range/detail/has_member_size.hpp

0001 // Boost.Range library
0002 //
0003 // Copyright Neil Groves 2014.
0004 //
0005 // Use, modification and distribution are subject to the Boost Software License,
0006 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
0007 // http://www.boost.org/LICENSE_1_0.txt).
0008 //
0009 // For more information, see http://www.boost.org/libs/range/
0010 //
0011 #ifndef BOOST_RANGE_DETAIL_HAS_MEMBER_SIZE_HPP
0012 #define BOOST_RANGE_DETAIL_HAS_MEMBER_SIZE_HPP
0013
0014 #include <boost/type_traits/is_class.hpp>
0015 #include <boost/type_traits/is_member_function_pointer.hpp>
0016 #include <boost/mpl/if.hpp>
0017 #include <boost/mpl/and.hpp>
0018 #include <boost/mpl/bool.hpp>
0019 #include <boost/cstdint.hpp>
0020
0021 namespace boost
0022 {
0023     namespace range_detail
0024     {
0025
0026 template<class T>
0027 class has_member_size_impl
0028 {
0029 private:
0030     template<class U, U>
0031     class check
0032     {
0033     };
0034
0035     template<class C>
0036     static boost::uint8_t f(check<std::size_t(C::*)(void) const, &C::size>*);
0037
0038     template<class C>
0039     static boost::uint16_t f(...);
0040
0041 public:
0042     static const bool value =
0043         (sizeof(f<T>(0)) == sizeof(boost::uint8_t));
0044
0045     typedef typename mpl::if_c<
0046         (sizeof(f<T>(0)) == sizeof(boost::uint8_t)),
0047         mpl::true_,
0048         mpl::false_
0049     >::type type;
0050 };
0051
0052 template<class T>
0053 struct has_member_size
0054 {
0055     typedef typename mpl::and_<
0056         typename is_class<T>::type,
0057         typename has_member_size_impl<const T>::type
0058     >::type type;
0059
0060     static const bool value =
0061         is_class<T>::value && has_member_size_impl<const T>::value;
0062 };
0063
0064     } // namespace range_detail
0065 }// namespace boost
0066
0067 #endif // include guard