Cache regular expressions used in String.search.

src/string.js

Index: src/string.js
diff --git a/src/string.js b/src/string.js
index e663ec304432f00b71c88765ac4858597e029156..1c72f3bc478d9a04ea3aa2f274efce5c0a2dfa01 100644
--- a/src/string.js
+++ b/src/string.js
@@ -521,9 +521,16 @@ function ApplyReplacementFunction(replace, matchInfo, subject) {
 }
 
 
+var re_cache = {}
+
+
 // ECMA-262 section 15.5.4.12
 function StringSearch(re) {
-  var regexp = new $RegExp(re);
+  var regexp = re_cache[re];
+  if (IS_UNDEFINED(regexp)) {

[sandholm, 2010/03/25 05:36:24]

Maybe reset cache at size 10, 100 or 1000 to avoid large memory increase and
longer lookup times. 

+    regexp = new $RegExp(re);
+    re_cache[re] = regexp;
+  }
   var s = TO_STRING_INLINE(this);
   var last_idx = regexp.lastIndex; // keep old lastIndex

[Lasse Reichstein, 2010/03/25 08:05:13]

Use:
  var match = DoRegExpExec(regexp, s, 0);
  if (match) {
    lastMatchInfo = match;
    return match[CAPTURE0];
  }
  return -1;

This avoids building the result of the exec call, it avoids calling exec
(depending on RegExp.prototype.exec not being changed), and it avoids hitting
the regexp exec cache (which may or may not be a good thing).

[Lasse Reichstein, 2010/03/25 08:53:11]

I'll just make a changelist for this on its own.

   regexp.lastIndex = 0;            // ignore re.global property