Chris@16: //-----------------------------------------------------------------------------
Chris@16: // boost variant/static_visitor.hpp header file
Chris@16: // See http://www.boost.org for updates, documentation, and revision history.
Chris@16: //-----------------------------------------------------------------------------
Chris@16: //
Chris@16: // Copyright (c) 2002-2003
Chris@16: // Eric Friedman
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_VARIANT_STATIC_VISITOR_HPP
Chris@16: #define BOOST_VARIANT_STATIC_VISITOR_HPP
Chris@16: 
Chris@16: #include "boost/config.hpp"
Chris@16: #include "boost/detail/workaround.hpp"
Chris@16: 
Chris@16: #include "boost/mpl/if.hpp"
Chris@16: #include "boost/type_traits/is_base_and_derived.hpp"
Chris@16: 
Chris@16: // should be the last #include
Chris@16: #include "boost/type_traits/detail/bool_trait_def.hpp"
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: //////////////////////////////////////////////////////////////////////////
Chris@16: // class template static_visitor
Chris@16: //
Chris@16: // An empty base class that typedefs the return type of a deriving static
Chris@16: // visitor. The class is analogous to std::unary_function in this role.
Chris@16: //
Chris@16: 
Chris@16: namespace detail {
Chris@16: 
Chris@16:     struct is_static_visitor_tag { };
Chris@16: 
Chris@16:     typedef void static_visitor_default_return;
Chris@16: 
Chris@16: } // namespace detail
Chris@16: 
Chris@16: template <typename R = ::boost::detail::static_visitor_default_return>
Chris@16: class static_visitor
Chris@16:     : public detail::is_static_visitor_tag
Chris@16: {
Chris@16: public: // typedefs
Chris@16: 
Chris@16:     typedef R result_type;
Chris@16: 
Chris@16: protected: // for use as base class only
Chris@101: #if !defined(BOOST_NO_CXX11_DEFAULTED_FUNCTIONS) && !defined(BOOST_NO_CXX11_NON_PUBLIC_DEFAULTED_FUNCTIONS)
Chris@101:     static_visitor() = default;
Chris@101:     ~static_visitor() = default;
Chris@101: #else
Chris@101:     static_visitor()  BOOST_NOEXCEPT { }
Chris@101:     ~static_visitor()  BOOST_NOEXCEPT { }
Chris@101: #endif
Chris@16: };
Chris@16: 
Chris@16: //////////////////////////////////////////////////////////////////////////
Chris@16: // metafunction is_static_visitor
Chris@16: //
Chris@16: // Value metafunction indicates whether the specified type derives from
Chris@16: // static_visitor<...>.
Chris@16: //
Chris@16: // NOTE #1: This metafunction does NOT check whether the specified type
Chris@16: //  fulfills the requirements of the StaticVisitor concept.
Chris@16: //
Chris@16: // NOTE #2: This template never needs to be specialized!
Chris@16: //
Chris@16: 
Chris@16: namespace detail {
Chris@16: 
Chris@16: template <typename T>
Chris@16: struct is_static_visitor_impl
Chris@16: {
Chris@16:     BOOST_STATIC_CONSTANT(bool, value = 
Chris@16:         (::boost::is_base_and_derived< 
Chris@16:             detail::is_static_visitor_tag,
Chris@16:             T
Chris@16:         >::value));
Chris@16: };
Chris@16: 
Chris@16: } // namespace detail
Chris@16: 
Chris@16: BOOST_TT_AUX_BOOL_TRAIT_DEF1(
Chris@16:       is_static_visitor
Chris@16:     , T
Chris@16:     , (::boost::detail::is_static_visitor_impl<T>::value)
Chris@16:     )
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include "boost/type_traits/detail/bool_trait_undef.hpp"
Chris@16: 
Chris@16: #endif // BOOST_VARIANT_STATIC_VISITOR_HPP