boost/tti/has_data.hpp
// (C) Copyright Edward Diener 2012,2013 // Use, modification and distribution are 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). #if !defined(BOOST_TTI_HAS_DATA_HPP) #define BOOST_TTI_HAS_DATA_HPP #include <boost/config.hpp> #include <boost/preprocessor/cat.hpp> #include <boost/type_traits/remove_const.hpp> #include <boost/tti/gen/has_data_gen.hpp> #include <boost/tti/detail/ddata.hpp> /* The succeeding comments in this file are in doxygen format. */ /** \file */ /// A macro which expands to a metafunction which tests whether member data or static member data with a particular name and type exists. /** BOOST_TTI_TRAIT_HAS_DATA is a macro which expands to a metafunction. The metafunction tests whether member data or static member data with a particular name and type exists. The macro takes the form of BOOST_TTI_TRAIT_HAS_DATA(trait,name) where trait = the name of the metafunction <br/> name = the name of the inner data. BOOST_TTI_TRAIT_HAS_DATA generates a metafunction called "trait" where 'trait' is the macro parameter. @code template<class BOOST_TTI_TP_T,class BOOST_TTI_TP_TYPE> struct trait { static const value = unspecified; typedef mpl::bool_<true-or-false> type; }; The metafunction types and return: BOOST_TTI_TP_T = the enclosing type in which to look for our 'name' The enclosing type can be a class, struct, or union. If the type is a union, static member data can only be found if the C++11 unrestricted union is implemented by the compiler being used, since prior to C++11 a union could not have static data members. BOOST_TTI_TP_TYPE = The type of the member data or static member. returns = 'value' is true if the 'name' exists, with the correct data type, otherwise 'value' is false. @endcode */ #define BOOST_TTI_TRAIT_HAS_DATA(trait,name) \ BOOST_TTI_DETAIL_TRAIT_HAS_DATA(trait,name) \ template<class BOOST_TTI_TP_T,class BOOST_TTI_TP_TYPE> \ struct trait \ { \ typedef typename \ BOOST_PP_CAT(trait,_detail_hd) \ < \ typename boost::remove_const<BOOST_TTI_TP_T>::type, \ BOOST_TTI_TP_TYPE \ >::type type; \ BOOST_STATIC_CONSTANT(bool,value=type::value); \ }; \ /**/ /// A macro which expands to a metafunction which tests whether member data or static member data with a particular name and type exists. /** BOOST_TTI_HAS_DATA is a macro which expands to a metafunction. The metafunction tests whether member data or static member data with a particular name and type exists. The macro takes the form of BOOST_TTI_HAS_DATA(name) where name = the name of the inner data. BOOST_TTI_HAS_DATA generates a metafunction called "has_data_name" where 'name' is the macro parameter. @code template<class BOOST_TTI_TP_T,class BOOST_TTI_TP_TYPE> struct has_data_'name' { static const value = unspecified; typedef mpl::bool_<true-or-false> type; }; The metafunction types and return: BOOST_TTI_TP_T = the enclosing type in which to look for our 'name' The enclosing type can be a class, struct, or union. If the type is a union, static member data can only be found if the C++11 unrestricted union is implemented by the compiler being used, since prior to C++11 a union could not have static data members. BOOST_TTI_TP_TYPE = The type of the member data or static member. returns = 'value' is true if the 'name' exists, with the correct data type, otherwise 'value' is false. @endcode */ #define BOOST_TTI_HAS_DATA(name) \ BOOST_TTI_TRAIT_HAS_DATA \ ( \ BOOST_TTI_HAS_DATA_GEN(name), \ name \ ) \ /**/ #endif // BOOST_TTI_HAS_DATA_HPP