RegExp: Add support for the ES6-proposed sticky flag

src/regexp.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.
 
 // This file relies on the fact that the following declaration has been made
 // in runtime.js:
 // var $Object = global.Object;
 // var $Array = global.Array;
 
 var $RegExp = global.RegExp;
 
 // -------------------------------------------------------------------
 
 // A recursive descent parser for Patterns according to the grammar of
 // ECMA-262 15.10.1, with deviations noted below.
 function DoConstructRegExp(object, pattern, flags) {
   // RegExp : Called as constructor; see ECMA-262, section 15.10.4.
   if (IS_REGEXP(pattern)) {
     if (!IS_UNDEFINED(flags)) {
       throw MakeTypeError('regexp_flags', []);
     }
     flags = (pattern.global ? 'g' : '')
         + (pattern.ignoreCase ? 'i' : '')
         + (pattern.multiline ? 'm' : '');
+    if (%HarmonyRegExps())

[Yang, 2014/09/15 09:23:16]

While I'm fine with this (will be removed eventually anyways), I think adding a
global value to the builtins object during bootstrapping to mirror the flag is
cleaner.

[Erik Corry, 2014/09/16 17:49:40]

Done.

+        flags += (pattern.sticky ? 'y' : '');
     pattern = pattern.source;
   }
 
   pattern = IS_UNDEFINED(pattern) ? '' : ToString(pattern);
   flags = IS_UNDEFINED(flags) ? '' : ToString(flags);
 
   var global = false;
   var ignoreCase = false;
   var multiline = false;
+  var sticky = false;
   for (var i = 0; i < flags.length; i++) {
     var c = %_CallFunction(flags, i, StringCharAt);
     switch (c) {
       case 'g':
         if (global) {
           throw MakeSyntaxError("invalid_regexp_flags", [flags]);
         }
         global = true;
         break;
       case 'i':
         if (ignoreCase) {
           throw MakeSyntaxError("invalid_regexp_flags", [flags]);
         }
         ignoreCase = true;
         break;
       case 'm':
         if (multiline) {
           throw MakeSyntaxError("invalid_regexp_flags", [flags]);
         }
         multiline = true;
         break;
+      case 'y':
+        if (!%HarmonyRegExps() || sticky) {
+          throw MakeSyntaxError("invalid_regexp_flags", [flags]);
+        }
+        sticky = true;
+        break;
       default:
         throw MakeSyntaxError("invalid_regexp_flags", [flags]);
     }
   }
 
-  %RegExpInitializeObject(object, pattern, global, ignoreCase, multiline);
+  %RegExpInitializeObject(object, pattern, global, ignoreCase, multiline, sticky);
 
   // Call internal function to compile the pattern.
   %RegExpCompile(object, pattern, flags);
 }
 
 
 function RegExpConstructor(pattern, flags) {
   if (%_IsConstructCall()) {
     DoConstructRegExp(this, pattern, flags);
   } else {
@@ skipping 149 matching lines @@
     }
     lastMatchInfoOverride = null;
     this.lastIndex = lastMatchInfo[CAPTURE1];
     return true;
   } else {
     // Non-global regexp.
     // Remove irrelevant preceeding '.*' in a non-global test regexp.
     // The expression checks whether this.source starts with '.*' and
     // that the third char is not a '?'.
     var regexp = this;
-    if (%_StringCharCodeAt(regexp.source, 0) == 46 &&  // '.'
+    if (!this.sticky &&

[Yang, 2014/09/15 09:23:16]

We also need to record .lastIndex for sticky. If I'm not mistaken, the global
and sticky case in here is the same. So we could just change line 219 to

if (this.global || this.sticky) {

[Erik Corry, 2014/09/16 17:49:40]

Done, and also added string length check.

+        %_StringCharCodeAt(regexp.source, 0) == 46 &&  // '.'
         %_StringCharCodeAt(regexp.source, 1) == 42 &&  // '*'
         %_StringCharCodeAt(regexp.source, 2) != 63) {  // '?'
       regexp = TrimRegExp(regexp);
     }
     // matchIndices is either null or the lastMatchInfo array.
     var matchIndices = %_RegExpExec(regexp, string, 0, lastMatchInfo);
     if (IS_NULL(matchIndices)) {
       this.lastIndex = 0;
       return false;
     }
@@ skipping 16 matching lines @@
 
 function RegExpToString() {
   if (!IS_REGEXP(this)) {
     throw MakeTypeError('incompatible_method_receiver',
                         ['RegExp.prototype.toString', this]);
   }
   var result = '/' + this.source + '/';
   if (this.global) result += 'g';
   if (this.ignoreCase) result += 'i';
   if (this.multiline) result += 'm';
+  if (%HarmonyRegExps() && this.sticky) result += 'y';
   return result;
 }
 
 
 // Getters for the static properties lastMatch, lastParen, leftContext, and
 // rightContext of the RegExp constructor.  The properties are computed based
 // on the captures array of the last successful match and the subject string
 // of the last successful match.
 function RegExpGetLastMatch() {
   if (lastMatchInfoOverride !== null) {
@@ skipping 178 matching lines @@
 
   for (var i = 1; i < 10; ++i) {
     %DefineAccessorPropertyUnchecked($RegExp, '$' + i,
                                      RegExpMakeCaptureGetter(i), NoOpSetter,
                                      DONT_DELETE);
   }
   %ToFastProperties($RegExp);
 }
 
 SetUpRegExp();