Optimizing BuildResultFromMatchInfo, StringReplace and StringSplit.

src/string.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 83 matching lines @@
     parts[i + 1] = TO_STRING_INLINE(part);
   }
   return %StringBuilderConcat(parts, len + 1, "");
 }
 
 // Match ES3 and Safari
 %FunctionSetLength(StringConcat, 1);
 
 
 // ECMA-262 section 15.5.4.7
-function StringIndexOf(searchString /* position */) {  // length == 1
-  var subject_str = TO_STRING_INLINE(this);
-  var pattern_str = TO_STRING_INLINE(searchString);
-  var subject_str_len = subject_str.length;
-  var pattern_str_len = pattern_str.length;
+function StringIndexOf(pattern /* position */) {  // length == 1
+  var subject = TO_STRING_INLINE(this);
+  var pattern = TO_STRING_INLINE(pattern);
+  var subject_len = subject.length;
+  var pattern_len = pattern.length;
   var index = 0;
   if (%_ArgumentsLength() > 1) {
     var arg1 = %_Arguments(1);  // position
     index = TO_INTEGER(arg1);
   }
   if (index < 0) index = 0;
-  if (index > subject_str_len) index = subject_str_len;
-  if (pattern_str_len + index > subject_str_len) return -1;
-  return %StringIndexOf(subject_str, pattern_str, index);
+  if (index > subject_len) index = subject_len;
+  if (pattern_len + index > subject_len) return -1;
+  return %StringIndexOf(subject, pattern, index);
 }
 
 
 // ECMA-262 section 15.5.4.8
-function StringLastIndexOf(searchString /* position */) {  // length == 1
+function StringLastIndexOf(pat /* position */) {  // length == 1
   var sub = TO_STRING_INLINE(this);
   var subLength = sub.length;
-  var pat = TO_STRING_INLINE(searchString);
+  var pat = TO_STRING_INLINE(pat);
   var patLength = pat.length;
   var index = subLength - patLength;
   if (%_ArgumentsLength() > 1) {
     var position = ToNumber(%_Arguments(1));
     if (!$isNaN(position)) {
       position = TO_INTEGER(position);
       if (position < 0) {
         position = 0;
       }
       if (position + patLength < subLength) {
         index = position
       }
     }
   }
   if (index < 0) {
     return -1;
   }
   return %StringLastIndexOf(sub, pat, index);
 }
 
 
 // ECMA-262 section 15.5.4.9
 //
 // This function is implementation specific.  For now, we do not
 // do anything locale specific.
 function StringLocaleCompare(other) {
   if (%_ArgumentsLength() === 0) return 0;
-
-  var this_str = TO_STRING_INLINE(this);
-  var other_str = TO_STRING_INLINE(other);
-  return %StringLocaleCompare(this_str, other_str);
+  return %StringLocaleCompare(TO_STRING_INLINE(this), 
+                              TO_STRING_INLINE(other));
 }
 
 
 // ECMA-262 section 15.5.4.10
 function StringMatch(regexp) {
   var subject = TO_STRING_INLINE(this);
   if (IS_REGEXP(regexp)) {
     if (!regexp.global) return regexp.exec(subject);
     %_Log('regexp', 'regexp-match,%0S,%1r', [subject, regexp]);
     // lastMatchInfo is defined in regexp.js.
     return %StringMatch(subject, regexp, lastMatchInfo);
   }
   // Non-regexp argument.
   regexp = new $RegExp(regexp);
   return RegExpExecNoTests(regexp, subject, 0);
 }
 
 
 // SubString is an internal function that returns the sub string of 'string'.
 // If resulting string is of length 1, we use the one character cache
 // otherwise we call the runtime system.
 function SubString(string, start, end) {
   // Use the one character string cache.
-  if (start + 1 == end) {
-    return %_StringCharAt(string, start);
-  }
+  if (start + 1 == end) return %_StringCharAt(string, start);
   return %_SubString(string, start, end);
 }
 
 
 // This has the same size as the lastMatchInfo array, and can be used for
 // functions that expect that structure to be returned.  It is used when the
 // needle is a string rather than a regexp.  In this case we can't update
 // lastMatchArray without erroneously affecting the properties on the global
 // RegExp object.
 var reusableMatchInfo = [2, "", "", -1, -1];
 
