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/and.hpp>
0017 #include <boost/mpl/bool.hpp>
0018 #include <boost/cstdint.hpp>
0019
0020 namespace boost
0021 {
0022     namespace range_detail
0023     {
0024
0025 template<class T>
0026 class has_member_size_impl
0027 {
0028 private:
0029     template<class U, U>
0030     class check
0031     {
0032     };
0033
0034     template<class C>
0035     static boost::uint8_t f(check<std::size_t(C::*)(void) const, &C::size>*);
0036
0037     template<class C>
0038     static boost::uint16_t f(...);
0039
0040 public:
0041     static const bool value =
0042         (sizeof(f<T>(0)) == sizeof(boost::uint8_t));
0043
0044     typedef typename mpl::if_c<
0045         (sizeof(f<T>(0)) == sizeof(boost::uint8_t)),
0046         mpl::true_,
0047         mpl::false_
0048     >::type type;
0049 };
0050
0051 template<class T>
0052 struct has_member_size
0053 {
0054     typedef typename mpl::and_<
0055         typename is_class<T>::type,
0056         typename has_member_size_impl<const T>::type
0057     >::type type;
0058
0059     static const bool value =
0060         is_class<T>::value && has_member_size_impl<const T>::value;
0061 };
0062
0063     } // namespace range_detail
0064 }// namespace boost
0065
0066 #endif // include guard