// shared_ptr and weak_ptr implementation -*- C++ -*-
-// Copyright (C) 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
+// Copyright (C) 2007-2021 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
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
-/** @file bits/shared_ptr.h
+/** @file
* This is an internal header file, included by other library headers.
- * You should not attempt to use it directly.
+ * Do not attempt to use it directly. @headername{memory}
*/
#ifndef _SHARED_PTR_H
#define _SHARED_PTR_H 1
+#include <iosfwd> // std::basic_ostream
#include <bits/shared_ptr_base.h>
-_GLIBCXX_BEGIN_NAMESPACE(std)
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @addtogroup pointer_abstractions
* @{
*/
- /// 2.2.3.7 shared_ptr I/O
+ // 20.7.2.2.11 shared_ptr I/O
+
+ /// Write the stored pointer to an ostream.
+ /// @relates shared_ptr
template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp>
inline std::basic_ostream<_Ch, _Tr>&
operator<<(std::basic_ostream<_Ch, _Tr>& __os,
return __os;
}
- /// 2.2.3.10 shared_ptr get_deleter (experimental)
template<typename _Del, typename _Tp, _Lock_policy _Lp>
inline _Del*
- get_deleter(const __shared_ptr<_Tp, _Lp>& __p)
+ get_deleter(const __shared_ptr<_Tp, _Lp>& __p) noexcept
{
-#ifdef __GXX_RTTI
+#if __cpp_rtti
return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
#else
return 0;
#endif
}
+ /// 20.7.2.2.10 shared_ptr get_deleter
+
+ /// If `__p` has a deleter of type `_Del`, return a pointer to it.
+ /// @relates shared_ptr
+ template<typename _Del, typename _Tp>
+ inline _Del*
+ get_deleter(const shared_ptr<_Tp>& __p) noexcept
+ {
+#if __cpp_rtti
+ return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
+#else
+ return 0;
+#endif
+ }
/**
* @brief A smart pointer with reference-counted copy semantics.
+ * @headerfile memory
+ * @since C++11
*
- * The object pointed to is deleted when the last shared_ptr pointing to
- * it is destroyed or reset.
+ * A `shared_ptr` object is either empty or _owns_ a pointer passed
+ * to the constructor. Copies of a `shared_ptr` share ownership of
+ * the same pointer. When the last `shared_ptr` that owns the pointer
+ * is destroyed or reset, the owned pointer is freed (either by `delete`
+ * or by invoking a custom deleter that was passed to the constructor).
+ *
+ * A `shared_ptr` also stores another pointer, which is usually
+ * (but not always) the same pointer as it owns. The stored pointer
+ * can be retrieved by calling the `get()` member function.
+ *
+ * The equality and relational operators for `shared_ptr` only compare
+ * the stored pointer returned by `get()`, not the owned pointer.
+ * To test whether two `shared_ptr` objects share ownership of the same
+ * pointer see `std::shared_ptr::owner_before` and `std::owner_less`.
*/
template<typename _Tp>
class shared_ptr : public __shared_ptr<_Tp>
{
+ template<typename... _Args>
+ using _Constructible = typename enable_if<
+ is_constructible<__shared_ptr<_Tp>, _Args...>::value
+ >::type;
+
+ template<typename _Arg>
+ using _Assignable = typename enable_if<
+ is_assignable<__shared_ptr<_Tp>&, _Arg>::value, shared_ptr&
+ >::type;
+
public:
+
+ /// The type pointed to by the stored pointer, remove_extent_t<_Tp>
+ using element_type = typename __shared_ptr<_Tp>::element_type;
+
+#if __cplusplus >= 201703L
+# define __cpp_lib_shared_ptr_weak_type 201606
+ /// The corresponding weak_ptr type for this shared_ptr
+ /// @since C++17
+ using weak_type = weak_ptr<_Tp>;
+#endif
/**
* @brief Construct an empty %shared_ptr.
* @post use_count()==0 && get()==0
*/
- constexpr shared_ptr()
- : __shared_ptr<_Tp>() { }
+ constexpr shared_ptr() noexcept : __shared_ptr<_Tp>() { }
+
+ shared_ptr(const shared_ptr&) noexcept = default; ///< Copy constructor
/**
* @brief Construct a %shared_ptr that owns the pointer @a __p.
* @post use_count() == 1 && get() == __p
* @throw std::bad_alloc, in which case @c delete @a __p is called.
