From: Tim Starling <tstarling@wikimedia.org>
Date: Thu, 11 Oct 2012 09:01:46 +0000 (+1100)
Subject: Fix various boundary cases in IcuCollation::findLowerBound()
X-Git-Tag: 1.31.0-rc.0~21989
X-Git-Url: http://git.heureux-cyclage.org/?a=commitdiff_plain;h=1eca50c3832a968ab4209e55673a600b0f13ec83;p=lhc%2Fweb%2Fwiklou.git

Fix various boundary cases in IcuCollation::findLowerBound()

Fix the following edge cases which were previously broken:

* Zero-length input array
* Target value before the start
* Target value past the end

They didn't really matter for my original application, but Liangent
wants to use this function for something else.

Change-Id: Ia5f5ed4ab3cb6c463177a4812fd3ce96c6d37b33
---

diff --git a/includes/Collation.php b/includes/Collation.php
index 8554c2b047..3cc7902855 100644
--- a/includes/Collation.php
+++ b/includes/Collation.php
@@ -335,8 +335,12 @@ class IcuCollation extends Collation {
 	 *     sorts before all items.
 	 */
 	function findLowerBound( $valueCallback, $valueCount, $comparisonCallback, $target ) {
+		if ( $valueCount === 0 ) {
+			return false;
+		}
+
 		$min = 0;
-		$max = $valueCount - 1;
+		$max = $valueCount;
 		do {
 			$mid = $min + ( ( $max - $min ) >> 1 );
 			$item = call_user_func( $valueCallback, $mid );
@@ -351,12 +355,15 @@ class IcuCollation extends Collation {
 			}
 		} while ( $min < $max - 1 );
 
-		if ( $min == 0 && $max == 0 && $comparison > 0 ) {
-			// Before the first item
-			return false;
-		} else {
-			return $min;
+		if ( $min == 0 ) {
+			$item = call_user_func( $valueCallback, $min );
+			$comparison = call_user_func( $comparisonCallback, $target, $item );
+			if ( $comparison < 0 ) {
+				// Before the first item
+				return false;
+			}
 		}
+		return $min;
 	}
 
 	static function isCjk( $codepoint ) {