ceph/src/boost/libs/lambda/include/boost/lambda/detail/is_instance_of.hpp

   1 // Boost Lambda Library - is_instance_of.hpp ---------------------
   2
   3 // Copyright (C) 2001 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi)
   4 //
   5 // Distributed under the Boost Software License, Version 1.0. (See
   6 // accompanying file LICENSE_1_0.txt or copy at
   7 // http://www.boost.org/LICENSE_1_0.txt)
   8 //
   9 // For more information, see www.boost.org
  10
  11 // ---------------------------------------------------------------
  12
  13 #ifndef BOOST_LAMBDA_IS_INSTANCE_OF
  14 #define BOOST_LAMBDA_IS_INSTANCE_OF
  15
  16 #include "boost/config.hpp" // for BOOST_STATIC_CONSTANT
  17 #include "boost/type_traits/conversion_traits.hpp" // for is_convertible
  18 #include "boost/preprocessor/enum_shifted_params.hpp"
  19 #include "boost/preprocessor/repeat_2nd.hpp"
  20
  21 // is_instance_of --------------------------------
  22 //
  23 // is_instance_of_n<A, B>::value is true, if type A is
  24 // an instantiation of a template B, or A derives from an instantiation
  25 // of template B
  26 //
  27 // n is the number of template arguments for B
  28 //
  29 // Example:
  30 // is_instance_of_2<std::istream, basic_stream>::value == true
  31
  32 // The original implementation was somewhat different, with different versions
  33 // for different compilers. However, there was still a problem
  34 // with gcc.3.0.2 and 3.0.3 compilers, which didn't think regard
  35 // is_instance_of_N<...>::value was a constant.
  36 // John Maddock suggested the way around this problem by building
  37 // is_instance_of templates using boost::is_convertible.
  38 // Now we only have one version of is_instance_of templates, which delagate
  39 // all the nasty compiler tricks to is_convertible.
  40
  41 #define BOOST_LAMBDA_CLASS(z, N,A) BOOST_PP_COMMA_IF(N) class
  42 #define BOOST_LAMBDA_CLASS_ARG(z, N,A) BOOST_PP_COMMA_IF(N) class A##N
  43 #define BOOST_LAMBDA_ARG(z, N,A) BOOST_PP_COMMA_IF(N) A##N
  44
  45 #define BOOST_LAMBDA_CLASS_LIST(n, NAME) BOOST_PP_REPEAT(n, BOOST_LAMBDA_CLASS, NAME)
  46
  47 #define BOOST_LAMBDA_CLASS_ARG_LIST(n, NAME) BOOST_PP_REPEAT(n, BOOST_LAMBDA_CLASS_ARG, NAME)
  48
  49 #define BOOST_LAMBDA_ARG_LIST(n, NAME) BOOST_PP_REPEAT(n, BOOST_LAMBDA_ARG, NAME)
  50
  51 namespace boost {
  52 namespace lambda {
  53
  54 #define BOOST_LAMBDA_IS_INSTANCE_OF_TEMPLATE(INDEX)                         \
  55                                                                             \
  56 namespace detail {                                                          \
  57                                                                             \
  58 template <template<BOOST_LAMBDA_CLASS_LIST(INDEX,T)> class F>               \
  59 struct BOOST_PP_CAT(conversion_tester_,INDEX) {                             \
  60   template<BOOST_LAMBDA_CLASS_ARG_LIST(INDEX,A)>                            \
  61   BOOST_PP_CAT(conversion_tester_,INDEX)                                    \
  62     (const F<BOOST_LAMBDA_ARG_LIST(INDEX,A)>&);                             \
  63 };                                                                          \
  64                                                                             \
  65 } /* end detail */                                                          \
  66                                                                             \
  67 template <class From, template <BOOST_LAMBDA_CLASS_LIST(INDEX,T)> class To> \
  68 struct BOOST_PP_CAT(is_instance_of_,INDEX)                                  \
  69 {                                                                           \
  70  private:                                                                   \
  71    typedef ::boost::is_convertible<                                         \
  72      From,                                                                  \
  73      BOOST_PP_CAT(detail::conversion_tester_,INDEX)<To>                     \
  74    > helper_type;                                                           \
  75                                                                             \
  76 public:                                                                     \
  77   BOOST_STATIC_CONSTANT(bool, value = helper_type::value);                  \
  78 };
  79
  80
  81 #define BOOST_LAMBDA_HELPER(z, N, A) BOOST_LAMBDA_IS_INSTANCE_OF_TEMPLATE( BOOST_PP_INC(N) )
  82
  83 // Generate the traits for 1-4 argument templates
  84
  85 BOOST_PP_REPEAT_2ND(4,BOOST_LAMBDA_HELPER,FOO)
  86
  87 #undef BOOST_LAMBDA_HELPER
  88 #undef BOOST_LAMBDA_IS_INSTANCE_OF_TEMPLATE
  89 #undef BOOST_LAMBDA_CLASS
  90 #undef BOOST_LAMBDA_ARG
  91 #undef BOOST_LAMBDA_CLASS_ARG
  92 #undef BOOST_LAMBDA_CLASS_LIST
  93 #undef BOOST_LAMBDA_ARG_LIST
  94 #undef BOOST_LAMBDA_CLASS_ARG_LIST
  95
  96 } // lambda
  97 } // boost
  98
  99 #endif
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