Avoids allocating a JSArray of capture information on each non-global

regular expression match.
Also moves all last-match information into one place where it can be
updated from C++ code (this will be used in another afsnit).
Review URL: http://codereview.chromium.org/28184

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1383 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/jsregexp.h

@@ -59,13 +59,15 @@ class RegExpImpl {
   // This function calls the garbage collector if necessary.
   static Handle<Object> Exec(Handle<JSRegExp> regexp,
                              Handle<String> subject,
-                             Handle<Object> index);
+                             int index,
+                             Handle<JSArray> lastMatchInfo);
 
   // Call RegExp.prototyp.exec(string) in a loop.
   // Used by String.prototype.match and String.prototype.replace.
   // This function calls the garbage collector if necessary.
   static Handle<Object> ExecGlobal(Handle<JSRegExp> regexp,
-                                   Handle<String> subject);
+                                   Handle<String> subject,
+                                   Handle<JSArray> lastMatchInfo);
 
   // Prepares a JSRegExp object with Irregexp-specific data.
   static Handle<Object> IrregexpPrepare(Handle<JSRegExp> re,
@@ -79,18 +81,22 @@ class RegExpImpl {
                                     Handle<String> match_pattern);
   static Handle<Object> AtomExec(Handle<JSRegExp> regexp,
                                  Handle<String> subject,
-                                 Handle<Object> index);
+                                 int index,
+                                 Handle<JSArray> lastMatchInfo);
 
   static Handle<Object> AtomExecGlobal(Handle<JSRegExp> regexp,
-                                       Handle<String> subject);
+                                       Handle<String> subject,
+                                       Handle<JSArray> lastMatchInfo);
 
   // Execute an Irregexp bytecode pattern.
   static Handle<Object> IrregexpExec(Handle<JSRegExp> regexp,
                                      Handle<String> subject,
-                                     Handle<Object> index);
+                                     int index,
+                                     Handle<JSArray> lastMatchInfo);
 
   static Handle<Object> IrregexpExecGlobal(Handle<JSRegExp> regexp,
-                                           Handle<String> subject);
+                                           Handle<String> subject,
+                                           Handle<JSArray> lastMatchInfo);
 
   static void NewSpaceCollectionPrologue();
   static void OldSpaceCollectionPrologue();
@@ -107,6 +113,30 @@ class RegExpImpl {
   static const int kIrregexpCodeIndex = 3;
   static const int kIrregexpDataLength = 4;
 
+  // Offsets in the lastMatchInfo array.
+  static const int kLastCaptureCount = 0;
+  static const int kLastSubject = 1;
+  static const int kLastInput = 2;
+  static const int kFirstCapture = 1;
+  static const int kLastMatchOverhead = 3;
+  static int GetCapture(FixedArray* array, int index) {
+    return Smi::cast(array->get(index + kFirstCapture))->value();
+  }
+  static void SetLastCaptureCount(FixedArray* array, int to) {
+    array->set(kLastCaptureCount, Smi::FromInt(to));
+  }
+  static void SetLastSubject(FixedArray* array, String* to) {
+    int capture_count = GetLastCaptureCount(array);
+    array->set(capture_count + kLastSubject, to);
+  }
+  static void SetLastInput(FixedArray* array, String* to) {
+    int capture_count = GetLastCaptureCount(array);
+    array->set(capture_count + kLastInput, to);
+  }
+  static void SetCapture(FixedArray* array, int index, int to) {
+    array->set(index + kFirstCapture, Smi::FromInt(to));
+  }
+
  private:
   static String* last_ascii_string_;
   static String* two_byte_cached_string_;
@@ -121,6 +151,7 @@ class RegExpImpl {
   // Returns an empty handle in case of an exception.
   static Handle<Object> IrregexpExecOnce(Handle<FixedArray> regexp,
                                          int num_captures,
+                                         Handle<JSArray> lastMatchInfo,
                                          Handle<String> subject16,
                                          int previous_index,
                                          int* ovector,
@@ -134,6 +165,10 @@ class RegExpImpl {
                               int character_position,
                               int utf8_position);
 
+  // Used to access the lastMatchInfo array.
+  static int GetLastCaptureCount(FixedArray* array) {
+    return Smi::cast(array->get(kLastCaptureCount))->value();
+  }
   // A one element cache of the last utf8_subject string and its length.  The
   // subject JS String object is cached in the heap.  We also cache a
   // translation between position and utf8 position.

