[es6] Implement @@match subclassing.

src/js/string.js

 // Copyright 2012 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.
 
 (function(global, utils) {
 
 %CheckIsBootstrapping();
 
 // -------------------------------------------------------------------
 // Imports
 
 var ArrayIndexOf;
 var ArrayJoin;
 var GlobalRegExp = global.RegExp;
 var GlobalString = global.String;
 var InternalArray = utils.InternalArray;
 var InternalPackedArray = utils.InternalPackedArray;
 var MakeRangeError;
 var MakeTypeError;
 var MathMax;
 var MathMin;
+var matchSymbol = utils.ImportNow("match_symbol");
 var RegExpExec;
 var RegExpExecNoTests;
 var RegExpLastMatchInfo;
 var splitSymbol = utils.ImportNow("split_symbol");
 
 utils.Import(function(from) {
   ArrayIndexOf = from.ArrayIndexOf;
   ArrayJoin = from.ArrayJoin;
   MakeRangeError = from.MakeRangeError;
   MakeTypeError = from.MakeTypeError;
@@ skipping 116 matching lines @@
 // This function is implementation specific.  For now, we do not
 // do anything locale specific.
 function StringLocaleCompareJS(other) {
   CHECK_OBJECT_COERCIBLE(this, "String.prototype.localeCompare");
 
   return %StringLocaleCompare(TO_STRING(this), TO_STRING(other));
 }
 
 
 // ECMA-262 section 15.5.4.10
-function StringMatchJS(regexp) {
+function StringMatchJS(pattern) {
   CHECK_OBJECT_COERCIBLE(this, "String.prototype.match");
 
+  if (!IS_NULL_OR_UNDEFINED(pattern)) {
+    var matcher = pattern[matchSymbol];
+    if (!IS_UNDEFINED(matcher)) {
+      if (!IS_CALLABLE(matcher)) {
+        throw MakeTypeError(kCalledNonCallable, matcher);
+      }
+      return %_Call(matcher, pattern, this);
+    }
+  }
+
   var subject = TO_STRING(this);
-  if (IS_REGEXP(regexp)) {
-    if (!REGEXP_GLOBAL(regexp)) return RegExpExecNoTests(regexp, subject, 0);
-    var result = %StringMatch(subject, regexp, RegExpLastMatchInfo);
-    regexp.lastIndex = 0;
-    return result;
-  }
+
   // Non-regexp argument.
-  regexp = new GlobalRegExp(regexp);
+  var regexp = new GlobalRegExp(pattern);
   return RegExpExecNoTests(regexp, subject, 0);
 }
 
 
 // ECMA-262 v6, section 21.1.3.12
 //
 // For now we do nothing, as proper normalization requires big tables.
 // If Intl is enabled, then i18n.js will override it and provide the the
 // proper functionality.
 function StringNormalizeJS() {
@@ skipping 923 matching lines @@
   to.StringLastIndexOf = StringLastIndexOfJS;
   to.StringMatch = StringMatchJS;
   to.StringReplace = StringReplace;
   to.StringSlice = StringSlice;
   to.StringSplit = StringSplitJS;
   to.StringSubstr = StringSubstr;
   to.StringSubstring = StringSubstring;
 });
 
 })