Implement experimental exponentiation operator

test/mjsunit/harmony/exponentiation.js

+// Copyright 2014 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-exponentiation
+
+(function testPrecedence() {
+  assertEquals(8, 2 ** 3);
+  assertEquals(24, 3 * 2 ** 3);
+  assertEquals(512, 2 ** 3 ** 2);
+  assertEquals(512, 2 ** (3 ** 2));
+  assertEquals(8, 0 || 2 ** 3);
+  assertEquals(0, 0 && 2 ** 3);
+  assertEquals(1, 2 ** -1 * 2);
+  var x = 2;
+  assertEquals(8, 2 ** ++x);
+  assertEquals(4, 2 ** --x);
+  assertEquals(3, 2 ** 2 - 1);
+  assertEquals(9007199254740991, 2 ** 53 - 1);
+})();
+
+
+(function testTypeCoercion() {
+  assertEquals(4, 2 ** '2');
+  assertEquals(4, 2 ** { valueOf: function() { return 2; } });
+  assertEquals(NaN, 2 ** {});
+
+  function MyError() {}
+
+  assertThrows(function() {
+    return 2 ** { valueOf: function() { throw new MyError(); } };
+  }, MyError);
+
+  assertThrows(function() {
+    return { valueOf: function() { throw new MyError(); } } ** 2;
+  }, MyError);
+})();
+
+
+(function testCommonCases() {
+  assertEquals(1, 0 ** 0); // Undefined case, but consistent with Math.pow
+  for (var i = 1; i < 10; ++i) {
+    assertEquals(0, 0 ** i);
+    assertEquals(Infinity, 0 ** -i);
+    assertEquals(1, i ** 0);
+    assertEquals(1, -i ** 0);
+    if (i & 1) {
+      assertEquals(-1, -1 ** i);
+    } else {
+      assertEquals(1, -1 ** i);
+    }
+  }
+
+  for (var i = 0, j = 1; i < 32; ++i, j *= 2) {
+    assertEquals(j, 2 ** i);
+  }
+})();
+
+
+(function testAssignment() {
+  var calls = 0;
+  var q = { q: 3 };
+  var o = {
+    get p() {
+      calls++;
+      return q;
+    }
+  };
+
+  o.p.q **= 2;
+  assertEquals(1, calls);
+  assertEquals(9, o.p.q);
+})();