[mem.res.private]

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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.allocation]) with a size of at least bytes, aligned to the specified alignment.

Throws: A derived class implementation shall throw an appropriate exception if it is unable to allocate memory with the requested size and alignment.

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virtual void do_deallocate(void* p, size_t bytes, size_t alignment) = 0;

Preconditions: p was returned from a prior call to allocate(bytes, alignment) on a memory resource equal to *this, and the storage at p has not yet been deallocated.

Throws: Nothing.

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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 1:

It is possible that the most-derived type of other does not match the type of *this.

For a derived class D, an implementation of this function can immediately return false if dynamic_cast<const D*>(&other) == nullptr.

— end note]

20 Memory management library [mem]

20.5 Memory resources [mem.res]

20.5.2 Class memory_resource [mem.res.class]

20.5.2.3 Private virtual member functions [mem.res.private]