Rework scanner-character-streams.

src/parsing/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_PARSING_SCANNER_CHARACTER_STREAMS_H_
 #define V8_PARSING_SCANNER_CHARACTER_STREAMS_H_
 
+#include "include/v8.h"  // for v8::ScriptCompiler
 #include "src/handles.h"
-#include "src/parsing/scanner.h"
-#include "src/vector.h"
 
 namespace v8 {
 namespace internal {
 
-// Forward declarations.
-class ExternalTwoByteString;
-class ExternalOneByteString;
+class Utf16CharacterStream;
 
-// 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 BufferedUtf16CharacterStream: public Utf16CharacterStream {
+class ScannerStream {
  public:
-  BufferedUtf16CharacterStream();
-  ~BufferedUtf16CharacterStream() override;
-
-  void PushBack(uc32 character) override;
-
- protected:
-  static const size_t kBufferSize = 512;
-  static const size_t kPushBackStepSize = 16;
-
-  size_t SlowSeekForward(size_t delta) override;
-  bool ReadBlock() override;
-  virtual void SlowPushBack(uc16 character);
-
-  virtual size_t BufferSeekForward(size_t delta) = 0;
-  virtual size_t FillBuffer(size_t position) = 0;
-
-  const uc16* pushback_limit_;
-  uc16 buffer_[kBufferSize];
-};
-
-
-// Generic string stream.
-class GenericStringUtf16CharacterStream: public BufferedUtf16CharacterStream {
- public:
-  GenericStringUtf16CharacterStream(Handle<String> data, size_t start_position,
-                                    size_t end_position);
-  ~GenericStringUtf16CharacterStream() override;
-
-  bool SetBookmark() override;
-  void ResetToBookmark() override;
-
- protected:
-  static const size_t kNoBookmark = -1;
-
-  size_t BufferSeekForward(size_t delta) override;
-  size_t FillBuffer(size_t position) override;
-
-  Handle<String> string_;
-  size_t length_;
-  size_t bookmark_;
-};
-
-
-// ExternalStreamingStream is a wrapper around an ExternalSourceStream (see
-// include/v8.h) subclass implemented by the embedder.
-class ExternalStreamingStream : public BufferedUtf16CharacterStream {
- public:
-  ExternalStreamingStream(ScriptCompiler::ExternalSourceStream* source_stream,
-                          v8::ScriptCompiler::StreamedSource::Encoding encoding)
-      : source_stream_(source_stream),
-        encoding_(encoding),
-        current_data_(NULL),
-        current_data_offset_(0),
-        current_data_length_(0),
-        utf8_split_char_buffer_length_(0),
-        bookmark_(0),
-        bookmark_data_is_from_current_data_(false),
-        bookmark_data_offset_(0),
-        bookmark_utf8_split_char_buffer_length_(0) {}
-
-  ~ExternalStreamingStream() override {
-    delete[] current_data_;
-    bookmark_buffer_.Dispose();
-    bookmark_data_.Dispose();
-  }
-
-  size_t BufferSeekForward(size_t delta) 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;
-  }
-
-  size_t FillBuffer(size_t position) override;
-
-  bool SetBookmark() override;
-  void ResetToBookmark() override;
-
- private:
-  void HandleUtf8SplitCharacters(size_t* data_in_buffer);
-  void FlushCurrent();
-
-  ScriptCompiler::ExternalSourceStream* source_stream_;
-  v8::ScriptCompiler::StreamedSource::Encoding encoding_;
-  const uint8_t* current_data_;
-  size_t current_data_offset_;
-  size_t current_data_length_;
-  // For converting UTF-8 characters which are split across two data chunks.
-  uint8_t utf8_split_char_buffer_[4];
-  size_t utf8_split_char_buffer_length_;
-
-  // Bookmark support. See comments in ExternalStreamingStream::SetBookmark
-  // for additional details.
-  size_t bookmark_;
-  Vector<uint16_t> bookmark_buffer_;
-  Vector<uint8_t> bookmark_data_;
-  bool bookmark_data_is_from_current_data_;
-  size_t bookmark_data_offset_;
-  uint8_t bookmark_utf8_split_char_buffer_[4];
-  size_t bookmark_utf8_split_char_buffer_length_;
-};
-
-
-// UTF16 buffer to read characters from an external string.
-class ExternalTwoByteStringUtf16CharacterStream: public Utf16CharacterStream {
- public:
-  ExternalTwoByteStringUtf16CharacterStream(Handle<ExternalTwoByteString> data,
-                                            int start_position,
-                                            int end_position);
-  ~ExternalTwoByteStringUtf16CharacterStream() override;
-
-  void PushBack(uc32 character) override {
-    DCHECK(buffer_cursor_ > raw_data_);
-    pos_--;
-    if (character != kEndOfInput) {
-      buffer_cursor_--;
-    }
-  }
-
-  bool SetBookmark() override;
-  void ResetToBookmark() override;
-
- private:
-  size_t SlowSeekForward(size_t delta) override {
-    // Fast case always handles seeking.
-    return 0;
-  }
-  bool ReadBlock() override {
-    // Entire string is read at start.
-    return false;
-  }
-  const uc16* raw_data_;  // Pointer to the actual array of characters.
-
-  static const size_t kNoBookmark = -1;
-
-  size_t bookmark_;
-};
-
-// UTF16 buffer to read characters from an external latin1 string.
-class ExternalOneByteStringUtf16CharacterStream
-    : public BufferedUtf16CharacterStream {
- public:
-  ExternalOneByteStringUtf16CharacterStream(Handle<ExternalOneByteString> data,
-                                            int start_position,
-                                            int end_position);
-  ~ExternalOneByteStringUtf16CharacterStream() override;
+  static Utf16CharacterStream* For(Handle<String> data);
+  static Utf16CharacterStream* For(Handle<String> data, int start_pos,
+                                   int end_pos);
+  static Utf16CharacterStream* For(
+      ScriptCompiler::ExternalSourceStream* source_stream,
+      ScriptCompiler::StreamedSource::Encoding encoding);
 
   // For testing:
-  explicit ExternalOneByteStringUtf16CharacterStream(const char* data);
-  ExternalOneByteStringUtf16CharacterStream(const char* data, size_t length);
-
-  bool SetBookmark() override;
-  void ResetToBookmark() override;
-
- private:
-  static const size_t kNoBookmark = -1;
-
-  size_t BufferSeekForward(size_t delta) override;
-  size_t FillBuffer(size_t position) override;
-
-  const uint8_t* raw_data_;  // Pointer to the actual array of characters.
-  size_t length_;
-  size_t bookmark_;
+  static std::unique_ptr<Utf16CharacterStream> ForTesting(const char* data);
+  static std::unique_ptr<Utf16CharacterStream> ForTesting(const char* data,
+                                                          size_t length);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_SCANNER_CHARACTER_STREAMS_H_