Factor out core elements of ol.TileQueue into ol.structs.PriorityQueue

test/spec/ol/structs/priorityqueue.test.js

@@ -0,0 +1,186 @@
+goog.provide('ol.test.structs.PriorityQueue');
+
+
+describe('ol.structs.PriorityQueue', function() {
+
+  describe('when empty', function() {
+
+    var pq;
+    beforeEach(function() {
+      pq = new ol.structs.PriorityQueue(
+          goog.identityFunction, goog.identityFunction);
+    });
+
+    it('is valid', function() {
+      expect(function() {
+        pq.assertValid();
+      }).not.to.throwException();
+    });
+
+    it('is empty', function() {
+      expect(pq.isEmpty()).to.be(true);
+    });
+
+    it('dequeue raises an exception', function() {
+      expect(function() {
+        pq.dequeue();
+      }).to.throwException();
+    });
+
+    it('enqueue adds an element', function() {
+      pq.enqueue(0);
+      expect(function() {
+        pq.assertValid();
+      }).not.to.throwException();
+      expect(pq.elements_).to.equalArray([0]);
+      expect(pq.priorities_).to.equalArray([0]);
+    });
+
+    it('maintains the pq property while elements are enqueued', function() {
+      var i;
+      for (i = 0; i < 32; ++i) {
+        pq.enqueue(Math.random());
+        expect(function() {
+          pq.assertValid();
+        }).not.to.throwException();
+      }
+    });
+
+  });
+
+  describe('when populated', function() {
+
+    var elements, pq;
+    beforeEach(function() {
+      elements = [];
+      pq = new ol.structs.PriorityQueue(
+          goog.identityFunction, goog.identityFunction);
+      var element, i;
+      for (i = 0; i < 32; ++i) {
+        element = Math.random();
+        pq.enqueue(element);
+        elements.push(element);
+      }
+    });
+
+    it('dequeues elements in the correct order', function() {
+      elements.sort();
+      var i;
+      for (i = 0; i < elements.length; ++i) {
+        expect(pq.dequeue()).to.be(elements[i]);
+      }
+      expect(pq.isEmpty()).to.be(true);
+    });
+
+  });
+
+  describe('with an impure priority function', function() {
+
+    var pq, target;
+    beforeEach(function() {
+      target = 0.5;
+      pq = new ol.structs.PriorityQueue(function(element) {
+        return Math.abs(element - target);
+      }, goog.identityFunction);
+      var element, i;
+      for (i = 0; i < 32; ++i) {
+        pq.enqueue(Math.random());
+      }
+    });
+
+    it('dequeue elements in the correct order', function() {
+      var lastDelta = 0;
+      var delta;
+      while (!pq.isEmpty()) {
+        delta = Math.abs(pq.dequeue() - target);
+        expect(lastDelta <= delta).to.be(true);
+        lastDelta = delta;
+      }
+    });
+
+    it('allows reprioritization', function() {
+      var target = 0.5;
+      pq.reprioritize();
+      var lastDelta = 0;
+      var delta;
+      while (!pq.isEmpty()) {
+        delta = Math.abs(pq.dequeue() - target);
+        expect(lastDelta <= delta).to.be(true);
+        lastDelta = delta;
+      }
+    });
+
+    it('allows dropping during reprioritization', function() {
+      var target = 0.5;
+      var i = 0;
+      pq.priorityFunction_ = function(element) {
+        if (i++ % 2 === 0) {
+          return Math.abs(element - target);
+        } else {
+          return ol.structs.PriorityQueue.DROP;
+        }
+      };
+      pq.reprioritize();
+      expect(pq.getCount()).to.be(16);
+      var lastDelta = 0;
+      var delta;
+      while (!pq.isEmpty()) {
+        delta = Math.abs(pq.dequeue() - target);
+        expect(lastDelta <= delta).to.be(true);
+        lastDelta = delta;
+      }
+    });
+
+  });
+
+  describe('tracks elements in the queue', function() {
+
+    var pq;
+    beforeEach(function() {
+      pq = new ol.structs.PriorityQueue(
+          goog.identityFunction, goog.identityFunction);
+      pq.enqueue('a');
+      pq.enqueue('b');
+      pq.enqueue('c');
+    });
+
+    it('tracks which elements have been queued', function() {
+      expect(pq.isQueued('a')).to.be(true);
+      expect(pq.isQueued('b')).to.be(true);
+      expect(pq.isQueued('c')).to.be(true);
+    });
+
+    it('tracks which elements have not been queued', function() {
+      expect(pq.isQueued('d')).to.be(false);
+    });
+
+    it('raises an error when an queued element is re-queued', function() {
+      expect(function() {
+        pq.enqueue('a');
+      }).to.throwException();
+    });
+
+    it('tracks which elements have be dequeued', function() {
+      expect(pq.isQueued('a')).to.be(true);
+      expect(pq.isQueued('b')).to.be(true);
+      expect(pq.isQueued('c')).to.be(true);
+      expect(pq.dequeue()).to.be('a');
+      expect(pq.isQueued('a')).to.be(false);
+      expect(pq.isQueued('b')).to.be(true);
+      expect(pq.isQueued('c')).to.be(true);
+      expect(pq.dequeue()).to.be('b');
+      expect(pq.isQueued('a')).to.be(false);
+      expect(pq.isQueued('b')).to.be(false);
+      expect(pq.isQueued('c')).to.be(true);
+      expect(pq.dequeue()).to.be('c');
+      expect(pq.isQueued('a')).to.be(false);
+      expect(pq.isQueued('b')).to.be(false);
+      expect(pq.isQueued('c')).to.be(false);
+    });
+
+  });
+
+});
+
+
+goog.require('ol.structs.PriorityQueue');