encodings.h

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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. All rights reserved.
//
// 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_ENCODINGS_H_
#define RAPIDJSON_ENCODINGS_H_

#include "rapidjson.h"

#if defined(_MSC_VER) && !defined(__clang__)
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(4244)  // conversion from 'type1' to 'type2', possible loss of data
RAPIDJSON_DIAG_OFF(4702)  // unreachable code
#elif defined(__GNUC__)
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(effc++)
RAPIDJSON_DIAG_OFF(overflow)
#endif

RAPIDJSON_NAMESPACE_BEGIN

// Encoding








// UTF8


template <typename CharType = char>
struct UTF8
{
  typedef CharType Ch;

  enum
  {
    supportUnicode = 1
  };

  template <typename OutputStream>
  static void Encode(OutputStream& os, unsigned codepoint)
  {
    if (codepoint <= 0x7F)
      os.Put(static_cast<Ch>(codepoint & 0xFF));
    else if (codepoint <= 0x7FF)
    {
      os.Put(static_cast<Ch>(0xC0 | ((codepoint >> 6) & 0xFF)));
      os.Put(static_cast<Ch>(0x80 | ((codepoint & 0x3F))));
    }
    else if (codepoint <= 0xFFFF)
    {
      os.Put(static_cast<Ch>(0xE0 | ((codepoint >> 12) & 0xFF)));
      os.Put(static_cast<Ch>(0x80 | ((codepoint >> 6) & 0x3F)));
      os.Put(static_cast<Ch>(0x80 | (codepoint & 0x3F)));
    }
    else
    {
      RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
      os.Put(static_cast<Ch>(0xF0 | ((codepoint >> 18) & 0xFF)));
      os.Put(static_cast<Ch>(0x80 | ((codepoint >> 12) & 0x3F)));
      os.Put(static_cast<Ch>(0x80 | ((codepoint >> 6) & 0x3F)));
      os.Put(static_cast<Ch>(0x80 | (codepoint & 0x3F)));
    }
  }

  template <typename OutputStream>
  static void EncodeUnsafe(OutputStream& os, unsigned codepoint)
  {
    if (codepoint <= 0x7F)
      PutUnsafe(os, static_cast<Ch>(codepoint & 0xFF));
    else if (codepoint <= 0x7FF)
    {
      PutUnsafe(os, static_cast<Ch>(0xC0 | ((codepoint >> 6) & 0xFF)));
      PutUnsafe(os, static_cast<Ch>(0x80 | ((codepoint & 0x3F))));
    }
    else if (codepoint <= 0xFFFF)
    {
      PutUnsafe(os, static_cast<Ch>(0xE0 | ((codepoint >> 12) & 0xFF)));
      PutUnsafe(os, static_cast<Ch>(0x80 | ((codepoint >> 6) & 0x3F)));
      PutUnsafe(os, static_cast<Ch>(0x80 | (codepoint & 0x3F)));
    }
    else
    {
      RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
      PutUnsafe(os, static_cast<Ch>(0xF0 | ((codepoint >> 18) & 0xFF)));
      PutUnsafe(os, static_cast<Ch>(0x80 | ((codepoint >> 12) & 0x3F)));
      PutUnsafe(os, static_cast<Ch>(0x80 | ((codepoint >> 6) & 0x3F)));
      PutUnsafe(os, static_cast<Ch>(0x80 | (codepoint & 0x3F)));
    }
  }

  template <typename InputStream>
  static bool Decode(InputStream& is, unsigned* codepoint)
  {
#define RAPIDJSON_COPY()                                                                                               \
  c = is.Take();                                                                                                       \
  *codepoint = (*codepoint << 6) | (static_cast<unsigned char>(c) & 0x3Fu)
#define RAPIDJSON_TRANS(mask) result &= ((GetRange(static_cast<unsigned char>(c)) & mask) != 0)
#define RAPIDJSON_TAIL()                                                                                               \
  RAPIDJSON_COPY();                                                                                                    \
  RAPIDJSON_TRANS(0x70)
    typename InputStream::Ch c = is.Take();
    if (!(c & 0x80))
    {
      *codepoint = static_cast<unsigned char>(c);
      return true;
    }

