Add StringBufferStream

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index b99ba44723122cbd4b38fa9e1cdd1b070c7710d9..f633a5c54d71ae6ba81c80b0164936482d9b6613 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -2512,6 +2512,79 @@ String* String::GetUnderlying() {
 }
 
 
+template<class Visitor, class ConsOp>
+void String::Visit(
+    String* string,
+    unsigned offset,
+    Visitor& visitor,
+    ConsOp& consOp,
+    int32_t type,
+    unsigned length) {
+
+  ASSERT(length == static_cast<unsigned>(string->length()));
+  ASSERT(offset <= length);
+
+  unsigned sliceOffset = offset;
+  while (true) {
+    ASSERT(type == string->map()->instance_type());
+
+    switch (type & (kStringRepresentationMask | kStringEncodingMask)) {
+    case kSeqStringTag | kOneByteStringTag:

[Yang, 2012/12/04 14:49:11]

We usually indent switch-case-clauses like
switch (x) {
  case y:
    z();
    break;
}

+      visitor.VisitOneByteString(
+          reinterpret_cast<const uint8_t*>(
+              SeqOneByteString::cast(string)->GetChars()) + sliceOffset,
+          length - offset);

[Yang, 2012/12/04 14:49:11]

I suggest adding four more spaces as indentation.

+      return;
+
+    case kSeqStringTag | kTwoByteStringTag:
+      visitor.VisitTwoByteString(
+          reinterpret_cast<const uint16_t*>(
+              SeqTwoByteString::cast(string)->GetChars()) + sliceOffset,
+          length - offset);
+      return;
+
+    case kExternalStringTag | kOneByteStringTag:
+      visitor.VisitOneByteString(
+          reinterpret_cast<const uint8_t*>(
+              ExternalAsciiString::cast(string)->GetChars()) + sliceOffset,
+          length - offset);
+      return;
+
+    case kExternalStringTag | kTwoByteStringTag:
+      visitor.VisitTwoByteString(
+          reinterpret_cast<const uint16_t*>(
+              ExternalTwoByteString::cast(string)->GetChars()) + sliceOffset,
+          length - offset);
+      return;
+
+    case kSlicedStringTag | kOneByteStringTag:
+    case kSlicedStringTag | kTwoByteStringTag:
+    {
+      SlicedString* slicedString = SlicedString::cast(string);
+      sliceOffset += slicedString->offset();
+      string = slicedString->parent();
+      type = string->map()->instance_type();
+      continue;
+    }
+
+    case kConsStringTag | kOneByteStringTag:
+    case kConsStringTag | kTwoByteStringTag:
+      string = consOp.Operate(
+          ConsString::cast(string), &offset, &type, &length);
+      if (string == NULL)

[Yang, 2012/12/04 14:49:11]

no line break here.

+        return;
+      sliceOffset = offset;
+      ASSERT(length == static_cast<unsigned>(string->length()));
+      continue;
+
+    default:
+      UNREACHABLE();
+      return;
+    }
+  }
+}
+
+
 uint16_t SeqOneByteString::SeqOneByteStringGet(int index) {
   ASSERT(index >= 0 && index < length());
   return READ_BYTE_FIELD(this, kHeaderSize + index * kCharSize);
@@ -2690,6 +2763,149 @@ const uint16_t* ExternalTwoByteString::ExternalTwoByteStringGetData(
 }
 
 
+unsigned ConsStringIteratorOp::OffsetForDepth(unsigned depth) {
+  return depth & depthMask;
+}
+
+
+uint32_t ConsStringIteratorOp::MaskForDepth(unsigned depth) {
+  return 1 << OffsetForDepth(depth);
+}
+
+
+void ConsStringIteratorOp::SetRightDescent() {
+  trace |= MaskForDepth(depth - 1);
+}
+
+
+void ConsStringIteratorOp::ClearRightDescent() {
+  trace &= ~MaskForDepth(depth - 1);
+}
+
+
+void ConsStringIteratorOp::PushLeft(ConsString* string) {
+  frames[depth++ & depthMask] = string;
+}
+
+
+void ConsStringIteratorOp::PushRight(ConsString* string, int32_t type) {
+  // Inplace update
+  frames[depth-1 & depthMask] = string;
+  // Optimization: can replace root here.
+  if (depth == 1) {
+    root = string;
+    rootType = type;
+    rootLength = root->length();
+  }
+}
+
+
+void ConsStringIteratorOp::AdjustMaximumDepth() {
+  if (depth > maximumDepth)
+    maximumDepth = depth;

[Yang, 2012/12/04 14:49:11]

No line break here.

+}
+
+
+void ConsStringIteratorOp::Pop() {
+  ASSERT(depth > 0);
+  ASSERT(depth <= maximumDepth);
+  depth--;
+}
+
+
+void ConsStringIteratorOp::Reset() {
+  consumed = 0;
+  ResetStack();
+}
+
+
+bool ConsStringIteratorOp::HasMore() {
+  return depth != 0;
+}
+
+
+void ConsStringIteratorOp::ResetStack() {
+  depth = 0;
+  maximumDepth = 0;
+}
+
+
+bool ConsStringIteratorOp::ContinueOperation(ContinueResponse* response) {
+  bool blewStack;
+  int32_t type;
+  String* string = NextLeaf(&blewStack, &type);
+  // String found.
+  if (string != NULL) {
+    unsigned length = string->length();
+    consumed += length;
+    response->string = string;
+    response->offset = 0;
+    response->length = length;
+    response->type = type;
+    return true;
+  }
+  // Traversal complete.
+  if (!blewStack)
+    return false;

[Yang, 2012/12/04 14:49:11]

no line break.

+  // Restart search.
+  ResetStack();
+  response->string = root;
+  response->offset = consumed;
+  response->length = root->length();
+  response->type = rootType;
+  return true;
+}
+
+
+uint16_t StringBufferStream::GetNext() {
+  return isOneByte ? *buffer8++ : *buffer16++;
+}
+
+
+void StringBufferStream::Reset(String* string, unsigned offset,

[Yang, 2012/12/04 14:49:11]

Please put all arguments on the second line.

+    ConsStringIteratorOp* op) {
+  buffer8 = NULL;
+  end = NULL;
+  this->op = op;
+  op->Reset();
+  String::Visit(string,
+      offset, *this, *op, string->map()->instance_type(), string->length());
+}
+
+
+bool StringBufferStream::has_more() {
+  if (buffer8 != end)
+    return true;

[Yang, 2012/12/04 14:49:11]

no line break here and in the following if.

+  if (!op->HasMore())
+    return false;
+  ConsStringIteratorOp::ContinueResponse response;
+  // This has been checked above
+  if (!op->ContinueOperation(&response)) {
+    UNREACHABLE();
+    return false;
+  }
+  String::Visit(response.string,
+      response.offset, *this, *op, response.type, response.length);
+  return true;
+}
+
+
+void StringBufferStream::VisitOneByteString(const uint8_t* chars,
+    unsigned length) {

[Yang, 2012/12/04 14:49:11]

Either align the two arguments or put both on the second line.

+  isOneByte = true;
+  buffer8 = chars;
+  end = chars + length;
+}
+
+
+void StringBufferStream::VisitTwoByteString(const uint16_t* chars,
+    unsigned length) {

[Yang, 2012/12/04 14:49:11]

Ditto.

+  isOneByte = false;
+  buffer16 = chars;
+  end = reinterpret_cast<const uint8_t*>(chars + length);
+}
+
+
 void JSFunctionResultCache::MakeZeroSize() {
   set_finger_index(kEntriesIndex);
   set_size(kEntriesIndex);