Added basic ol.parser.polyline module

This module will contain the low-level functions for Google's "Encoded
Polyline" algorithm.

src/ol/parser/polyline.js

@@ -0,0 +1,35 @@
+goog.provide('ol.parser.polyline');
+
+
+/**
+ * Encode one single signed integer and return an encoded string
+ *
+ * @param {number} num Signed integer that should be encoded.
+ * @return {string} The encoded string.
+ */
+ol.parser.polyline.encodeSignedInteger = function(num) {
+  var sgn_num = num << 1;
+  if (num < 0)
+    sgn_num = ~(sgn_num);
+
+  return ol.parser.polyline.encodeUnsignedInteger(sgn_num);
+};
+
+
+/**
+ * Encode one single unsigned integer and return an encoded string
+ *
+ * @param {number} num Unsigned integer that should be encoded.
+ * @return {string} The encoded string.
+ */
+ol.parser.polyline.encodeUnsignedInteger = function(num) {
+  var value, encodeString = '';
+  while (num >= 0x20) {
+    value = (0x20 | (num & 0x1f)) + 63;
+    encodeString += (String.fromCharCode(value));
+    num >>= 5;
+  }
+  value = num + 63;
+  encodeString += (String.fromCharCode(value));
+  return encodeString;
+};

test/spec/ol/parser/polyline.test.js

@@ -0,0 +1,41 @@
+goog.provide('ol.test.parser.polyline');
+
+describe('ol.parser.polyline', function() {
+
+  describe('encodeSignedInteger', function() {
+    it('returns expected value', function() {
+      var encodeSignedInteger = ol.parser.polyline.encodeSignedInteger;
+
+      expect(encodeSignedInteger(0)).toEqual('?');
+      expect(encodeSignedInteger(-1)).toEqual('@');
+      expect(encodeSignedInteger(1)).toEqual('A');
+      expect(encodeSignedInteger(-2)).toEqual('B');
+      expect(encodeSignedInteger(2)).toEqual('C');
+      expect(encodeSignedInteger(15)).toEqual(']');
+      expect(encodeSignedInteger(-16)).toEqual('^');
+
+      expect(encodeSignedInteger(16)).toEqual('_@');
+      expect(encodeSignedInteger(16 * 32)).toEqual('__@');
+      expect(encodeSignedInteger(16 * 32 * 32)).toEqual('___@');
+    });
+  });
+
+  describe('encodeUnsignedInteger', function() {
+    it('returns expected value', function() {
+      var encodeUnsignedInteger = ol.parser.polyline.encodeUnsignedInteger;
+
+      expect(encodeUnsignedInteger(0)).toEqual('?');
+      expect(encodeUnsignedInteger(1)).toEqual('@');
+      expect(encodeUnsignedInteger(2)).toEqual('A');
+      expect(encodeUnsignedInteger(30)).toEqual(']');
+      expect(encodeUnsignedInteger(31)).toEqual('^');
+      expect(encodeUnsignedInteger(32)).toEqual('_@');
+
+      expect(encodeUnsignedInteger(32 * 32)).toEqual('__@');
+      expect(encodeUnsignedInteger(5 * 32 * 32)).toEqual('__D');
+      expect(encodeUnsignedInteger(32 * 32 * 32)).toEqual('___@');
+    });
+  });
+});
+
+goog.require('ol.parser.polyline');