libstdc++
std::shared_ptr< _Tp > Class Template Reference

Inherits std::__shared_ptr< _Tp, _Lp >.

Public Types

using element_type = typename __shared_ptr< _Tp >::element_type
 
using weak_type = weak_ptr< _Tp >
 

Public Member Functions

constexpr shared_ptr () noexcept
 
template<typename _Yp , typename = _Constructible<_Yp*>>
 shared_ptr (_Yp *__p)
 
template<typename _Yp , typename _Deleter , typename = _Constructible<_Yp*, _Deleter>>
 shared_ptr (_Yp *__p, _Deleter __d)
 
template<typename _Yp , typename _Deleter , typename _Alloc , typename = _Constructible<_Yp*, _Deleter, _Alloc>>
 shared_ptr (_Yp *__p, _Deleter __d, _Alloc __a)
 
 shared_ptr (const shared_ptr &) noexcept=default
 
template<typename _Yp , typename = _Constructible<const shared_ptr<_Yp>&>>
 shared_ptr (const shared_ptr< _Yp > &__r) noexcept
 
template<typename _Yp >
 shared_ptr (const shared_ptr< _Yp > &__r, element_type *__p) noexcept
 
template<typename _Yp , typename = _Constructible<const weak_ptr<_Yp>&>>
 shared_ptr (const weak_ptr< _Yp > &__r)
 
template<typename _Deleter >
 shared_ptr (nullptr_t __p, _Deleter __d)
 
template<typename _Deleter , typename _Alloc >
 shared_ptr (nullptr_t __p, _Deleter __d, _Alloc __a)
 
constexpr shared_ptr (nullptr_t) noexcept
 
 shared_ptr (shared_ptr &&__r) noexcept
 
template<typename _Yp , typename = _Constructible<shared_ptr<_Yp>>>
 shared_ptr (shared_ptr< _Yp > &&__r) noexcept
 
template<typename _Tp1 , typename >
 shared_ptr (std::auto_ptr< _Tp1 > &&__r)
 
template<typename _Yp , typename _Del , typename = _Constructible<unique_ptr<_Yp, _Del>>>
 shared_ptr (unique_ptr< _Yp, _Del > &&__r)
 
element_typeget () const noexcept
 
 operator bool () const noexcept
 
element_typeoperator* () const noexcept
 
element_typeoperator-> () const noexcept
 
shared_ptroperator= (const shared_ptr &) noexcept=default
 
template<typename _Yp >
_Assignable< const shared_ptr< _Yp > & > operator= (const shared_ptr< _Yp > &__r) noexcept
 
shared_ptroperator= (shared_ptr &&__r) noexcept
 
template<class _Yp >
_Assignable< shared_ptr< _Yp > > operator= (shared_ptr< _Yp > &&__r) noexcept
 
template<typename _Yp , typename _Del >
_Assignable< unique_ptr< _Yp, _Del > > operator= (unique_ptr< _Yp, _Del > &&__r)
 
void reset () noexcept
 
template<typename _Yp >
_SafeConv< _Yp > reset (_Yp *__p)
 
template<typename _Yp , typename _Deleter >
_SafeConv< _Yp > reset (_Yp *__p, _Deleter __d)
 
template<typename _Yp , typename _Deleter , typename _Alloc >
_SafeConv< _Yp > reset (_Yp *__p, _Deleter __d, _Alloc __a)
 
void swap (__shared_ptr< _Tp, _Lp > &__other) noexcept
 
bool unique () const noexcept
 
long use_count () const noexcept
 
template<typename _Tp1 >
bool owner_before (__shared_ptr< _Tp1, _Lp > const &__rhs) const noexcept
 
template<typename _Tp1 >
bool owner_before (__weak_ptr< _Tp1, _Lp > const &__rhs) const noexcept
 

Friends

template<typename _Yp , typename _Alloc , typename... _Args>
shared_ptr< _Yp > allocate_shared (const _Alloc &__a, _Args &&... __args)
 
class weak_ptr< _Tp >
 

Related Functions

(Note that these are not member functions.)

template<typename _Del , typename _Tp >
_Del * get_deleter (const shared_ptr< _Tp > &__p) noexcept
 
template<typename _Ch , typename _Tr , typename _Tp , _Lock_policy _Lp>
std::basic_ostream< _Ch, _Tr > & operator<< (std::basic_ostream< _Ch, _Tr > &__os, const __shared_ptr< _Tp, _Lp > &__p)
 
template<typename _Tp , typename _Up >
bool operator== (const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
 
template<typename _Tp >
bool operator== (const shared_ptr< _Tp > &__a, nullptr_t) noexcept
 
template<typename _Tp >
bool operator== (nullptr_t, const shared_ptr< _Tp > &__a) noexcept
 
template<typename _Tp , typename _Up >
bool operator!= (const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
 
template<typename _Tp >
bool operator!= (const shared_ptr< _Tp > &__a, nullptr_t) noexcept
 
template<typename _Tp >
bool operator!= (nullptr_t, const shared_ptr< _Tp > &__a) noexcept
 
template<typename _Tp , typename _Up >
bool operator< (const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
 
template<typename _Tp >
bool operator< (const shared_ptr< _Tp > &__a, nullptr_t) noexcept
 
template<typename _Tp >
bool operator< (nullptr_t, const shared_ptr< _Tp > &__a) noexcept
 
template<typename _Tp , typename _Up >
bool operator<= (const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
 
template<typename _Tp >
bool operator<= (const shared_ptr< _Tp > &__a, nullptr_t) noexcept
 
template<typename _Tp >
bool operator<= (nullptr_t, const shared_ptr< _Tp > &__a) noexcept
 
template<typename _Tp , typename _Up >
bool operator> (const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
 
template<typename _Tp >
bool operator> (const shared_ptr< _Tp > &__a, nullptr_t) noexcept
 
template<typename _Tp >
bool operator> (nullptr_t, const shared_ptr< _Tp > &__a) noexcept
 
template<typename _Tp , typename _Up >
bool operator>= (const shared_ptr< _Tp > &__a, const shared_ptr< _Up > &__b) noexcept
 
template<typename _Tp >
bool operator>= (const shared_ptr< _Tp > &__a, nullptr_t) noexcept
 
template<typename _Tp >
bool operator>= (nullptr_t, const shared_ptr< _Tp > &__a) noexcept
 
template<typename _Tp >
void swap (shared_ptr< _Tp > &__a, shared_ptr< _Tp > &__b) noexcept
 
template<typename _Tp , typename _Up >
shared_ptr< _Tp > static_pointer_cast (const shared_ptr< _Up > &__r) noexcept
 
template<typename _Tp , typename _Up >
shared_ptr< _Tp > const_pointer_cast (const shared_ptr< _Up > &__r) noexcept
 
template<typename _Tp , typename _Up >
shared_ptr< _Tp > dynamic_pointer_cast (const shared_ptr< _Up > &__r) noexcept
 
template<typename _Tp , typename _Up >
shared_ptr< _Tp > reinterpret_pointer_cast (const shared_ptr< _Up > &__r) noexcept
 
template<typename _Tp , typename _Alloc , typename... _Args>
shared_ptr< _Tp > allocate_shared (const _Alloc &__a, _Args &&... __args)
 
template<typename _Tp , typename... _Args>
shared_ptr< _Tp > make_shared (_Args &&... __args)
 
template<typename _Tp , _Lock_policy _Lp>
bool atomic_is_lock_free (const __shared_ptr< _Tp, _Lp > *__p)
 
template<typename _Tp >
shared_ptr< _Tp > atomic_load_explicit (const shared_ptr< _Tp > *__p, memory_order)
 
template<typename _Tp >
void atomic_store_explicit (shared_ptr< _Tp > *__p, shared_ptr< _Tp > __r, memory_order)
 
template<typename _Tp >
shared_ptr< _Tp > atomic_exchange_explicit (shared_ptr< _Tp > *__p, shared_ptr< _Tp > __r, memory_order)
 
template<typename _Tp >
bool atomic_compare_exchange_strong_explicit (shared_ptr< _Tp > *__p, shared_ptr< _Tp > *__v, shared_ptr< _Tp > __w, memory_order, memory_order)
 

Detailed Description

template<typename _Tp>
class std::shared_ptr< _Tp >

A smart pointer with reference-counted copy semantics.

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.

Definition at line 122 of file bits/shared_ptr.h.

Member Typedef Documentation

◆ element_type

template<typename _Tp >
using std::shared_ptr< _Tp >::element_type = typename __shared_ptr<_Tp>::element_type

The type pointed to by the stored pointer, remove_extent_t<_Tp>

Definition at line 137 of file bits/shared_ptr.h.

◆ weak_type

template<typename _Tp >
using std::shared_ptr< _Tp >::weak_type = weak_ptr<_Tp>

The corresponding weak_ptr type for this shared_ptr.

Definition at line 142 of file bits/shared_ptr.h.

Constructor & Destructor Documentation

◆ shared_ptr() [1/13]

template<typename _Tp >
constexpr std::shared_ptr< _Tp >::shared_ptr ( )
inlineconstexprnoexcept

Construct an empty shared_ptr.

Postcondition
use_count()==0 && get()==0

Definition at line 148 of file bits/shared_ptr.h.

◆ shared_ptr() [2/13]

template<typename _Tp >
std::shared_ptr< _Tp >::shared_ptr ( const shared_ptr< _Tp > &  )
defaultnoexcept

Copy constructor.

◆ shared_ptr() [3/13]

template<typename _Tp >
template<typename _Yp , typename = _Constructible<_Yp*>>
std::shared_ptr< _Tp >::shared_ptr ( _Yp *  __p)
inlineexplicit

Construct a shared_ptr that owns the pointer __p.

Parameters
__pA pointer that is convertible to element_type*.
Postcondition
use_count() == 1 && get() == __p
Exceptions
std::bad_alloc,inwhich case delete __p is called.

Definition at line 160 of file bits/shared_ptr.h.

◆ shared_ptr() [4/13]

template<typename _Tp >
template<typename _Yp , typename _Deleter , typename = _Constructible<_Yp*, _Deleter>>
std::shared_ptr< _Tp >::shared_ptr ( _Yp *  __p,
_Deleter  __d 
)
inline

Construct a shared_ptr that owns the pointer __p and the deleter __d.

Parameters
__pA pointer.
__dA deleter.
Postcondition
use_count() == 1 && get() == __p
Exceptions
std::bad_alloc,inwhich case __d(__p) is called.

Requirements: _Deleter's copy constructor and destructor must not throw

__shared_ptr will release __p by calling __d(__p)

Definition at line 177 of file bits/shared_ptr.h.

◆ shared_ptr() [5/13]

template<typename _Tp >
template<typename _Deleter >
std::shared_ptr< _Tp >::shared_ptr ( nullptr_t  __p,
_Deleter  __d 
)
inline

Construct a shared_ptr that owns a null pointer and the deleter __d.

Parameters
__pA null pointer constant.
__dA deleter.
Postcondition
use_count() == 1 && get() == __p
Exceptions
std::bad_alloc,inwhich case __d(__p) is called.

Requirements: _Deleter's copy constructor and destructor must not throw

The last owner will call __d(__p)

Definition at line 194 of file bits/shared_ptr.h.

◆ shared_ptr() [6/13]

template<typename _Tp >
template<typename _Yp , typename _Deleter , typename _Alloc , typename = _Constructible<_Yp*, _Deleter, _Alloc>>
std::shared_ptr< _Tp >::shared_ptr ( _Yp *  __p,
_Deleter  __d,
_Alloc  __a 
)
inline

Construct a shared_ptr that owns the pointer __p and the deleter __d.

Parameters
__pA pointer.
__dA deleter.
__aAn allocator.
Postcondition
use_count() == 1 && get() == __p
Exceptions
std::bad_alloc,inwhich case __d(__p) is called.

Requirements: _Deleter's copy constructor and destructor must not throw _Alloc's copy constructor and destructor must not throw.

__shared_ptr will release __p by calling __d(__p)

Definition at line 214 of file bits/shared_ptr.h.

◆ shared_ptr() [7/13]

template<typename _Tp >
template<typename _Deleter , typename _Alloc >
std::shared_ptr< _Tp >::shared_ptr ( nullptr_t  __p,
_Deleter  __d,
_Alloc  __a 
)
inline

Construct a shared_ptr that owns a null pointer and the deleter __d.

Parameters
__pA null pointer constant.
__dA deleter.
__aAn allocator.
Postcondition
use_count() == 1 && get() == __p
Exceptions
std::bad_alloc,inwhich case __d(__p) is called.

Requirements: _Deleter's copy constructor and destructor must not throw _Alloc's copy constructor and destructor must not throw.

The last owner will call __d(__p)

Definition at line 233 of file bits/shared_ptr.h.

◆ shared_ptr() [8/13]

template<typename _Tp >
template<typename _Yp >
std::shared_ptr< _Tp >::shared_ptr ( const shared_ptr< _Yp > &  __r,
element_type __p 
)
inlinenoexcept

Constructs a shared_ptr instance that stores __p and shares ownership with __r.

Parameters
__rA shared_ptr.
__pA pointer that will remain valid while *__r is valid.
Postcondition
get() == __p && use_count() == __r.use_count()

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.

shared_ptr<pair<int,int>> pii(new pair<int,int>());
shared_ptr<int> pi(pii, &pii->first);
assert(pii.use_count() == 2);

Definition at line 257 of file bits/shared_ptr.h.

◆ shared_ptr() [9/13]

template<typename _Tp >
template<typename _Yp , typename = _Constructible<const shared_ptr<_Yp>&>>
std::shared_ptr< _Tp >::shared_ptr ( const shared_ptr< _Yp > &  __r)
inlinenoexcept

If __r is empty, constructs an empty shared_ptr; otherwise construct a shared_ptr that shares ownership with __r.

Parameters
__rA shared_ptr.
Postcondition
get() == __r.get() && use_count() == __r.use_count()

Definition at line 296 of file bits/shared_ptr.h.

◆ shared_ptr() [10/13]

template<typename _Tp >
std::shared_ptr< _Tp >::shared_ptr ( shared_ptr< _Tp > &&  __r)
inlinenoexcept

Move-constructs a shared_ptr instance from __r.

Parameters
__rA shared_ptr rvalue.
Postcondition
*this contains the old value of __r, __r is empty.

Definition at line 304 of file bits/shared_ptr.h.

◆ shared_ptr() [11/13]

template<typename _Tp >
template<typename _Yp , typename = _Constructible<shared_ptr<_Yp>>>
std::shared_ptr< _Tp >::shared_ptr ( shared_ptr< _Yp > &&  __r)
inlinenoexcept

Move-constructs a shared_ptr instance from __r.

Parameters
__rA shared_ptr rvalue.
Postcondition
*this contains the old value of __r, __r is empty.

Definition at line 313 of file bits/shared_ptr.h.

◆ shared_ptr() [12/13]

template<typename _Tp >
template<typename _Yp , typename = _Constructible<const weak_ptr<_Yp>&>>
std::shared_ptr< _Tp >::shared_ptr ( const weak_ptr< _Yp > &  __r)
inlineexplicit

Constructs a shared_ptr that shares ownership with __r and stores a copy of the pointer stored in __r.

Parameters
__rA weak_ptr.
Postcondition
use_count() == __r.use_count()
Exceptions
bad_weak_ptrwhen __r.expired(), in which case the constructor has no effect.

Definition at line 325 of file bits/shared_ptr.h.

◆ shared_ptr() [13/13]

template<typename _Tp >
constexpr std::shared_ptr< _Tp >::shared_ptr ( nullptr_t  )
inlineconstexprnoexcept

Construct an empty shared_ptr.

Postcondition
use_count() == 0 && get() == nullptr

Definition at line 357 of file bits/shared_ptr.h.

Member Function Documentation

◆ get()

template<typename _Tp , _Lock_policy _Lp>
element_type* std::__shared_ptr< _Tp, _Lp >::get ( void  ) const
inlinenoexceptinherited

Return the stored pointer.

Definition at line 1295 of file shared_ptr_base.h.

◆ operator bool()

template<typename _Tp , _Lock_policy _Lp>
std::__shared_ptr< _Tp, _Lp >::operator bool ( ) const
inlineexplicitnoexceptinherited

Return true if the stored pointer is not null.

Definition at line 1299 of file shared_ptr_base.h.

◆ owner_before() [1/2]

template<typename _Tp , _Lock_policy _Lp>
template<typename _Tp1 >
bool std::__shared_ptr< _Tp, _Lp >::owner_before ( __shared_ptr< _Tp1, _Lp > const &  __rhs) const
inlinenoexceptinherited

Define an ordering based on ownership.

This function defines a strict weak ordering between two shared_ptr or weak_ptr objects, such that one object is less than the other unless they share ownership of the same pointer, or are both empty.

Definition at line 1329 of file shared_ptr_base.h.

◆ owner_before() [2/2]

template<typename _Tp , _Lock_policy _Lp>
template<typename _Tp1 >
bool std::__shared_ptr< _Tp, _Lp >::owner_before ( __weak_ptr< _Tp1, _Lp > const &  __rhs) const
inlinenoexceptinherited

Define an ordering based on ownership.

This function defines a strict weak ordering between two shared_ptr or weak_ptr objects, such that one object is less than the other unless they share ownership of the same pointer, or are both empty.

Definition at line 1334 of file shared_ptr_base.h.

◆ swap()

template<typename _Tp , _Lock_policy _Lp>
void std::__shared_ptr< _Tp, _Lp >::swap ( __shared_ptr< _Tp, _Lp > &  __other)
inlinenoexceptinherited

Exchange both the owned pointer and the stored pointer.

Definition at line 1314 of file shared_ptr_base.h.

◆ unique()

template<typename _Tp , _Lock_policy _Lp>
bool std::__shared_ptr< _Tp, _Lp >::unique ( ) const
inlinenoexceptinherited

Return true if use_count() == 1.

Definition at line 1304 of file shared_ptr_base.h.

◆ use_count()

template<typename _Tp , _Lock_policy _Lp>
long std::__shared_ptr< _Tp, _Lp >::use_count ( ) const
inlinenoexceptinherited

If *this owns a pointer, return the number of owners, otherwise zero.

Definition at line 1309 of file shared_ptr_base.h.


The documentation for this class was generated from the following files: