boost/utility/result_of.hpp

   1 // Boost result_of library
   2
   3 //  Copyright Douglas Gregor 2004. Use, modification and
   4 //  distribution is subject to the Boost Software License, Version
   5 //  1.0. (See accompanying file LICENSE_1_0.txt or copy at
   6 //  http://www.boost.org/LICENSE_1_0.txt)
   7
   8 // For more information, see http://www.boost.org/libs/utility
   9 #ifndef BOOST_RESULT_OF_HPP
  10 #define BOOST_RESULT_OF_HPP
  11
  12 #include <boost/config.hpp>
  13 #include <boost/preprocessor/iteration/iterate.hpp>
  14 #include <boost/preprocessor/punctuation/comma_if.hpp>
  15 #include <boost/preprocessor/repetition/enum_params.hpp>
  16 #include <boost/preprocessor/repetition/enum_shifted_params.hpp>
  17 #include <boost/detail/workaround.hpp>
  18 #include <boost/mpl/has_xxx.hpp>
  19 #include <boost/mpl/if.hpp>
  20 #include <boost/mpl/bool.hpp>
  21 #include <boost/mpl/or.hpp>
  22 #include <boost/type_traits/is_pointer.hpp>
  23 #include <boost/type_traits/is_member_function_pointer.hpp>
  24 #include <boost/type_traits/remove_cv.hpp>
  25
  26 #ifndef BOOST_RESULT_OF_NUM_ARGS
  27 #  define BOOST_RESULT_OF_NUM_ARGS 10
  28 #endif
  29
  30 namespace boost {
  31
  32 template<typename F> struct result_of;
  33
  34 #if !defined(BOOST_NO_SFINAE) && !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
  35 namespace detail {
  36
  37 BOOST_MPL_HAS_XXX_TRAIT_DEF(result_type)
  38
  39 template<typename F, typename FArgs, bool HasResultType> struct result_of_impl;
  40 template<typename F> struct result_of_decltype_impl;
  41
  42 template<typename F>
  43 struct result_of_void_impl
  44 {
  45   typedef void type;
  46 };
  47
  48 template<typename R>
  49 struct result_of_void_impl<R (*)(void)>
  50 {
  51   typedef R type;
  52 };
  53
  54 template<typename R>
  55 struct result_of_void_impl<R (&)(void)>
  56 {
  57   typedef R type;
  58 };
  59
  60 // Determine the return type of a function pointer or pointer to member.
  61 template<typename F, typename FArgs>
  62 struct result_of_pointer
  63   : result_of_impl<typename remove_cv<F>::type, FArgs, false> { };
  64
  65 template<typename F, typename FArgs>
  66 struct result_of_impl<F, FArgs, true>
  67 {
  68   typedef typename F::result_type type;
  69 };
  70
  71 template<typename FArgs>
  72 struct is_function_with_no_args : mpl::false_ {};
  73
  74 template<typename F>
  75 struct is_function_with_no_args<F(void)> : mpl::true_ {};
  76
  77 template<typename F, typename FArgs>
  78 struct result_of_nested_result : F::template result<FArgs>
  79 {};
  80
  81 template<typename F, typename FArgs>
  82 struct result_of_impl<F, FArgs, false>
  83   : mpl::if_<is_function_with_no_args<FArgs>,
  84              result_of_void_impl<F>,
  85              result_of_nested_result<F, FArgs> >::type
  86 {};
  87
  88 } // end namespace detail
  89
  90 #define BOOST_PP_ITERATION_PARAMS_1 (3,(0,BOOST_RESULT_OF_NUM_ARGS,<boost/utility/detail/result_of_iterate.hpp>))
  91 #include BOOST_PP_ITERATE()
  92
  93 #else
  94 #  define BOOST_NO_RESULT_OF 1
  95 #endif
  96
  97 }
  98
  99 #endif // BOOST_RESULT_OF_HPP