Optimizing BuildResultFromMatchInfo, StringReplace and StringSplit.

src/regexp.js

 // Copyright 2006-2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 102 matching lines @@
 
 function DoRegExpExec(regexp, string, index) {
   var result = %_RegExpExec(regexp, string, index, lastMatchInfo);
   if (result !== null) lastMatchInfoOverride = null;
   return result;
 }
 
 
 function BuildResultFromMatchInfo(lastMatchInfo, s) {
   var numResults = NUMBER_OF_CAPTURES(lastMatchInfo) >> 1;
-  var result = %_RegExpConstructResult(numResults, lastMatchInfo[CAPTURE0], s);
-  if (numResults === 1) {
-    var matchStart = lastMatchInfo[CAPTURE(0)];
-    var matchEnd = lastMatchInfo[CAPTURE(1)];
-    result[0] = SubString(s, matchStart, matchEnd);
+  var start = lastMatchInfo[CAPTURE0];
+  var end = lastMatchInfo[CAPTURE1];
+  var result = %_RegExpConstructResult(numResults, start, s);
+  if (start + 1 == end) {
+    result[0] = %_StringCharAt(s, start);
   } else {
-    for (var i = 0; i < numResults; i++) {
-      var matchStart = lastMatchInfo[CAPTURE(i << 1)];
-      var matchEnd = lastMatchInfo[CAPTURE((i << 1) + 1)];
-      if (matchStart != -1 && matchEnd != -1) {
-        result[i] = SubString(s, matchStart, matchEnd);
+    result[0] = %_SubString(s, start, end);
+  }
+  var j = REGEXP_FIRST_CAPTURE + 2;
+  for (var i = 1; i < numResults; i++) {
+    start = lastMatchInfo[j++];
+    end = lastMatchInfo[j++];
+    if (end != -1) {
+      if (start + 1 == end) {
+        result[i] = %_StringCharAt(s, start);
       } else {
-        // Make sure the element is present. Avoid reading the undefined
-        // property from the global object since this may change.
-        result[i] = void 0;
+        result[i] = %_SubString(s, start, end);
       }
+    } else {
+      // Make sure the element is present. Avoid reading the undefined
+      // property from the global object since this may change.
+      result[i] = void 0;
     }
   }
   return result;
 }
 
 
 function RegExpExecNoTests(regexp, string, start) {
   // Must be called with RegExp, string and positive integer as arguments.
   var matchInfo = DoRegExpExec(regexp, string, start);
   var result = null;
@@ skipping 10 matching lines @@
                         ['RegExp.prototype.exec', this]);
   }
 
   if (%_ArgumentsLength() === 0) {
     var regExpInput = LAST_INPUT(lastMatchInfo);
     if (IS_UNDEFINED(regExpInput)) {
       throw MakeError('no_input_to_regexp', [this]);
     }
     string = regExpInput;
   }
-  var s;
-  if (IS_STRING(string)) {
-    s = string;
-  } else {
-    s = ToString(string);
-  }
+  string = TO_STRING_INLINE(string);
   var lastIndex = this.lastIndex;
 
   // Conversion is required by the ES5 specification (RegExp.prototype.exec
   // algorithm, step 5) even if the value is discarded for non-global RegExps.
   var i = TO_INTEGER(lastIndex);
 
   var global = this.global;
   if (global) {
-    if (i < 0 || i > s.length) {
+    if (i < 0 || i > string.length) {
       this.lastIndex = 0;
       return null;
     }
   } else {
     i = 0;
   }
 
-  %_Log('regexp', 'regexp-exec,%0r,%1S,%2i', [this, s, lastIndex]);
+  %_Log('regexp', 'regexp-exec,%0r,%1S,%2i', [this, string, lastIndex]);
   // matchIndices is either null or the lastMatchInfo array.
-  var matchIndices = %_RegExpExec(this, s, i, lastMatchInfo);
+  var matchIndices = %_RegExpExec(this, string, i, lastMatchInfo);
 
   if (matchIndices === null) {
     if (global) this.lastIndex = 0;
     return null;
   }
 