    unsigned char type = GetRange(static_cast<unsigned char>(c));
    if (type >= 32)
    {
      *codepoint = 0;
    }
    else
    {
      *codepoint = (0xFFu >> type) & static_cast<unsigned char>(c);
    }
    bool result = true;
    switch (type)
    {
      case 2:
        RAPIDJSON_TAIL();
        return result;
      case 3:
        RAPIDJSON_TAIL();
        RAPIDJSON_TAIL();
        return result;
      case 4:
        RAPIDJSON_COPY();
        RAPIDJSON_TRANS(0x50);
        RAPIDJSON_TAIL();
        return result;
      case 5:
        RAPIDJSON_COPY();
        RAPIDJSON_TRANS(0x10);
        RAPIDJSON_TAIL();
        RAPIDJSON_TAIL();
        return result;
      case 6:
        RAPIDJSON_TAIL();
        RAPIDJSON_TAIL();
        RAPIDJSON_TAIL();
        return result;
      case 10:
        RAPIDJSON_COPY();
        RAPIDJSON_TRANS(0x20);
        RAPIDJSON_TAIL();
        return result;
      case 11:
        RAPIDJSON_COPY();
        RAPIDJSON_TRANS(0x60);
        RAPIDJSON_TAIL();
        RAPIDJSON_TAIL();
        return result;
      default:
        return false;
    }
#undef RAPIDJSON_COPY
#undef RAPIDJSON_TRANS
#undef RAPIDJSON_TAIL
  }

  template <typename InputStream, typename OutputStream>
  static bool Validate(InputStream& is, OutputStream& os)
  {
#define RAPIDJSON_COPY() os.Put(c = is.Take())
#define RAPIDJSON_TRANS(mask) result &= ((GetRange(static_cast<unsigned char>(c)) & mask) != 0)
#define RAPIDJSON_TAIL()                                                                                               \
  RAPIDJSON_COPY();                                                                                                    \
  RAPIDJSON_TRANS(0x70)
    Ch c;
    RAPIDJSON_COPY();
    if (!(c & 0x80))
      return true;

    bool result = true;
    switch (GetRange(static_cast<unsigned char>(c)))
    {
      case 2:
        RAPIDJSON_TAIL();
        return result;
      case 3:
        RAPIDJSON_TAIL();
        RAPIDJSON_TAIL();
        return result;
      case 4:
        RAPIDJSON_COPY();
        RAPIDJSON_TRANS(0x50);
        RAPIDJSON_TAIL();
        return result;
      case 5:
        RAPIDJSON_COPY();
        RAPIDJSON_TRANS(0x10);
        RAPIDJSON_TAIL();
        RAPIDJSON_TAIL();
        return result;
      case 6:
        RAPIDJSON_TAIL();
        RAPIDJSON_TAIL();
        RAPIDJSON_TAIL();
        return result;
      case 10:
        RAPIDJSON_COPY();
        RAPIDJSON_TRANS(0x20);
        RAPIDJSON_TAIL();
        return result;
      case 11:
        RAPIDJSON_COPY();
        RAPIDJSON_TRANS(0x60);
        RAPIDJSON_TAIL();
        RAPIDJSON_TAIL();
        return result;
      default:
        return false;
    }
#undef RAPIDJSON_COPY
#undef RAPIDJSON_TRANS
#undef RAPIDJSON_TAIL
  }

  static unsigned char GetRange(unsigned char c)
  {
    // Referring to DFA of http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
    // With new mapping 1 -> 0x10, 7 -> 0x20, 9 -> 0x40, such that AND operation can test multiple types.
    static const unsigned char type[] = {
      0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
      0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
      0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
      0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
      0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
      0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
      0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0x10, 0x10, 0x10, 0x10, 0x10,
      0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
      0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
      0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
      0x20, 0x20, 8,    8,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,
      2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    2,    10,   3,    3,    3,
      3,    3,    3,    3,    3,    3,    3,    3,    3,    4,    3,    3,    11,   6,    6,    6,    5,    8,    8,
      8,    8,    8,    8,    8,    8,    8,    8,    8,
    };
    return type[c];
  }

