The arena, a fast but limited type of allocator.
Arenas are a type of allocator that destroy the objects within, all at once, once the arena itself is destroyed. They do not support deallocation of individual objects while the arena itself is still alive. The benefit of an arena is very fast allocation; just a pointer bump.
This crate implements several kinds of arena.
An arena which can be used to allocate any type.
Allocating in this arena is unsafe since the type system
doesn't know which types it contains. In order to
allocate safely, you must store a PhantomData
An arena that can hold objects of only one type.