src/macros.py

-# Copyright 2006-2008 the V8 project authors. All rights reserved.
+# 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:
@@ -99,3 +99,22 @@ python macro CHAR_CODE(str) = ord(str[1]);
 # Accessors for original global properties that ensure they have been loaded.
 const ORIGINAL_REGEXP = (global.RegExp, $RegExp);
 const ORIGINAL_DATE   = (global.Date, $Date);
+
+# Constants used on an array to implement the properties of the RegExp object.
+const REGEXP_NUMBER_OF_CAPTURES = 0;
+const REGEXP_FIRST_CAPTURE = 1;
+
+# We can't put macros in macros so we use constants here.
+# REGEXP_NUMBER_OF_CAPTURES
+macro NUMBER_OF_CAPTURES(array) = ((array)[0]);
+
+# Last input and last subject are after the captures so we can omit them on
+# results returned from global searches.  Beware - these evaluate their
+# arguments twice.
+macro LAST_SUBJECT(array) = ((array)[(array)[0] + 1]);
+macro LAST_INPUT(array) = ((array)[(array)[0] + 2]);
+
+# REGEXP_FIRST_CAPTURE
+macro CAPTURE(index) = (1 + (index));
+const CAPTURE0 = 1;
+const CAPTURE1 = 2;

src/objects.cc

@@ -4879,6 +4879,20 @@ Object* JSArray::Initialize(int capacity) {
 }
 
 
+void JSArray::EnsureSize(int required_size) {
+  ASSERT(HasFastElements());
+  if (elements()->length() >= required_size) return;
+  Handle<FixedArray> old_backing(elements());
+  int old_size = old_backing->length();
+  // Doubling in size would be overkill, but leave some slack to avoid
+  // constantly growing.
+  int new_size = required_size + (required_size >> 3);
+  Handle<FixedArray> new_backing = Factory::NewFixedArray(new_size);
+  for (int i = 0; i < old_size; i++) new_backing->set(i, old_backing->get(i));
+  SetContent(*new_backing);
+}
+
+
 // Computes the new capacity when expanding the elements of a JSObject.
 static int NewElementsCapacity(int old_capacity) {
   // (old_capacity + 50%) + 16

src/objects.h

@@ -3779,6 +3779,10 @@ class JSArray: public JSObject {
   // Casting.
   static inline JSArray* cast(Object* obj);
 
+  // Uses handles.  Ensures that the fixed array backing the JSArray has at
+  // least the stated size.
+  void EnsureSize(int minimum_size_of_backing_fixed_array);
+
   // Dispatched behavior.
 #ifdef DEBUG
   void JSArrayPrint();

src/regexp-delay.js

-// Copyright 2006-2008 the V8 project authors. All rights reserved.
+// 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:
@@ -52,7 +52,7 @@ function DoConstructRegExp(object, pattern, flags, isConstructorCall) {
   var multiline = false;
 
   for (var i = 0; i < flags.length; i++) {
-    var c = flags.charAt(i);
+    var c = StringCharAt.call(flags, i);
     switch (c) {
       case 'g':
         // Allow duplicate flags to be consistent with JSC and others.
@@ -117,15 +117,15 @@ function RegExpConstructor(pattern, flags) {
 
 // Deprecated RegExp.prototype.compile method.  We behave like the constructor
 // were called again.  In SpiderMonkey, this method returns the regexp object.
-// In KJS, it returns undefined.  For compatibility with KJS, we match their
+// In JSC, it returns undefined.  For compatibility with JSC, we match their
 // behavior.
 function CompileRegExp(pattern, flags) {
-  // Both KJS and SpiderMonkey treat a missing pattern argument as the
+  // Both JSC and SpiderMonkey treat a missing pattern argument as the
   // empty subject string, and an actual undefined value passed as the
-  // patter as the string 'undefined'.  Note that KJS is inconsistent
+  // pattern as the string 'undefined'.  Note that JSC is inconsistent
   // here, treating undefined values differently in
   // RegExp.prototype.compile and in the constructor, where they are
-  // the empty string.  For compatibility with KJS, we match their
+  // the empty string.  For compatibility with JSC, we match their
   // behavior.
   if (IS_UNDEFINED(pattern) && %_ArgumentsLength() != 0) {
     DoConstructRegExp(this, 'undefined', flags, false);
@@ -135,32 +135,20 @@ function CompileRegExp(pattern, flags) {
 }
 
 
-// DoRegExpExec and DoRegExpExecGlobal are wrappers around the runtime
-// %RegExp and %RegExpGlobal functions that ensure that the static
-// properties of the RegExp constructor are set.
 function DoRegExpExec(regexp, string, index) {
-  var matchIndices = %RegExpExec(regexp, string, index);
-  if (!IS_NULL(matchIndices)) {
-    regExpCaptures = matchIndices;
-    regExpSubject = regExpInput = string;
-  }
-  return matchIndices;
+  return %RegExpExec(regexp, string, index, lastMatchInfo);
 }
 
 
 function DoRegExpExecGlobal(regexp, string) {
-  // Here, matchIndices is an array of arrays of substring indices.
-  var matchIndices = %RegExpExecGlobal(regexp, string);
-  if (matchIndices.length != 0) {
-    regExpCaptures = matchIndices[matchIndices.length - 1];
-    regExpSubject = regExpInput = string;
-  }
-  return matchIndices;
+  // Returns an array of arrays of substring indices.
+  return %RegExpExecGlobal(regexp, string, lastMatchInfo);
 }
 
 
 function RegExpExec(string) {
   if (%_ArgumentsLength() == 0) {
+    var regExpInput = LAST_INPUT(lastMatchInfo);
     if (IS_UNDEFINED(regExpInput)) {
       throw MakeError('no_input_to_regexp', [this]);
     }
@@ -177,23 +165,21 @@ function RegExpExec(string) {
   }
 
   %_Log('regexp', 'regexp-exec,%0r,%1S,%2i', [this, s, lastIndex]);
-  // matchIndices is an array of integers with length of captures*2,
-  // each pair of integers specified the start and the end of index
-  // in the string.
-  var matchIndices = DoRegExpExec(this, s, i);
+  // matchIndices is either null or the lastMatchInfo array.
+  var matchIndices = %RegExpExec(this, s, i, lastMatchInfo);
 
   if (matchIndices == null) {
     if (this.global) this.lastIndex = 0;
     return matchIndices; // no match
   }
 
-  var numResults = matchIndices.length >> 1;
+  var numResults = NUMBER_OF_CAPTURES(lastMatchInfo) >> 1;
   var result = new $Array(numResults);
   for (var i = 0; i < numResults; i++) {
-    var matchStart = matchIndices[2*i];
-    var matchEnd = matchIndices[2*i + 1];
+    var matchStart = lastMatchInfo[CAPTURE(i << 1)];
+    var matchEnd = lastMatchInfo[CAPTURE((i << 1) + 1)];
     if (matchStart != -1 && matchEnd != -1) {
-      result[i] = s.slice(matchStart, matchEnd);
+      result[i] = SubString(s, matchStart, matchEnd);
     } else {
       // Make sure the element is present. Avoid reading the undefined
       // property from the global object since this may change.
@@ -202,13 +188,15 @@ function RegExpExec(string) {
   }
 
   if (this.global)
-    this.lastIndex = matchIndices[1];
-  result.index = matchIndices[0];
+    this.lastIndex = lastMatchInfo[CAPTURE1];
+  result.index = lastMatchInfo[CAPTURE0];
   result.input = s;
   return result;
 }
 
 
+// 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 even if it changes.
 function RegExpTest(string) {
   var result = (%_ArgumentsLength() == 0) ? this.exec() : this.exec(string);
   return result != null;
@@ -236,56 +224,69 @@ function RegExpToString() {
 // on the captures array of the last successful match and the subject string
 // of the last successful match.
 function RegExpGetLastMatch() {
-  return regExpSubject.slice(regExpCaptures[0], regExpCaptures[1]);
+  var regExpSubject = LAST_SUBJECT(lastMatchInfo);
+  return SubString(regExpSubject,
+                   lastMatchInfo[CAPTURE0],
+                   lastMatchInfo[CAPTURE1]);
 }
 
 
 function RegExpGetLastParen() {
-  var length = regExpCaptures.length;
-  if (length <= 2) return ''; // There were no captures.
+  var length = NUMBER_OF_CAPTURES(lastMatchInfo);
+  if (length <= 2) return '';  // There were no captures.
   // We match the SpiderMonkey behavior: return the substring defined by the
   // last pair (after the first pair) of elements of the capture array even if
   // it is empty.
-  return regExpSubject.slice(regExpCaptures[length - 2],
-                             regExpCaptures[length - 1]);
+  var regExpSubject = LAST_SUBJECT(lastMatchInfo);
+  return SubString(regExpSubject,
+                   lastMatchInfo[CAPTURE(length - 2)],
+                   lastMatchInfo[CAPTURE(length - 1)]);
 }
 
