TypedArray(length) constructor

R=rossberg@chromium.org

Review URL: https://codereview.chromium.org/14460008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14486 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/typedarray.js

@@ -85,11 +85,7 @@ function ArrayBufferSlice(start, end) {
 // --------------- Typed Arrays ---------------------
 
 function CreateTypedArrayConstructor(name, elementSize, arrayId, constructor) {
-  return function (buffer, byteOffset, length) {
-    if (%_IsConstructCall()) {
-      if (!IS_ARRAYBUFFER(buffer)) {
-        throw MakeTypeError("Type error!");
-      }
+  function ConstructByArrayBuffer(obj, buffer, byteOffset, length) {
     var offset = IS_UNDEFINED(byteOffset)
       ? 0 : offset = TO_POSITIVE_INTEGER(byteOffset);
 
@@ -118,9 +114,25 @@ function CreateTypedArrayConstructor(name, elementSize, arrayId, constructor) {
     if (newByteLength > bufferByteLength) {
       throw MakeRangeError("invalid_typed_array_length");
     }
-      %TypedArrayInitialize(this, arrayId, buffer, offset, newByteLength);
+    %TypedArrayInitialize(obj, arrayId, buffer, offset, newByteLength);
+  }
+
+  function ConstructByLength(obj, length) {
+    var l = IS_UNDEFINED(length) ? 0 : TO_POSITIVE_INTEGER(length);
+    var byteLength = l * elementSize;
+    var buffer = new $ArrayBuffer(byteLength);
+    %TypedArrayInitialize(obj, arrayId, buffer, 0, byteLength);
+  }
+
+  return function (arg1, arg2, arg3) {
+    if (%_IsConstructCall()) {
+      if (IS_ARRAYBUFFER(arg1)) {
+        ConstructByArrayBuffer(this, arg1, arg2, arg3);
       } else {
-      return new constructor(buffer, byteOffset, length);
+        ConstructByLength(this, arg1);
+      }
+    } else {
+      return new constructor(arg1, arg2, arg3);
     }
   }
 }
@@ -164,9 +176,10 @@ function SetUpArrayBuffer() {
 SetUpArrayBuffer();
 
 function SetupTypedArray(arrayId, name, constructor, elementSize) {
-  var f = CreateTypedArrayConstructor(name, elementSize,
+  %CheckIsBootstrapping();
+  var fun = CreateTypedArrayConstructor(name, elementSize,
                                         arrayId, constructor);
-  %SetCode(constructor, f);
+  %SetCode(constructor, fun);
   %FunctionSetPrototype(constructor, new $Object());
 
   %SetProperty(constructor.prototype,

test/mjsunit/harmony/typedarrays.js

@@ -113,6 +113,27 @@ TestArrayBufferSlice();
 function TestTypedArray(proto, elementSize, typicalElement) {
   var ab = new ArrayBuffer(256*elementSize);
 
+  var a0 = new proto(30);
+  assertSame(elementSize, a0.BYTES_PER_ELEMENT);
+  assertSame(30, a0.length);
+  assertSame(30*elementSize, a0.byteLength);
+  assertSame(0, a0.byteOffset);
+  assertSame(30*elementSize, a0.buffer.byteLength);
+
+  var aLen0 = new proto(0);
+  assertSame(elementSize, aLen0.BYTES_PER_ELEMENT);
+  assertSame(0, aLen0.length);
+  assertSame(0, aLen0.byteLength);
+  assertSame(0, aLen0.byteOffset);
+  assertSame(0, aLen0.buffer.byteLength);
+
+  var aOverBufferLen0 = new proto(ab, 128*elementSize, 0);
+  assertSame(ab, aOverBufferLen0.buffer);
+  assertSame(elementSize, aOverBufferLen0.BYTES_PER_ELEMENT);
+  assertSame(0, aOverBufferLen0.length);
+  assertSame(0, aOverBufferLen0.byteLength);
+  assertSame(128*elementSize, aOverBufferLen0.byteOffset);
+
   var a1 = new proto(ab, 128*elementSize, 128);
   assertSame(ab, a1.buffer);
   assertSame(elementSize, a1.BYTES_PER_ELEMENT);