ptr_traits.h
Go to the documentation of this file.
// Pointer Traits -*- C++ -*-
// Copyright (C) 2011-2013 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 <type_traits> // For _GLIBCXX_HAS_NESTED_TYPE
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
_GLIBCXX_HAS_NESTED_TYPE(element_type)
_GLIBCXX_HAS_NESTED_TYPE(difference_type)
template<typename _Tp, bool = __has_element_type<_Tp>::value>
struct __ptrtr_elt_type;
template<typename _Tp>
struct __ptrtr_elt_type<_Tp, true>
{
typedef typename _Tp::element_type __type;
};
template<template<typename, typename...> class _SomePtr, typename _Tp,
typename... _Args>
struct __ptrtr_elt_type<_SomePtr<_Tp, _Args...>, false>
{
typedef _Tp __type;
};
template<typename _Tp, bool = __has_difference_type<_Tp>::value>
struct __ptrtr_diff_type
{
typedef typename _Tp::difference_type __type;
};
template<typename _Tp>
struct __ptrtr_diff_type<_Tp, false>
{
typedef ptrdiff_t __type;
};
template<typename _Ptr, typename _Up>
class __ptrtr_rebind_helper
{
template<typename _Ptr2, typename _Up2>
static constexpr bool
_S_chk(typename _Ptr2::template rebind<_Up2>*)
{ return true; }
template<typename, typename>
static constexpr bool
_S_chk(...)
{ return false; }
public:
static const bool __value = _S_chk<_Ptr, _Up>(nullptr);
};
template<typename _Ptr, typename _Up>
const bool __ptrtr_rebind_helper<_Ptr, _Up>::__value;
template<typename _Tp, typename _Up,
bool = __ptrtr_rebind_helper<_Tp, _Up>::__value>
struct __ptrtr_rebind;
template<typename _Tp, typename _Up>
struct __ptrtr_rebind<_Tp, _Up, true>
{
typedef typename _Tp::template rebind<_Up> __type;
};
template<template<typename, typename...> class _SomePtr, typename _Up,
typename _Tp, typename... _Args>
struct __ptrtr_rebind<_SomePtr<_Tp, _Args...>, _Up, false>
{
typedef _SomePtr<_Up, _Args...> __type;
};
template<typename _Tp, typename = typename remove_cv<_Tp>::type>
struct __ptrtr_not_void
{
typedef _Tp __type;
};
template<typename _Tp>
struct __ptrtr_not_void<_Tp, void>
{
struct __type { };
};
template<typename _Ptr>
class __ptrtr_pointer_to
{
typedef typename __ptrtr_elt_type<_Ptr>::__type __orig_type;
typedef typename __ptrtr_not_void<__orig_type>::__type __element_type;
public:
static _Ptr pointer_to(__element_type& __e)
{ return _Ptr::pointer_to(__e); }
};
/**
* @brief Uniform interface to all pointer-like types
* @ingroup pointer_abstractions
*/
template<typename _Ptr>
struct pointer_traits : __ptrtr_pointer_to<_Ptr>
{
/// The pointer type
typedef _Ptr pointer;
/// The type pointed to
typedef typename __ptrtr_elt_type<_Ptr>::__type element_type;
/// Type used to represent the difference between two pointers
typedef typename __ptrtr_diff_type<_Ptr>::__type difference_type;
template<typename _Up>
using rebind = typename __ptrtr_rebind<_Ptr, _Up>::__type;
};
/**
* @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(typename __ptrtr_not_void<element_type>::__type& __r) noexcept
{ return std::addressof(__r); }
};
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif
#endif