unique_ptr.h
Go to the documentation of this file.
// unique_ptr implementation -*- C++ -*-
// Copyright (C) 2008-2013 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/unique_ptr.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{memory}
*/
#ifndef _UNIQUE_PTR_H
#define _UNIQUE_PTR_H 1
#include <bits/c++config.h>
#include <debug/debug.h>
#include <type_traits>
#include <utility>
#include <tuple>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @addtogroup pointer_abstractions
* @{
*/
#if _GLIBCXX_USE_DEPRECATED
template<typename> class auto_ptr;
#endif
/// Primary template of default_delete, used by unique_ptr
template<typename _Tp>
struct default_delete
{
/// Default constructor
constexpr default_delete() noexcept = default;
/** @brief Converting constructor.
*
* Allows conversion from a deleter for arrays of another type, @p _Up,
* only if @p _Up* is convertible to @p _Tp*.
*/
template<typename _Up, typename = typename
enable_if<is_convertible<_Up*, _Tp*>::value>::type>
default_delete(const default_delete<_Up>&) noexcept { }
/// Calls @c delete @p __ptr
void
operator()(_Tp* __ptr) const
{
static_assert(sizeof(_Tp)>0,
"can't delete pointer to incomplete type");
delete __ptr;
}
};
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// DR 740 - omit specialization for array objects with a compile time length
/// Specialization for arrays, default_delete.
template<typename _Tp>
struct default_delete<_Tp[]>
{
private:
template<typename _Up>
using __remove_cv = typename remove_cv<_Up>::type;
// Like is_base_of<_Tp, _Up> but false if unqualified types are the same
template<typename _Up>
using __is_derived_Tp
= __and_< is_base_of<_Tp, _Up>,
__not_<is_same<__remove_cv<_Tp>, __remove_cv<_Up>>> >;
public:
/// Default constructor
constexpr default_delete() noexcept = default;
/** @brief Converting constructor.
*
* Allows conversion from a deleter for arrays of another type, such as
* a const-qualified version of @p _Tp.
*
* Conversions from types derived from @c _Tp are not allowed because
* it is unsafe to @c delete[] an array of derived types through a
* pointer to the base type.
*/
template<typename _Up, typename = typename
enable_if<!__is_derived_Tp<_Up>::value>::type>
default_delete(const default_delete<_Up[]>&) noexcept { }
/// Calls @c delete[] @p __ptr
void
operator()(_Tp* __ptr) const
{
static_assert(sizeof(_Tp)>0,
"can't delete pointer to incomplete type");
delete [] __ptr;
}
template<typename _Up>
typename enable_if<__is_derived_Tp<_Up>::value>::type
operator()(_Up*) const = delete;
};
/// 20.7.1.2 unique_ptr for single objects.
template <typename _Tp, typename _Dp = default_delete<_Tp> >
class unique_ptr
{
// use SFINAE to determine whether _Del::pointer exists
class _Pointer
{
template<typename _Up>
static typename _Up::pointer __test(typename _Up::pointer*);
template<typename _Up>
static _Tp* __test(...);
typedef typename remove_reference<_Dp>::type _Del;
public:
typedef decltype(__test<_Del>(0)) type;
};
typedef std::tuple<typename _Pointer::type, _Dp> __tuple_type;
__tuple_type _M_t;
public:
typedef typename _Pointer::type pointer;
typedef _Tp element_type;
typedef _Dp deleter_type;
// Constructors.
/// Default constructor, creates a unique_ptr that owns nothing.
constexpr unique_ptr() noexcept
: _M_t()
{ static_assert(!is_pointer<deleter_type>::value,
"constructed with null function pointer deleter"); }
/** Takes ownership of a pointer.
*
* @param __p A pointer to an object of @c element_type
*
* The deleter will be value-initialized.
*/
explicit
unique_ptr(pointer __p) noexcept
: _M_t(__p, deleter_type())
{ static_assert(!is_pointer<deleter_type>::value,
"constructed with null function pointer deleter"); }
/** Takes ownership of a pointer.
*
* @param __p A pointer to an object of @c element_type
* @param __d A reference to a deleter.
*
* The deleter will be initialized with @p __d
*/
unique_ptr(pointer __p,
typename conditional<is_reference<deleter_type>::value,
deleter_type, const deleter_type&>::type __d) noexcept
: _M_t(__p, __d) { }
/** Takes ownership of a pointer.
*
* @param __p A pointer to an object of @c element_type
* @param __d An rvalue reference to a deleter.
