Add script streaming API

src/scanner-character-streams.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_SCANNER_CHARACTER_STREAMS_H_
 #define V8_SCANNER_CHARACTER_STREAMS_H_
 
 #include "src/scanner.h"
 
 namespace v8 {
@@ skipping 41 matching lines @@
   unsigned length_;
 };
 
 
 // Utf16 stream based on a literal UTF-8 string.
 class Utf8ToUtf16CharacterStream: public BufferedUtf16CharacterStream {
  public:
   Utf8ToUtf16CharacterStream(const byte* data, unsigned length);
   virtual ~Utf8ToUtf16CharacterStream();
 
+  static unsigned CopyChars(uint16_t* dest, unsigned length, const byte* src,
+                            unsigned* src_pos, unsigned src_length);
+
  protected:
   virtual unsigned BufferSeekForward(unsigned delta);
   virtual unsigned FillBuffer(unsigned char_position);
   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_;
 };
 
 
+// ExternalStreamingStream is a wrapper around an ExternalSourceStream (see
+// include/v8.h) subclass implemented by the embedder.
+class ExternalStreamingStream : public BufferedUtf16CharacterStream {
+ public:
+  explicit ExternalStreamingStream(ExternalSourceStream* source_stream)
+      : source_stream_(source_stream),
+        current_data_(NULL),
+        current_data_offset_(0),
+        current_data_length_(0),
+        raw_position_(0) {}
+
+  virtual ~ExternalStreamingStream() { delete[] current_data_; }
+
+  virtual unsigned BufferSeekForward(unsigned delta) V8_OVERRIDE {
+    // We never need to seek forward when streaming scripts. We only seek
+    // forward when we want to parse a function whose location we already know,
+    // and when streaming, we don't know the locations of anything we haven't
+    // seen yet.
+    UNREACHABLE();
+    return 0;
+  }
+
+  virtual unsigned FillBuffer(unsigned position);
+
+ private:
+  ExternalSourceStream* source_stream_;
+  const char* current_data_;
+  unsigned current_data_offset_;
+  unsigned current_data_length_;
+  unsigned raw_position_;
+};
+
+
 // UTF16 buffer to read characters from an external string.
 class ExternalTwoByteStringUtf16CharacterStream: public Utf16CharacterStream {
  public:
   ExternalTwoByteStringUtf16CharacterStream(Handle<ExternalTwoByteString> data,
                                             int start_position,
                                             int end_position);
   virtual ~ExternalTwoByteStringUtf16CharacterStream();
 
   virtual void PushBack(uc32 character) {
     DCHECK(buffer_cursor_ > raw_data_);
@@ skipping 10 matching lines @@
     // 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_