Separate String.prototype.replace into RegExp.prototype[Symbol.replace]

src/js/string.js

Index: src/js/string.js
diff --git a/src/js/string.js b/src/js/string.js
index b220038b74ce1283f0575943533d8fde8e9180ae..e906a563652782ace88005b3aa11fbbbef1d9503 100644
--- a/src/js/string.js
+++ b/src/js/string.js
@@ -20,9 +20,8 @@ var MakeTypeError;
 var MathMax;
 var MathMin;
 var matchSymbol = utils.ImportNow("match_symbol");
-var RegExpExec;
 var RegExpExecNoTests;
-var RegExpLastMatchInfo;
+var replaceSymbol = utils.ImportNow("replace_symbol");
 var searchSymbol = utils.ImportNow("search_symbol");
 var splitSymbol = utils.ImportNow("split_symbol");
 
@@ -33,9 +32,7 @@ utils.Import(function(from) {
   MakeTypeError = from.MakeTypeError;
   MathMax = from.MathMax;
   MathMin = from.MathMin;
-  RegExpExec = from.RegExpExec;
   RegExpExecNoTests = from.RegExpExecNoTests;
-  RegExpLastMatchInfo = from.RegExpLastMatchInfo;
 });
 
 //-------------------------------------------------------------------
@@ -206,14 +203,12 @@ function StringNormalizeJS() {
 var reusableMatchInfo = [2, "", "", -1, -1];
 
 
-// ECMA-262, section 15.5.4.11
+// ES6, section 21.1.3.14
 function StringReplace(search, replace) {
   CHECK_OBJECT_COERCIBLE(this, "String.prototype.replace");
 
-  var subject = TO_STRING(this);
-
   // Decision tree for dispatch
-  // .. regexp search
+  // .. regexp search (in src/js/regexp.js, RegExpReplace)
   // .... string replace
   // ...... non-global search
   // ........ empty string replace
@@ -229,40 +224,15 @@ function StringReplace(search, replace) {
   // ...... function replace
   // ...... string replace (with $-expansion)
 
-  if (IS_REGEXP(search)) {
-    if (!IS_CALLABLE(replace)) {
-      replace = TO_STRING(replace);
-
-      if (!REGEXP_GLOBAL(search)) {
-        // Non-global regexp search, string replace.
-        var match = RegExpExec(search, subject, 0);
-        if (match == null) {
-          search.lastIndex = 0
-          return subject;
-        }
-        if (replace.length == 0) {
-          return %_SubString(subject, 0, match[CAPTURE0]) +
-                 %_SubString(subject, match[CAPTURE1], subject.length)
-        }
-        return ExpandReplacement(replace, subject, RegExpLastMatchInfo,
-                                 %_SubString(subject, 0, match[CAPTURE0])) +
-               %_SubString(subject, match[CAPTURE1], subject.length);
-      }
-
-      // Global regexp search, string replace.
-      search.lastIndex = 0;
-      return %StringReplaceGlobalRegExpWithString(
-          subject, search, replace, RegExpLastMatchInfo);
+  if (!IS_NULL_OR_UNDEFINED(search)) {
+    var replacer = search[replaceSymbol];
+    if (!IS_UNDEFINED(replacer)) {
+      return %_Call(replacer, search, this, replace);
     }
-
-    if (REGEXP_GLOBAL(search)) {
-      // Global regexp search, function replace.
-      return StringReplaceGlobalRegExpWithFunction(subject, search, replace);
-    }
-    // Non-global regexp search, function replace.
-    return StringReplaceNonGlobalRegExpWithFunction(subject, search, replace);
   }
 
+  var subject = TO_STRING(this);
+
   search = TO_STRING(search);
 
   if (search.length == 1 &&
@@ -379,130 +349,6 @@ function ExpandReplacement(string, subject, matchInfo, result) {
 }
 