*
* The deleter will be initialized with @p std::move(__d)
*/
unique_ptr(pointer __p,
typename remove_reference<deleter_type>::type&& __d) noexcept
: _M_t(std::move(__p), std::move(__d))
{ static_assert(!std::is_reference<deleter_type>::value,
"rvalue deleter bound to reference"); }
/// Creates a unique_ptr that owns nothing.
constexpr unique_ptr(nullptr_t) noexcept : unique_ptr() { }
// Move constructors.
/// Move constructor.
unique_ptr(unique_ptr&& __u) noexcept
: _M_t(__u.release(), std::forward<deleter_type>(__u.get_deleter())) { }
/** @brief Converting constructor from another type
*
* Requires that the pointer owned by @p __u is convertible to the
* type of pointer owned by this object, @p __u does not own an array,
* and @p __u has a compatible deleter type.
*/
template<typename _Up, typename _Ep, typename = _Require<
is_convertible<typename unique_ptr<_Up, _Ep>::pointer, pointer>,
__not_<is_array<_Up>>,
typename conditional<is_reference<_Dp>::value,
is_same<_Ep, _Dp>,
is_convertible<_Ep, _Dp>>::type>>
unique_ptr(unique_ptr<_Up, _Ep>&& __u) noexcept
: _M_t(__u.release(), std::forward<_Ep>(__u.get_deleter()))
{ }
#if _GLIBCXX_USE_DEPRECATED
/// Converting constructor from @c auto_ptr
template<typename _Up, typename = _Require<
is_convertible<_Up*, _Tp*>, is_same<_Dp, default_delete<_Tp>>>>
unique_ptr(auto_ptr<_Up>&& __u) noexcept;
#endif
/// Destructor, invokes the deleter if the stored pointer is not null.
~unique_ptr() noexcept
{
auto& __ptr = std::get<0>(_M_t);
if (__ptr != nullptr)
get_deleter()(__ptr);
__ptr = pointer();
}
// Assignment.
/** @brief Move assignment operator.
*
* @param __u The object to transfer ownership from.
*
* Invokes the deleter first if this object owns a pointer.
*/
unique_ptr&
operator=(unique_ptr&& __u) noexcept
{
reset(__u.release());
get_deleter() = std::forward<deleter_type>(__u.get_deleter());
return *this;
}
/** @brief Assignment from another type.
*
* @param __u The object to transfer ownership from, which owns a
* convertible pointer to a non-array object.
*
* Invokes the deleter first if this object owns a pointer.
*/
template<typename _Up, typename _Ep>
typename enable_if< __and_<
is_convertible<typename unique_ptr<_Up, _Ep>::pointer, pointer>,
__not_<is_array<_Up>>
>::value,
unique_ptr&>::type
operator=(unique_ptr<_Up, _Ep>&& __u) noexcept
{
reset(__u.release());
get_deleter() = std::forward<_Ep>(__u.get_deleter());
return *this;
}
/// Reset the %unique_ptr to empty, invoking the deleter if necessary.
unique_ptr&
operator=(nullptr_t) noexcept
{
reset();
return *this;
}
// Observers.
/// Dereference the stored pointer.
typename add_lvalue_reference<element_type>::type
operator*() const
{
_GLIBCXX_DEBUG_ASSERT(get() != pointer());
return *get();
}
/// Return the stored pointer.
pointer
operator->() const noexcept
{
_GLIBCXX_DEBUG_ASSERT(get() != pointer());
return get();
}
/// Return the stored pointer.
pointer
get() const noexcept
{ return std::get<0>(_M_t); }
/// Return a reference to the stored deleter.
deleter_type&
get_deleter() noexcept
{ return std::get<1>(_M_t); }
/// Return a reference to the stored deleter.
const deleter_type&
get_deleter() const noexcept
{ return std::get<1>(_M_t); }
/// Return @c true if the stored pointer is not null.
explicit operator bool() const noexcept
{ return get() == pointer() ? false : true; }
// Modifiers.
/// Release ownership of any stored pointer.
pointer
release() noexcept
{
pointer __p = get();
std::get<0>(_M_t) = pointer();
return __p;
}
/** @brief Replace the stored pointer.
*
* @param __p The new pointer to store.
*
* The deleter will be invoked if a pointer is already owned.