  template <typename InputByteStream>
  static CharType TakeBOM(InputByteStream& is)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
    typename InputByteStream::Ch c = Take(is);
    if (static_cast<unsigned char>(c) != 0xEFu)
      return c;
    c = is.Take();
    if (static_cast<unsigned char>(c) != 0xBBu)
      return c;
    c = is.Take();
    if (static_cast<unsigned char>(c) != 0xBFu)
      return c;
    c = is.Take();
    return c;
  }

  template <typename InputByteStream>
  static Ch Take(InputByteStream& is)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
    return static_cast<Ch>(is.Take());
  }

  template <typename OutputByteStream>
  static void PutBOM(OutputByteStream& os)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
    os.Put(static_cast<typename OutputByteStream::Ch>(0xEFu));
    os.Put(static_cast<typename OutputByteStream::Ch>(0xBBu));
    os.Put(static_cast<typename OutputByteStream::Ch>(0xBFu));
  }

  template <typename OutputByteStream>
  static void Put(OutputByteStream& os, Ch c)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
    os.Put(static_cast<typename OutputByteStream::Ch>(c));
  }
};

// UTF16


template <typename CharType = wchar_t>
struct UTF16
{
  typedef CharType Ch;
  RAPIDJSON_STATIC_ASSERT(sizeof(Ch) >= 2);

  enum
  {
    supportUnicode = 1
  };

  template <typename OutputStream>
  static void Encode(OutputStream& os, unsigned codepoint)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputStream::Ch) >= 2);
    if (codepoint <= 0xFFFF)
    {
      RAPIDJSON_ASSERT(codepoint < 0xD800 || codepoint > 0xDFFF);  // Code point itself cannot be surrogate pair
      os.Put(static_cast<typename OutputStream::Ch>(codepoint));
    }
    else
    {
      RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
      unsigned v = codepoint - 0x10000;
      os.Put(static_cast<typename OutputStream::Ch>((v >> 10) | 0xD800));
      os.Put(static_cast<typename OutputStream::Ch>((v & 0x3FF) | 0xDC00));
    }
  }

  template <typename OutputStream>
  static void EncodeUnsafe(OutputStream& os, unsigned codepoint)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputStream::Ch) >= 2);
    if (codepoint <= 0xFFFF)
    {
      RAPIDJSON_ASSERT(codepoint < 0xD800 || codepoint > 0xDFFF);  // Code point itself cannot be surrogate pair
      PutUnsafe(os, static_cast<typename OutputStream::Ch>(codepoint));
    }
    else
    {
      RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
      unsigned v = codepoint - 0x10000;
      PutUnsafe(os, static_cast<typename OutputStream::Ch>((v >> 10) | 0xD800));
      PutUnsafe(os, static_cast<typename OutputStream::Ch>((v & 0x3FF) | 0xDC00));
    }
  }

  template <typename InputStream>
  static bool Decode(InputStream& is, unsigned* codepoint)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputStream::Ch) >= 2);
    typename InputStream::Ch c = is.Take();
    if (c < 0xD800 || c > 0xDFFF)
    {
      *codepoint = static_cast<unsigned>(c);
      return true;
    }
    else if (c <= 0xDBFF)
    {
      *codepoint = (static_cast<unsigned>(c) & 0x3FF) << 10;
      c = is.Take();
      *codepoint |= (static_cast<unsigned>(c) & 0x3FF);
      *codepoint += 0x10000;
      return c >= 0xDC00 && c <= 0xDFFF;
    }
    return false;
  }

  template <typename InputStream, typename OutputStream>
  static bool Validate(InputStream& is, OutputStream& os)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputStream::Ch) >= 2);
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputStream::Ch) >= 2);
    typename InputStream::Ch c;
    os.Put(static_cast<typename OutputStream::Ch>(c = is.Take()));
    if (c < 0xD800 || c > 0xDFFF)
      return true;
    else if (c <= 0xDBFF)
    {
      os.Put(c = is.Take());
      return c >= 0xDC00 && c <= 0xDFFF;
    }
    return false;
  }
};

template <typename CharType = wchar_t>
struct UTF16LE : UTF16<CharType>
{
  template <typename InputByteStream>
  static CharType TakeBOM(InputByteStream& is)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
    CharType c = Take(is);
    return static_cast<uint16_t>(c) == 0xFEFFu ? Take(is) : c;
  }

  template <typename InputByteStream>
  static CharType Take(InputByteStream& is)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
    unsigned c = static_cast<uint8_t>(is.Take());
    c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 8;
    return static_cast<CharType>(c);
  }

  template <typename OutputByteStream>
  static void PutBOM(OutputByteStream& os)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
    os.Put(static_cast<typename OutputByteStream::Ch>(0xFFu));
    os.Put(static_cast<typename OutputByteStream::Ch>(0xFEu));
  }

  template <typename OutputByteStream>
  static void Put(OutputByteStream& os, CharType c)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
    os.Put(static_cast<typename OutputByteStream::Ch>(static_cast<unsigned>(c) & 0xFFu));
    os.Put(static_cast<typename OutputByteStream::Ch>((static_cast<unsigned>(c) >> 8) & 0xFFu));
  }
};

template <typename CharType = wchar_t>
struct UTF16BE : UTF16<CharType>
{
  template <typename InputByteStream>
  static CharType TakeBOM(InputByteStream& is)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
    CharType c = Take(is);
    return static_cast<uint16_t>(c) == 0xFEFFu ? Take(is) : c;
  }

  template <typename InputByteStream>
  static CharType Take(InputByteStream& is)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
    unsigned c = static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 8;
    c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take()));
    return static_cast<CharType>(c);
  }

  template <typename OutputByteStream>
  static void PutBOM(OutputByteStream& os)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
    os.Put(static_cast<typename OutputByteStream::Ch>(0xFEu));
    os.Put(static_cast<typename OutputByteStream::Ch>(0xFFu));
  }

  template <typename OutputByteStream>
  static void Put(OutputByteStream& os, CharType c)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
    os.Put(static_cast<typename OutputByteStream::Ch>((static_cast<unsigned>(c) >> 8) & 0xFFu));
    os.Put(static_cast<typename OutputByteStream::Ch>(static_cast<unsigned>(c) & 0xFFu));
  }
};

// UTF32


template <typename CharType = unsigned>
struct UTF32
{
  typedef CharType Ch;
  RAPIDJSON_STATIC_ASSERT(sizeof(Ch) >= 4);

  enum
  {
    supportUnicode = 1
  };

  template <typename OutputStream>
  static void Encode(OutputStream& os, unsigned codepoint)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputStream::Ch) >= 4);
    RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
    os.Put(codepoint);
  }

  template <typename OutputStream>
  static void EncodeUnsafe(OutputStream& os, unsigned codepoint)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputStream::Ch) >= 4);
    RAPIDJSON_ASSERT(codepoint <= 0x10FFFF);
    PutUnsafe(os, codepoint);
  }

  template <typename InputStream>
  static bool Decode(InputStream& is, unsigned* codepoint)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputStream::Ch) >= 4);
    Ch c = is.Take();
    *codepoint = c;
    return c <= 0x10FFFF;
  }

  template <typename InputStream, typename OutputStream>
  static bool Validate(InputStream& is, OutputStream& os)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputStream::Ch) >= 4);
    Ch c;
    os.Put(c = is.Take());
    return c <= 0x10FFFF;
  }
};

template <typename CharType = unsigned>
struct UTF32LE : UTF32<CharType>
{
  template <typename InputByteStream>
  static CharType TakeBOM(InputByteStream& is)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
    CharType c = Take(is);
    return static_cast<uint32_t>(c) == 0x0000FEFFu ? Take(is) : c;
  }

  template <typename InputByteStream>
  static CharType Take(InputByteStream& is)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
    unsigned c = static_cast<uint8_t>(is.Take());
    c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 8;
    c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 16;
    c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 24;
    return static_cast<CharType>(c);
  }

  template <typename OutputByteStream>
  static void PutBOM(OutputByteStream& os)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
    os.Put(static_cast<typename OutputByteStream::Ch>(0xFFu));
    os.Put(static_cast<typename OutputByteStream::Ch>(0xFEu));
    os.Put(static_cast<typename OutputByteStream::Ch>(0x00u));
    os.Put(static_cast<typename OutputByteStream::Ch>(0x00u));
  }

