New tile queue implementation (heapify-powered)

test/spec/ol/tilequeue.test.js

@@ -0,0 +1,68 @@
+describe('ol.TileQueue', function() {
+
+  // is the tile queue's array a heap?
+  function isHeap(tq) {
+    var heap = tq.heap_;
+    var i;
+    var key;
+    var leftKey;
+    var rightKey;
+    for (i = 0; i < (heap.length >> 1) - 1; i++) {
+      key = heap[i][0];
+      leftKey = heap[tq.getLeftChildIndex_(i)][0];
+      rightKey = heap[tq.getRightChildIndex_(i)][0];
+      if (leftKey < key || rightKey < key) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  function addRandomPriorityTiles(tq, num) {
+    var i, tile, priority;
+    for (i = 0; i < num; i++) {
+      tile = new ol.Tile();
+      priority = Math.floor(Math.random() * 100);
+      tq.heap_.push([priority, tile, new ol.Coordinate(0, 0), 1]);
+      tq.queuedTileKeys_[tile.getKey()] = true;
+    }
+  }
+
+  describe('heapify', function() {
+    it('does convert an arbitrary array into a heap', function() {
+
+      var tq = new ol.TileQueue(function() {});
+      addRandomPriorityTiles(tq, 100);
+
+      tq.heapify_();
+      expect(isHeap(tq)).toBeTruthy();
+    });
+  });
+
+  describe('reprioritize', function() {
+    it('does reprioritize the array', function() {
+
+      var tq = new ol.TileQueue(function() {});
+      addRandomPriorityTiles(tq, 100);
+
+      tq.heapify_();
+
+      // now reprioritize, changing the priority of 50 tiles and removing the
+      // rest
+
+      var i = 0;
+      tq.tilePriorityFunction_ = function() {
+        if ((i++) % 2 === 0) {
+          return undefined;
+        }
+        return Math.floor(Math.random() * 100);
+      };
+
+      tq.reprioritize();
+      expect(tq.heap_.length).toEqual(50);
+      expect(isHeap(tq)).toBeTruthy();
+
+    });
+  });
+});
+