1 //===----------------------------------------------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is dual licensed under the MIT and the University of Illinois Open 6 // Source Licenses. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 // <memory> 11 12 // template <class Alloc> 13 // struct allocator_traits 14 // { 15 // typedef Alloc::difference_type 16 // | pointer_traits<pointer>::difference_type difference_type; 17 // ... 18 // }; 19 20 #include <memory> 21 #include <type_traits> 22 23 template <class T> 24 struct A 25 { 26 typedef T value_type; 27 typedef short difference_type; 28 }; 29 30 template <class T> 31 struct B 32 { 33 typedef T value_type; 34 }; 35 36 template <class T> 37 struct C 38 { 39 typedef T value_type; 40 struct pointer {}; 41 struct const_pointer {}; 42 struct void_pointer {}; 43 struct const_void_pointer {}; 44 }; 45 46 namespace std 47 { 48 49 template <> 50 struct pointer_traits<C<char>::pointer> 51 { 52 typedef signed char difference_type; 53 }; 54 55 } 56 57 int main() 58 { 59 static_assert((std::is_same<std::allocator_traits<A<char> >::difference_type, short>::value), ""); 60 static_assert((std::is_same<std::allocator_traits<B<char> >::difference_type, std::ptrdiff_t>::value), ""); 61 static_assert((std::is_same<std::allocator_traits<C<char> >::difference_type, signed char>::value), ""); 62 } 63
