X-Git-Url: http://git.shiar.net/gitweb.cgi/perl/list-index.git/blobdiff_plain/f467842b8e311a78d9900c4626583fc08a8ce31b..e0d12a55c119c9473d1ea57c4e57bb5c6ff87157:/lib/List/Index.pm
diff --git a/lib/List/Index.pm b/lib/List/Index.pm
index 483d1eb..4ce9c25 100644
--- a/lib/List/Index.pm
+++ b/lib/List/Index.pm
@@ -24,37 +24,52 @@ sub ranges {
$pagesize = @$self / $pages;
my $offset = $pagesize + .5;
+ my $shrunk = 0;
+ my $enlarged = 0;
my @links = ('');
while ($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] : '.';
+ my $penalty = 0;
+ # take a value slightly before the current offset
+ if ((my $before = $offset - $context + $shrunk) > 0) {
# see how much of it matches the current link
my $trim = 1;
- for my $match (split //, $before) {
+ for my $match (split //, $self->[$before - 1]) {
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 $link;
+ if ($trim < length $link) {
+ substr($link, $trim) = '';
+ for (reverse $before .. $offset) {
+ $self->[$offset - $penalty] =~ /^\Q$link/ or last;
+ $penalty++;
+ }
+ }
}
- if ($offset + $context < $#$self) {
- # take a value after the current offset
- my $after = $self->[$offset + $context];
+ $shrunk = 0;
+ # take a value after the current offset
+ if ((my $after = $offset + $context - $enlarged) < $#$self) {
# see how much of it matches the current link
my $trim = 1;
- for my $match (split //, $after) {
+ for my $match (split //, $self->[$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;
+ $link = substr $self->[$after], 0, $trim;
+ # advance lookbehind offset on the next page
+ $penalty = 0;
+ for ($offset .. $#$self) {
+ last if $self->[$offset + $shrunk] =~ /^\Q$link/;
+ $shrunk++;
+ }
}
}
+ $enlarged = $penalty;
}
push @links, $link;
@@ -164,18 +179,18 @@ __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 = $index->ranges({pagesize => 50});
- printf '%1$s ', @$_ for @pages;
+ say "$_" 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