i;
-		$links[$i]->[1] = $link;
+		my ($link, $lastchar) = $links[$i + 1] =~ /(.*)(.)/;
+		$link .= $lastchar le 'a' ? '.' : chr( ord($lastchar) - 1 );
+		next if $link eq $links[$i] and $i;
+		$links[$i] .= '-'.$link;
 	}
-	$links[-1]->[1] = '';
-	$links[0]->[0] = '';
+	$links[-1] .= '-';
 
 	return \@links;
 }