   // Successful match.
   lastMatchInfoOverride = null;
   if (global) {
     this.lastIndex = lastMatchInfo[CAPTURE1];
   }
-  return BuildResultFromMatchInfo(matchIndices, s);
+  return BuildResultFromMatchInfo(matchIndices, string);
 }
 
 
 // One-element cache for the simplified test regexp.
 var regexp_key;
 var regexp_val;
 
 // Section 15.10.6.3 doesn't actually make sense, but the intention seems to be
 // that test is defined in terms of String.prototype.exec. However, it probably
 // means the original value of String.prototype.exec, which is what everybody
 // else implements.
 function RegExpTest(string) {
   if (!IS_REGEXP(this)) {
     throw MakeTypeError('incompatible_method_receiver',
                         ['RegExp.prototype.test', this]);
   }
   if (%_ArgumentsLength() == 0) {
     var regExpInput = LAST_INPUT(lastMatchInfo);
     if (IS_UNDEFINED(regExpInput)) {
       throw MakeError('no_input_to_regexp', [this]);
     }
     string = regExpInput;
   }
 
-  var s;
-  if (IS_STRING(string)) {
-    s = string;
-  } else {
-    s = ToString(string);
-  }
+  string = TO_STRING_INLINE(string);
 
   var lastIndex = this.lastIndex;
 
   // Conversion is required by the ES5 specification (RegExp.prototype.exec
   // algorithm, step 5) even if the value is discarded for non-global RegExps.
   var i = TO_INTEGER(lastIndex);
   
   if (this.global) {
-    if (i < 0 || i > s.length) {
+    if (i < 0 || i > string.length) {
       this.lastIndex = 0;
       return false;
     }
-    %_Log('regexp', 'regexp-exec,%0r,%1S,%2i', [this, s, lastIndex]);
+    %_Log('regexp', 'regexp-exec,%0r,%1S,%2i', [this, string, lastIndex]);
     // matchIndices is either null or the lastMatchInfo array.
-    var matchIndices = %_RegExpExec(this, s, i, lastMatchInfo);
+    var matchIndices = %_RegExpExec(this, string, i, lastMatchInfo);
     if (matchIndices === null) {
       this.lastIndex = 0;
       return false;
     }
     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 '?'.
     if (%_StringCharCodeAt(this.source, 0) == 46 &&  // '.'
         %_StringCharCodeAt(this.source, 1) == 42 &&  // '*'
         %_StringCharCodeAt(this.source, 2) != 63) {  // '?'
       if (!%_ObjectEquals(regexp_key, this)) {
         regexp_key = this;
         regexp_val = new $RegExp(this.source.substring(2, this.source.length),
                                  (this.ignoreCase ? 'i' : '')
                                  + (this.multiline ? 'm' : ''));
       }
-      if (!regexp_val.test(s)) return false;
+      if (!regexp_val.test(string)) return false;
     }    
-    %_Log('regexp', 'regexp-exec,%0r,%1S,%2i', [this, s, lastIndex]);
+    %_Log('regexp', 'regexp-exec,%0r,%1S,%2i', [this, string, lastIndex]);
     // matchIndices is either null or the lastMatchInfo array.
-    var matchIndices = %_RegExpExec(this, s, 0, lastMatchInfo);
+    var matchIndices = %_RegExpExec(this, string, 0, lastMatchInfo);
     if (matchIndices === null) return false;
     lastMatchInfoOverride = null;
     return true;
   }
 }
 
 
 function RegExpToString() {
   // If this.source is an empty string, output /(?:)/.
   // http://bugzilla.mozilla.org/show_bug.cgi?id=225550
@@ skipping 188 matching lines @@
   %DefineAccessor($RegExp, "$'", SETTER, NoOpSetter, DONT_ENUM | DONT_DELETE);
 
   for (var i = 1; i < 10; ++i) {
     %DefineAccessor($RegExp, '$' + i, GETTER, RegExpMakeCaptureGetter(i), DONT_DELETE);
     %DefineAccessor($RegExp, '$' + i, SETTER, NoOpSetter, DONT_DELETE);
   }
 }
 
 
 SetupRegExp();