XXX: comment ranges method code

[perl/list-index.git] / lib / List / Index.pm

diff --git a/lib/List/Index.pm b/lib/List/Index.pm
index c42db44eadb5be52310a3ec76b54df640eb06209..574613e8b1c38e2e6b3eaf4c751fd42d53c6930e 100644 (file)
--- 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;
 }