  template <typename OutputByteStream>
  static void Put(OutputByteStream& os, CharType c)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
    os.Put(static_cast<typename OutputByteStream::Ch>(c & 0xFFu));
    os.Put(static_cast<typename OutputByteStream::Ch>((c >> 8) & 0xFFu));
    os.Put(static_cast<typename OutputByteStream::Ch>((c >> 16) & 0xFFu));
    os.Put(static_cast<typename OutputByteStream::Ch>((c >> 24) & 0xFFu));
  }
};

template <typename CharType = unsigned>
struct UTF32BE : UTF32<CharType>
{
  template <typename InputByteStream>
  static CharType TakeBOM(InputByteStream& is)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
    CharType c = Take(is);
    return static_cast<uint32_t>(c) == 0x0000FEFFu ? Take(is) : c;
  }

  template <typename InputByteStream>
  static CharType Take(InputByteStream& is)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
    unsigned c = static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 24;
    c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 16;
    c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take())) << 8;
    c |= static_cast<unsigned>(static_cast<uint8_t>(is.Take()));
    return static_cast<CharType>(c);
  }

  template <typename OutputByteStream>
  static void PutBOM(OutputByteStream& os)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
    os.Put(static_cast<typename OutputByteStream::Ch>(0x00u));
    os.Put(static_cast<typename OutputByteStream::Ch>(0x00u));
    os.Put(static_cast<typename OutputByteStream::Ch>(0xFEu));
    os.Put(static_cast<typename OutputByteStream::Ch>(0xFFu));
  }

  template <typename OutputByteStream>
  static void Put(OutputByteStream& os, CharType c)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
    os.Put(static_cast<typename OutputByteStream::Ch>((c >> 24) & 0xFFu));
    os.Put(static_cast<typename OutputByteStream::Ch>((c >> 16) & 0xFFu));
    os.Put(static_cast<typename OutputByteStream::Ch>((c >> 8) & 0xFFu));
    os.Put(static_cast<typename OutputByteStream::Ch>(c & 0xFFu));
  }
};

// ASCII


template <typename CharType = char>
struct ASCII
{
  typedef CharType Ch;

  enum
  {
    supportUnicode = 0
  };

  template <typename OutputStream>
  static void Encode(OutputStream& os, unsigned codepoint)
  {
    RAPIDJSON_ASSERT(codepoint <= 0x7F);
    os.Put(static_cast<Ch>(codepoint & 0xFF));
  }

  template <typename OutputStream>
  static void EncodeUnsafe(OutputStream& os, unsigned codepoint)
  {
    RAPIDJSON_ASSERT(codepoint <= 0x7F);
    PutUnsafe(os, static_cast<Ch>(codepoint & 0xFF));
  }

  template <typename InputStream>
  static bool Decode(InputStream& is, unsigned* codepoint)
  {
    uint8_t c = static_cast<uint8_t>(is.Take());
    *codepoint = c;
    return c <= 0X7F;
  }

  template <typename InputStream, typename OutputStream>
  static bool Validate(InputStream& is, OutputStream& os)
  {
    uint8_t c = static_cast<uint8_t>(is.Take());
    os.Put(static_cast<typename OutputStream::Ch>(c));
    return c <= 0x7F;
  }

  template <typename InputByteStream>
  static CharType TakeBOM(InputByteStream& is)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
    uint8_t c = static_cast<uint8_t>(Take(is));
    return static_cast<Ch>(c);
  }

  template <typename InputByteStream>
  static Ch Take(InputByteStream& is)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
    return static_cast<Ch>(is.Take());
  }

  template <typename OutputByteStream>
  static void PutBOM(OutputByteStream& os)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
    (void)os;
  }

  template <typename OutputByteStream>
  static void Put(OutputByteStream& os, Ch c)
  {
    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
    os.Put(static_cast<typename OutputByteStream::Ch>(c));
  }
};

// AutoUTF

enum UTFType
{
  kUTF8 = 0,     
  kUTF16LE = 1,  
  kUTF16BE = 2,  
  kUTF32LE = 3,  
  kUTF32BE = 4   
};


template <typename CharType>
struct AutoUTF
{
  typedef CharType Ch;

  enum
  {
    supportUnicode = 1
  };

