std::pmr::operator==, std::pmr::operator!=

 

C++

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功能特性测试宏(C++20)

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符号索引

外部库

 

内存管理库

voidify (仅用于阐述*) 分配器 allocator allocator_traits (C++11) allocation_result (C++23) scoped_allocator_adaptor (C++11) pmr::polymorphic_allocator (C++17) allocator_arg (C++11) uses_allocator (C++11) uses_allocator_construction_args (C++20) make_obj_using_allocator (C++20) uninitialized_construct_using_allocator (C++20) 未初始化内存算法 uninitialized_copy uninitialized_fill uninitialized_move (C++17) uninitialized_copy_n (C++11) uninitialized_fill_n uninitialized_move_n (C++17) construct_at (C++20) uninitialized_default_construct (C++17) uninitialized_value_construct (C++17) destroy (C++17) uninitialized_default_construct_n (C++17) uninitialized_value_construct_n (C++17) destroy_n (C++17) destroy_at (C++17) 受约束的未初始化内存算法 ranges::uninitialized_copy (C++20) ranges::uninitialized_fill (C++20) ranges::uninitialized_move (C++20) ranges::uninitialized_copy_n (C++20)  ranges::uninitialized_fill_n (C++20) ranges::uninitialized_move_n (C++20) ranges::construct_at (C++20) ranges::uninitialized_default_construct (C++20) ranges::uninitialized_value_construct (C++20) ranges::destroy (C++20) ranges::uninitialized_default_construct_n (C++20)  ranges::uninitialized_value_construct_n (C++20) ranges::destroy_n (C++20) ranges::destroy_at (C++20) 内存资源 pmr::memory_resource (C++17) pmr::get_default_resource (C++17) pmr::set_default_resource (C++17) pmr::new_delete_resource (C++17) pmr::pool_options (C++17) pmr::null_memory_resource (C++17) pmr::synchronized_pool_resource (C++17) pmr::unsynchronized_pool_resource (C++17) pmr::monotonic_buffer_resource (C++17) 显式生存期管理 start_lifetime_as (C++23) start_lifetime_as_array (C++23) 用于复合类设计的类型 indirect (C++26) polymorphic (C++26) 未初始化存储(C++20 前) raw_storage_iterator (C++17 弃用) get_temporary_buffer (C++17 弃用) return_temporary_buffer (C++17 弃用) 垃圾收集器支持(C++23 前) declare_reachable (C++11)(C++23 前) declare_no_pointers (C++11)(C++23 前) pointer_safety (C++11)(C++23 前) undeclare_reachable (C++11)(C++23 前) undeclare_no_pointers (C++11)(C++23 前) get_pointer_safety (C++11)(C++23 前)

低层内存管理 operator newoperator new[] operator deleteoperator delete[] nothrow_t nothrow new_handler set_new_handler get_new_handler (C++11) bad_alloc bad_array_new_length (C++11) align_val_t (C++17) destroying_delete_t (C++20) launder (C++17) 智能指针 unique_ptr (C++11) shared_ptr (C++11) weak_ptr (C++11) auto_ptr (C++17 前*) owner_less (C++11) owner_less<void> (C++17) owner_hash (C++26) owner_equal (C++26) enable_shared_from_this (C++11) bad_weak_ptr (C++11) default_delete (C++11) out_ptr_t (C++23) inout_ptr_t (C++23) 杂项 pointer_traits (C++11) to_address (C++20) addressof (C++11) align (C++11) assume_aligned (C++20) is_sufficiently_aligned (C++26) C 库 malloc calloc realloc free aligned_alloc (C++17)

 

std::pmr::polymorphic_allocator

成员函数

polymorphic_allocator::polymorphic_allocator

polymorphic_allocator::allocate

polymorphic_allocator::deallocate

polymorphic_allocator::construct

polymorphic_allocator::destroy (C++20/26*)

polymorphic_allocator::allocate_bytes (C++20)

polymorphic_allocator::deallocate_bytes (C++20)

polymorphic_allocator::allocate_object (C++20)

polymorphic_allocator::deallocate_object (C++20)

polymorphic_allocator::new_object (C++20)

polymorphic_allocator::delete_object (C++20)

polymorphic_allocator::select_on_container_copy_construction

polymorphic_allocator::resource

非成员函数

operator==operator!= (C++20 前)

 

在标头 <memory_resource> 定义
template<class T1, class T2 > bool operator==(conststd::pmr::polymorphic_allocator<T1>& lhs,                  conststd::pmr::polymorphic_allocator<T2>& rhs )noexcept;	(1)	(C++17 起)
friendbool operator==(const polymorphic_allocator& lhs,                         const polymorphic_allocator& rhs )noexcept;	(2)	(C++17 起)
template<class T1, class T2 > bool operator!=(conststd::pmr::polymorphic_allocator<T1>& lhs,                  conststd::pmr::polymorphic_allocator<T2>& rhs )noexcept;	(3)	(C++17 起) (C++20 前)
friendbool operator!=(const polymorphic_allocator& lhs,                         const polymorphic_allocator& rhs )noexcept;	(4)	(C++17 起) (C++20 前)

比较两个多态分配器。若两个多态分配器的底层内存资源比较相等，则它们比较相等。

1) 返回 *lhs.resource()==*rhs.resource()。

2) 同 (1)，允许到 polymorphic_allocator 的转换。
此函数对常规的无限定或有限定查找不可见，而只能在 std::pmr::polymorphic_allocator 为实参的关联类时由实参依赖查找找到。

3) 返回 !(lhs == rhs)。

4) 同 (3)，允许到 polymorphic_allocator 的转换。
此函数对常规的无限定或有限定查找不可见，而只能在 std::pmr::polymorphic_allocator 为实参的关联类时由实参依赖查找找到。

!= 运算符从 operator== 运算符合成。

(C++20 起)

参数

lhs, rhs

-

要比较的多态分配器

返回值

1,2)*lhs.resource()==*rhs.resource()

3,4)!(lhs == rhs)

缺陷报告

下列更改行为的缺陷报告追溯地应用于以前出版的 C++ 标准。

缺陷报告	应用于	出版时的行为	正确行为
LWG 3683	C++17	polymorphic_allocator 不能与能转换到它的类型比较	添加了重载