boost/variant/detail/variant_io.hpp

//-----------------------------------------------------------------------------
// boost variant/detail/variant_io.hpp header file
// See http://www.boost.org for updates, documentation, and revision history.
//-----------------------------------------------------------------------------
//
// Copyright (c) 2002-2003
// Eric Friedman, Itay Maman
//
// Distributed under 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)
#ifndef BOOST_VARIANT_DETAIL_VARIANT_IO_HPP
#define BOOST_VARIANT_DETAIL_VARIANT_IO_HPP
#include <iosfwd> // for std::basic_ostream forward declare
#include <boost/variant/variant_fwd.hpp>
#include <boost/detail/templated_streams.hpp>
#include <boost/variant/static_visitor.hpp>
namespace boost {
///////////////////////////////////////////////////////////////////////////////
// function template operator<<
//
// Outputs the content of the given variant to the given ostream.
//
// forward declare (allows output of embedded variant< variant< ... >, ... >)
template <
      BOOST_TEMPLATED_STREAM_ARGS(E,T)
    BOOST_TEMPLATED_STREAM_COMMA
      BOOST_VARIANT_ENUM_PARAMS(typename U)
    >
inline BOOST_TEMPLATED_STREAM(ostream, E,T)& operator<<(
      BOOST_TEMPLATED_STREAM(ostream, E,T)& out
    , const variant< BOOST_VARIANT_ENUM_PARAMS(U) >& rhs
    );
namespace detail { namespace variant {
template <typename OStream>
class printer
    : public boost::static_visitor<>
{
private: // representation
    OStream& out_;
public: // structors
    explicit printer(OStream& out)
        : out_( out )
    {
    }
public: // visitor interface
    template <typename T>
    void operator()(const T& operand) const
    {
        out_ << operand;
    }
private:
    printer& operator=(const printer&);
};
}} // namespace detail::variant
template <
      BOOST_TEMPLATED_STREAM_ARGS(E,T)
    BOOST_TEMPLATED_STREAM_COMMA
      BOOST_VARIANT_ENUM_PARAMS(typename U)
    >
inline BOOST_TEMPLATED_STREAM(ostream, E,T)& operator<<(
      BOOST_TEMPLATED_STREAM(ostream, E,T)& out
    , const variant< BOOST_VARIANT_ENUM_PARAMS(U) >& rhs
    )
{
    detail::variant::printer<
          BOOST_TEMPLATED_STREAM(ostream, E,T)
        > visitor(out);
    rhs.apply_visitor(visitor);
    return out;
}
} // namespace boost
#endif // BOOST_VARIANT_DETAIL_VARIANT_IO_HPP