= `storage_ptr` Variable-length containers in this library all use dynamically allocated memory to store their contents. Callers can gain control over the strategy used for allocation by specifying a <<ref_storage_ptr>> in select constructors and function parameter lists. A <<ref_storage_ptr>> has these properties:

A storage pointer always points to a valid,

type-erased {ref_memory_resource}.

Default-constructed storage pointers reference the

<<default_memory_resource,default resource>>, an implementation-defined instance which always uses the equivalent of global operator new and delete.

Storage pointers constructed from a {ref_memory_resource} or

{ref_polymorphic_allocator} do not acquire ownership; the caller is responsible for ensuring that the lifetime of the resource extends until it is no longer referenced.

A storage pointer obtained from <<ref_make_shared_resource>> acquires shared

ownership of the memory resource; the lifetime of the resource is extended until all copies of the storage pointer are destroyed.

The storage pointer remembers the value of <<ref_is_deallocate_trivial>>

before type-erasing the resource, allowing the value to be queried at run-time.

This lists all of the allocation-related types and functions available when using the library:

Name

Description

<<ref_get_null_resource>>

Returns a pointer to a memory resource instance which always throws an

exception upon allocation. This is used to to achieve the invariant that no parsing or container operation will dynamically allocate memory.

<<ref_is_deallocate_trivial>>

A customization point allowing a memory resource type to indicate that calls

to deallocate are trivial.