From bf31b614e8becb8e414dff974196e399bd7b0d02 Mon Sep 17 00:00:00 2001
From: Tom Payne <twpayne@gmail.com>
Date: Sun, 15 Jul 2012 22:21:25 +0200
Subject: [PATCH] Allow out-of-range signalling with undefined

---
 src/ol/tileurlfunction.js      | 26 +++++++++++++++++++-------
 src/ol/tileurlfunction_test.js |  3 +++
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/src/ol/tileurlfunction.js b/src/ol/tileurlfunction.js
index c6a319a4e5..8135a644c6 100644
--- a/src/ol/tileurlfunction.js
+++ b/src/ol/tileurlfunction.js
@@ -6,7 +6,7 @@ goog.require('ol.TileCoord');
 
 
 /**
- * @typedef {function(ol.TileCoord): string}
+ * @typedef {function(ol.TileCoord): string|undefined}
  */
 ol.TileUrlFunctionType;
 
@@ -17,9 +17,13 @@ ol.TileUrlFunctionType;
  */
 ol.TileUrlFunction.createFromTemplate = function(template) {
   return function(tileCoord) {
-    return template.replace(/\{z\}/, tileCoord.z)
-                   .replace(/\{x\}/, tileCoord.x)
-                   .replace(/\{y\}/, tileCoord.y);
+    if (goog.isNull(tileCoord)) {
+      return undefined;
+    } else {
+      return template.replace(/\{z\}/, tileCoord.z)
+                     .replace(/\{x\}/, tileCoord.x)
+                     .replace(/\{y\}/, tileCoord.y);
+    }
   };
 };
 
@@ -30,8 +34,12 @@ ol.TileUrlFunction.createFromTemplate = function(template) {
  */
 ol.TileUrlFunction.createFromTileUrlFunctions = function(tileUrlFunctions) {
   return function(tileCoord) {
-    var index = goog.math.modulo(tileCoord.hash(), tileUrlFunctions.length);
-    return tileUrlFunctions[index](tileCoord);
+    if (goog.isNull(tileCoord)) {
+      return undefined;
+    } else {
+      var index = goog.math.modulo(tileCoord.hash(), tileUrlFunctions.length);
+      return tileUrlFunctions[index](tileCoord);
+    }
   };
 };
 
@@ -54,6 +62,10 @@ ol.TileUrlFunction.createFromTemplates = function(templates) {
 ol.TileUrlFunction.withTileCoordTransform =
     function(transform, tileUrlFunction) {
   return function(tileCoord) {
-    return tileUrlFunction(transform(tileCoord));
+    if (goog.isNull(tileCoord)) {
+      return undefined;
+    } else {
+      return tileUrlFunction(transform(tileCoord));
+    }
   };
 };
diff --git a/src/ol/tileurlfunction_test.js b/src/ol/tileurlfunction_test.js
index b009ec49ec..965305eb96 100644
--- a/src/ol/tileurlfunction_test.js
+++ b/src/ol/tileurlfunction_test.js
@@ -6,6 +6,7 @@ goog.require('ol.TileUrlFunction');
 function testCreateFromTemplate() {
   var tileUrl = ol.TileUrlFunction.createFromTemplate('{z}/{x}/{y}');
   assertEquals('3/2/1', tileUrl(new ol.TileCoord(3, 2, 1)));
+  assertUndefined(tileUrl(null));
 }
 
 
@@ -16,6 +17,7 @@ function testWithTileCoordTransform() {
       },
       ol.TileUrlFunction.createFromTemplate('{z}/{x}/{y}'));
   assertEquals('3/2/1', tileUrl(new ol.TileCoord(3, 2, -1)));
+  assertUndefined(tileUrl(null));
 }
 
 
@@ -27,4 +29,5 @@ function testCreateFromTileUrlFunctions() {
   var tileUrl1 = tileUrl(new ol.TileCoord(1, 0, 0));
   var tileUrl2 = tileUrl(new ol.TileCoord(1, 0, 1));
   assertTrue(tileUrl1 != tileUrl2);
+  assertUndefined(tileUrl(null));
 }