src/scanner-character-streams.h

   1 // Copyright 2011 the V8 project authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef V8_SCANNER_CHARACTER_STREAMS_H_
   6 #define V8_SCANNER_CHARACTER_STREAMS_H_
   7
   8 #include "src/scanner.h"
   9
  10 namespace v8 {
  11 namespace internal {
  12
  13 // A buffered character stream based on a random access character
  14 // source (ReadBlock can be called with pos_ pointing to any position,
  15 // even positions before the current).
  16 class BufferedUtf16CharacterStream: public Utf16CharacterStream {
  17  public:
  18   BufferedUtf16CharacterStream();
  19   virtual ~BufferedUtf16CharacterStream();
  20
  21   virtual void PushBack(uc32 character);
  22
  23  protected:
  24   static const unsigned kBufferSize = 512;
  25   static const unsigned kPushBackStepSize = 16;
  26
  27   virtual unsigned SlowSeekForward(unsigned delta);
  28   virtual bool ReadBlock();
  29   virtual void SlowPushBack(uc16 character);
  30
  31   virtual unsigned BufferSeekForward(unsigned delta) = 0;
  32   virtual unsigned FillBuffer(unsigned position) = 0;
  33
  34   const uc16* pushback_limit_;
  35   uc16 buffer_[kBufferSize];
  36 };
  37
  38
  39 // Generic string stream.
  40 class GenericStringUtf16CharacterStream: public BufferedUtf16CharacterStream {
  41  public:
  42   GenericStringUtf16CharacterStream(Handle<String> data,
  43                                     unsigned start_position,
  44                                     unsigned end_position);
  45   virtual ~GenericStringUtf16CharacterStream();
  46
  47  protected:
  48   virtual unsigned BufferSeekForward(unsigned delta);
  49   virtual unsigned FillBuffer(unsigned position);
  50
  51   Handle<String> string_;
  52   unsigned length_;
  53 };
  54
  55
  56 // Utf16 stream based on a literal UTF-8 string.
  57 class Utf8ToUtf16CharacterStream: public BufferedUtf16CharacterStream {
  58  public:
  59   Utf8ToUtf16CharacterStream(const byte* data, unsigned length);
  60   virtual ~Utf8ToUtf16CharacterStream();
  61
  62  protected:
  63   virtual unsigned BufferSeekForward(unsigned delta);
  64   virtual unsigned FillBuffer(unsigned char_position);
  65   void SetRawPosition(unsigned char_position);
  66
  67   const byte* raw_data_;
  68   unsigned raw_data_length_;  // Measured in bytes, not characters.
  69   unsigned raw_data_pos_;
  70   // The character position of the character at raw_data[raw_data_pos_].
  71   // Not necessarily the same as pos_.
  72   unsigned raw_character_position_;
  73 };
  74
  75
  76 // UTF16 buffer to read characters from an external string.
  77 class ExternalTwoByteStringUtf16CharacterStream: public Utf16CharacterStream {
  78  public:
  79   ExternalTwoByteStringUtf16CharacterStream(Handle<ExternalTwoByteString> data,
  80                                             int start_position,
  81                                             int end_position);
  82   virtual ~ExternalTwoByteStringUtf16CharacterStream();
  83
  84   virtual void PushBack(uc32 character) {
  85     DCHECK(buffer_cursor_ > raw_data_);
  86     buffer_cursor_--;
  87     pos_--;
  88   }
  89
  90  protected:
  91   virtual unsigned SlowSeekForward(unsigned delta) {
  92     // Fast case always handles seeking.
  93     return 0;
  94   }
  95   virtual bool ReadBlock() {
  96     // Entire string is read at start.
  97     return false;
  98   }
  99   Handle<ExternalTwoByteString> source_;
 100   const uc16* raw_data_;  // Pointer to the actual array of characters.
 101 };
 102
 103 } }  // namespace v8::internal
 104
 105 #endif  // V8_SCANNER_CHARACTER_STREAMS_H_