 
-// Compute the string of a given regular expression capture.
-function CaptureString(string, lastCaptureInfo, index) {
-  // Scale the index.
-  var scaled = index << 1;
-  // Compute start and end.
-  var start = lastCaptureInfo[CAPTURE(scaled)];
-  // If start isn't valid, return undefined.
-  if (start < 0) return;
-  var end = lastCaptureInfo[CAPTURE(scaled + 1)];
-  return %_SubString(string, start, end);
-}
-
-
-// TODO(lrn): This array will survive indefinitely if replace is never
-// called again. However, it will be empty, since the contents are cleared
-// in the finally block.
-var reusableReplaceArray = new InternalArray(4);
-
-// Helper function for replacing regular expressions with the result of a
-// function application in String.prototype.replace.
-function StringReplaceGlobalRegExpWithFunction(subject, regexp, replace) {
-  var resultArray = reusableReplaceArray;
-  if (resultArray) {
-    reusableReplaceArray = null;
-  } else {
-    // Inside a nested replace (replace called from the replacement function
-    // of another replace) or we have failed to set the reusable array
-    // back due to an exception in a replacement function. Create a new
-    // array to use in the future, or until the original is written back.
-    resultArray = new InternalArray(16);
-  }
-  var res = %RegExpExecMultiple(regexp,
-                                subject,
-                                RegExpLastMatchInfo,
-                                resultArray);
-  regexp.lastIndex = 0;
-  if (IS_NULL(res)) {
-    // No matches at all.
-    reusableReplaceArray = resultArray;
-    return subject;
-  }
-  var len = res.length;
-  if (NUMBER_OF_CAPTURES(RegExpLastMatchInfo) == 2) {
-    // If the number of captures is two then there are no explicit captures in
-    // the regexp, just the implicit capture that captures the whole match.  In
-    // this case we can simplify quite a bit and end up with something faster.
-    // The builder will consist of some integers that indicate slices of the
-    // input string and some replacements that were returned from the replace
-    // function.
-    var match_start = 0;
-    for (var i = 0; i < len; i++) {
-      var elem = res[i];
-      if (%_IsSmi(elem)) {
-        // Integers represent slices of the original string.
-        if (elem > 0) {
-          match_start = (elem >> 11) + (elem & 0x7ff);
-        } else {
-          match_start = res[++i] - elem;
-        }
-      } else {
-        var func_result = replace(elem, match_start, subject);
-        // Overwrite the i'th element in the results with the string we got
-        // back from the callback function.
-        res[i] = TO_STRING(func_result);
-        match_start += elem.length;
-      }
-    }
-  } else {
-    for (var i = 0; i < len; i++) {
-      var elem = res[i];
-      if (!%_IsSmi(elem)) {
-        // elem must be an Array.
-        // Use the apply argument as backing for global RegExp properties.
-        var func_result = %Apply(replace, UNDEFINED, elem, 0, elem.length);
-        // Overwrite the i'th element in the results with the string we got
-        // back from the callback function.
-        res[i] = TO_STRING(func_result);
-      }
-    }
-  }
-  var result = %StringBuilderConcat(res, len, subject);
-  resultArray.length = 0;
-  reusableReplaceArray = resultArray;
-  return result;
-}
-
-
-function StringReplaceNonGlobalRegExpWithFunction(subject, regexp, replace) {
-  var matchInfo = RegExpExec(regexp, subject, 0);
-  if (IS_NULL(matchInfo)) {
-    regexp.lastIndex = 0;
-    return subject;
-  }
-  var index = matchInfo[CAPTURE0];
-  var result = %_SubString(subject, 0, index);
-  var endOfMatch = matchInfo[CAPTURE1];
-  // Compute the parameter list consisting of the match, captures, index,
-  // and subject for the replace function invocation.
-  // The number of captures plus one for the match.
-  var m = NUMBER_OF_CAPTURES(matchInfo) >> 1;
-  var replacement;
-  if (m == 1) {
-    // No captures, only the match, which is always valid.
-    var s = %_SubString(subject, index, endOfMatch);
-    // Don't call directly to avoid exposing the built-in global object.
-    replacement = replace(s, index, subject);
-  } else {
-    var parameters = new InternalArray(m + 2);
-    for (var j = 0; j < m; j++) {
-      parameters[j] = CaptureString(subject, matchInfo, j);
-    }
-    parameters[j] = index;
-    parameters[j + 1] = subject;
-
-    replacement = %Apply(replace, UNDEFINED, parameters, 0, j + 2);
-  }
-
-  result += replacement;  // The add method converts to string if necessary.
-  // Can't use matchInfo any more from here, since the function could
-  // overwrite it.
-  return result + %_SubString(subject, endOfMatch, subject.length);
-}
-
-
 // ES6 21.1.3.15.
 function StringSearch(pattern) {
   CHECK_OBJECT_COERCIBLE(this, "String.prototype.search");
@@ -1098,6 +944,7 @@ utils.InstallFunctions(GlobalString.prototype, DONT_ENUM, [
 // Exports
 
 utils.Export(function(to) {
+  to.ExpandReplacement = ExpandReplacement;
   to.StringCharAt = StringCharAtJS;
   to.StringIndexOf = StringIndexOfJS;
   to.StringLastIndexOf = StringLastIndexOfJS;