Chris@16: // Boost Lambda Library - is_instance_of.hpp ---------------------
Chris@16: 
Chris@16: // Copyright (C) 2001 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi)
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: // For more information, see www.boost.org
Chris@16: 
Chris@16: // ---------------------------------------------------------------
Chris@16: 
Chris@16: #ifndef BOOST_LAMBDA_IS_INSTANCE_OF
Chris@16: #define BOOST_LAMBDA_IS_INSTANCE_OF
Chris@16: 
Chris@16: #include "boost/config.hpp" // for BOOST_STATIC_CONSTANT
Chris@16: #include "boost/type_traits/conversion_traits.hpp" // for is_convertible
Chris@16: #include "boost/preprocessor/enum_shifted_params.hpp"
Chris@16: #include "boost/preprocessor/repeat_2nd.hpp"
Chris@16: 
Chris@16: // is_instance_of --------------------------------
Chris@16: // 
Chris@16: // is_instance_of_n<A, B>::value is true, if type A is 
Chris@16: // an instantiation of a template B, or A derives from an instantiation 
Chris@16: // of template B
Chris@16: //
Chris@16: // n is the number of template arguments for B
Chris@16: // 
Chris@16: // Example:
Chris@16: // is_instance_of_2<std::istream, basic_stream>::value == true
Chris@16: 
Chris@16: // The original implementation was somewhat different, with different versions
Chris@16: // for different compilers. However, there was still a problem
Chris@16: // with gcc.3.0.2 and 3.0.3 compilers, which didn't think regard
Chris@16: // is_instance_of_N<...>::value was a constant.
Chris@16: // John Maddock suggested the way around this problem by building 
Chris@16: // is_instance_of templates using boost::is_convertible.
Chris@16: // Now we only have one version of is_instance_of templates, which delagate
Chris@16: // all the nasty compiler tricks to is_convertible. 
Chris@16: 
Chris@16: #define BOOST_LAMBDA_CLASS(z, N,A) BOOST_PP_COMMA_IF(N) class
Chris@16: #define BOOST_LAMBDA_CLASS_ARG(z, N,A) BOOST_PP_COMMA_IF(N) class A##N 
Chris@16: #define BOOST_LAMBDA_ARG(z, N,A) BOOST_PP_COMMA_IF(N) A##N 
Chris@16: 
Chris@16: #define BOOST_LAMBDA_CLASS_LIST(n, NAME) BOOST_PP_REPEAT(n, BOOST_LAMBDA_CLASS, NAME)
Chris@16: 
Chris@16: #define BOOST_LAMBDA_CLASS_ARG_LIST(n, NAME) BOOST_PP_REPEAT(n, BOOST_LAMBDA_CLASS_ARG, NAME)
Chris@16: 
Chris@16: #define BOOST_LAMBDA_ARG_LIST(n, NAME) BOOST_PP_REPEAT(n, BOOST_LAMBDA_ARG, NAME)
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace lambda {
Chris@16: 
Chris@16: #define BOOST_LAMBDA_IS_INSTANCE_OF_TEMPLATE(INDEX)                         \
Chris@16:                                                                             \
Chris@16: namespace detail {                                                          \
Chris@16:                                                                             \
Chris@16: template <template<BOOST_LAMBDA_CLASS_LIST(INDEX,T)> class F>               \
Chris@16: struct BOOST_PP_CAT(conversion_tester_,INDEX) {                             \
Chris@16:   template<BOOST_LAMBDA_CLASS_ARG_LIST(INDEX,A)>                            \
Chris@16:   BOOST_PP_CAT(conversion_tester_,INDEX)                                    \
Chris@16:     (const F<BOOST_LAMBDA_ARG_LIST(INDEX,A)>&);                             \
Chris@16: };                                                                          \
Chris@16:                                                                             \
Chris@16: } /* end detail */                                                          \
Chris@16:                                                                             \
Chris@16: template <class From, template <BOOST_LAMBDA_CLASS_LIST(INDEX,T)> class To> \
Chris@16: struct BOOST_PP_CAT(is_instance_of_,INDEX)                                  \
Chris@16: {                                                                           \
Chris@16:  private:                                                                   \
Chris@16:    typedef ::boost::is_convertible<                                         \
Chris@16:      From,                                                                  \
Chris@16:      BOOST_PP_CAT(detail::conversion_tester_,INDEX)<To>                     \
Chris@16:    > helper_type;                                                           \
Chris@16:                                                                             \
Chris@16: public:                                                                     \
Chris@16:   BOOST_STATIC_CONSTANT(bool, value = helper_type::value);                  \
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: #define BOOST_LAMBDA_HELPER(z, N, A) BOOST_LAMBDA_IS_INSTANCE_OF_TEMPLATE( BOOST_PP_INC(N) )
Chris@16: 
Chris@16: // Generate the traits for 1-4 argument templates
Chris@16: 
Chris@16: BOOST_PP_REPEAT_2ND(4,BOOST_LAMBDA_HELPER,FOO)
Chris@16: 
Chris@16: #undef BOOST_LAMBDA_HELPER
Chris@16: #undef BOOST_LAMBDA_IS_INSTANCE_OF_TEMPLATE
Chris@16: #undef BOOST_LAMBDA_CLASS
Chris@16: #undef BOOST_LAMBDA_ARG
Chris@16: #undef BOOST_LAMBDA_CLASS_ARG
Chris@16: #undef BOOST_LAMBDA_CLASS_LIST
Chris@16: #undef BOOST_LAMBDA_ARG_LIST
Chris@16: #undef BOOST_LAMBDA_CLASS_ARG_LIST
Chris@16: 
Chris@16: } // lambda
Chris@16: } // boost
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: