Allow TypedArrays to be initialized with iterables

test/mjsunit/harmony/typedarrays.js

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 258 matching lines @@
   var a = new constr(ab, 64*elementSize, 128);
   assertEquals("[object " + constr.name + "]",
       Object.prototype.toString.call(a));
   var desc = Object.getOwnPropertyDescriptor(
       constr.prototype, Symbol.toStringTag);
   assertTrue(desc.configurable);
   assertFalse(desc.enumerable);
   assertFalse(!!desc.writable);
   assertFalse(!!desc.set);
   assertEquals("function", typeof desc.get);
+
+  // Test that the constructor can be called with an iterable
+  function* gen() { for (var i = 0; i < 10; i++) yield i; }
+  var genArr = new constr(gen());
+  assertEquals(10, genArr.length);
+  assertEquals(0, genArr[0]);
+  assertEquals(9, genArr[9]);
+  // Arrays can be converted to TypedArrays
+  genArr = new constr([1, 2, 3]);
+  assertEquals(3, genArr.length);
+  assertEquals(1, genArr[0]);
+  assertEquals(3, genArr[2]);
+  // Redefining Array.prototype[Symbol.iterator] still works
+  var arrayIterator = Array.prototype[Symbol.iterator];
+  Array.prototype[Symbol.iterator] = gen;
+  genArr = new constr([1, 2, 3]);
+  assertEquals(10, genArr.length);
+  assertEquals(0, genArr[0]);
+  assertEquals(9, genArr[9]);
+  Array.prototype[Symbol.iterator] = arrayIterator;
+  // Other array-like things can be made into a TypedArray
+  var myObject = { 0: 5, 1: 6, length: 2 };
+  genArr = new constr(myObject);
+  assertEquals(2, genArr.length);
+  assertEquals(5, genArr[0]);
+  assertEquals(6, genArr[1]);
+  // Iterator takes precedence over array-like, and the property
+  // is read only once.
+  var iteratorReadCount = 0;
+  Object.defineProperty(myObject, Symbol.iterator, {
+    get: function() { iteratorReadCount++; return gen; }
+  });
+  genArr = new constr(myObject);
+  assertEquals(10, genArr.length);
+  assertEquals(0, genArr[0]);
+  assertEquals(9, genArr[9]);
+  assertEquals(1, iteratorReadCount);
 }
 
 TestTypedArray(Uint8Array, 1, 0xFF);
 TestTypedArray(Int8Array, 1, -0x7F);
 TestTypedArray(Uint16Array, 2, 0xFFFF);
 TestTypedArray(Int16Array, 2, -0x7FFF);
 TestTypedArray(Uint32Array, 4, 0xFFFFFFFF);
 TestTypedArray(Int32Array, 4, -0x7FFFFFFF);
 TestTypedArray(Float32Array, 4, 0.5);
 TestTypedArray(Float64Array, 8, 0.5);
@@ skipping 423 matching lines @@
 TestArbitrary(new ArrayBuffer(256));
 for(i = 0; i < typedArrayConstructors.length; i++) {
   TestArbitrary(new typedArrayConstructors[i](10));
 }
 TestArbitrary(new DataView(new ArrayBuffer(256)));
 
 
 // Test direct constructor call
 assertThrows(function() { ArrayBuffer(); }, TypeError);
 assertThrows(function() { DataView(new ArrayBuffer()); }, TypeError);