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      1 // Copyright 2011 the V8 project authors. All rights reserved.
      2 // Redistribution and use in source and binary forms, with or without
      3 // modification, are permitted provided that the following conditions are
      4 // met:
      5 //
      6 //     * Redistributions of source code must retain the above copyright
      7 //       notice, this list of conditions and the following disclaimer.
      8 //     * Redistributions in binary form must reproduce the above
      9 //       copyright notice, this list of conditions and the following
     10 //       disclaimer in the documentation and/or other materials provided
     11 //       with the distribution.
     12 //     * Neither the name of Google Inc. nor the names of its
     13 //       contributors may be used to endorse or promote products derived
     14 //       from this software without specific prior written permission.
     15 //
     16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 #ifndef V8_SCANNER_CHARACTER_STREAMS_H_
     29 #define V8_SCANNER_CHARACTER_STREAMS_H_
     30 
     31 #include "scanner.h"
     32 
     33 namespace v8 {
     34 namespace 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).
     39 class 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.
     63 class 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.
     81 class 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.
    101 class 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