X-Git-Url: http://git.shiar.net/perl/list-index.git/blobdiff_plain/df37e7ec6afd25d57679dc37999a36887d2247ca..f201c1cafae5e0a87e562961316c7650b0e2231a:/lib/List/Index.pm

diff --git a/lib/List/Index.pm b/lib/List/Index.pm
index e30beef..3663c24 100644
--- a/lib/List/Index.pm
+++ b/lib/List/Index.pm
@@ -23,33 +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) {
-			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];
+		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;
 }
@@ -72,6 +92,7 @@ sub rangematch {
 			my $next = $char;
 			$next = chr( ord($char) + 1 ) if length $s1 > $i + 1;
 			my $last = 'z';
+			next if $next gt $last;
 			if (length $s2 > $i) {
 				if ($s2 =~ /^\Q$prefix/) {
 					$last = substr $s2, $i, 1;