#define RAPIDJSON_ENCODINGS_FUNC(x) UTF8<Ch>::x, UTF16LE<Ch>::x, UTF16BE<Ch>::x, UTF32LE<Ch>::x, UTF32BE<Ch>::x

  template <typename OutputStream>
  static RAPIDJSON_FORCEINLINE void Encode(OutputStream& os, unsigned codepoint)
  {
    typedef void (*EncodeFunc)(OutputStream&, unsigned);
    static const EncodeFunc f[] = { RAPIDJSON_ENCODINGS_FUNC(Encode) };
    (*f[os.GetType()])(os, codepoint);
  }

  template <typename OutputStream>
  static RAPIDJSON_FORCEINLINE void EncodeUnsafe(OutputStream& os, unsigned codepoint)
  {
    typedef void (*EncodeFunc)(OutputStream&, unsigned);
    static const EncodeFunc f[] = { RAPIDJSON_ENCODINGS_FUNC(EncodeUnsafe) };
    (*f[os.GetType()])(os, codepoint);
  }

  template <typename InputStream>
  static RAPIDJSON_FORCEINLINE bool Decode(InputStream& is, unsigned* codepoint)
  {
    typedef bool (*DecodeFunc)(InputStream&, unsigned*);
    static const DecodeFunc f[] = { RAPIDJSON_ENCODINGS_FUNC(Decode) };
    return (*f[is.GetType()])(is, codepoint);
  }

  template <typename InputStream, typename OutputStream>
  static RAPIDJSON_FORCEINLINE bool Validate(InputStream& is, OutputStream& os)
  {
    typedef bool (*ValidateFunc)(InputStream&, OutputStream&);
    static const ValidateFunc f[] = { RAPIDJSON_ENCODINGS_FUNC(Validate) };
    return (*f[is.GetType()])(is, os);
  }

#undef RAPIDJSON_ENCODINGS_FUNC
};

// Transcoder

template <typename SourceEncoding, typename TargetEncoding>
struct Transcoder
{
  template <typename InputStream, typename OutputStream>
  static RAPIDJSON_FORCEINLINE bool Transcode(InputStream& is, OutputStream& os)
  {
    unsigned codepoint;
    if (!SourceEncoding::Decode(is, &codepoint))
      return false;
    TargetEncoding::Encode(os, codepoint);
    return true;
  }

  template <typename InputStream, typename OutputStream>
  static RAPIDJSON_FORCEINLINE bool TranscodeUnsafe(InputStream& is, OutputStream& os)
  {
    unsigned codepoint;
    if (!SourceEncoding::Decode(is, &codepoint))
      return false;
    TargetEncoding::EncodeUnsafe(os, codepoint);
    return true;
  }

  template <typename InputStream, typename OutputStream>
  static RAPIDJSON_FORCEINLINE bool Validate(InputStream& is, OutputStream& os)
  {
    return Transcode(is, os);  // Since source/target encoding is different, must transcode.
  }
};

// Forward declaration.
template <typename Stream>
inline void PutUnsafe(Stream& stream, typename Stream::Ch c);

template <typename Encoding>
struct Transcoder<Encoding, Encoding>
{
  template <typename InputStream, typename OutputStream>
  static RAPIDJSON_FORCEINLINE bool Transcode(InputStream& is, OutputStream& os)
  {
    os.Put(is.Take());  // Just copy one code unit. This semantic is different from primary template class.
    return true;
  }

  template <typename InputStream, typename OutputStream>
  static RAPIDJSON_FORCEINLINE bool TranscodeUnsafe(InputStream& is, OutputStream& os)
  {
    PutUnsafe(os, is.Take());  // Just copy one code unit. This semantic is different from primary template class.
    return true;
  }

  template <typename InputStream, typename OutputStream>
  static RAPIDJSON_FORCEINLINE bool Validate(InputStream& is, OutputStream& os)
  {
    return Encoding::Validate(is, os);  // source/target encoding are the same
  }
};

RAPIDJSON_NAMESPACE_END

#if defined(__GNUC__) || (defined(_MSC_VER) && !defined(__clang__))
RAPIDJSON_DIAG_POP
#endif

#endif  // RAPIDJSON_ENCODINGS_H_