src/v8/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   static unsigned CopyChars(uint16_t* dest, unsigned length, const byte* src,
  63                             unsigned* src_pos, unsigned src_length);
  64
  65  protected:
  66   virtual unsigned BufferSeekForward(unsigned delta);
  67   virtual unsigned FillBuffer(unsigned char_position);
  68   void SetRawPosition(unsigned char_position);
  69
  70   const byte* raw_data_;
  71   unsigned raw_data_length_;  // Measured in bytes, not characters.
  72   unsigned raw_data_pos_;
  73   // The character position of the character at raw_data[raw_data_pos_].
  74   // Not necessarily the same as pos_.
  75   unsigned raw_character_position_;
  76 };
  77
  78
  79 // ExternalStreamingStream is a wrapper around an ExternalSourceStream (see
  80 // include/v8.h) subclass implemented by the embedder.
  81 class ExternalStreamingStream : public BufferedUtf16CharacterStream {
  82  public:
  83   ExternalStreamingStream(ScriptCompiler::ExternalSourceStream* source_stream,
  84                           v8::ScriptCompiler::StreamedSource::Encoding encoding)
  85       : source_stream_(source_stream),
  86         encoding_(encoding),
  87         current_data_(NULL),
  88         current_data_offset_(0),
  89         current_data_length_(0),
  90         utf8_split_char_buffer_length_(0) {}
  91
  92   virtual ~ExternalStreamingStream() { delete[] current_data_; }
  93
  94   virtual unsigned BufferSeekForward(unsigned delta) OVERRIDE {
  95     // We never need to seek forward when streaming scripts. We only seek
  96     // forward when we want to parse a function whose location we already know,
  97     // and when streaming, we don't know the locations of anything we haven't
  98     // seen yet.
  99     UNREACHABLE();
 100     return 0;
 101   }
 102
 103   virtual unsigned FillBuffer(unsigned position) OVERRIDE;
 104
 105  private:
 106   void HandleUtf8SplitCharacters(unsigned* data_in_buffer);
 107
 108   ScriptCompiler::ExternalSourceStream* source_stream_;
 109   v8::ScriptCompiler::StreamedSource::Encoding encoding_;
 110   const uint8_t* current_data_;
 111   unsigned current_data_offset_;
 112   unsigned current_data_length_;
 113   // For converting UTF-8 characters which are split across two data chunks.
 114   uint8_t utf8_split_char_buffer_[4];
 115   unsigned utf8_split_char_buffer_length_;
 116 };
 117
 118
 119 // UTF16 buffer to read characters from an external string.
 120 class ExternalTwoByteStringUtf16CharacterStream: public Utf16CharacterStream {
 121  public:
 122   ExternalTwoByteStringUtf16CharacterStream(Handle<ExternalTwoByteString> data,
 123                                             int start_position,
 124                                             int end_position);
 125   virtual ~ExternalTwoByteStringUtf16CharacterStream();
 126
 127   virtual void PushBack(uc32 character) {
 128     DCHECK(buffer_cursor_ > raw_data_);
 129     buffer_cursor_--;
 130     pos_--;
 131   }
 132
 133  protected:
 134   virtual unsigned SlowSeekForward(unsigned delta) {
 135     // Fast case always handles seeking.
 136     return 0;
 137   }
 138   virtual bool ReadBlock() {
 139     // Entire string is read at start.
 140     return false;
 141   }
 142   Handle<ExternalTwoByteString> source_;
 143   const uc16* raw_data_;  // Pointer to the actual array of characters.
 144 };
 145
 146 } }  // namespace v8::internal
 147
 148 #endif  // V8_SCANNER_CHARACTER_STREAMS_H_