boost/variant/detail/initializer.hpp
//----------------------------------------------------------------------------- // boost variant/detail/initializer.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_INITIALIZER_HPP #define BOOST_VARIANT_DETAIL_INITIALIZER_HPP #include <new> // for placement new #include <boost/config.hpp> #include <boost/call_traits.hpp> #include <boost/detail/reference_content.hpp> #include <boost/variant/recursive_wrapper_fwd.hpp> #include <boost/variant/detail/move.hpp> #if !defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE) # include <boost/mpl/aux_/value_wknd.hpp> # include <boost/mpl/int.hpp> # include <boost/mpl/iter_fold.hpp> # include <boost/mpl/next.hpp> # include <boost/mpl/deref.hpp> # include <boost/mpl/pair.hpp> # include <boost/mpl/protect.hpp> #else # include <boost/variant/variant_fwd.hpp> # include <boost/preprocessor/cat.hpp> # include <boost/preprocessor/enum.hpp> # include <boost/preprocessor/repeat.hpp> #endif namespace boost { namespace detail { namespace variant { /////////////////////////////////////////////////////////////////////////////// // (detail) support to simulate standard overload resolution rules // // The below initializers allows variant to follow standard overload // resolution rules over the specified set of bounded types. // // On compilers where using declarations in class templates can correctly // avoid name hiding, use an optimal solution based on the variant's typelist. // // Otherwise, use a preprocessor workaround based on knowledge of the fixed // size of the variant's psuedo-variadic template parameter list. // #if !defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE) // (detail) quoted metafunction make_initializer_node // // Exposes a pair whose first type is a node in the initializer hierarchy. // struct make_initializer_node { template <typename BaseIndexPair, typename Iterator> struct apply { private: // helpers, for metafunction result (below) typedef typename BaseIndexPair::first base; typedef typename BaseIndexPair::second index; class initializer_node : public base { private: // helpers, for static functions (below) typedef typename mpl::deref<Iterator>::type recursive_enabled_T; typedef typename unwrap_recursive<recursive_enabled_T>::type public_T; #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES typedef boost::is_reference<public_T> is_reference_content_t; typedef typename boost::mpl::if_<is_reference_content_t, public_T, const public_T& >::type param_T; template <class T> struct disable_overload{}; typedef typename boost::mpl::if_<is_reference_content_t, disable_overload<public_T>, public_T&& >::type param2_T; #else typedef typename call_traits<public_T>::param_type param_T; #endif public: // static functions using base::initialize; static int initialize(void* dest, param_T operand) { typedef typename boost::detail::make_reference_content< recursive_enabled_T >::type internal_T; new(dest) internal_T(operand); return BOOST_MPL_AUX_VALUE_WKND(index)::value; // which } #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES static int initialize(void* dest, param2_T operand) { // This assert must newer trigger, because all the reference contents are // handled by the initilize(void* dest, param_T operand) function above BOOST_ASSERT(!is_reference_content_t::value); typedef typename boost::mpl::if_<is_reference_content_t, param2_T, recursive_enabled_T>::type value_T; new(dest) value_T( boost::detail::variant::move(operand) ); return BOOST_MPL_AUX_VALUE_WKND(index)::value; // which } #endif }; friend class initializer_node; public: // metafunction result typedef mpl::pair< initializer_node , typename mpl::next< index >::type > type; }; }; // (detail) class initializer_root // // Every level of the initializer hierarchy must expose the name // "initialize," so initializer_root provides a dummy function: // class initializer_root { public: // static functions static void initialize(); }; #else // defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE) // Obsolete. Remove. #define BOOST_VARIANT_AUX_PP_INITIALIZER_TEMPLATE_PARAMS \ BOOST_VARIANT_ENUM_PARAMS(typename recursive_enabled_T) \ /**/ // Obsolete. Remove. #define BOOST_VARIANT_AUX_PP_INITIALIZER_DEFINE_PARAM_T(N) \ typedef typename unwrap_recursive< \ BOOST_PP_CAT(recursive_enabled_T,N) \ >::type BOOST_PP_CAT(public_T,N); \ typedef typename call_traits< \ BOOST_PP_CAT(public_T,N) \ >::param_type BOOST_PP_CAT(param_T,N); \ /**/ template < BOOST_VARIANT_ENUM_PARAMS(typename recursive_enabled_T) > struct preprocessor_list_initializer { public: // static functions #define BOOST_VARIANT_AUX_PP_INITIALIZE_FUNCTION(z,N,_) \ typedef typename unwrap_recursive< \ BOOST_PP_CAT(recursive_enabled_T,N) \ >::type BOOST_PP_CAT(public_T,N); \ typedef typename call_traits< \ BOOST_PP_CAT(public_T,N) \ >::param_type BOOST_PP_CAT(param_T,N); \ static int initialize( \ void* dest \ , BOOST_PP_CAT(param_T,N) operand \ ) \ { \ typedef typename boost::detail::make_reference_content< \ BOOST_PP_CAT(recursive_enabled_T,N) \ >::type internal_T; \ \ new(dest) internal_T(operand); \ return (N); /*which*/ \ } \ /**/ BOOST_PP_REPEAT( BOOST_VARIANT_LIMIT_TYPES , BOOST_VARIANT_AUX_PP_INITIALIZE_FUNCTION , _ ) #undef BOOST_VARIANT_AUX_PP_INITIALIZE_FUNCTION }; #endif // BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE workaround }} // namespace detail::variant } // namespace boost /////////////////////////////////////////////////////////////////////////////// // macro BOOST_VARIANT_AUX_INITIALIZER_T // // Given both the variant's typelist and a basename for forming the list of // bounded types (i.e., T becomes T1, T2, etc.), exposes the initializer // most appropriate to the current compiler. // #if !defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE) #define BOOST_VARIANT_AUX_INITIALIZER_T( mpl_seq, typename_base ) \ ::boost::mpl::iter_fold< \ mpl_seq \ , ::boost::mpl::pair< \ ::boost::detail::variant::initializer_root \ , ::boost::mpl::int_<0> \ > \ , ::boost::mpl::protect< \ ::boost::detail::variant::make_initializer_node \ > \ >::type::first \ /**/ #else // defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE) // Obsolete. Remove. #define BOOST_VARIANT_AUX_PP_INITIALIZER_TEMPLATE_ARGS(typename_base) \ BOOST_VARIANT_ENUM_PARAMS(typename_base) \ /**/ #define BOOST_VARIANT_AUX_INITIALIZER_T( mpl_seq, typename_base ) \ ::boost::detail::variant::preprocessor_list_initializer< \ BOOST_VARIANT_ENUM_PARAMS(typename_base) \ > \ /**/ #endif // BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE workaround #endif // BOOST_VARIANT_DETAIL_INITIALIZER_HPP