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 // Tencent is pleased to support the open source community by making RapidJSON available.
 //
 // Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip.
 //
 // Licensed under the MIT License (the "License"); you may not use this file except
 // in compliance with the License. You may obtain a copy of the License at
 //
 // http://opensource.org/licenses/MIT
 //
 // Unless required by applicable law or agreed to in writing, software distributed
 // under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
 // CONDITIONS OF ANY KIND, either express or implied. See the License for the
 // specific language governing permissions and limitations under the License.
  
 #ifndef RAPIDJSON_ENCODEDSTREAM_H_
 #define RAPIDJSON_ENCODEDSTREAM_H_
  
 #include "stream.h"
 #include "memorystream.h"
  
 #ifdef __GNUC__
 RAPIDJSON_DIAG_PUSH
 RAPIDJSON_DIAG_OFF(effc++)
 #endif
  
 #ifdef __clang__
 RAPIDJSON_DIAG_PUSH
 RAPIDJSON_DIAG_OFF(padded)
 #endif
  
 RAPIDJSON_NAMESPACE_BEGIN
  
  
 template <typename Encoding, typename InputByteStream>
 class EncodedInputStream
 {
     RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
  
     public:
     typedef typename Encoding::Ch Ch;
  
     EncodedInputStream(InputByteStream& is) : is_(is) { current_ = Encoding::TakeBOM(is_); }
  
     Ch Peek() const { return current_; }
     Ch Take()
     {
         Ch c     = current_;
         current_ = Encoding::Take(is_);
         return c;
     }
     size_t Tell() const { return is_.Tell(); }
  
     // Not implemented
     void Put(Ch) { RAPIDJSON_ASSERT(false); }
     void Flush() { RAPIDJSON_ASSERT(false); }
     Ch* PutBegin()
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
     size_t PutEnd(Ch*)
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
  
     private:
     EncodedInputStream(const EncodedInputStream&);
     EncodedInputStream& operator=(const EncodedInputStream&);
  
     InputByteStream& is_;
     Ch current_;
 };
  
 template <>
 class EncodedInputStream<UTF8<>, MemoryStream>
 {
     public:
     typedef UTF8<>::Ch Ch;
  
     EncodedInputStream(MemoryStream& is) : is_(is)
     {
         if(static_cast<unsigned char>(is_.Peek()) == 0xEFu)
             is_.Take();
         if(static_cast<unsigned char>(is_.Peek()) == 0xBBu)
             is_.Take();
         if(static_cast<unsigned char>(is_.Peek()) == 0xBFu)
             is_.Take();
     }
     Ch Peek() const { return is_.Peek(); }
     Ch Take() { return is_.Take(); }
     size_t Tell() const { return is_.Tell(); }
  
     // Not implemented
     void Put(Ch) {}
     void Flush() {}
     Ch* PutBegin() { return 0; }
     size_t PutEnd(Ch*) { return 0; }
  
     MemoryStream& is_;
  
     private:
     EncodedInputStream(const EncodedInputStream&);
     EncodedInputStream& operator=(const EncodedInputStream&);
 };
  
  
 template <typename Encoding, typename OutputByteStream>
 class EncodedOutputStream
 {
     RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
  
     public:
     typedef typename Encoding::Ch Ch;
  
     EncodedOutputStream(OutputByteStream& os, bool putBOM = true) : os_(os)
     {
         if(putBOM)
             Encoding::PutBOM(os_);
     }
  
     void Put(Ch c) { Encoding::Put(os_, c); }
     void Flush() { os_.Flush(); }
  
     // Not implemented
     Ch Peek() const
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
     Ch Take()
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
     size_t Tell() const
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
     Ch* PutBegin()
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
     size_t PutEnd(Ch*)
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
  
     private:
     EncodedOutputStream(const EncodedOutputStream&);
     EncodedOutputStream& operator=(const EncodedOutputStream&);
  
     OutputByteStream& os_;
 };
  
 #define RAPIDJSON_ENCODINGS_FUNC(x) \
     UTF8<Ch>::x, UTF16LE<Ch>::x, UTF16BE<Ch>::x, UTF32LE<Ch>::x, UTF32BE<Ch>::x
  
  
 template <typename CharType, typename InputByteStream>
 class AutoUTFInputStream
 {
     RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
  
     public:
     typedef CharType Ch;
  
  
     AutoUTFInputStream(InputByteStream& is, UTFType type = kUTF8)
         : is_(&is), type_(type), hasBOM_(false)
     {
         RAPIDJSON_ASSERT(type >= kUTF8 && type <= kUTF32BE);
         DetectType();
         static const TakeFunc f[] = {RAPIDJSON_ENCODINGS_FUNC(Take)};
         takeFunc_                 = f[type_];
         current_                  = takeFunc_(*is_);
     }
  
     UTFType GetType() const { return type_; }
     bool HasBOM() const { return hasBOM_; }
  
     Ch Peek() const { return current_; }
     Ch Take()
     {
         Ch c     = current_;
         current_ = takeFunc_(*is_);
         return c;
     }
     size_t Tell() const { return is_->Tell(); }
  
     // Not implemented
     void Put(Ch) { RAPIDJSON_ASSERT(false); }
     void Flush() { RAPIDJSON_ASSERT(false); }
     Ch* PutBegin()
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
     size_t PutEnd(Ch*)
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
  
     private:
     AutoUTFInputStream(const AutoUTFInputStream&);
     AutoUTFInputStream& operator=(const AutoUTFInputStream&);
  
     // Detect encoding type with BOM or RFC 4627
     void DetectType()
     {
         // BOM (Byte Order Mark):
         // 00 00 FE FF  UTF-32BE
         // FF FE 00 00  UTF-32LE
         // FE FF        UTF-16BE
         // FF FE        UTF-16LE
         // EF BB BF     UTF-8
  
         const unsigned char* c = reinterpret_cast<const unsigned char*>(is_->Peek4());
         if(!c)
             return;
  
         unsigned bom = static_cast<unsigned>(c[0] | (c[1] << 8) | (c[2] << 16) | (c[3] << 24));
         hasBOM_      = false;
         if(bom == 0xFFFE0000)
         {
             type_   = kUTF32BE;
             hasBOM_ = true;
             is_->Take();
             is_->Take();
             is_->Take();
             is_->Take();
         }
         else if(bom == 0x0000FEFF)
         {
             type_   = kUTF32LE;
             hasBOM_ = true;
             is_->Take();
             is_->Take();
             is_->Take();
             is_->Take();
         }
         else if((bom & 0xFFFF) == 0xFFFE)
         {
             type_   = kUTF16BE;
             hasBOM_ = true;
             is_->Take();
             is_->Take();
         }
         else if((bom & 0xFFFF) == 0xFEFF)
         {
             type_   = kUTF16LE;
             hasBOM_ = true;
             is_->Take();
             is_->Take();
         }
         else if((bom & 0xFFFFFF) == 0xBFBBEF)
         {
             type_   = kUTF8;
             hasBOM_ = true;
             is_->Take();
             is_->Take();
             is_->Take();
         }
  
         // RFC 4627: Section 3
         // "Since the first two characters of a JSON text will always be ASCII
         // characters [RFC0020], it is possible to determine whether an octet
         // stream is UTF-8, UTF-16 (BE or LE), or UTF-32 (BE or LE) by looking
         // at the pattern of nulls in the first four octets."
         // 00 00 00 xx  UTF-32BE
         // 00 xx 00 xx  UTF-16BE
         // xx 00 00 00  UTF-32LE
         // xx 00 xx 00  UTF-16LE
         // xx xx xx xx  UTF-8
  
         if(!hasBOM_)
         {
             int pattern = (c[0] ? 1 : 0) | (c[1] ? 2 : 0) | (c[2] ? 4 : 0) | (c[3] ? 8 : 0);
             switch(pattern)
             {
             case 0x08: type_ = kUTF32BE; break;
             case 0x0A: type_ = kUTF16BE; break;
             case 0x01: type_ = kUTF32LE; break;
             case 0x05: type_ = kUTF16LE; break;
             case 0x0F: type_ = kUTF8; break;
             default: break; // Use type defined by user.
             }
         }
  
         // Runtime check whether the size of character type is sufficient. It only perform checks
         // with assertion.
         if(type_ == kUTF16LE || type_ == kUTF16BE)
             RAPIDJSON_ASSERT(sizeof(Ch) >= 2);
         if(type_ == kUTF32LE || type_ == kUTF32BE)
             RAPIDJSON_ASSERT(sizeof(Ch) >= 4);
     }
  
     typedef Ch (*TakeFunc)(InputByteStream& is);
     InputByteStream* is_;
     UTFType type_;
     Ch current_;
     TakeFunc takeFunc_;
     bool hasBOM_;
 };
  
  
 template <typename CharType, typename OutputByteStream>
 class AutoUTFOutputStream
 {
     RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
  
     public:
     typedef CharType Ch;
  
  
     AutoUTFOutputStream(OutputByteStream& os, UTFType type, bool putBOM) : os_(&os), type_(type)
     {
         RAPIDJSON_ASSERT(type >= kUTF8 && type <= kUTF32BE);
  
         // Runtime check whether the size of character type is sufficient. It only perform checks
         // with assertion.
         if(type_ == kUTF16LE || type_ == kUTF16BE)
             RAPIDJSON_ASSERT(sizeof(Ch) >= 2);
         if(type_ == kUTF32LE || type_ == kUTF32BE)
             RAPIDJSON_ASSERT(sizeof(Ch) >= 4);
  
         static const PutFunc f[] = {RAPIDJSON_ENCODINGS_FUNC(Put)};
         putFunc_                 = f[type_];
  
         if(putBOM)
             PutBOM();
     }
  
     UTFType GetType() const { return type_; }
  
     void Put(Ch c) { putFunc_(*os_, c); }
     void Flush() { os_->Flush(); }
  
     // Not implemented
     Ch Peek() const
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
     Ch Take()
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
     size_t Tell() const
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
     Ch* PutBegin()
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
     size_t PutEnd(Ch*)
     {
         RAPIDJSON_ASSERT(false);
         return 0;
     }
  
     private:
     AutoUTFOutputStream(const AutoUTFOutputStream&);
     AutoUTFOutputStream& operator=(const AutoUTFOutputStream&);
  
     void PutBOM()
     {
         typedef void (*PutBOMFunc)(OutputByteStream&);
         static const PutBOMFunc f[] = {RAPIDJSON_ENCODINGS_FUNC(PutBOM)};
         f[type_](*os_);
     }
  
     typedef void (*PutFunc)(OutputByteStream&, Ch);
  
     OutputByteStream* os_;
     UTFType type_;
     PutFunc putFunc_;
 };
  
 #undef RAPIDJSON_ENCODINGS_FUNC
  
 RAPIDJSON_NAMESPACE_END
  
 #ifdef __clang__
 RAPIDJSON_DIAG_POP
 #endif
  
 #ifdef __GNUC__
 RAPIDJSON_DIAG_POP
 #endif
  
 #endif // RAPIDJSON_FILESTREAM_H_