*/
- template<typename _Tp1>
- explicit shared_ptr(_Tp1* __p)
- : __shared_ptr<_Tp>(__p) { }
+ template<typename _Yp, typename = _Constructible<_Yp*>>
+ explicit
+ shared_ptr(_Yp* __p) : __shared_ptr<_Tp>(__p) { }
/**
* @brief Construct a %shared_ptr that owns the pointer @a __p
*
* __shared_ptr will release __p by calling __d(__p)
*/
- template<typename _Tp1, typename _Deleter>
- shared_ptr(_Tp1* __p, _Deleter __d) : __shared_ptr<_Tp>(__p, __d) { }
+ template<typename _Yp, typename _Deleter,
+ typename = _Constructible<_Yp*, _Deleter>>
+ shared_ptr(_Yp* __p, _Deleter __d)
+ : __shared_ptr<_Tp>(__p, std::move(__d)) { }
/**
* @brief Construct a %shared_ptr that owns a null pointer
*/
template<typename _Deleter>
shared_ptr(nullptr_t __p, _Deleter __d)
- : __shared_ptr<_Tp>(__p, __d) { }
+ : __shared_ptr<_Tp>(__p, std::move(__d)) { }
/**
* @brief Construct a %shared_ptr that owns the pointer @a __p
*
* __shared_ptr will release __p by calling __d(__p)
*/
- template<typename _Tp1, typename _Deleter, typename _Alloc>
- shared_ptr(_Tp1* __p, _Deleter __d, const _Alloc& __a)
- : __shared_ptr<_Tp>(__p, __d, __a) { }
+ template<typename _Yp, typename _Deleter, typename _Alloc,
+ typename = _Constructible<_Yp*, _Deleter, _Alloc>>
+ shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a)
+ : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { }
/**
* @brief Construct a %shared_ptr that owns a null pointer
* The last owner will call __d(__p)
*/
template<typename _Deleter, typename _Alloc>
- shared_ptr(nullptr_t __p, _Deleter __d, const _Alloc& __a)
- : __shared_ptr<_Tp>(__p, __d, __a) { }
+ shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
+ : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { }
// Aliasing constructor
/**
- * @brief Constructs a %shared_ptr instance that stores @a __p
- * and shares ownership with @a __r.
- * @param __r A %shared_ptr.
- * @param __p A pointer that will remain valid while @a *__r is valid.
- * @post get() == __p && use_count() == __r.use_count()
+ * @brief Constructs a `shared_ptr` instance that stores `__p`
+ * and shares ownership with `__r`.
+ * @param __r A `shared_ptr`.
+ * @param __p A pointer that will remain valid while `*__r` is valid.
+ * @post `get() == __p && use_count() == __r.use_count()`
*
- * This can be used to construct a @c shared_ptr to a sub-object
- * of an object managed by an existing @c shared_ptr.
+ * This can be used to construct a `shared_ptr` to a sub-object
+ * of an object managed by an existing `shared_ptr`. The complete
+ * object will remain valid while any `shared_ptr` owns it, even
+ * if they don't store a pointer to the complete object.
*
* @code
- * shared_ptr< pair<int,int> > pii(new pair<int,int>());
+ * shared_ptr<pair<int,int>> pii(new pair<int,int>());
* shared_ptr<int> pi(pii, &pii->first);
* assert(pii.use_count() == 2);
* @endcode
*/
- template<typename _Tp1>
- shared_ptr(const shared_ptr<_Tp1>& __r, _Tp* __p)
+ template<typename _Yp>
+ shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) noexcept
: __shared_ptr<_Tp>(__r, __p) { }
+#if __cplusplus > 201703L
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 2996. Missing rvalue overloads for shared_ptr operations
+ /**
+ * @brief Constructs a `shared_ptr` instance that stores `__p`
+ * and shares ownership with `__r`.
+ * @param __r A `shared_ptr`.
+ * @param __p A pointer that will remain valid while `*__r` is valid.
+ * @post `get() == __p && !__r.use_count() && !__r.get()`
+ * @since C++17
+ *
+ * This can be used to construct a `shared_ptr` to a sub-object
+ * of an object managed by an existing `shared_ptr`. The complete
+ * object will remain valid while any `shared_ptr` owns it, even
+ * if they don't store a pointer to the complete object.
+ *
+ * @code
+ * shared_ptr<pair<int,int>> pii(new pair<int,int>());
+ * shared_ptr<int> pi1(pii, &pii->first);
+ * assert(pii.use_count() == 2);
+ * shared_ptr<int> pi2(std::move(pii), &pii->second);
+ * assert(pii.use_count() == 0);
+ * @endcode
+ */
+ template<typename _Yp>
+ shared_ptr(shared_ptr<_Yp>&& __r, element_type* __p) noexcept
+ : __shared_ptr<_Tp>(std::move(__r), __p) { }
+#endif
/**
* @brief If @a __r is empty, constructs an empty %shared_ptr;
* otherwise construct a %shared_ptr that shares ownership
* @param __r A %shared_ptr.
* @post get() == __r.get() && use_count() == __r.use_count()
*/
- template<typename _Tp1, typename = typename
- std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
- shared_ptr(const shared_ptr<_Tp1>& __r)
+ template<typename _Yp,
+ typename = _Constructible<const shared_ptr<_Yp>&>>
+ shared_ptr(const shared_ptr<_Yp>& __r) noexcept
: __shared_ptr<_Tp>(__r) { }
/**
* @param __r A %shared_ptr rvalue.
* @post *this contains the old value of @a __r, @a __r is empty.
*/
- shared_ptr(shared_ptr&& __r)
+ shared_ptr(shared_ptr&& __r) noexcept
: __shared_ptr<_Tp>(std::move(__r)) { }
/**
* @param __r A %shared_ptr rvalue.
* @post *this contains the old value of @a __r, @a __r is empty.
*/
- template<typename _Tp1, typename = typename
- std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
- shared_ptr(shared_ptr<_Tp1>&& __r)
+ template<typename _Yp, typename = _Constructible<shared_ptr<_Yp>>>
+ shared_ptr(shared_ptr<_Yp>&& __r) noexcept
: __shared_ptr<_Tp>(std::move(__r)) { }
/**
* @throw bad_weak_ptr when __r.expired(),
* in which case the constructor has no effect.
*/
- template<typename _Tp1>
- explicit shared_ptr(const weak_ptr<_Tp1>& __r)
+ template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>>
+ explicit shared_ptr(const weak_ptr<_Yp>& __r)
: __shared_ptr<_Tp>(__r) { }
-#if _GLIBCXX_DEPRECATED
- template<typename _Tp1>
- shared_ptr(std::auto_ptr<_Tp1>&& __r)
- : __shared_ptr<_Tp>(std::move(__r)) { }
+#if _GLIBCXX_USE_DEPRECATED
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+ template<typename _Yp, typename = _Constructible<auto_ptr<_Yp>>>
+ shared_ptr(auto_ptr<_Yp>&& __r);
+#pragma GCC diagnostic pop
#endif
- template<typename _Tp1, typename _Del>
- shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r)
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 2399. shared_ptr's constructor from unique_ptr should be constrained
+ template<typename _Yp, typename _Del,
+ typename = _Constructible<unique_ptr<_Yp, _Del>>>
+ shared_ptr(unique_ptr<_Yp, _Del>&& __r)
: __shared_ptr<_Tp>(std::move(__r)) { }
+#if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED
+ // This non-standard constructor exists to support conversions that
+ // were possible in C++11 and C++14 but are ill-formed in C++17.
+ // If an exception is thrown this constructor has no effect.
+ template<typename _Yp, typename _Del,
+ _Constructible<unique_ptr<_Yp, _Del>, __sp_array_delete>* = 0>
+ shared_ptr(unique_ptr<_Yp, _Del>&& __r)
+ : __shared_ptr<_Tp>(std::move(__r), __sp_array_delete()) { }
+#endif
+
/**
* @brief Construct an empty %shared_ptr.
- * @param __p A null pointer constant.
* @post use_count() == 0 && get() == nullptr
*/
- constexpr shared_ptr(nullptr_t __p)
- : __shared_ptr<_Tp>(__p) { }
+ constexpr shared_ptr(nullptr_t) noexcept : shared_ptr() { }
- template<typename _Tp1>
- shared_ptr&
- operator=(const shared_ptr<_Tp1>& __r) // never throws
+ shared_ptr& operator=(const shared_ptr&) noexcept = default;
+
+ template<typename _Yp>
+ _Assignable<const shared_ptr<_Yp>&>
+ operator=(const shared_ptr<_Yp>& __r) noexcept
{
this->__shared_ptr<_Tp>::operator=(__r);
return *this;
}
-#if _GLIBCXX_DEPRECATED
- template<typename _Tp1>
- shared_ptr&
- operator=(std::auto_ptr<_Tp1>&& __r)
+#if _GLIBCXX_USE_DEPRECATED
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+ template<typename _Yp>
+ _Assignable<auto_ptr<_Yp>>
+ operator=(auto_ptr<_Yp>&& __r)
{
this->__shared_ptr<_Tp>::operator=(std::move(__r));
return *this;
}
+#pragma GCC diagnostic pop
#endif
shared_ptr&
- operator=(shared_ptr&& __r)
+ operator=(shared_ptr&& __r) noexcept
{
this->__shared_ptr<_Tp>::operator=(std::move(__r));
return *this;
}
- template<class _Tp1>
- shared_ptr&
- operator=(shared_ptr<_Tp1>&& __r)
+ template<class _Yp>
+ _Assignable<shared_ptr<_Yp>>
+ operator=(shared_ptr<_Yp>&& __r) noexcept
{
this->__shared_ptr<_Tp>::operator=(std::move(__r));
return *this;
}
- template<typename _Tp1, typename _Del>
- shared_ptr&
- operator=(std::unique_ptr<_Tp1, _Del>&& __r)
+ template<typename _Yp, typename _Del>
+ _Assignable<unique_ptr<_Yp, _Del>>
+ operator=(unique_ptr<_Yp, _Del>&& __r)
{
this->__shared_ptr<_Tp>::operator=(std::move(__r));
return *this;
private:
// This constructor is non-standard, it is used by allocate_shared.
template<typename _Alloc, typename... _Args>
- shared_ptr(_Sp_make_shared_tag __tag, _Alloc __a, _Args&&... __args)
- : __shared_ptr<_Tp>(__tag, __a, std::forward<_Args>(__args)...)
+ shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args)
+ : __shared_ptr<_Tp>(__tag, std::forward<_Args>(__args)...)
{ }
- template<typename _Tp1, typename _Alloc, typename... _Args>
- friend shared_ptr<_Tp1>
- allocate_shared(_Alloc __a, _Args&&... __args);
+ template<typename _Yp, typename _Alloc, typename... _Args>
+ friend shared_ptr<_Yp>
+ allocate_shared(const _Alloc& __a, _Args&&... __args);
+
+ // This constructor is non-standard, it is used by weak_ptr::lock().
+ shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t) noexcept
+ : __shared_ptr<_Tp>(__r, std::nothrow) { }
+
+ friend class weak_ptr<_Tp>;
};
- // 20.8.13.2.7 shared_ptr comparisons
- template<typename _Tp1, typename _Tp2>
- inline bool
- operator==(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
+#if __cpp_deduction_guides >= 201606
+ template<typename _Tp>
+ shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>;
+ template<typename _Tp, typename _Del>
+ shared_ptr(unique_ptr<_Tp, _Del>) -> shared_ptr<_Tp>;
+#endif
+
+ // 20.7.2.2.7 shared_ptr comparisons
+
+ /// @relates shared_ptr @{
+
+ /// Equality operator for shared_ptr objects, compares the stored pointers
+ template<typename _Tp, typename _Up>
+ _GLIBCXX_NODISCARD inline bool
+ operator==(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
{ return __a.get() == __b.get(); }
+ /// shared_ptr comparison with nullptr
template<typename _Tp>
- inline bool
- operator==(const shared_ptr<_Tp>& __a, nullptr_t)
- { return __a.get() == nullptr; }
+ _GLIBCXX_NODISCARD inline bool
+ operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
+ { return !__a; }
- template<typename _Tp>
- inline bool
- operator==(nullptr_t, const shared_ptr<_Tp>& __b)
- { return nullptr == __b.get(); }
+#ifdef __cpp_lib_three_way_comparison
+ template<typename _Tp, typename _Up>
+ inline strong_ordering
+ operator<=>(const shared_ptr<_Tp>& __a,
+ const shared_ptr<_Up>& __b) noexcept
+ { return compare_three_way()(__a.get(), __b.get()); }
- template<typename _Tp1, typename _Tp2>
- inline bool
- operator!=(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
+ template<typename _Tp>
+ inline strong_ordering
+ operator<=>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
+ {
+ using pointer = typename shared_ptr<_Tp>::element_type*;
+ return compare_three_way()(__a.get(), static_cast<pointer>(nullptr));
+ }
+#else
+ /// shared_ptr comparison with nullptr
+ template<typename _Tp>
+ _GLIBCXX_NODISCARD inline bool
+ operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
+ { return !__a; }
+
+ /// Inequality operator for shared_ptr objects, compares the stored pointers
+ template<typename _Tp, typename _Up>
+ _GLIBCXX_NODISCARD inline bool
+ operator!=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
{ return __a.get() != __b.get(); }
+ /// shared_ptr comparison with nullptr
+ template<typename _Tp>
+ _GLIBCXX_NODISCARD inline bool
+ operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
+ { return (bool)__a; }
+
+ /// shared_ptr comparison with nullptr
template<typename _Tp>
- inline bool
- operator!=(const shared_ptr<_Tp>& __a, nullptr_t)
- { return __a.get() != nullptr; }
+ _GLIBCXX_NODISCARD inline bool
+ operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
+ { return (bool)__a; }
+
+ /// Relational operator for shared_ptr objects, compares the stored pointers
+ template<typename _Tp, typename _Up>
+ _GLIBCXX_NODISCARD inline bool
+ operator<(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
+ {
+ using _Tp_elt = typename shared_ptr<_Tp>::element_type;
+ using _Up_elt = typename shared_ptr<_Up>::element_type;
+ using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type;
+ return less<_Vp>()(__a.get(), __b.get());
+ }
+ /// shared_ptr comparison with nullptr
template<typename _Tp>
- inline bool
- operator!=(nullptr_t, const shared_ptr<_Tp>& __b)
- { return nullptr != __b.get(); }
+ _GLIBCXX_NODISCARD inline bool
+ operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
+ {
+ using _Tp_elt = typename shared_ptr<_Tp>::element_type;
+ return less<_Tp_elt*>()(__a.get(), nullptr);
+ }
- template<typename _Tp1, typename _Tp2>
- inline bool
- operator<(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
- { return __a.get() < __b.get(); }
+ /// shared_ptr comparison with nullptr
+ template<typename _Tp>
+ _GLIBCXX_NODISCARD inline bool
+ operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
+ {
+ using _Tp_elt = typename shared_ptr<_Tp>::element_type;
+ return less<_Tp_elt*>()(nullptr, __a.get());
+ }
+ /// Relational operator for shared_ptr objects, compares the stored pointers
+ template<typename _Tp, typename _Up>
+ _GLIBCXX_NODISCARD inline bool
+ operator<=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
+ { return !(__b < __a); }
+
+ /// shared_ptr comparison with nullptr
template<typename _Tp>
- struct less<shared_ptr<_Tp>> : public _Sp_less<shared_ptr<_Tp>>
- { };
+ _GLIBCXX_NODISCARD inline bool
+ operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
+ { return !(nullptr < __a); }
+
+ /// shared_ptr comparison with nullptr
+ template<typename _Tp>
+ _GLIBCXX_NODISCARD inline bool
+ operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
+ { return !(__a < nullptr); }
+
+ /// Relational operator for shared_ptr objects, compares the stored pointers
+ template<typename _Tp, typename _Up>
+ _GLIBCXX_NODISCARD inline bool
+ operator>(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
+ { return (__b < __a); }
+
+ /// shared_ptr comparison with nullptr
+ template<typename _Tp>
+ _GLIBCXX_NODISCARD inline bool
+ operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
+ { return nullptr < __a; }
+
+ /// shared_ptr comparison with nullptr
+ template<typename _Tp>
+ _GLIBCXX_NODISCARD inline bool
+ operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
+ { return __a < nullptr; }
+
+ /// Relational operator for shared_ptr objects, compares the stored pointers
+ template<typename _Tp, typename _Up>
+ _GLIBCXX_NODISCARD inline bool
+ operator>=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
+ { return !(__a < __b); }
- // 20.8.13.2.9 shared_ptr specialized algorithms.
+ /// shared_ptr comparison with nullptr
+ template<typename _Tp>
+ _GLIBCXX_NODISCARD inline bool
+ operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
+ { return !(__a < nullptr); }
+
+ /// shared_ptr comparison with nullptr
+ template<typename _Tp>
+ _GLIBCXX_NODISCARD inline bool
+ operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
+ { return !(nullptr < __a); }
+#endif
+
+ // 20.7.2.2.8 shared_ptr specialized algorithms.
+
+ /// Swap overload for shared_ptr
template<typename _Tp>
inline void
- swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b)
+ swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept
{ __a.swap(__b); }
- // 20.8.13.2.10 shared_ptr casts.
- template<typename _Tp, typename _Tp1>
+ // 20.7.2.2.9 shared_ptr casts.
+
+ /// Convert type of `shared_ptr`, via `static_cast`
+ template<typename _Tp, typename _Up>
+ inline shared_ptr<_Tp>
+ static_pointer_cast(const shared_ptr<_Up>& __r) noexcept
+ {
+ using _Sp = shared_ptr<_Tp>;
+ return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get()));
+ }
+
+ /// Convert type of `shared_ptr`, via `const_cast`
+ template<typename _Tp, typename _Up>
inline shared_ptr<_Tp>
- static_pointer_cast(const shared_ptr<_Tp1>& __r)
- { return shared_ptr<_Tp>(__r, static_cast<_Tp*>(__r.get())); }
+ const_pointer_cast(const shared_ptr<_Up>& __r) noexcept
+ {
+ using _Sp = shared_ptr<_Tp>;
+ return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get()));
+ }
- template<typename _Tp, typename _Tp1>
+ /// Convert type of `shared_ptr`, via `dynamic_cast`
+ template<typename _Tp, typename _Up>
inline shared_ptr<_Tp>
- const_pointer_cast(const shared_ptr<_Tp1>& __r)
- { return shared_ptr<_Tp>(__r, const_cast<_Tp*>(__r.get())); }
+ dynamic_pointer_cast(const shared_ptr<_Up>& __r) noexcept
+ {
+ using _Sp = shared_ptr<_Tp>;
+ if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
+ return _Sp(__r, __p);
+ return _Sp();
+ }
- template<typename _Tp, typename _Tp1>
+#if __cplusplus >= 201703L
+ /// Convert type of `shared_ptr`, via `reinterpret_cast`
+ /// @since C++17
+ template<typename _Tp, typename _Up>
inline shared_ptr<_Tp>
- dynamic_pointer_cast(const shared_ptr<_Tp1>& __r)
+ reinterpret_pointer_cast(const shared_ptr<_Up>& __r) noexcept
{
- if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
- return shared_ptr<_Tp>(__r, __p);
- return shared_ptr<_Tp>();
+ using _Sp = shared_ptr<_Tp>;
+ return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get()));
}
+#if __cplusplus > 201703L
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 2996. Missing rvalue overloads for shared_ptr operations
+
+ /// Convert type of `shared_ptr` rvalue, via `static_cast`
+ /// @since C++20
+ template<typename _Tp, typename _Up>
+ inline shared_ptr<_Tp>
+ static_pointer_cast(shared_ptr<_Up>&& __r) noexcept
+ {
+ using _Sp = shared_ptr<_Tp>;
+ return _Sp(std::move(__r),
+ static_cast<typename _Sp::element_type*>(__r.get()));
+ }
+
+ /// Convert type of `shared_ptr` rvalue, via `const_cast`
+ /// @since C++20
+ template<typename _Tp, typename _Up>
+ inline shared_ptr<_Tp>
+ const_pointer_cast(shared_ptr<_Up>&& __r) noexcept
+ {
+ using _Sp = shared_ptr<_Tp>;
+ return _Sp(std::move(__r),
+ const_cast<typename _Sp::element_type*>(__r.get()));
+ }
+
+ /// Convert type of `shared_ptr` rvalue, via `dynamic_cast`
+ /// @since C++20
+ template<typename _Tp, typename _Up>
+ inline shared_ptr<_Tp>
+ dynamic_pointer_cast(shared_ptr<_Up>&& __r) noexcept
+ {
+ using _Sp = shared_ptr<_Tp>;
+ if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
+ return _Sp(std::move(__r), __p);
+ return _Sp();
+ }
+
+ /// Convert type of `shared_ptr` rvalue, via `reinterpret_cast`
+ /// @since C++20
+ template<typename _Tp, typename _Up>
+ inline shared_ptr<_Tp>
+ reinterpret_pointer_cast(shared_ptr<_Up>&& __r) noexcept
+ {
+ using _Sp = shared_ptr<_Tp>;
+ return _Sp(std::move(__r),
+ reinterpret_cast<typename _Sp::element_type*>(__r.get()));
+ }
+#endif // C++20
+#endif // C++17
+
+ /// @}
/**
- * @brief A smart pointer with weak semantics.
+ * @brief A non-owning observer for a pointer owned by a shared_ptr
+ * @headerfile memory
+ * @since C++11
+ *
+ * A weak_ptr provides a safe alternative to a raw pointer when you want
+ * a non-owning reference to an object that is managed by a shared_ptr.
*
- * With forwarding constructors and assignment operators.
+ * Unlike a raw pointer, a weak_ptr can be converted to a new shared_ptr
+ * that shares ownership with every other shared_ptr that already owns
+ * the pointer. In other words you can upgrade from a non-owning "weak"
+ * reference to an owning shared_ptr, without having access to any of
+ * the existing shared_ptr objects.
+ *
+ * Also unlike a raw pointer, a weak_ptr does not become "dangling" after
+ * the object it points to has been destroyed. Instead, a weak_ptr
+ * becomes _expired_ and can no longer be converted to a shared_ptr that
+ * owns the freed pointer, so you cannot accidentally access the pointed-to
+ * object after it has been destroyed.
*/
template<typename _Tp>
class weak_ptr : public __weak_ptr<_Tp>
{
+ template<typename _Arg>
+ using _Constructible = typename enable_if<
+ is_constructible<__weak_ptr<_Tp>, _Arg>::value
+ >::type;
+
+ template<typename _Arg>
+ using _Assignable = typename enable_if<
+ is_assignable<__weak_ptr<_Tp>&, _Arg>::value, weak_ptr&
+ >::type;
+
public:
- constexpr weak_ptr()
- : __weak_ptr<_Tp>() { }
+ constexpr weak_ptr() noexcept = default;
- template<typename _Tp1, typename = typename
- std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
- weak_ptr(const weak_ptr<_Tp1>& __r)
+ template<typename _Yp,
+ typename = _Constructible<const shared_ptr<_Yp>&>>
+ weak_ptr(const shared_ptr<_Yp>& __r) noexcept
: __weak_ptr<_Tp>(__r) { }
- template<typename _Tp1, typename = typename
- std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
- weak_ptr(const shared_ptr<_Tp1>& __r)
+ weak_ptr(const weak_ptr&) noexcept = default;
+
+ template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>>
+ weak_ptr(const weak_ptr<_Yp>& __r) noexcept
: __weak_ptr<_Tp>(__r) { }
- template<typename _Tp1>
- weak_ptr&
- operator=(const weak_ptr<_Tp1>& __r) // never throws
+ weak_ptr(weak_ptr&&) noexcept = default;
+
+ template<typename _Yp, typename = _Constructible<weak_ptr<_Yp>>>
+ weak_ptr(weak_ptr<_Yp>&& __r) noexcept
+ : __weak_ptr<_Tp>(std::move(__r)) { }
+
+ weak_ptr&
+ operator=(const weak_ptr& __r) noexcept = default;
+
+ template<typename _Yp>
+ _Assignable<const weak_ptr<_Yp>&>
+ operator=(const weak_ptr<_Yp>& __r) noexcept
{
this->__weak_ptr<_Tp>::operator=(__r);
return *this;
}
- template<typename _Tp1>
- weak_ptr&
- operator=(const shared_ptr<_Tp1>& __r) // never throws
+ template<typename _Yp>
+ _Assignable<const shared_ptr<_Yp>&>
+ operator=(const shared_ptr<_Yp>& __r) noexcept
{
this->__weak_ptr<_Tp>::operator=(__r);
return *this;
}
+ weak_ptr&
+ operator=(weak_ptr&& __r) noexcept = default;
+
+ template<typename _Yp>
+ _Assignable<weak_ptr<_Yp>>
+ operator=(weak_ptr<_Yp>&& __r) noexcept
+ {
+ this->__weak_ptr<_Tp>::operator=(std::move(__r));
+ return *this;
+ }
+
shared_ptr<_Tp>
- lock() const // never throws
- {
-#ifdef __GTHREADS
- if (this->expired())
- return shared_ptr<_Tp>();
-
- __try
- {
- return shared_ptr<_Tp>(*this);
- }
- __catch(const bad_weak_ptr&)
- {
- return shared_ptr<_Tp>();
- }
-#else
- return this->expired() ? shared_ptr<_Tp>() : shared_ptr<_Tp>(*this);
-#endif
- }
+ lock() const noexcept
+ { return shared_ptr<_Tp>(*this, std::nothrow); }
};
- // 20.8.13.3.7 weak_ptr specialized algorithms.
+#if __cpp_deduction_guides >= 201606
+ template<typename _Tp>
+ weak_ptr(shared_ptr<_Tp>) -> weak_ptr<_Tp>;
+#endif
+
+ // 20.7.2.3.6 weak_ptr specialized algorithms.
+ /// Swap overload for weak_ptr
+ /// @relates weak_ptr
template<typename _Tp>
inline void
- swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b)
+ swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept
{ __a.swap(__b); }
/// Primary template owner_less
- template<typename _Tp>
+ template<typename _Tp = void>
struct owner_less;
+ /// Void specialization of owner_less compares either shared_ptr or weak_ptr
+ template<>
+ struct owner_less<void> : _Sp_owner_less<void, void>
+ { };
+
/// Partial specialization of owner_less for shared_ptr.
template<typename _Tp>
struct owner_less<shared_ptr<_Tp>>
{ };
/**
- * @brief Base class allowing use of member function shared_from_this.
+ * @brief Base class allowing use of the member function `shared_from_this`.
+ * @headerfile memory
+ * @since C++11
*/
template<typename _Tp>
class enable_shared_from_this
{
protected:
- constexpr enable_shared_from_this() { }
+ constexpr enable_shared_from_this() noexcept { }
- enable_shared_from_this(const enable_shared_from_this&) { }
+ enable_shared_from_this(const enable_shared_from_this&) noexcept { }
enable_shared_from_this&
- operator=(const enable_shared_from_this&)
+ operator=(const enable_shared_from_this&) noexcept
{ return *this; }
~enable_shared_from_this() { }
shared_from_this() const
{ return shared_ptr<const _Tp>(this->_M_weak_this); }
+#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
+#define __cpp_lib_enable_shared_from_this 201603
+ /** @{
+ * Get a `weak_ptr` referring to the object that has `*this` as its base.
+ * @since C++17
+ */
+ weak_ptr<_Tp>
+ weak_from_this() noexcept
+ { return this->_M_weak_this; }
+
+ weak_ptr<const _Tp>
+ weak_from_this() const noexcept
+ { return this->_M_weak_this; }
+ /// @}
+#endif
+
private:
template<typename _Tp1>
void
- _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const
+ _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept
{ _M_weak_this._M_assign(__p, __n); }
- template<typename _Tp1>
- friend void
- __enable_shared_from_this_helper(const __shared_count<>& __pn,
- const enable_shared_from_this* __pe,
- const _Tp1* __px)
- {
- if (__pe != 0)
- __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
- }
+ // Found by ADL when this is an associated class.
+ friend const enable_shared_from_this*
+ __enable_shared_from_this_base(const __shared_count<>&,
+ const enable_shared_from_this* __p)
+ { return __p; }
+
+ template<typename, _Lock_policy>
+ friend class __shared_ptr;
mutable weak_ptr<_Tp> _M_weak_this;
};
+ /// @relates shared_ptr @{
+
/**
* @brief Create an object that is owned by a shared_ptr.
* @param __a An allocator.
*/
template<typename _Tp, typename _Alloc, typename... _Args>
inline shared_ptr<_Tp>
- allocate_shared(_Alloc __a, _Args&&... __args)
+ allocate_shared(const _Alloc& __a, _Args&&... __args)
{
- return shared_ptr<_Tp>(_Sp_make_shared_tag(), std::forward<_Alloc>(__a),
+ static_assert(!is_array<_Tp>::value, "make_shared<T[]> not supported");
+
+ return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{__a},
std::forward<_Args>(__args)...);
}
inline shared_ptr<_Tp>
make_shared(_Args&&... __args)
{
- typedef typename std::remove_const<_Tp>::type _Tp_nc;
- return allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
- std::forward<_Args>(__args)...);
+ typedef typename std::remove_cv<_Tp>::type _Tp_nc;
+ return std::allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
+ std::forward<_Args>(__args)...);
}
/// std::hash specialization for shared_ptr.
template<typename _Tp>
struct hash<shared_ptr<_Tp>>
- : public std::unary_function<shared_ptr<_Tp>, size_t>
+ : public __hash_base<size_t, shared_ptr<_Tp>>
{
size_t
- operator()(const shared_ptr<_Tp>& __s) const
- { return std::hash<_Tp*>()(__s.get()); }
+ operator()(const shared_ptr<_Tp>& __s) const noexcept
+ {
+ return std::hash<typename shared_ptr<_Tp>::element_type*>()(__s.get());
+ }
};
- // @} group pointer_abstractions
-
-_GLIBCXX_END_NAMESPACE
+ /// @} relates shared_ptr
+ /// @} group pointer_abstractions
+
+#if __cplusplus >= 201703L
+ namespace __detail::__variant
+ {
+ template<typename> struct _Never_valueless_alt; // see <variant>
+
+ // Provide the strong exception-safety guarantee when emplacing a
+ // shared_ptr into a variant.
+ template<typename _Tp>
+ struct _Never_valueless_alt<std::shared_ptr<_Tp>>
+ : std::true_type
+ { };
+
+ // Provide the strong exception-safety guarantee when emplacing a
+ // weak_ptr into a variant.
+ template<typename _Tp>
+ struct _Never_valueless_alt<std::weak_ptr<_Tp>>
+ : std::true_type
+ { };
+ } // namespace __detail::__variant
+#endif // C++17
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace
#endif // _SHARED_PTR_H
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