X-Git-Url: http://git.shiar.net/perl/list-index.git/blobdiff_plain/923bf7c029470b51452733cd1c17df0b1397e63b..e7b831494ed2dfb7333f0cf59f91cd7f14f9f9b6:/t/10-ranges.t

diff --git a/t/10-ranges.t b/t/10-ranges.t
index 1ec5d60..84f4dbb 100644
--- a/t/10-ranges.t
+++ b/t/10-ranges.t
@@ -2,7 +2,7 @@
 use strict;
 use warnings;
 
-use Test::More tests => 6;
+use Test::More tests => 7;
 use Test::NoWarnings;
 use Data::Dump 'pp';
 
@@ -29,7 +29,76 @@ subtest 'uniform alphanumeric' => sub {
 		.-bp bq-dm dn-fi fj-hf hg-i j-k l-m n-os ot-qp qq-sm sn-uj uk-wf wg-x y-
 
 	)], 'default ranges');
-	is_deeply($index->ranges({pagesize => 300}), [qw(-c d-o p-)], 'large pagesize');
+	is_deeply($index->ranges({pagesize => 300}), [qw(-c d-n o-)], 'large pagesize');
+};
+
+subtest 'context' => sub {
+	plan tests => 9;
+	my $index = List::Index->new([qw(
+		kkeg kl km kmlu knsy    koxb kpeo kuaa kuab kuac
+		kuapa kuq kur kux kzb   lc lg lgu lgua lguc
+		lguq lgur lgus lgx lka  lkq lks lln llq llx
+	)]) or return;
+	is_deeply(
+		$index->ranges({ pagesize=>10, context=>0, length=>5 }),
+		# ranges should match offsets exactly
+		[qw(-kuap. kuapa-lgup lguq-)],
+		'no context'
+	);
+	is_deeply(
+		$index->ranges({ pagesize=>10, context=>0 }),
+		# default length limits to 4 chars
+		[qw(-kuao kuap-lgup lguq-)],
+		'default length'
+	);
+	is_deeply(
+		$index->ranges({ pagesize=>10, context=>1 }),
+		# lookbehinds aren't shorter (kuac<kuap, lguc<lguq)
+		# 'kuap' can advance to 'kuq'
+		[qw(-kup kuq-lgup lguq-)],
+		'lookahead'
+	);
+TODO: {
+	local $TODO = 'backtrack';
+	is_deeply(
+		$index->ranges({ pagesize=>10, context=>2 }),
+		# allowed to advance to 'kur', but provides no benefits over 'kuq'
+		[qw(-kup kuq-lgup lguq-)],
+		'minimal lookahead'
+	);
+}
+	is_deeply(
+		$index->ranges({ pagesize=>10, context=>3 }),
+		# shorten 'kuap' to 'ku' because lookbehind is 'kp...'
+		# 'lguq' matches 'lg', but may only backtrack to 'lgu'
+		[qw(-kt ku-lgt lgu-)],
+		'lookbehind'
+	);
+	is_deeply(
+		$index->ranges({ pagesize=>10, context=>4 }),
+		[qw(-kt ku-lf lg-)],
+		'maximal lookahead'
+	);
+	is_deeply(
+		$index->ranges({ pagesize=>10, context=>5 }),
+		# after forwarding 'kuap' to 'lc'
+		# disallow backtracking of 'lguq' to 'lc' to prevent qw[-k l-]
+		# so only lookahead (to 'lkq') remains
+		[qw(-k l-lj lk-)],
+		'no lookbehind after full lookahead'
+	);
+	is_deeply(
+		$index->ranges({ pagesize=>10, context=>9 }),
+		# allow a single (10-9) entry (l-lf = lc) to remain
+		[qw(-k l-lf lg-)],
+		'lookbehind after full lookahead'
+	);
+	is_deeply(
+		$index->ranges({ pagesize=>10, context=>10 }),
+		# allow the last page to go back upto 'lc', replacing the 2nd page
+		[qw(-k l-)],
+		'full overlap'
+	);
 };
 
 subtest 'context' => sub {
@@ -41,12 +110,12 @@ subtest 'context' => sub {
 		qw(-baa. baa.-bbb bbc-daa. daaa-eaa. eaaa-)
 	], 'no context');
 	is_deeply($index->ranges({pagesize => 2}), [
-		qw(-a b c d-ea. eaa-)
+		qw(-a b c d e-)
 	], 'default context');  # context should be 1
 	is_deeply($index->ranges({pagesize => 2, context => 2}), [
 		qw(-a b-c d e-)
 	], 'overlap');  # first item equals second due to large context
-	is_deeply($index->ranges({pagesize => 2, length => 1}), [
+	is_deeply($index->ranges({pagesize => 2, context => 0, length => 1}), [
 		qw(-a b-c d e-)
 	], 'single char');