*/
void
reset(pointer __p = pointer()) noexcept
{
using std::swap;
swap(std::get<0>(_M_t), __p);
if (__p != pointer())
get_deleter()(__p);
}
/// Exchange the pointer and deleter with another object.
void
swap(unique_ptr& __u) noexcept
{
using std::swap;
swap(_M_t, __u._M_t);
}
// Disable copy from lvalue.
unique_ptr(const unique_ptr&) = delete;
unique_ptr& operator=(const unique_ptr&) = delete;
};
/// 20.7.1.3 unique_ptr for array objects with a runtime length
// [unique.ptr.runtime]
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// DR 740 - omit specialization for array objects with a compile time length
template<typename _Tp, typename _Dp>
class unique_ptr<_Tp[], _Dp>
{
// use SFINAE to determine whether _Del::pointer exists
class _Pointer
{
template<typename _Up>
static typename _Up::pointer __test(typename _Up::pointer*);
template<typename _Up>
static _Tp* __test(...);
typedef typename remove_reference<_Dp>::type _Del;
public:
typedef decltype(__test<_Del>(0)) type;
};
typedef std::tuple<typename _Pointer::type, _Dp> __tuple_type;
__tuple_type _M_t;
template<typename _Up>
using __remove_cv = typename remove_cv<_Up>::type;
// like is_base_of<_Tp, _Up> but false if unqualified types are the same
template<typename _Up>
using __is_derived_Tp
= __and_< is_base_of<_Tp, _Up>,
__not_<is_same<__remove_cv<_Tp>, __remove_cv<_Up>>> >;
template<typename _Up, typename _Ep,
typename _Tp_pointer = typename _Pointer::type,
typename _Up_pointer = typename unique_ptr<_Up, _Ep>::pointer>
using __safe_conversion = __and_<
is_convertible<_Up_pointer, _Tp_pointer>,
is_array<_Up>,
__or_<__not_<is_pointer<_Up_pointer>>,
__not_<is_pointer<_Tp_pointer>>,
__not_<__is_derived_Tp<typename remove_extent<_Up>::type>>
>
>;
public:
typedef typename _Pointer::type pointer;
typedef _Tp element_type;
typedef _Dp deleter_type;
// Constructors.
/// Default constructor, creates a unique_ptr that owns nothing.
constexpr unique_ptr() noexcept
: _M_t()
{ static_assert(!std::is_pointer<deleter_type>::value,
"constructed with null function pointer deleter"); }
/** Takes ownership of a pointer.
*
* @param __p A pointer to an array of @c element_type
*
* The deleter will be value-initialized.
*/
explicit
unique_ptr(pointer __p) noexcept
: _M_t(__p, deleter_type())
{ static_assert(!is_pointer<deleter_type>::value,
"constructed with null function pointer deleter"); }
// Disable construction from convertible pointer types.
template<typename _Up, typename = _Require<is_pointer<pointer>,
is_convertible<_Up*, pointer>, __is_derived_Tp<_Up>>>
explicit
unique_ptr(_Up* __p) = delete;
/** Takes ownership of a pointer.
*
* @param __p A pointer to an array of @c element_type
* @param __d A reference to a deleter.
*
* The deleter will be initialized with @p __d
*/
unique_ptr(pointer __p,
typename conditional<is_reference<deleter_type>::value,
deleter_type, const deleter_type&>::type __d) noexcept
: _M_t(__p, __d) { }
/** Takes ownership of a pointer.
*
* @param __p A pointer to an array of @c element_type
* @param __d A reference to a deleter.
*
* The deleter will be initialized with @p std::move(__d)
*/
unique_ptr(pointer __p, typename
remove_reference<deleter_type>::type&& __d) noexcept
: _M_t(std::move(__p), std::move(__d))
{ static_assert(!is_reference<deleter_type>::value,
"rvalue deleter bound to reference"); }
/// Move constructor.
unique_ptr(unique_ptr&& __u) noexcept
: _M_t(__u.release(), std::forward<deleter_type>(__u.get_deleter())) { }
/// Creates a unique_ptr that owns nothing.
constexpr unique_ptr(nullptr_t) noexcept : unique_ptr() { }
template<typename _Up, typename _Ep,
typename = _Require<__safe_conversion<_Up, _Ep>,
typename conditional<is_reference<_Dp>::value,
is_same<_Ep, _Dp>,
is_convertible<_Ep, _Dp>>::type
>>
unique_ptr(unique_ptr<_Up, _Ep>&& __u) noexcept
: _M_t(__u.release(), std::forward<_Ep>(__u.get_deleter()))
{ }
/// Destructor, invokes the deleter if the stored pointer is not null.
~unique_ptr()
{
auto& __ptr = std::get<0>(_M_t);
if (__ptr != nullptr)
get_deleter()(__ptr);
__ptr = pointer();
}
// Assignment.
/** @brief Move assignment operator.
*
* @param __u The object to transfer ownership from.
*
* Invokes the deleter first if this object owns a pointer.
*/
unique_ptr&
operator=(unique_ptr&& __u) noexcept
{
reset(__u.release());
get_deleter() = std::forward<deleter_type>(__u.get_deleter());
return *this;
}
/** @brief Assignment from another type.
*
* @param __u The object to transfer ownership from, which owns a
* convertible pointer to an array object.
*
* Invokes the deleter first if this object owns a pointer.
*/
template<typename _Up, typename _Ep>
typename
enable_if<__safe_conversion<_Up, _Ep>::value, unique_ptr&>::type
operator=(unique_ptr<_Up, _Ep>&& __u) noexcept
{
reset(__u.release());
get_deleter() = std::forward<_Ep>(__u.get_deleter());
return *this;
}
/// Reset the %unique_ptr to empty, invoking the deleter if necessary.
unique_ptr&
operator=(nullptr_t) noexcept
{
reset();
return *this;
}
// Observers.
/// Access an element of owned array.
typename std::add_lvalue_reference<element_type>::type
operator[](size_t __i) const
{
_GLIBCXX_DEBUG_ASSERT(get() != pointer());
return get()[__i];
}
/// Return the stored pointer.
pointer
get() const noexcept
{ return std::get<0>(_M_t); }
/// Return a reference to the stored deleter.
deleter_type&
get_deleter() noexcept
{ return std::get<1>(_M_t); }
/// Return a reference to the stored deleter.
const deleter_type&
get_deleter() const noexcept
{ return std::get<1>(_M_t); }
/// Return @c true if the stored pointer is not null.
explicit operator bool() const noexcept
{ return get() == pointer() ? false : true; }
// Modifiers.
/// Release ownership of any stored pointer.
pointer
release() noexcept
{
pointer __p = get();
std::get<0>(_M_t) = pointer();
return __p;
}
/** @brief Replace the stored pointer.
*
* @param __p The new pointer to store.
*
* The deleter will be invoked if a pointer is already owned.
*/
void
reset(pointer __p = pointer()) noexcept
{
using std::swap;
swap(std::get<0>(_M_t), __p);
if (__p != nullptr)
get_deleter()(__p);
}
// Disable resetting from convertible pointer types.
template<typename _Up, typename = _Require<is_pointer<pointer>,
is_convertible<_Up*, pointer>, __is_derived_Tp<_Up>>>
void reset(_Up*) = delete;
/// Exchange the pointer and deleter with another object.
void
swap(unique_ptr& __u) noexcept
{
using std::swap;
swap(_M_t, __u._M_t);
}
// Disable copy from lvalue.
unique_ptr(const unique_ptr&) = delete;
unique_ptr& operator=(const unique_ptr&) = delete;
// Disable construction from convertible pointer types.
template<typename _Up, typename = _Require<is_pointer<pointer>,
is_convertible<_Up*, pointer>, __is_derived_Tp<_Up>>>
unique_ptr(_Up*, typename
conditional<is_reference<deleter_type>::value,
deleter_type, const deleter_type&>::type) = delete;
// Disable construction from convertible pointer types.
template<typename _Up, typename = _Require<is_pointer<pointer>,
is_convertible<_Up*, pointer>, __is_derived_Tp<_Up>>>
unique_ptr(_Up*, typename
remove_reference<deleter_type>::type&&) = delete;
};
template<typename _Tp, typename _Dp>
inline void
swap(unique_ptr<_Tp, _Dp>& __x,
unique_ptr<_Tp, _Dp>& __y) noexcept
{ __x.swap(__y); }
template<typename _Tp, typename _Dp,
typename _Up, typename _Ep>
inline bool
operator==(const unique_ptr<_Tp, _Dp>& __x,
const unique_ptr<_Up, _Ep>& __y)
{ return __x.get() == __y.get(); }
template<typename _Tp, typename _Dp>
inline bool
operator==(const unique_ptr<_Tp, _Dp>& __x, nullptr_t) noexcept
{ return !__x; }
template<typename _Tp, typename _Dp>
inline bool
operator==(nullptr_t, const unique_ptr<_Tp, _Dp>& __x) noexcept
{ return !__x; }
template<typename _Tp, typename _Dp,
typename _Up, typename _Ep>
inline bool
operator!=(const unique_ptr<_Tp, _Dp>& __x,
const unique_ptr<_Up, _Ep>& __y)
{ return __x.get() != __y.get(); }
template<typename _Tp, typename _Dp>
inline bool
operator!=(const unique_ptr<_Tp, _Dp>& __x, nullptr_t) noexcept
{ return (bool)__x; }
template<typename _Tp, typename _Dp>
inline bool
operator!=(nullptr_t, const unique_ptr<_Tp, _Dp>& __x) noexcept
{ return (bool)__x; }
template<typename _Tp, typename _Dp,
typename _Up, typename _Ep>
inline bool
operator<(const unique_ptr<_Tp, _Dp>& __x,
const unique_ptr<_Up, _Ep>& __y)
{
typedef typename
std::common_type<typename unique_ptr<_Tp, _Dp>::pointer,
typename unique_ptr<_Up, _Ep>::pointer>::type _CT;
return std::less<_CT>()(__x.get(), __y.get());
}
template<typename _Tp, typename _Dp>
inline bool
operator<(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
{ return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(__x.get(),
nullptr); }
template<typename _Tp, typename _Dp>
inline bool
operator<(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
{ return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(nullptr,
__x.get()); }
template<typename _Tp, typename _Dp,
typename _Up, typename _Ep>
inline bool
operator<=(const unique_ptr<_Tp, _Dp>& __x,
const unique_ptr<_Up, _Ep>& __y)
{ return !(__y < __x); }
template<typename _Tp, typename _Dp>
inline bool
operator<=(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
{ return !(nullptr < __x); }
template<typename _Tp, typename _Dp>
inline bool
operator<=(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
{ return !(__x < nullptr); }
template<typename _Tp, typename _Dp,
typename _Up, typename _Ep>
inline bool
operator>(const unique_ptr<_Tp, _Dp>& __x,
const unique_ptr<_Up, _Ep>& __y)
{ return (__y < __x); }
template<typename _Tp, typename _Dp>
inline bool
operator>(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
{ return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(nullptr,
__x.get()); }
template<typename _Tp, typename _Dp>
inline bool
operator>(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
{ return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(__x.get(),
nullptr); }
template<typename _Tp, typename _Dp,
typename _Up, typename _Ep>
inline bool
operator>=(const unique_ptr<_Tp, _Dp>& __x,
const unique_ptr<_Up, _Ep>& __y)
{ return !(__x < __y); }
template<typename _Tp, typename _Dp>
inline bool
operator>=(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
{ return !(__x < nullptr); }
template<typename _Tp, typename _Dp>
inline bool
operator>=(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
{ return !(nullptr < __x); }
/// std::hash specialization for unique_ptr.
template<typename _Tp, typename _Dp>
struct hash<unique_ptr<_Tp, _Dp>>
: public __hash_base<size_t, unique_ptr<_Tp, _Dp>>
{
size_t
operator()(const unique_ptr<_Tp, _Dp>& __u) const noexcept
{
typedef unique_ptr<_Tp, _Dp> _UP;
return std::hash<typename _UP::pointer>()(__u.get());
}
};
#if __cplusplus > 201103L
template<typename _Tp>
struct _MakeUniq
{ typedef unique_ptr<_Tp> __single_object; };
template<typename _Tp>
struct _MakeUniq<_Tp[]>
{ typedef unique_ptr<_Tp[]> __array; };
template<typename _Tp, size_t _Bound>
struct _MakeUniq<_Tp[_Bound]>
{ struct __invalid_type { }; };
/// std::make_unique for single objects
template<typename _Tp, typename... _Args>
inline typename _MakeUniq<_Tp>::__single_object
make_unique(_Args&&... __args)
{ return unique_ptr<_Tp>(new _Tp(std::forward<_Args>(__args)...)); }
/// std::make_unique for arrays of unknown bound
template<typename _Tp>
inline typename _MakeUniq<_Tp>::__array
make_unique(size_t __num)
{ return unique_ptr<_Tp>(new typename remove_extent<_Tp>::type[__num]()); }
/// Disable std::make_unique for arrays of known bound
template<typename _Tp, typename... _Args>
inline typename _MakeUniq<_Tp>::__invalid_type
make_unique(_Args&&...) = delete;
#endif
// @} group pointer_abstractions
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif /* _UNIQUE_PTR_H */