boost/tti/has_data.hpp

0001
0002 //  (C) Copyright Edward Diener 2012,2013
0003 //  Use, modification and distribution are subject to the Boost Software License,
0004 //  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
0005 //  http://www.boost.org/LICENSE_1_0.txt).
0006
0007 #if !defined(BOOST_TTI_HAS_DATA_HPP)
0008 #define BOOST_TTI_HAS_DATA_HPP
0009
0010 #include <boost/config.hpp>
0011 #include <boost/preprocessor/cat.hpp>
0012 #include <boost/type_traits/remove_const.hpp>
0013 #include <boost/tti/gen/has_data_gen.hpp>
0014 #include <boost/tti/detail/ddata.hpp>
0015
0016 /*
0017
0018   The succeeding comments in this file are in doxygen format.
0019
0020 */
0021
0022 /** \file
0023 */
0024
0025 /// A macro which expands to a metafunction which tests whether member data or static member data with a particular name and type exists.
0026 /**
0027
0028     BOOST_TTI_TRAIT_HAS_DATA is a macro which expands to a metafunction.
0029     The metafunction tests whether member data or static member data with a particular
0030     name and type exists. The macro takes the form of BOOST_TTI_TRAIT_HAS_DATA(trait,name) where
0031
0032     trait = the name of the metafunction <br/>
0033     name  = the name of the inner data.
0034
0035     BOOST_TTI_TRAIT_HAS_DATA generates a metafunction called "trait" where 'trait' is the macro parameter.
0036
0037   @code
0038
0039               template<class BOOST_TTI_TP_T,class BOOST_TTI_TP_TYPE>
0040               struct trait
0041                 {
0042                 static const value = unspecified;
0043                 typedef mpl::bool_<true-or-false> type;
0044                 };
0045
0046               The metafunction types and return:
0047
0048                 BOOST_TTI_TP_T    = the enclosing type in which to look for our 'name'
0049                                     The enclosing type can be a class, struct, or union.
0050                                     If the type is a union, static member data can only
0051                                     be found if the C++11 unrestricted union is implemented
0052                                     by the compiler being used, since prior to C++11 a union
0053                                     could not have static data members.
0054
0055                 BOOST_TTI_TP_TYPE = The type of the member data or static member.
0056
0057                 returns  = 'value' is true if the 'name' exists, with the correct data type,
0058                            otherwise 'value' is false.
0059
0060   @endcode
0061
0062 */
0063 #define BOOST_TTI_TRAIT_HAS_DATA(trait,name) \
0064   BOOST_TTI_DETAIL_TRAIT_HAS_DATA(trait,name) \
0065   template<class BOOST_TTI_TP_T,class BOOST_TTI_TP_TYPE> \
0066   struct trait \
0067     { \
0068     typedef typename \
0069     BOOST_PP_CAT(trait,_detail_hd) \
0070       < \
0071       typename boost::remove_const<BOOST_TTI_TP_T>::type, \
0072       BOOST_TTI_TP_TYPE \
0073       >::type type; \
0074     BOOST_STATIC_CONSTANT(bool,value=type::value); \
0075     }; \
0076 /**/
0077
0078 /// A macro which expands to a metafunction which tests whether member data or static member data with a particular name and type exists.
0079 /**
0080
0081     BOOST_TTI_HAS_DATA is a macro which expands to a metafunction.
0082     The metafunction tests whether member data or static member data with a particular
0083     name and type exists. The macro takes the form of BOOST_TTI_HAS_DATA(name) where
0084
0085     name  = the name of the inner data.
0086
0087     BOOST_TTI_HAS_DATA generates a metafunction called "has_data_name" where 'name' is the macro parameter.
0088
0089   @code
0090
0091               template<class BOOST_TTI_TP_T,class BOOST_TTI_TP_TYPE>
0092               struct has_data_'name'
0093                 {
0094                 static const value = unspecified;
0095                 typedef mpl::bool_<true-or-false> type;
0096                 };
0097
0098               The metafunction types and return:
0099
0100                 BOOST_TTI_TP_T    = the enclosing type in which to look for our 'name'
0101                                     The enclosing type can be a class, struct, or union.
0102                                     If the type is a union, static member data can only
0103                                     be found if the C++11 unrestricted union is implemented
0104                                     by the compiler being used, since prior to C++11 a union
0105                                     could not have static data members.
0106
0107                 BOOST_TTI_TP_TYPE = The type of the member data or static member.
0108
0109                 returns  = 'value' is true if the 'name' exists, with the correct data type,
0110                            otherwise 'value' is false.
0111
0112   @endcode
0113
0114 */
0115 #define BOOST_TTI_HAS_DATA(name) \
0116   BOOST_TTI_TRAIT_HAS_DATA \
0117   ( \
0118   BOOST_TTI_HAS_DATA_GEN(name), \
0119   name \
0120   ) \
0121 /**/
0122
0123 #endif // BOOST_TTI_HAS_DATA_HPP