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diff --git a/deps/v8/src/scanner-character-streams.h b/deps/v8/src/scanner-character-streams.h
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+// Copyright 2011 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_SCANNER_CHARACTER_STREAMS_H_
+#define V8_SCANNER_CHARACTER_STREAMS_H_
+
+#include "scanner.h"
+
+namespace v8 {
+namespace internal {
+
+// A buffered character stream based on a random access character
+// source (ReadBlock can be called with pos_ pointing to any position,
+// even positions before the current).
+class BufferedUC16CharacterStream: public UC16CharacterStream {
+ public:
+  BufferedUC16CharacterStream();
+  virtual ~BufferedUC16CharacterStream();
+
+  virtual void PushBack(uc32 character);
+
+ protected:
+  static const unsigned kBufferSize = 512;
+  static const unsigned kPushBackStepSize = 16;
+
+  virtual unsigned SlowSeekForward(unsigned delta);
+  virtual bool ReadBlock();
+  virtual void SlowPushBack(uc16 character);
+
+  virtual unsigned BufferSeekForward(unsigned delta) = 0;
+  virtual unsigned FillBuffer(unsigned position, unsigned length) = 0;
+
+  const uc16* pushback_limit_;
+  uc16 buffer_[kBufferSize];
+};
+
+
+// Generic string stream.
+class GenericStringUC16CharacterStream: public BufferedUC16CharacterStream {
+ public:
+  GenericStringUC16CharacterStream(Handle<String> data,
+                                   unsigned start_position,
+                                   unsigned end_position);
+  virtual ~GenericStringUC16CharacterStream();
+
+ protected:
+  virtual unsigned BufferSeekForward(unsigned delta);
+  virtual unsigned FillBuffer(unsigned position, unsigned length);
+
+  Handle<String> string_;
+  unsigned start_position_;
+  unsigned length_;
+};
+
+
+// UC16 stream based on a literal UTF-8 string.
+class Utf8ToUC16CharacterStream: public BufferedUC16CharacterStream {
+ public:
+  Utf8ToUC16CharacterStream(const byte* data, unsigned length);
+  virtual ~Utf8ToUC16CharacterStream();
+
+ protected:
+  virtual unsigned BufferSeekForward(unsigned delta);
+  virtual unsigned FillBuffer(unsigned char_position, unsigned length);
+  void SetRawPosition(unsigned char_position);
+
+  const byte* raw_data_;
+  unsigned raw_data_length_;  // Measured in bytes, not characters.
+  unsigned raw_data_pos_;
+  // The character position of the character at raw_data[raw_data_pos_].
+  // Not necessarily the same as pos_.
+  unsigned raw_character_position_;
+};
+
+
+// UTF16 buffer to read characters from an external string.
+class ExternalTwoByteStringUC16CharacterStream: public UC16CharacterStream {
+ public:
+  ExternalTwoByteStringUC16CharacterStream(Handle<ExternalTwoByteString> data,
+                                           int start_position,
+                                           int end_position);
+  virtual ~ExternalTwoByteStringUC16CharacterStream();
+
+  virtual void PushBack(uc32 character) {
+    ASSERT(buffer_cursor_ > raw_data_);
+    buffer_cursor_--;
+    pos_--;
+  }
+
+ protected:
+  virtual unsigned SlowSeekForward(unsigned delta) {
+    // Fast case always handles seeking.
+    return 0;
+  }
+  virtual bool ReadBlock() {
+    // Entire string is read at start.
+    return false;
+  }
+  Handle<ExternalTwoByteString> source_;
+  const uc16* raw_data_;  // Pointer to the actual array of characters.
+};
+
+} }  // namespace v8::internal
+
+#endif  // V8_SCANNER_CHARACTER_STREAMS_H_