Issue 150 - [Typed objects] Implement string type

lib/typedObjects/stringType.js

Index: lib/typedObjects/stringType.js
===================================================================
new file mode 100644
--- /dev/null
+++ b/lib/typedObjects/stringType.js
@@ -0,0 +1,63 @@
+/*
+ * This file is part of Adblock Plus <http://adblockplus.org/>,
+ * Copyright (C) 2006-2014 Eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+"use strict";
+
+let {uint16} = require("typedObjects/primitiveTypes");
+
+let string = exports.string = uint16.Array({
+  toString: function()
+  {
+    let buffer = this.getArrayBuffer();
+    if (!buffer)
+      return "";
+    let array = new Uint16Array(buffer, this.arrayByteOffset, this.length);
+    return String.fromCharCode.apply(null, array);
+  }
+}, {
+  constructor: function(value, offset, length)
+  {
+    let type = typeof value;
+    if (type == "number")
+      this.length = value | 0;
+    else if (type == "string" || (value && string.isInstance(value)))
+    {
+      let sourceLength = value.length | 0;
+      offset = Math.min(sourceLength, offset | 0)
+      length = (typeof length == "number" ? length | 0 : sourceLength);
+      length = Math.min(length, sourceLength - offset);
+      this.length = length;
+
+      if (length > 0)
+      {
+        let dest = new Uint16Array(this.getArrayBuffer(), this.arrayByteOffset, length);
+        if (type == "string")
+        {
+          for (let i = 0; i < length; i++, offset++)
+            dest[i] = value.charCodeAt(offset);
+        }
+        else
+        {
+          let src = new Uint16Array(value.getArrayBuffer(),
+              value.arrayByteOffset + offset * (uint16.referenceLength | 0),
+              length);
+          dest.set(src);
+        }
+      }
+    }
+  }
+});