| lib.rs |
The arena, a fast but limited type of allocator.
**A fast (but limited) allocation arena for values of a single type.**
Allocated objects are destroyed all at once, when the arena itself is
destroyed. There is no deallocation of individual objects while the arena
itself is still alive. The flipside is that allocation is fast: typically
just a vector push.
There is also a method `into_vec()` to recover ownership of allocated
objects when the arena is no longer required, instead of destroying
everything.
## Example
```
use typed_arena_nomut::Arena;
struct Monster {
level: u32,
}
let monsters = Arena::new();
let goku = monsters.alloc(Monster { level: 9001 });
assert!(goku.level > 9000);
```
## Safe Cycles
All allocated objects get the same lifetime, so you can safely create cycles
between them. This can be useful for certain data structures, such as graphs
and trees with parent pointers.
```
use std::cell::Cell;
use typed_arena_nomut::Arena;
struct CycleParticipant<'a> {
other: Cell<Option<&'a CycleParticipant<'a>>>,
}
let arena = Arena::new();
let a = arena.alloc(CycleParticipant { other: Cell::new(None) });
let b = arena.alloc(CycleParticipant { other: Cell::new(None) });
a.other.set(Some(b));
b.other.set(Some(a));
``` |
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