std::pmr::polymorphic_allocator
| Defined in header <memory_resource>
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||
| template< class T > class polymorphic_allocator; |
(since C++17) | |
The class template std::pmr::polymorphic_allocator is an Allocator whose allocation behavior depends on the memory resource it is constructed with. Thus, different instances of polymorphic_allocator can exhibit entirely different allocation behavior. This runtime polymorphism allows objects using polymorphic_allocator to behave as if they used different allocator types at run time despite the identical static allocator type.
All specializations of polymorphic_allocator meet the Allocator completeness requirements.
Member types
| Member type | definition |
value_type
|
T
|
Member functions
Constructs a polymorphic_allocator (public member function) | |
| (destructor) (implicitly declared) |
Implicitly declared destructor (public member function) |
| operator= [deleted] |
Copy assignment operator is deleted (public member function) |
Public member functions | |
| Allocate memory (public member function) | |
| Deallocate memory (public member function) | |
| Constructs an object in allocated storage (public member function) | |
| Destroys an object in allocated storage (public member function) | |
Create a new polymorphic_allocator for use by a container's copy constructor (public member function) | |
| Returns a pointer to the underlying memory resource (public member function) | |
Non-member functions
compare two polymorphic_allocators (function) |
Notes
polymorphic_allocator does not propagate on container copy assignment, move assignment, or swap. As a result, move assignment of a polymorphic_allocator-using container can throw, and swapping two polymorphic_allocator-using containers whose allocators do not compare equal results in undefined behavior.
See also
| (C++17) |
an abstract interface for classes that encapsulate memory resources (class) |