//-----------------------------------------------------------------------------

// boost variant/detail/apply_visitor_delayed.hpp header file

// See http://www.boost.org for updates, documentation, and revision history.

//-----------------------------------------------------------------------------

//

// Copyright (c) 2002-2003

// Eric Friedman

//

// 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_APPLY_VISITOR_DELAYED_HPP

#define BOOST_VARIANT_DETAIL_APPLY_VISITOR_DELAYED_HPP

#include "boost/variant/detail/generic_result_type.hpp"

#include "boost/variant/detail/apply_visitor_unary.hpp"

#include "boost/variant/detail/apply_visitor_binary.hpp"

namespace boost {

//////////////////////////////////////////////////////////////////////////

// function template apply_visitor(visitor)

//

// Returns a function object, overloaded for unary and binary usage, that

// visits its arguments using visitor (or a copy of visitor) via

//  * apply_visitor( visitor, [argument] )

// under unary invocation, or

//  * apply_visitor( visitor, [argument1], [argument2] )

// under binary invocation.

//

// NOTE: Unlike other apply_visitor forms, the visitor object must be

//   non-const; this prevents user from giving temporary, to disastrous

//   effect (i.e., returned function object would have dead reference).

//

template <typename Visitor>

class apply_visitor_delayed_t

{

public: // visitor typedefs

    typedef typename Visitor::result_type

        result_type;

private: // representation

    Visitor& visitor_;

public: // structors

    explicit apply_visitor_delayed_t(Visitor& visitor)

      : visitor_(visitor)

    {

    }

public: // unary visitor interface

    template <typename Visitable>

        BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(result_type)

    operator()(Visitable& visitable)

    {

        return apply_visitor(visitor_, visitable);

    }

public: // binary visitor interface

    template <typename Visitable1, typename Visitable2>

        BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(result_type)

    operator()(Visitable1& visitable1, Visitable2& visitable2)

    {

        return apply_visitor(visitor_, visitable1, visitable2);

    }

};

template <typename Visitor>

inline apply_visitor_delayed_t<Visitor> apply_visitor(Visitor& visitor)

{

    return apply_visitor_delayed_t<Visitor>(visitor);

}

} // namespace boost

#endif // BOOST_VARIANT_DETAIL_APPLY_VISITOR_DELAYED_HPP