| //===----------------------------------------------------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is dual licensed under the MIT and the University of Illinois Open |
| // Source Licenses. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| // <memory> |
| |
| // template <class Alloc> |
| // struct allocator_traits |
| // { |
| // typedef Alloc::difference_type |
| // | pointer_traits<pointer>::difference_type difference_type; |
| // ... |
| // }; |
| |
| #include <memory> |
| #include <type_traits> |
| |
| template <class T> |
| struct A |
| { |
| typedef T value_type; |
| typedef short difference_type; |
| }; |
| |
| template <class T> |
| struct B |
| { |
| typedef T value_type; |
| }; |
| |
| template <class T> |
| struct C |
| { |
| typedef T value_type; |
| struct pointer {}; |
| struct const_pointer {}; |
| struct void_pointer {}; |
| struct const_void_pointer {}; |
| }; |
| |
| namespace std |
| { |
| |
| template <> |
| struct pointer_traits<C<char>::pointer> |
| { |
| typedef signed char difference_type; |
| }; |
| |
| } |
| |
| int main() |
| { |
| static_assert((std::is_same<std::allocator_traits<A<char> >::difference_type, short>::value), ""); |
| static_assert((std::is_same<std::allocator_traits<B<char> >::difference_type, std::ptrdiff_t>::value), ""); |
| static_assert((std::is_same<std::allocator_traits<C<char> >::difference_type, signed char>::value), ""); |
| } |