Boost C++ Libraries

boost/archive/array/oarchive.hpp

#ifndef BOOST_ARCHIVE_ARRAY_OARCHIVE_HPP
#define BOOST_ARCHIVE_ARRAY_OARCHIVE_HPP

// (C) Copyright 2005 Matthias Troyer and Dave Abrahams
// Use, modification and distribution is subject to the Boost Software
// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)


#include <boost/archive/basic_archive.hpp>
#include <boost/archive/detail/common_oarchive.hpp>
#include <boost/serialization/array.hpp>
#include <boost/serialization/collection_size_type.hpp>
#include <boost/serialization/nvp.hpp>
#include <boost/serialization/detail/get_data.hpp>
#include <boost/type_traits/remove_const.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/mpl/apply.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/pfto.hpp>

namespace boost { namespace archive { namespace array {

  // To conveniently array-optimize an output archive X:
  //
  //   * Derive it from oarchive<X, Impl>, where Impl is an 
  //     archive implementation base class from 
  //     Boost.Serialization
  //
  //   * add a member function template that implements the
  //     procedure for serializing arrays of T (for appropriate T)
  //
  //       template <class T>
  //       save_array(serialization::array<T> const &, unsigned int)
  //
  //   * add a unary MPL lambda expression member called
  //     use_array_optimization whose result is convertible to
  //     mpl::true_ iff array elements of type T can be serialized
  //     with the load_array member function, and to mpl::false_ if
  //     the unoptimized procedure must be used. 

template <class Archive>
class oarchive
 : public archive::detail::common_oarchive<Archive>
{
  typedef archive::detail::common_oarchive<Archive> Base;
public:

  oarchive(unsigned int flags)
   : archive::detail::common_oarchive<Archive>(flags)
  {}
  
  // save_override for std::vector and serialization::array dispatches to 
  // save_optimized with an additional argument.
  // 
  // If that argument is of type mpl::true_, an optimized serialization is provided
  // If it is false, we just forward to the default serialization in the base class
  
  //the default version dispatches to the base class
  template<class T>
  void save_optimized(T const &t, unsigned int version, mpl::false_)
  {
    Base::save_override(t, version);
  }


  // the optimized implementation for vector uses serialization::array
//  template<class ValueType, class Allocator>
//  void save_optimized(
//    const std::vector<ValueType, Allocator> &t, unsigned int, mpl::true_)
//  {
//    const serialization::collection_size_type count(t.size());
//    * this->This() << BOOST_SERIALIZATION_NVP(count);
//    if (!t.empty())
//      * this->This() << serialization::make_array(serialization::detail::get_data(t),t.size());
//  }

  // the optimized implementation for serialization::array uses save_array
  template<class ValueType>
  void save_optimized(
    const serialization::array<ValueType> &t, unsigned int version, mpl::true_)
  {
    this->This()->save_array(t,version);
  }


  // to save a vector:
  // if the value type is trivially constructable or an optimized array save exists, 
  // then we can use the optimized version

//  template<class ValueType, class Allocator>
//  void save_override(std::vector<ValueType,Allocator> const &x, unsigned int version)
//  {
//    typedef BOOST_DEDUCED_TYPENAME remove_const<ValueType>::type value_type;
//    typedef typename mpl::and_<
//      mpl::not_<is_same<value_type,bool> >,
//      mpl::apply1<
//        BOOST_DEDUCED_TYPENAME Archive::use_array_optimization
//      , value_type>
//    >::type use_optimized;
//    save_optimized(x,version,use_optimized() );   
//  }

  
  
  // dispatch saving of arrays to the optimized version where supported
  template<class ValueType>
  void save_override(serialization::array<ValueType> const& x, unsigned int version)
  {
    typedef typename mpl::apply1<
        BOOST_DEDUCED_TYPENAME Archive::use_array_optimization
      , BOOST_DEDUCED_TYPENAME remove_const<ValueType>::type
    >::type use_optimized;
    save_optimized(x,version,use_optimized());
  }

  // Load everything else in the usual way, forwarding on to the
  // Base class
  template<class T>
  void save_override(T const& x, unsigned BOOST_PFTO int version)
  {
    Base::save_override(x, static_cast<unsigned int>(version));
  }
};

} } } // end namespace boost::archive::array


#endif // BOOST_ARCHIVE_ARRAY_OARCHIVE_HPP