portable_binary.hpp

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/*
  Copyright (c) 2014, Randolph Voorhies, Shane Grant
  All rights reserved.
 
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:
      * Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.
      * Redistributions in binary form must reproduce the above copyright
        notice, this list of conditions and the following disclaimer in the
        documentation and/or other materials provided with the distribution.
      * Neither the name of the copyright holder nor the
        names of its contributors may be used to endorse or promote products
        derived from this software without specific prior written permission.
 
  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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*/
#ifndef CEREAL_ARCHIVES_PORTABLE_BINARY_HPP_
#define CEREAL_ARCHIVES_PORTABLE_BINARY_HPP_
 
#include "cereal/cereal.hpp"
#include <sstream>
#include <limits>
 
namespace cereal
{
  namespace portable_binary_detail
  {
 
    inline std::uint8_t is_little_endian()
    {
      static std::int32_t test = 1;
      return *reinterpret_cast<std::int8_t*>( &test ) == 1;
    }
 
 
    template <std::size_t DataSize>
    inline void swap_bytes( std::uint8_t * data )
    {
      for( std::size_t i = 0, end = DataSize / 2; i < end; ++i )
        std::swap( data[i], data[DataSize - i - 1] );
    }
  } // end namespace portable_binary_detail
 
  // ######################################################################
 
  class PortableBinaryOutputArchive : public OutputArchive<PortableBinaryOutputArchive, AllowEmptyClassElision>
  {
    public:
      class Options
      {
        public:
          enum class Endianness : std::uint8_t
          { big, little };
 
          static Options Default(){ return Options(); }
 
          static Options LittleEndian(){ return Options( Endianness::little ); }
 
          static Options BigEndian(){ return Options( Endianness::big ); }
 
 
          explicit Options( Endianness outputEndian = getEndianness() ) :
            itsOutputEndianness( outputEndian ) { }
 
        private:
          inline static Endianness getEndianness()
          { return portable_binary_detail::is_little_endian() ? Endianness::little : Endianness::big; }
 
          inline std::uint8_t is_little_endian() const
          { return itsOutputEndianness == Endianness::little; }
 
          friend class PortableBinaryOutputArchive;
          Endianness itsOutputEndianness;
      };
 
 
      PortableBinaryOutputArchive(std::ostream & stream, Options const & options = Options::Default()) :
        OutputArchive<PortableBinaryOutputArchive, AllowEmptyClassElision>(this),
        itsStream(stream),
        itsConvertEndianness( portable_binary_detail::is_little_endian() ^ options.is_little_endian() )
      {
        this->operator()( options.is_little_endian() );
      }
 
      ~PortableBinaryOutputArchive() CEREAL_NOEXCEPT = default;
 
      template <std::streamsize DataSize> inline
      void saveBinary( const void * data, std::streamsize size )
      {
        std::streamsize writtenSize = 0;
 
        if( itsConvertEndianness )
        {
          for( std::streamsize i = 0; i < size; i += DataSize )
            for( std::streamsize j = 0; j < DataSize; ++j )
              writtenSize += itsStream.rdbuf()->sputn( reinterpret_cast<const char*>( data ) + DataSize - j - 1 + i, 1 );
        }
        else
          writtenSize = itsStream.rdbuf()->sputn( reinterpret_cast<const char*>( data ), size );
 
        if(writtenSize != size)
          throw Exception("Failed to write " + std::to_string(size) + " bytes to output stream! Wrote " + std::to_string(writtenSize));
      }
 
    private:
      std::ostream & itsStream;
      const uint8_t itsConvertEndianness; 
  };
 
  // ######################################################################
 
  class PortableBinaryInputArchive : public InputArchive<PortableBinaryInputArchive, AllowEmptyClassElision>
  {
    public:
      class Options
      {
        public:
          enum class Endianness : std::uint8_t
          { big, little };
 
          static Options Default(){ return Options(); }
 
          static Options LittleEndian(){ return Options( Endianness::little ); }
 
          static Options BigEndian(){ return Options( Endianness::big ); }
 
 
          explicit Options( Endianness inputEndian = getEndianness() ) :
            itsInputEndianness( inputEndian ) { }
 
        private:
          inline static Endianness getEndianness()
          { return portable_binary_detail::is_little_endian() ? Endianness::little : Endianness::big; }
 
          inline std::uint8_t is_little_endian() const
          { return itsInputEndianness == Endianness::little; }
 
          friend class PortableBinaryInputArchive;
          Endianness itsInputEndianness;
      };
 
 
      PortableBinaryInputArchive(std::istream & stream, Options const & options = Options::Default()) :
        InputArchive<PortableBinaryInputArchive, AllowEmptyClassElision>(this),
        itsStream(stream),
        itsConvertEndianness( false )
      {
        uint8_t streamLittleEndian;
        this->operator()( streamLittleEndian );
        itsConvertEndianness = options.is_little_endian() ^ streamLittleEndian;
      }
 
      ~PortableBinaryInputArchive() CEREAL_NOEXCEPT = default;
 
 
      template <std::streamsize DataSize> inline
      void loadBinary( void * const data, std::streamsize size )
      {
        // load data
        auto const readSize = itsStream.rdbuf()->sgetn( reinterpret_cast<char*>( data ), size );
 
        if(readSize != size)
          throw Exception("Failed to read " + std::to_string(size) + " bytes from input stream! Read " + std::to_string(readSize));
 
        // flip bits if needed
        if( itsConvertEndianness )
        {
          std::uint8_t * ptr = reinterpret_cast<std::uint8_t*>( data );
          for( std::streamsize i = 0; i < size; i += DataSize )
            portable_binary_detail::swap_bytes<DataSize>( ptr + i );
        }
      }
 
    private:
      std::istream & itsStream;
      uint8_t itsConvertEndianness; 
  };
 
  // ######################################################################
  // Common BinaryArchive serialization functions
 
  template<class T> inline
  typename std::enable_if<std::is_arithmetic<T>::value, void>::type
  CEREAL_SAVE_FUNCTION_NAME(PortableBinaryOutputArchive & ar, T const & t)
  {
    static_assert( !std::is_floating_point<T>::value ||
                   (std::is_floating_point<T>::value && std::numeric_limits<T>::is_iec559),
                   "Portable binary only supports IEEE 754 standardized floating point" );
    ar.template saveBinary<sizeof(T)>(std::addressof(t), sizeof(t));
  }
 
  template<class T> inline
  typename std::enable_if<std::is_arithmetic<T>::value, void>::type
  CEREAL_LOAD_FUNCTION_NAME(PortableBinaryInputArchive & ar, T & t)
  {
    static_assert( !std::is_floating_point<T>::value ||
                   (std::is_floating_point<T>::value && std::numeric_limits<T>::is_iec559),
                   "Portable binary only supports IEEE 754 standardized floating point" );
    ar.template loadBinary<sizeof(T)>(std::addressof(t), sizeof(t));
  }
 
  template <class Archive, class T> inline
  CEREAL_ARCHIVE_RESTRICT(PortableBinaryInputArchive, PortableBinaryOutputArchive)
  CEREAL_SERIALIZE_FUNCTION_NAME( Archive & ar, NameValuePair<T> & t )
  {
    ar( t.value );
  }
 
  template <class Archive, class T> inline
  CEREAL_ARCHIVE_RESTRICT(PortableBinaryInputArchive, PortableBinaryOutputArchive)
  CEREAL_SERIALIZE_FUNCTION_NAME( Archive & ar, SizeTag<T> & t )
  {
    ar( t.size );
  }
 
  template <class T> inline
  void CEREAL_SAVE_FUNCTION_NAME(PortableBinaryOutputArchive & ar, BinaryData<T> const & bd)
  {
    typedef typename std::remove_pointer<T>::type TT;
    static_assert( !std::is_floating_point<TT>::value ||
                   (std::is_floating_point<TT>::value && std::numeric_limits<TT>::is_iec559),
                   "Portable binary only supports IEEE 754 standardized floating point" );
 
    ar.template saveBinary<sizeof(TT)>( bd.data, static_cast<std::streamsize>( bd.size ) );
  }
 
  template <class T> inline
  void CEREAL_LOAD_FUNCTION_NAME(PortableBinaryInputArchive & ar, BinaryData<T> & bd)
  {
    typedef typename std::remove_pointer<T>::type TT;
    static_assert( !std::is_floating_point<TT>::value ||
                   (std::is_floating_point<TT>::value && std::numeric_limits<TT>::is_iec559),
                   "Portable binary only supports IEEE 754 standardized floating point" );
 
    ar.template loadBinary<sizeof(TT)>( bd.data, static_cast<std::streamsize>( bd.size ) );
  }
} // namespace cereal
 
// register archives for polymorphic support
CEREAL_REGISTER_ARCHIVE(cereal::PortableBinaryOutputArchive)
CEREAL_REGISTER_ARCHIVE(cereal::PortableBinaryInputArchive)
 
// tie input and output archives together
CEREAL_SETUP_ARCHIVE_TRAITS(cereal::PortableBinaryInputArchive, cereal::PortableBinaryOutputArchive)
 
#endif // CEREAL_ARCHIVES_PORTABLE_BINARY_HPP_