 
 // ECMA-262, section 15.5.4.11
 function StringReplace(search, replace) {
   var subject = TO_STRING_INLINE(this);
 
   // Delegate to one of the regular expression variants if necessary.
   if (IS_REGEXP(search)) {
     %_Log('regexp', 'regexp-replace,%0r,%1S', [search, subject]);
     if (IS_FUNCTION(replace)) {
       if (search.global) {
         return StringReplaceGlobalRegExpWithFunction(subject, search, replace);
       } else {
         return StringReplaceNonGlobalRegExpWithFunction(subject,
                                                         search,
                                                         replace);
       }
     } else {
-      return StringReplaceRegExp(subject, search, replace);
+      return %StringReplaceRegExpWithString(subject,
+                                            search,
+                                            TO_STRING_INLINE(replace),
+                                            lastMatchInfo);
     }
   }
 
   // Convert the search argument to a string and search for it.
   search = TO_STRING_INLINE(search);
   var start = %StringIndexOf(subject, search, 0);
   if (start < 0) return subject;
   var end = start + search.length;
 
   var builder = new ReplaceResultBuilder(subject);
   // prefix
   builder.addSpecialSlice(0, start);
 
   // Compute the string to replace with.
   if (IS_FUNCTION(replace)) {
-    builder.add(replace.call(null, search, start, subject));
+    builder.add(%_CallFunction(%GetGlobalReceiver(),
+                               search,
+                               start,
+                               subject,
+                               replace));
   } else {
     reusableMatchInfo[CAPTURE0] = start;
     reusableMatchInfo[CAPTURE1] = end;
     replace = TO_STRING_INLINE(replace);
     ExpandReplacement(replace, subject, reusableMatchInfo, builder);
   }
 
   // suffix
   builder.addSpecialSlice(end, subject.length);
 
   return builder.generate();
 }
 
 
-// Helper function for regular expressions in String.prototype.replace.
-function StringReplaceRegExp(subject, regexp, replace) {
-  return %StringReplaceRegExpWithString(subject,
-                                        regexp,
-                                        TO_STRING_INLINE(replace),
-                                        lastMatchInfo);
-}
-
-
 // Expand the $-expressions in the string and return a new string with
 // the result.
 function ExpandReplacement(string, subject, matchInfo, builder) {
   var next = %StringIndexOf(string, '$', 0);
   if (next < 0) {
     builder.add(string);
     return;
   }
 
   // Compute the number of captures; see ECMA-262, 15.5.4.11, p. 102.
@@ skipping 140 matching lines @@
           match_start = (elem >> 11) + (elem & 0x7ff);
         } else {
           match_start = res[++i] - elem;
         }
       } else {
         override[0] = elem;
         override[1] = match_start;
         lastMatchInfoOverride = override;
         var func_result =
             %_CallFunction(receiver, elem, match_start, subject, replace);
-        if (!IS_STRING(func_result)) {
-          func_result = NonStringToString(func_result);
-        }
+        func_result = TO_STRING_INLINE(func_result); 
         res[i] = func_result;
         match_start += elem.length;
       }
       i++;
     }
   } else {
     while (i < len) {
       var elem = res[i];
       if (!%_IsSmi(elem)) {
         // elem must be an Array.
         // Use the apply argument as backing for global RegExp properties.
         lastMatchInfoOverride = elem;
         var func_result = replace.apply(null, elem);
-        if (!IS_STRING(func_result)) {
-          func_result = NonStringToString(func_result);
-        }
+        func_result = TO_STRING_INLINE(func_result); 
         res[i] = func_result;
       }
       i++;
     }
   }
   var resultBuilder = new ReplaceResultBuilder(subject, res);
   var result = resultBuilder.generate();
   resultArray.length = 0;
   reusableReplaceArray = resultArray;
   return result;
@@ skipping 40 matching lines @@
 // ECMA-262 section 15.5.4.12
 function StringSearch(re) {
   var regexp;
   if (IS_STRING(re)) {
     regexp = %_GetFromCache(STRING_TO_REGEXP_CACHE_ID, re);
   } else if (IS_REGEXP(re)) {
     regexp = re;
   } else {
     regexp = new $RegExp(re);
   }
-  var s = TO_STRING_INLINE(this);
-  var match = DoRegExpExec(regexp, s, 0);
+  var match = DoRegExpExec(regexp, TO_STRING_INLINE(this), 0);
   if (match) {
     return match[CAPTURE0];
   }
   return -1;
 }
 
