[destructuring] Implement parameter pattern matching.

test/mjsunit/harmony/destructuring.js

 // 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-destructuring --harmony-computed-property-names
+// Flags: --harmony-arrow-functions
 
 (function TestObjectLiteralPattern() {
   var { x : x, y : y } = { x : 1, y : 2 };
   assertEquals(1, x);
   assertEquals(2, y);
 
   var {z} = { z : 3 };
   assertEquals(3, z);
 
 
@@ skipping 663 matching lines @@
   var o = { __proto__:null, 'a1':1, 'b2':2 };
   var sx = '';
   var sy = '';
   for (var [x,y] in o) {
     sx += x;
     sy += y;
   }
   assertEquals('ab', sx);
   assertEquals('12', sy);
 }());
+
+
+(function TestParameters() {

[rossberg, 2015/06/16 17:02:13]

Can we have a few more tests? In particular, including arrow patterns and nested
patterns?
Also, checks that "function({x}) { var x; }' etc is a syntax error.

[Dmitry Lomov (no reviews), 2015/06/19 15:25:14]

Done.

+  function f({a, b}) { return a - b; }
+  assertEquals(1, f({a : 6, b : 5}));
+
+  function f1(c, {a, b}) { return c + a - b; }
+  assertEquals(8, f1(7, {a : 6, b : 5}));
+
+  var g = {a, b} => { return a - b; };

[arv (Not doing code reviews), 2015/06/16 16:56:36]

This should be a SyntaxError. Only when using a single BindingIdentifier is the
parens optional.

http://people.mozilla.org/~jorendorff/es6-draft.html#sec-arrow-function-defin...

Remove and file bug.

[Dmitry Lomov (no reviews), 2015/06/19 15:25:14]

Done.

+  assertEquals(1, g({a : 6, b : 5}));
+
+  var g1 = (c, {a, b}) => { return c + a - b; };
+  assertEquals(8, g1(7, {a : 6, b : 5}));
+
+  var h = {a, b} => a - b;

[rossberg, 2015/06/16 17:02:13]

AFAICT this is not legal ES6 syntax, see the grammar in
https://people.mozilla.org/~jorendorff/es6-draft.html#sec-arrow-function-defi...

[Dmitry Lomov (no reviews), 2015/06/19 15:25:14]

Done.

+  assertEquals(1, h({a : 6, b : 5}));
+
+  var h1 = (c, {a, b}) => c + a - b;
+  assertEquals(8, h1(7, {a : 6, b : 5}));
+}());