RegExp: Add support for the ES6-proposed sticky flag

src/regexp.js

Index: src/regexp.js
diff --git a/src/regexp.js b/src/regexp.js
index d8e3ea49bec7e236a0d7dc1dcf4a624b460679eb..628fdd2a3de13746c4324e09de4916edf9309641 100644
--- a/src/regexp.js
+++ b/src/regexp.js
@@ -22,6 +22,8 @@ function DoConstructRegExp(object, pattern, 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;
   }
 
@@ -31,6 +33,7 @@ function DoConstructRegExp(object, pattern, 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) {
@@ -52,12 +55,18 @@ function DoConstructRegExp(object, pattern, 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);
@@ -227,7 +236,8 @@ function RegExpTest(string) {
     // 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);
@@ -264,6 +274,7 @@ function RegExpToString() {
   if (this.global) result += 'g';
   if (this.ignoreCase) result += 'i';
   if (this.multiline) result += 'm';
+  if (%HarmonyRegExps() && this.sticky) result += 'y';
   return result;
 }