 
 // ECMA-262 section 15.5.4.13
 function StringSlice(start, end) {
   var s = TO_STRING_INLINE(this);
@@ skipping 67 matching lines @@
   }
 
   var currentIndex = 0;
   var startIndex = 0;
   var result = [];
 
   outer_loop:
   while (true) {
 
     if (startIndex === length) {
-      result[result.length] = subject.slice(currentIndex, length);
+      result.push(subject.slice(currentIndex, length));
       break;
     }
 
     var matchInfo = splitMatch(separator, subject, currentIndex, startIndex);
 
     if (IS_NULL(matchInfo)) {
-      result[result.length] = subject.slice(currentIndex, length);
+      result.push(subject.slice(currentIndex, length));
       break;
     }
 
     var endIndex = matchInfo[CAPTURE1];
 
     // We ignore a zero-length match at the currentIndex.
     if (startIndex === endIndex && endIndex === currentIndex) {
       startIndex++;
       continue;
     }
 
-    result[result.length] = SubString(subject, currentIndex, matchInfo[CAPTURE0]);
+    result.push(SubString(subject, currentIndex, matchInfo[CAPTURE0]));
     if (result.length === limit) break;
 
-    var num_captures = NUMBER_OF_CAPTURES(matchInfo);
-    for (var i = 2; i < num_captures; i += 2) {
-      var start = matchInfo[CAPTURE(i)];
-      var end = matchInfo[CAPTURE(i + 1)];
-      if (start != -1 && end != -1) {
-        result[result.length] = SubString(subject, start, end);
+    var matchinfo_len = NUMBER_OF_CAPTURES(matchInfo) + REGEXP_FIRST_CAPTURE;
+    for (var i = REGEXP_FIRST_CAPTURE + 2; i < matchinfo_len; ) {
+      var start = matchInfo[i++];
+      var end = matchInfo[i++];
+      if (end != -1) {
+        if (start + 1 == end) {
+          result.push(%_StringCharAt(subject, start));
+        } else {
+          result.push(%_SubString(subject, start, end));
+        }
       } else {
-        result[result.length] = void 0;
+        result.push(void 0);
       }
       if (result.length === limit) break outer_loop;
     }
 
     startIndex = currentIndex = endIndex;
   }
   return result;
 }
 
 
@@ skipping 30 matching lines @@
     } else {
       if (end_i < 0) end_i = 0;
       if (start_i > end_i) {
         var tmp = end_i;
         end_i = start_i;
         start_i = tmp;
       }
     }
   }
 
-  return SubString(s, start_i, end_i);
+  return (start_i + 1 == end_i
+          ? %_StringCharAt(s, start_i)
+          : %_SubString(s, start_i, end_i));
 }
 
 
 // This is not a part of ECMA-262.
 function StringSubstr(start, n) {
   var s = TO_STRING_INLINE(this);
   var len;
 
   // Correct n: If not given, set to string length; if explicitly
   // set to undefined, zero, or negative, returns empty string.
@@ skipping 17 matching lines @@
     // use zero.
     if (start < 0) {
       start += s.length;
       if (start < 0) start = 0;
     }
   }
 
   var end = start + len;
   if (end > s.length) end = s.length;
 
-  return SubString(s, start, end);
+  return (start + 1 == end
+          ? %_StringCharAt(s, start)
+          : %_SubString(s, start, end));
 }
 
 
 // ECMA-262, 15.5.4.16
 function StringToLowerCase() {
   return %StringToLowerCase(TO_STRING_INLINE(this));
 }
 
 
 // ECMA-262, 15.5.4.17
@@ skipping 221 matching lines @@
     "small", StringSmall,
     "strike", StringStrike,
     "sub", StringSub,
     "sup", StringSup,
     "toJSON", StringToJSON
   ));
 }
 
 
 SetupString();