| // Pointer Traits -*- C++ -*- |
| |
| // Copyright (C) 2011-2016 Free Software Foundation, Inc. |
| // |
| // This file is part of the GNU ISO C++ Library. This library is free |
| // software; you can redistribute it and/or modify it under the |
| // terms of the GNU General Public License as published by the |
| // Free Software Foundation; either version 3, or (at your option) |
| // any later version. |
| |
| // This library is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| |
| // Under Section 7 of GPL version 3, you are granted additional |
| // permissions described in the GCC Runtime Library Exception, version |
| // 3.1, as published by the Free Software Foundation. |
| |
| // You should have received a copy of the GNU General Public License and |
| // a copy of the GCC Runtime Library Exception along with this program; |
| // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
| // <http://www.gnu.org/licenses/>. |
| |
| /** @file bits/ptr_traits.h |
| * This is an internal header file, included by other library headers. |
| * Do not attempt to use it directly. @headername{memory} |
| */ |
| |
| #ifndef _PTR_TRAITS_H |
| #define _PTR_TRAITS_H 1 |
| |
| #if __cplusplus >= 201103L |
| |
| #include <bits/move.h> |
| |
| namespace std _GLIBCXX_VISIBILITY(default) |
| { |
| _GLIBCXX_BEGIN_NAMESPACE_VERSION |
| |
| class __undefined; |
| |
| // Given Template<T, ...> return T, otherwise invalid. |
| template<typename _Tp> |
| struct __get_first_arg |
| { using type = __undefined; }; |
| |
| template<template<typename, typename...> class _Template, typename _Tp, |
| typename... _Types> |
| struct __get_first_arg<_Template<_Tp, _Types...>> |
| { using type = _Tp; }; |
| |
| template<typename _Tp> |
| using __get_first_arg_t = typename __get_first_arg<_Tp>::type; |
| |
| // Given Template<T, ...> and U return Template<U, ...>, otherwise invalid. |
| template<typename _Tp, typename _Up> |
| struct __replace_first_arg |
| { using type = __undefined; }; |
| |
| template<template<typename, typename...> class _Template, typename _Up, |
| typename _Tp, typename... _Types> |
| struct __replace_first_arg<_Template<_Tp, _Types...>, _Up> |
| { using type = _Template<_Up, _Types...>; }; |
| |
| template<typename _Tp, typename _Up> |
| using __replace_first_arg_t = typename __replace_first_arg<_Tp, _Up>::type; |
| |
| template<typename _Tp> |
| using __make_not_void |
| = typename conditional<is_void<_Tp>::value, __undefined, _Tp>::type; |
| |
| /** |
| * @brief Uniform interface to all pointer-like types |
| * @ingroup pointer_abstractions |
| */ |
| template<typename _Ptr> |
| struct pointer_traits |
| { |
| private: |
| template<typename _Tp> |
| using __element_type = typename _Tp::element_type; |
| |
| template<typename _Tp> |
| using __difference_type = typename _Tp::difference_type; |
| |
| template<typename _Tp, typename _Up> |
| using __rebind = typename _Tp::template rebind<_Up>; |
| |
| public: |
| /// The pointer type. |
| using pointer = _Ptr; |
| |
| /// The type pointed to. |
| using element_type |
| = __detected_or_t_<__get_first_arg_t, __element_type, _Ptr>; |
| |
| /// The type used to represent the difference between two pointers. |
| using difference_type |
| = __detected_or_t<ptrdiff_t, __difference_type, _Ptr>; |
| |
| /// A pointer to a different type. |
| template<typename _Up> |
| using rebind |
| = __detected_or_t_<__replace_first_arg_t, __rebind, _Ptr, _Up>; |
| |
| static _Ptr |
| pointer_to(__make_not_void<element_type>& __e) |
| { return _Ptr::pointer_to(__e); } |
| |
| static_assert(!is_same<element_type, __undefined>::value, |
| "pointer type defines element_type or is like SomePointer<T, Args>"); |
| static_assert(!is_same<rebind<element_type>, __undefined>::value, |
| "pointer type defines rebind<U> or is like SomePointer<T, Args>"); |
| }; |
| |
| /** |
| * @brief Partial specialization for built-in pointers. |
| * @ingroup pointer_abstractions |
| */ |
| template<typename _Tp> |
| struct pointer_traits<_Tp*> |
| { |
| /// The pointer type |
| typedef _Tp* pointer; |
| /// The type pointed to |
| typedef _Tp element_type; |
| /// Type used to represent the difference between two pointers |
| typedef ptrdiff_t difference_type; |
| |
| template<typename _Up> |
| using rebind = _Up*; |
| |
| /** |
| * @brief Obtain a pointer to an object |
| * @param __r A reference to an object of type @c element_type |
| * @return @c addressof(__r) |
| */ |
| static pointer |
| pointer_to(__make_not_void<element_type>& __r) noexcept |
| { return std::addressof(__r); } |
| }; |
| |
| /// Convenience alias for rebinding pointers. |
| template<typename _Ptr, typename _Tp> |
| using __ptr_rebind = typename pointer_traits<_Ptr>::template rebind<_Tp>; |
| |
| _GLIBCXX_END_NAMESPACE_VERSION |
| } // namespace std |
| |
| #endif |
| |
| #endif |