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boost/optional/optional_io.hpp

// Copyright (C) 2005, Fernando Luis Cacciola Carballal.
//
// 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)
//
// See http://www.boost.org/libs/optional for documentation.
//
// You are welcome to contact the author at:
//  fernando_cacciola@hotmail.com
//
#ifndef BOOST_OPTIONAL_OPTIONAL_IO_FLC_19NOV2002_HPP
#define BOOST_OPTIONAL_OPTIONAL_IO_FLC_19NOV2002_HPP

#if defined __GNUC__
#  if (__GNUC__ == 2 && __GNUC_MINOR__ <= 97)
#    define BOOST_OPTIONAL_NO_TEMPLATED_STREAMS
#  endif
#endif // __GNUC__

#if defined BOOST_OPTIONAL_NO_TEMPLATED_STREAMS
#  include <iostream>
#else
#  include <istream>
#  include <ostream>
#endif

#include <boost/none.hpp>
#include <boost/assert.hpp>
#include "boost/optional/optional.hpp"
#include "boost/utility/value_init.hpp"

namespace boost
{

#if defined (BOOST_NO_TEMPLATED_STREAMS)
template<class T>
inline std::ostream& operator<<(std::ostream& out, optional<T> const& v)
#else
template<class CharType, class CharTrait, class T>
inline
std::basic_ostream<CharType, CharTrait>&
operator<<(std::basic_ostream<CharType, CharTrait>& out, optional<T> const& v)
#endif
{
  if ( out.good() )
  {
    if ( !v )
         out << "--" ;
    else out << ' ' << *v ;
  }

  return out;
}

#if defined (BOOST_NO_TEMPLATED_STREAMS)
template<class T>
inline std::istream& operator>>(std::istream& in, optional<T>& v)
#else
template<class CharType, class CharTrait, class T>
inline
std::basic_istream<CharType, CharTrait>&
operator>>(std::basic_istream<CharType, CharTrait>& in, optional<T>& v)
#endif
{
  if (in.good())
  {
    int d = in.get();
    if (d == ' ')
    {
      T x;
      in >> x;
      v = x;
    }
    else
    {
      if (d == '-')
      {
        d = in.get();

        if (d == '-')
        {
          v = none;
          return in;
        }
      }

      in.setstate( std::ios::failbit );
    }
  }

  return in;
}

} // namespace boost

#endif