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      1 // Copyright 2014 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_UNICODE_DECODER_H_
      6 #define V8_UNICODE_DECODER_H_
      7 
      8 #include <sys/types.h>
      9 #include "src/globals.h"
     10 
     11 namespace unibrow {
     12 
     13 class Utf8DecoderBase {
     14  public:
     15   // Initialization done in subclass.
     16   inline Utf8DecoderBase();
     17   inline Utf8DecoderBase(uint16_t* buffer, size_t buffer_length,
     18                          const uint8_t* stream, size_t stream_length);
     19   inline size_t Utf16Length() const { return utf16_length_; }
     20 
     21  protected:
     22   // This reads all characters and sets the utf16_length_.
     23   // The first buffer_length utf16 chars are cached in the buffer.
     24   void Reset(uint16_t* buffer, size_t buffer_length, const uint8_t* stream,
     25              size_t stream_length);
     26   static void WriteUtf16Slow(const uint8_t* stream, size_t stream_length,
     27                              uint16_t* data, size_t length);
     28   const uint8_t* unbuffered_start_;
     29   size_t unbuffered_length_;
     30   size_t utf16_length_;
     31   bool last_byte_of_buffer_unused_;
     32 
     33  private:
     34   DISALLOW_COPY_AND_ASSIGN(Utf8DecoderBase);
     35 };
     36 
     37 template <size_t kBufferSize>
     38 class Utf8Decoder : public Utf8DecoderBase {
     39  public:
     40   inline Utf8Decoder() {}
     41   inline Utf8Decoder(const char* stream, size_t length);
     42   inline void Reset(const char* stream, size_t length);
     43   inline size_t WriteUtf16(uint16_t* data, size_t length) const;
     44 
     45  private:
     46   uint16_t buffer_[kBufferSize];
     47 };
     48 
     49 
     50 Utf8DecoderBase::Utf8DecoderBase()
     51     : unbuffered_start_(NULL),
     52       unbuffered_length_(0),
     53       utf16_length_(0),
     54       last_byte_of_buffer_unused_(false) {}
     55 
     56 
     57 Utf8DecoderBase::Utf8DecoderBase(uint16_t* buffer, size_t buffer_length,
     58                                  const uint8_t* stream, size_t stream_length) {
     59   Reset(buffer, buffer_length, stream, stream_length);
     60 }
     61 
     62 
     63 template <size_t kBufferSize>
     64 Utf8Decoder<kBufferSize>::Utf8Decoder(const char* stream, size_t length)
     65     : Utf8DecoderBase(buffer_, kBufferSize,
     66                       reinterpret_cast<const uint8_t*>(stream), length) {}
     67 
     68 
     69 template <size_t kBufferSize>
     70 void Utf8Decoder<kBufferSize>::Reset(const char* stream, size_t length) {
     71   Utf8DecoderBase::Reset(buffer_, kBufferSize,
     72                          reinterpret_cast<const uint8_t*>(stream), length);
     73 }
     74 
     75 
     76 template <size_t kBufferSize>
     77 size_t Utf8Decoder<kBufferSize>::WriteUtf16(uint16_t* data,
     78                                             size_t length) const {
     79   DCHECK(length > 0);
     80   if (length > utf16_length_) length = utf16_length_;
     81   // memcpy everything in buffer.
     82   size_t buffer_length =
     83       last_byte_of_buffer_unused_ ? kBufferSize - 1 : kBufferSize;
     84   size_t memcpy_length = length <= buffer_length ? length : buffer_length;
     85   v8::internal::MemCopy(data, buffer_, memcpy_length * sizeof(uint16_t));
     86   if (length <= buffer_length) return length;
     87   DCHECK(unbuffered_start_ != NULL);
     88   // Copy the rest the slow way.
     89   WriteUtf16Slow(unbuffered_start_, unbuffered_length_, data + buffer_length,
     90                  length - buffer_length);
     91   return length;
     92 }
     93 
     94 class Latin1 {
     95  public:
     96   static const unsigned kMaxChar = 0xff;
     97   // Returns 0 if character does not convert to single latin-1 character
     98   // or if the character doesn't not convert back to latin-1 via inverse
     99   // operation (upper to lower, etc).
    100   static inline uint16_t ConvertNonLatin1ToLatin1(uint16_t);
    101 };
    102 
    103 
    104 uint16_t Latin1::ConvertNonLatin1ToLatin1(uint16_t c) {
    105   DCHECK(c > Latin1::kMaxChar);
    106   switch (c) {
    107     // This are equivalent characters in unicode.
    108     case 0x39c:
    109     case 0x3bc:
    110       return 0xb5;
    111     // This is an uppercase of a Latin-1 character
    112     // outside of Latin-1.
    113     case 0x178:
    114       return 0xff;
    115   }
    116   return 0;
    117 }
    118 
    119 
    120 }  // namespace unibrow
    121 
    122 #endif  // V8_UNICODE_DECODER_H_
    123