std::pmr::polymorphic_allocator<T>::polymorphic_allocator

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Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros(C++20)
Language support library
Concepts library(C++20)
Diagnostics library
Memory management library
Metaprogramming library(C++11)
General utilities library
Containers library
Iterators library
Ranges library(C++20)
Algorithms library
Strings library
Text processing library
Numerics library
Date and time library
Input/output library
Filesystem library(C++17)
Concurrency support library(C++11)
Execution control library(C++26)
Technical specifications
Symbols index
External libraries

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Memory management library

voidify

(exposition only*)

Allocators

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)

Uninitialized memory algorithms

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)

Constrained uninitialized memory algorithms

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)

Memory resources

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)

Explicit lifetime management
start_lifetime_as (C++23)
start_lifetime_as_array (C++23)

Types for composite class design
indirect (C++26)
polymorphic (C++26)

Uninitialized storage(until C++20)

raw_storage_iterator (until C++20*)
get_temporary_buffer (until C++20*)

return_temporary_buffer (until C++20*)

Garbage collector support(until C++23)

declare_reachable (C++11)(until C++23)
declare_no_pointers (C++11)(until C++23)
pointer_safety (C++11)(until C++23)

undeclare_reachable (C++11)(until C++23)
undeclare_no_pointers (C++11)(until C++23)
get_pointer_safety (C++11)(until C++23)

Low level memory
management

operator newoperator new[]

operator deleteoperator delete[]

(C++11)

(C++11)

(C++17)

(C++20)

(C++17)

(C++11)

(C++11)

(C++11)

(until C++17*)

(C++11)

(C++17)

(C++26)

(C++26)

enable_shared_from_this

(C++11)

(C++11)

(C++11)

(C++23)

(C++23)

(C++11)

(C++20)

(C++11)

(C++11)

(C++20)

is_sufficiently_aligned

(C++26)

C Library

malloc
calloc
realloc

free
aligned_alloc (C++17)

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std::pmr::polymorphic_allocator

Member functions
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
Non-member functions
operator==operator!= (until C++20)

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polymorphic_allocator()noexcept;	(1)
polymorphic_allocator(const polymorphic_allocator& other)=default;	(2)
template<class U> polymorphic_allocator(const polymorphic_allocator<U>& other)noexcept;	(3)
polymorphic_allocator(std::pmr::memory_resource* r);	(4)

Constructs a newpolymorphic_allocator.

1) Constructs apolymorphic_allocator using the return value ofstd::pmr::get_default_resource() as the underlying memory resource.

2,3) Constructs apolymorphic_allocator usingother.resource() as the underlying memory resource.

4) Constructs apolymorphic_allocator usingr as the underlying memory resource. This constructor provides an implicit conversion fromstd::pmr::memory_resource*.

[edit]Parameters

other	-	another`polymorphic_allocator` to copy from
r	-	pointer to the memory resource to use. May not be null

[edit]Exceptions

4) Throws nothing.

[edit] Notes

Copying a container using apolymorphic_allocator will not call the allocator's copy constructor. Instead, the new container will use the return value ofselect_on_container_copy_construction (a default-constructedpolymorphic_allocator) as its allocator.