virtual void* do_allocate(size_t bytes, size_t alignment) = 0;
Returns: A derived class shall implement this function to return a pointer to allocated storage ([basic.stc.dynamic.deallocation]) with a size of at least bytes. The returned storage is aligned to the specified alignment, if such alignment is supported ([basic.align]); otherwise it is aligned to max_align.
Throws: A derived class implementation shall throw an appropriate exception if it is unable to allocate memory with the requested size and alignment.
virtual void do_deallocate(void* p, size_t bytes, size_t alignment) = 0;
Requires: p shall have been returned from a prior call to allocate(bytes, alignment) on a memory resource equal to *this, and the storage at p shall not yet have been deallocated.
virtual bool do_is_equal(const memory_resource& other) const noexcept = 0;
Returns: A derived class shall implement this function to return true if memory allocated from this can be deallocated from other and vice-versa, otherwise false. [ Note: The most-derived type of other might not match the type of this. For a derived class D, a typical implementation of this function will immediately return false if dynamic_cast<const D*>(&other) == nullptr. — end note ]