Reland r13275 and 13276 (Remove most uses of StringInputBuffer).

src/api.cc

 // Copyright 2012 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 4026 matching lines @@
     // once without a capacity limit, which will get into the other branch of
     // this 'if'.
     int utf8_bytes = i::Utf8Length(str);
     if ((options & NO_NULL_TERMINATION) == 0) utf8_bytes++;
     if (utf8_bytes <= capacity) {
       return WriteUtf8(buffer, -1, nchars_ref, options);
     }
   }
 
   // Slow case.
-  i::StringInputBuffer& write_input_buffer = *isolate->write_input_buffer();
+  i::StringCharacterStream stream(*str, isolate->write_iterator());
   isolate->string_tracker()->RecordWrite(str);
 
-  write_input_buffer.Reset(0, *str);
   int len = str->length();
   // Encode the first K - 3 bytes directly into the buffer since we
   // know there's room for them.  If no capacity is given we copy all
   // of them here.
   int fast_end = capacity - (unibrow::Utf8::kMaxEncodedSize - 1);
   int i;
   int pos = 0;
   int nchars = 0;
   int previous = unibrow::Utf16::kNoPreviousCharacter;
   for (i = 0; i < len && (capacity == -1 || pos < fast_end); i++) {
-    i::uc32 c = write_input_buffer.GetNext();
+    i::uc32 c = stream.GetNext();
     int written = unibrow::Utf8::Encode(buffer + pos, c, previous);
     pos += written;
     nchars++;
     previous = c;
   }
   if (i < len) {
     // For the last characters we need to check the length for each one
     // because they may be longer than the remaining space in the
     // buffer.
     char intermediate[unibrow::Utf8::kMaxEncodedSize];
     for (; i < len && pos < capacity; i++) {
-      i::uc32 c = write_input_buffer.GetNext();
+      i::uc32 c = stream.GetNext();
       if (unibrow::Utf16::IsTrailSurrogate(c) &&
           unibrow::Utf16::IsLeadSurrogate(previous)) {
         // We can't use the intermediate buffer here because the encoding
         // of surrogate pairs is done under assumption that you can step
         // back and fix the UTF8 stream.  Luckily we only need space for one
         // more byte, so there is always space.
         ASSERT(pos < capacity);
         int written = unibrow::Utf8::Encode(buffer + pos, c, previous);
         ASSERT(written == 1);
         pos += written;
@@ skipping 35 matching lines @@
   LOG_API(isolate, "String::WriteAscii");
   ENTER_V8(isolate);
   ASSERT(start >= 0 && length >= -1);
   i::Handle<i::String> str = Utils::OpenHandle(this);
   isolate->string_tracker()->RecordWrite(str);
   if (options & HINT_MANY_WRITES_EXPECTED) {
     FlattenString(str);  // Flatten the string for efficiency.
   }
 
   if (str->IsOneByteRepresentation()) {
-    // WriteToFlat is faster than using the StringInputBuffer.
+    // WriteToFlat is faster than using the StringCharacterStream.
     if (length == -1) length = str->length() + 1;
     int len = i::Min(length, str->length() - start);
     i::String::WriteToFlat(*str, buffer, start, start + len);
     if (!(options & PRESERVE_ASCII_NULL)) {
       for (int i = 0; i < len; i++) {
         if (buffer[i] == '\0') buffer[i] = ' ';
       }
     }
     if (!(options & NO_NULL_TERMINATION) && length > len) {
       buffer[len] = '\0';
     }
     return len;
   }
 
-  i::StringInputBuffer& write_input_buffer = *isolate->write_input_buffer();
   int end = length;
   if ((length == -1) || (length > str->length() - start)) {
     end = str->length() - start;
   }
   if (end < 0) return 0;
-  write_input_buffer.Reset(start, *str);
+  i::StringCharacterStream write_stream(*str, isolate->write_iterator(), start);
   int i;
   for (i = 0; i < end; i++) {
-    char c = static_cast<char>(write_input_buffer.GetNext());
+    char c = static_cast<char>(write_stream.GetNext());
     if (c == '\0' && !(options & PRESERVE_ASCII_NULL)) c = ' ';
     buffer[i] = c;
   }
   if (!(options & NO_NULL_TERMINATION) && (length == -1 || i < length)) {
     buffer[i] = '\0';
   }
   return i;
 }
 
 
 int String::Write(uint16_t* buffer,
                   int start,
                   int length,
                   int options) const {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   if (IsDeadCheck(isolate, "v8::String::Write()")) return 0;
   LOG_API(isolate, "String::Write");
   ENTER_V8(isolate);
   ASSERT(start >= 0 && length >= -1);
   i::Handle<i::String> str = Utils::OpenHandle(this);
   isolate->string_tracker()->RecordWrite(str);
   if (options & HINT_MANY_WRITES_EXPECTED) {
     // Flatten the string for efficiency.  This applies whether we are
-    // using StringInputBuffer or Get(i) to access the characters.
+    // using StringCharacterStream or Get(i) to access the characters.
     FlattenString(str);
   }
   int end = start + length;
   if ((length == -1) || (length > str->length() - start) )
     end = str->length();
   if (end < 0) return 0;
   i::String::WriteToFlat(*str, buffer, start, end);
   if (!(options & NO_NULL_TERMINATION) &&
       (length == -1 || end - start < length)) {
     buffer[end - start] = '\0';
@@ skipping 2526 matching lines @@
 
   v->VisitPointers(blocks_.first(), first_block_limit_);
 
   for (int i = 1; i < blocks_.length(); i++) {
     v->VisitPointers(blocks_[i], &blocks_[i][kHandleBlockSize]);
   }
 }
 
 
 } }  // namespace v8::internal