 
 function RegExpGetLeftContext() {
-  return regExpSubject.slice(0, regExpCaptures[0]);
+  return SubString(LAST_SUBJECT(lastMatchInfo),
+                   0,
+                   lastMatchInfo[CAPTURE0]);
 }
 
 
 function RegExpGetRightContext() {
-  return regExpSubject.slice(regExpCaptures[1], regExpSubject.length);
+  var subject = LAST_SUBJECT(lastMatchInfo);
+  return SubString(subject,
+                   lastMatchInfo[CAPTURE1],
+                   subject.length);
 }
 
 
 // The properties $1..$9 are the first nine capturing substrings of the last
 // successful match, or ''.  The function RegExpMakeCaptureGetter will be
-// called with an index greater than or equal to 1 but it actually works for
-// any non-negative index.
+// called with indeces from 1 to 9.
 function RegExpMakeCaptureGetter(n) {
   return function() {
     var index = n * 2;
-    if (index >= regExpCaptures.length) return '';
-    var matchStart = regExpCaptures[index];
-    var matchEnd = regExpCaptures[index + 1];
+    if (index >= NUMBER_OF_CAPTURES(lastMatchInfo)) return '';
+    var matchStart = lastMatchInfo[CAPTURE(index)];
+    var matchEnd = lastMatchInfo[CAPTURE(index + 1)];
     if (matchStart == -1 || matchEnd == -1) return '';
-    return regExpSubject.slice(matchStart, matchEnd);
+    return SubString(LAST_SUBJECT(lastMatchInfo), matchStart, matchEnd);
   };
 }
 
 
-// Properties of the builtins object for recording the result of the last
-// regexp match.  The property regExpCaptures is the matchIndices array of the
-// last successful regexp match (an array of start/end index pairs for the
-// match and all the captured substrings), the invariant is that there is at
-// least two elements.  The property regExpSubject is the subject string for
-// the last successful match.
-var regExpCaptures = [0, 0];
-var regExpSubject = '';
-var regExpInput;
+// Property of the builtins object for recording the result of the last
+// regexp match.  The property lastMatchInfo includes the matchIndices
+// array of the last successful regexp match (an array of start/end index
+// pairs for the match and all the captured substrings), the invariant is
+// that there are at least two capture indeces.  The array also contains
+// the subject string for the last successful match.
+var lastMatchInfo = [
+    2,                 // REGEXP_NUMBER_OF_CAPTURES
+    0,                 // REGEXP_FIRST_CAPTURE + 0
+    0,                 // REGEXP_FIRST_CAPTURE + 1
+    "",                // Last subject.
+    void 0,            // Last input - settable with RegExpSetInput.
+];
 
 // -------------------------------------------------------------------
 
@@ -303,19 +304,22 @@ function SetupRegExp() {
   ));
 
   // The spec says nothing about the length of exec and test, but
-  // SpiderMonkey and KJS have length equal to 0.
+  // SpiderMonkey and JSC have length equal to 0.
   %FunctionSetLength($RegExp.prototype.exec, 0);
   %FunctionSetLength($RegExp.prototype.test, 0);
   // The length of compile is 1 in SpiderMonkey.
   %FunctionSetLength($RegExp.prototype.compile, 1);
 
   // The properties input, $input, and $_ are aliases for each other.  When this
-  // value is set the value it is set to is coerced to a string. 
+  // value is set the value it is set to is coerced to a string.
   // Getter and setter for the input.
   function RegExpGetInput() {
+    var regExpInput = LAST_INPUT(lastMatchInfo);
     return IS_UNDEFINED(regExpInput) ? "" : regExpInput;
   }
-  function RegExpSetInput(string) { regExpInput = ToString(string); }
+  function RegExpSetInput(string) {
+    lastMatchInfo[lastMatchInfo[REGEXP_NUMBER_OF_CAPTURES] + 2] = string;
+  };
 
   %DefineAccessor($RegExp, 'input', GETTER, RegExpGetInput, DONT_DELETE);
   %DefineAccessor($RegExp, 'input', SETTER, RegExpSetInput, DONT_DELETE);

src/runtime.cc

@@ -858,14 +858,21 @@ static Object* Runtime_InitializeConstContextSlot(Arguments args) {
 
 static Object* Runtime_RegExpExec(Arguments args) {
   HandleScope scope;
-  ASSERT(args.length() == 3);
+  ASSERT(args.length() == 4);
   CONVERT_CHECKED(JSRegExp, raw_regexp, args[0]);
   Handle<JSRegExp> regexp(raw_regexp);
   CONVERT_CHECKED(String, raw_subject, args[1]);
   Handle<String> subject(raw_subject);
-  Handle<Object> index(args[2]);
-  ASSERT(index->IsNumber());
-  Handle<Object> result = RegExpImpl::Exec(regexp, subject, index);
+  // Due to the way the JS files are constructed this must be less than the
+  // length of a string, i.e. it is always a Smi.  We check anyway for security.
+  CONVERT_CHECKED(Smi, index, args[2]);
+  CONVERT_CHECKED(JSArray, raw_last_match_info, args[3]);
+  Handle<JSArray> last_match_info(raw_last_match_info);
+  CHECK(last_match_info->HasFastElements());
+  Handle<Object> result = RegExpImpl::Exec(regexp,
+                                           subject,
+                                           index->value(),
+                                           last_match_info);
   if (result.is_null()) return Failure::Exception();
   return *result;
 }
@@ -873,12 +880,16 @@ static Object* Runtime_RegExpExec(Arguments args) {
 
 static Object* Runtime_RegExpExecGlobal(Arguments args) {
   HandleScope scope;
-  ASSERT(args.length() == 2);
+  ASSERT(args.length() == 3);
   CONVERT_CHECKED(JSRegExp, raw_regexp, args[0]);
   Handle<JSRegExp> regexp(raw_regexp);
   CONVERT_CHECKED(String, raw_subject, args[1]);
   Handle<String> subject(raw_subject);
-  Handle<Object> result = RegExpImpl::ExecGlobal(regexp, subject);
+  CONVERT_CHECKED(JSArray, raw_last_match_info, args[2]);
+  Handle<JSArray> last_match_info(raw_last_match_info);
+  CHECK(last_match_info->HasFastElements());
+  Handle<Object> result =
+      RegExpImpl::ExecGlobal(regexp, subject, last_match_info);
   if (result.is_null()) return Failure::Exception();
   return *result;
 }

src/runtime.h

@@ -137,8 +137,8 @@ namespace v8 { namespace internal {
   \
   /* Regular expressions */ \
   F(RegExpCompile, 3) \
-  F(RegExpExec, 3) \
-  F(RegExpExecGlobal, 2) \
+  F(RegExpExec, 4) \
+  F(RegExpExecGlobal, 3) \
   \
   /* Strings */ \
   F(StringCharCodeAt, 2) \

test/mjsunit/regexp-string-methods.js

+// Regexp shouldn't use String.prototype.slice()
+var s = new String("foo");
+assertEquals("f", s.slice(0,1));
+String.prototype.slice = function() { return "x"; }
+assertEquals("x", s.slice(0,1));
+assertEquals("g", /g/.exec("gg"));
+
+// Regexp shouldn't use String.prototype.charAt()
+var f1 = new RegExp("f", "i");
+assertEquals("F", f1.exec("F"));
+assertEquals("f", "foo".charAt(0));
+String.prototype.charAt = function(idx) { return 'g'; };
+assertEquals("g", "foo".charAt(0));
+var f2 = new RegExp("[g]", "i");
+assertEquals("G", f2.exec("G"));
+assertTrue(f2.ignoreCase);
+
+// On the other hand test is defined in a semi-coherent way as a call to exec.
+// 15.10.6.3
+// SpiderMonkey fails this one.
+RegExp.prototype.exec = function(string) { return 'x'; }
+assertTrue(/f/.test('x'));

tools/js2c.py

@@ -104,7 +104,7 @@ def ExpandConstants(lines, constants):
 
 def ExpandMacros(lines, macros):
   for name, macro in macros.items():
-    start = lines.find(name, 0)
+    start = lines.find(name + '(', 0)
     while start != -1:
       # Scan over the arguments
       assert lines[start + len(name)] == '('
@@ -132,7 +132,7 @@ def ExpandMacros(lines, macros):
       result = macro.expand(mapping)
       # Replace the occurrence of the macro with the expansion
       lines = lines[:start] + result + lines[end:]
-      start = lines.find(name, end)
+      start = lines.find(name + '(', end)
   return lines
 
 class TextMacro: