pw::WeakPtr< T > Class Template Reference

Overview

template<typename T>
class pw::WeakPtr< T >

A std::weak_ptr<T>-like type that integrates with pw::SharedPtr.

Template Parameters

T	The type being pointed to. This may be an array type, e.g. pw::WeakPtr<T[]>.

Inheritance diagram for pw::WeakPtr< T >:

Public Types
using	element_type = typename Base::element_type

Public Member Functions
constexpr	WeakPtr () noexcept=default
	Creates an empty (nullptr) instance.
constexpr	WeakPtr (std::nullptr_t) noexcept
	Creates an empty (nullptr) instance.
	WeakPtr (const WeakPtr &other) noexcept
	Copy-constructs a WeakPtr<T> from a WeakPtr<T>.
template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>
	WeakPtr (const WeakPtr< U > &other) noexcept
template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>
	WeakPtr (const SharedPtr< U > &other) noexcept
template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>
	WeakPtr (WeakPtr< U > &&other) noexcept
constexpr WeakPtr &	operator= (const WeakPtr &other) noexcept
	Copy-assigns a WeakPtr<T> from a WeakPtr<T>.
template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>
WeakPtr &	operator= (const WeakPtr< U > &other) noexcept
template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>
WeakPtr &	operator= (const SharedPtr< U > &other) noexcept
template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>
WeakPtr &	operator= (WeakPtr< U > &&other) noexcept
template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>
constexpr	operator const WeakPtr< U > & () const
void	reset () noexcept
void	swap (WeakPtr &other) noexcept
	Swaps the managed pointer and deallocator of this and another object.
int32_t	use_count () const noexcept
bool	expired () const noexcept
SharedPtr< T >	Lock () const noexcept
template<typename PtrType >
bool	owner_before (const PtrType &other) const noexcept
template<typename U , typename >
WeakPtr< T > &	operator= (const WeakPtr< U > &other) noexcept
template<typename U , typename >
WeakPtr< T > &	operator= (const SharedPtr< U > &other) noexcept
template<typename U , typename >
WeakPtr< T > &	operator= (WeakPtr< U > &&other) noexcept

Constructor & Destructor Documentation

WeakPtr() [1/3]

template<typename T >

template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>

pw::WeakPtr< T >::WeakPtr ( const WeakPtr< U > &  other )

inlinenoexcept

Copy-constructs a WeakPtr<T> from a WeakPtr<U>.

This allows not only pure move construction where T == U, but also converting construction where T is a base class of U.

WeakPtr() [2/3]

template<typename T >

template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>

pw::WeakPtr< T >::WeakPtr ( const SharedPtr< U > &  other )

inlinenoexcept

Copy-constructs a WeakPtr<T> from a SharedPtr<U>.

This allows not only pure move construction where T == U, but also converting construction where T is a base class of U.

WeakPtr() [3/3]

template<typename T >

template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>

pw::WeakPtr< T >::WeakPtr ( WeakPtr< U > &&  other )

inlinenoexcept

Move-constructs a SharedPtr<T> from a SharedPtr<U>.

This allows not only pure move construction where T == U, but also converting construction where T is a base class of U, like SharedPtr<Base> base(deallocator.MakeShared<Child>());.

Member Function Documentation

expired()

template<typename T >

bool pw::WeakPtr< T >::expired ( ) const

inlinenoexcept

Returns true if the associated object has been destroyed; otherwise returns false.

operator const WeakPtr< U > &()

template<typename T >

template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>

constexpr pw::WeakPtr< T >::operator const WeakPtr< U > & ( ) const

inlineexplicitconstexpr

Explicit conversion operator for downcasting.

If an arbitrary type A derives from another type B, a shared or weak pointer to A can be automatically upcast to one of type B. This operator performs the reverse operation with an explicit cast.

pw::SharedPtr<A> a1 = allocator.MakeShared<A>();
pw::WeakPtr<B> b = a1;
pw::WeakPtr<A> a2 = static_cast<pw::WeakPtr<A>>(b);

operator=() [1/3]

template<typename T >

template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>

WeakPtr & pw::WeakPtr< T >::operator= ( const SharedPtr< U > &  other )

noexcept

Copy-assigns a WeakPtr<T> from a SharedPtr<U>.

This allows not only pure move construction where T == U, but also converting construction where T is a base class of U.

operator=() [2/3]

template<typename T >

template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>

WeakPtr & pw::WeakPtr< T >::operator= ( const WeakPtr< U > &  other )

noexcept

Copy-assigns a SharedPtr<T> from a SharedPtr<U>.

This allows not only pure copy assignment where T == U, but also converting assignment where T is a base class of U.

operator=() [3/3]

template<typename T >

template<typename U , typename = std::enable_if_t<std::is_assignable_v<T*&, U*>>>

WeakPtr & pw::WeakPtr< T >::operator= ( WeakPtr< U > &&  other )

noexcept

Move-assigns a WeakPtr<T> from a SharedPtr<U>.

This allows not only pure move construction where T == U, but also converting construction where T is a base class of U.

owner_before()

template<typename T >

template<typename PtrType >

bool pw::WeakPtr< T >::owner_before ( const PtrType &  other ) const

inlinenoexcept

Checks whether this precedes other based on an ordering of their control blocks.

use_count()

template<typename T >

int32_t pw::WeakPtr< T >::use_count ( ) const

inlinenoexcept

Returns the number of shared pointers to the associated object, or 0 if this object is empty.

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

• pw_allocator/public/pw_allocator/shared_ptr.h
• pw_allocator/public/pw_allocator/weak_ptr.h