Add ol.array.reverseSubArray

src/ol/array.js

@@ -84,3 +84,21 @@ ol.array.linearFindNearest = function(arr, target, direction) {
     return n - 1;
   }
 };
+
+
+/**
+ * @param {Array.<*>} arr Array.
+ * @param {number} begin Begin index.
+ * @param {number} end End index.
+ */
+ol.array.reverseSubArray = function(arr, begin, end) {
+  goog.asserts.assert(begin >= 0);
+  goog.asserts.assert(end < arr.length);
+  while (begin < end) {
+    var tmp = arr[begin];
+    arr[begin] = arr[end];
+    arr[end] = tmp;
+    ++begin;
+    --end;
+  }
+};

test/spec/ol/array.test.js

@@ -73,6 +73,29 @@ describe('ol.array', function() {
       expect(ol.array.linearFindNearest(arr, 50, -1)).to.eql(2);
     });
   });
+
+  describe.only('reverseSubArray', function() {
+    it('returns expected value', function() {
+      var arr;
+      var expected = [1, 2, 3, 4, 5, 6];
+
+      arr = [1, 5, 4, 3, 2, 6];
+      ol.array.reverseSubArray(arr, 1, 4);
+      expect(arr).to.eql(expected);
+
+      arr = [3, 2, 1, 4, 5, 6];
+      ol.array.reverseSubArray(arr, 0, 2);
+      expect(arr).to.eql(expected);
+
+      arr = [1, 2, 3, 6, 5, 4];
+      ol.array.reverseSubArray(arr, 3, 5);
+      expect(arr).to.eql(expected);
+
+      arr = [6, 5, 4, 3, 2, 1];
+      ol.array.reverseSubArray(arr, 0, 5);
+      expect(arr).to.eql(expected);
+    });
+  });
 });
 
 goog.require('ol.array');