Add TypedArray.from method

test/mjsunit/harmony/typedarray-from.js

Index: test/mjsunit/harmony/typedarray-from.js
diff --git a/test/mjsunit/harmony/typedarray-from.js b/test/mjsunit/harmony/typedarray-from.js
new file mode 100644
index 0000000000000000000000000000000000000000..4c5fcdf1686c6502df3273e8154e4105171df4b0
--- /dev/null
+++ b/test/mjsunit/harmony/typedarray-from.js
@@ -0,0 +1,127 @@
+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-arrays
+
+var typedArrayConstructors = [
+  Uint8Array,
+  Int8Array,
+  Uint16Array,
+  Int16Array,
+  Uint32Array,
+  Int32Array,
+  Uint8ClampedArray,
+  Float32Array,
+  Float64Array];

[arv (Not doing code reviews), 2015/05/15 00:20:22]

] on next line

[dehrenberg, 2015/05/15 23:39:15]

Done.

+
+typedArrayConstructors.forEach(function(constructor) {

[arv (Not doing code reviews), 2015/05/15 00:20:22]

I find for-of loops easier to read

[dehrenberg, 2015/05/15 23:39:15]

Done.

+
+assertEquals(1, constructor.from.length);

[arv (Not doing code reviews), 2015/05/15 00:20:22]

indent

[dehrenberg, 2015/05/15 23:39:15]

Done.

+
+// TypedArray.from only callable on this subclassing %TypedArray%
+assertThrows(function () {constructor.from.call(Array, [])}, TypeError);
+
+var construct_fn = constructor.construct;

[arv (Not doing code reviews), 2015/05/15 00:20:22]

Where did construct come from?

[dehrenberg, 2015/05/15 23:39:14]

Oops, this was a remnant for a test that I deleted, and it was supposed to read
constructor.constructor.

+
+function assertArrayLikeEquals(value, expected, type) {
+  assertInstanceof(value, type);

[arv (Not doing code reviews), 2015/05/15 00:20:22]

I tend to prefer to check the __proto__ or Object.getPrototypeOf since it is
more exact. Checking instanceof does not care if there are extra object in the
prototype chain.

[dehrenberg, 2015/05/15 23:39:15]

Done.

+  assertEquals(expected.length, value.length);
+  for (var i=0; i<value.length; ++i) {

[arv (Not doing code reviews), 2015/05/15 00:20:22]

ws around binops

[dehrenberg, 2015/05/15 23:39:15]

Done.

+    assertEquals(expected[i], value[i]);
+  }
+}
+
+// Assert that calling mapfn with / without thisArg in sloppy and strict modes
+// works as expected.
+var global = this;
+function non_strict(){ assertEquals(global, this); }

[arv (Not doing code reviews), 2015/05/15 00:20:23]

ws before {

[dehrenberg, 2015/05/15 23:39:15]

Done.

+function strict(){ "use strict"; assertEquals(void 0, this); }

[arv (Not doing code reviews), 2015/05/15 00:20:22]

you can use undefined in tests if you want

[dehrenberg, 2015/05/15 23:39:14]

Done.

+function strict_null(){ "use strict"; assertEquals(null, this); }
+constructor.from([1], non_strict);
+constructor.from([1], non_strict, void 0);
+constructor.from([1], non_strict, null);
+constructor.from([1], strict);
+constructor.from([1], strict, void 0);
+constructor.from([1], strict_null, null);
+
+// TypedArray.from can only be called on TypedArray constructors
+assertThrows(function() {constructor.from.call({}, [])}, TypeError);
+assertThrows(function() {constructor.from.call([], [])}, TypeError);
+assertThrows(function() {constructor.from.call(1, [])}, TypeError);
+assertThrows(function() {constructor.from.call(undefined, [])}, TypeError);
+
+// Converting from various other types, demonstrating that it can
+// operate on array-like objects as well as iterables.
+// TODO(dehrenberg): constructors should have similar flexibility.
+assertArrayLikeEquals(constructor.from(
+    { length: 1, '0': 5 }), [5], constructor);

[arv (Not doing code reviews), 2015/05/15 00:20:22]

no need to quote the key here.

[dehrenberg, 2015/05/15 23:39:15]

Done.

+
+assertArrayLikeEquals(constructor.from(
+    { length: -1, '0': 5 }), [], constructor);
+
+assertArrayLikeEquals(constructor.from(
+    [1, 2, 3]), [1, 2, 3], constructor);
+
+var kSet = new Set([1, 2, 3]);
+assertArrayLikeEquals(constructor.from(kSet), [1, 2, 3],
+      constructor);
+
+function* generator() {
+  yield 4;
+  yield 5;
+  yield 6;
+}
+
+assertArrayLikeEquals(constructor.from(generator()),
+                      [4, 5, 6], constructor);
+
+assertThrows(function() { constructor.from(null); }, TypeError);
+assertThrows(function() { constructor.from(undefined); }, TypeError);
+assertThrows(function() { constructor.from([], null); }, TypeError);
+assertThrows(function() { constructor.from([], "noncallable"); },

[arv (Not doing code reviews), 2015/05/15 00:20:22]

stick to either " or '

[dehrenberg, 2015/05/15 23:39:15]

Done.

+             TypeError);
+
+var nullIterator = {};
+nullIterator[Symbol.iterator] = null;
+assertArrayLikeEquals(constructor.from(nullIterator), [],
+                      constructor);
+
+var nonObjIterator = {};
+nonObjIterator[Symbol.iterator] = function() { return "nonObject"; };
+assertThrows(function() { constructor.from(nonObjIterator); },
+             TypeError);
+
+assertThrows(function() { constructor.from([], null); }, TypeError);
+
+// Ensure iterator is only accessed once, and only invoked once
+var called = false;
+var arr = [1, 2, 3];
+var obj = {};
+
+// Test order --- only get iterator method once
+function testIterator() {
+  assertFalse(called, "@@iterator should be called only once");
+  called = true;
+  assertEquals(obj, this);
+  return arr[Symbol.iterator]();
+}
+var getCalled = false;
+Object.defineProperty(obj, Symbol.iterator, {
+  get: function() {
+    assertFalse(getCalled, "@@iterator should be accessed only once");
+    getCalled = true;
+    return testIterator;
+  },
+  set: function() {
+    assertUnreachable("@@iterator should not be set");
+  }
+});
+assertArrayLikeEquals(constructor.from(obj), [1, 2, 3], constructor);
+assertEquals(getCalled, true);
+assertEquals(called, true);
+
+assertEquals(constructor, Uint8Array.from.call(constructor, [1]).constructor);
+assertEquals(Uint8Array, constructor.from.call(Uint8Array, [1]).constructor);
+
+});