1// Copyright 2011 the V8 project authors. All rights reserved.
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3// modification, are permitted provided that the following conditions are
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27
28#ifndef V8_SCANNER_CHARACTER_STREAMS_H_
29#define V8_SCANNER_CHARACTER_STREAMS_H_
30
31#include "scanner.h"
32
33namespace v8 {
34namespace internal {
35
36// A buffered character stream based on a random access character
37// source (ReadBlock can be called with pos_ pointing to any position,
38// even positions before the current).
39class BufferedUtf16CharacterStream: public Utf16CharacterStream {
40 public:
41  BufferedUtf16CharacterStream();
42  virtual ~BufferedUtf16CharacterStream();
43
44  virtual void PushBack(uc32 character);
45
46 protected:
47  static const unsigned kBufferSize = 512;
48  static const unsigned kPushBackStepSize = 16;
49
50  virtual unsigned SlowSeekForward(unsigned delta);
51  virtual bool ReadBlock();
52  virtual void SlowPushBack(uc16 character);
53
54  virtual unsigned BufferSeekForward(unsigned delta) = 0;
55  virtual unsigned FillBuffer(unsigned position, unsigned length) = 0;
56
57  const uc16* pushback_limit_;
58  uc16 buffer_[kBufferSize];
59};
60
61
62// Generic string stream.
63class GenericStringUtf16CharacterStream: public BufferedUtf16CharacterStream {
64 public:
65  GenericStringUtf16CharacterStream(Handle<String> data,
66                                    unsigned start_position,
67                                    unsigned end_position);
68  virtual ~GenericStringUtf16CharacterStream();
69
70 protected:
71  virtual unsigned BufferSeekForward(unsigned delta);
72  virtual unsigned FillBuffer(unsigned position, unsigned length);
73
74  Handle<String> string_;
75  unsigned start_position_;
76  unsigned length_;
77};
78
79
80// Utf16 stream based on a literal UTF-8 string.
81class Utf8ToUtf16CharacterStream: public BufferedUtf16CharacterStream {
82 public:
83  Utf8ToUtf16CharacterStream(const byte* data, unsigned length);
84  virtual ~Utf8ToUtf16CharacterStream();
85
86 protected:
87  virtual unsigned BufferSeekForward(unsigned delta);
88  virtual unsigned FillBuffer(unsigned char_position, unsigned length);
89  void SetRawPosition(unsigned char_position);
90
91  const byte* raw_data_;
92  unsigned raw_data_length_;  // Measured in bytes, not characters.
93  unsigned raw_data_pos_;
94  // The character position of the character at raw_data[raw_data_pos_].
95  // Not necessarily the same as pos_.
96  unsigned raw_character_position_;
97};
98
99
100// UTF16 buffer to read characters from an external string.
101class ExternalTwoByteStringUtf16CharacterStream: public Utf16CharacterStream {
102 public:
103  ExternalTwoByteStringUtf16CharacterStream(Handle<ExternalTwoByteString> data,
104                                            int start_position,
105                                            int end_position);
106  virtual ~ExternalTwoByteStringUtf16CharacterStream();
107
108  virtual void PushBack(uc32 character) {
109    ASSERT(buffer_cursor_ > raw_data_);
110    buffer_cursor_--;
111    pos_--;
112  }
113
114 protected:
115  virtual unsigned SlowSeekForward(unsigned delta) {
116    // Fast case always handles seeking.
117    return 0;
118  }
119  virtual bool ReadBlock() {
120    // Entire string is read at start.
121    return false;
122  }
123  Handle<ExternalTwoByteString> source_;
124  const uc16* raw_data_;  // Pointer to the actual array of characters.
125};
126
127} }  // namespace v8::internal
128
129#endif  // V8_SCANNER_CHARACTER_STREAMS_H_
130