lookbehind before context, so page increment is _upto_ context rows

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

diff --git a/lib/List/Index.pm b/lib/List/Index.pm
index dca0d1f3970b83ffad665fc385ea2ed00b8bd778..4a2118910cf3708c11ada4bc07644930a33f3486 100644 (file)
--- a/lib/List/Index.pm
+++ b/lib/List/Index.pm
@@ -23,14 +23,14 @@ sub ranges {
        my $pages    = $options->{pages   } || 1 + int $#$self / $pagesize;
 
        $pagesize = @$self / $pages;
-       my $offset = $pagesize;
+       my $offset = $pagesize + .5;
        my @links = ('');
        while ($offset < @$self) {
                my $link = substr $self->[$offset], 0, $length;
                if ($context) {
-                       {
+                       if ($offset > $context - 1) {
                                # take a value slightly before the current offset
-                               my $before = $offset > $context ? $self->[$offset - $context] : '.';
+                               my $before = $self->[$offset - $context - 1];
                                # see how much of it matches the current link
                                my $trim = 1;
                                for my $match (split //, $before) {
@@ -164,18 +164,18 @@ __END__
 
 =head1 NAME
 
-List::Index - Paginate alphabetic entries by finding minimal prefixes
+List::Index - Find and apply prefix ranges to paginate keywords
 
 =head1 SYNOPSIS
 
        use List::Index;
        my $index = List::Index->new(\@values);
        my @pages = $index->ranges({pagesize => 50});
-       printf '<a href="?q=%s-%s">%1$s</a> ', @$_ for @pages;
+       say "<a href='?q=$_'>$_</a>" for @pages;
 
        use List::Index 'rangematch';
-       my $limit = rangematch('b-bmq');  # matches prefix like 'baa'..'bmq'
-       @results = grep { $limit } @results;
+       my $limit = rangematch('b-bmq');  # ge 'b' && le 'bmq'
+       @request = grep { $limit } @values;
 
 =head1 DESCRIPTION