Crate cachedhash 

For a type T, CachedHash<T> wraps T and implements Hash in a way that caches T’s hash value. This is useful when T is expensive to hash (for example if it contains a large vector) and you need to hash it multiple times with few modifications (for example by moving it between multiple HashSets).

Stored hash is invalidated whenever the stored value is accessed mutably (via DerefMut, AsMut, BorrowMut or explicitly via a provided associated function). In order for the hash to be invalidated correctly the stored type cannot use interior mutability in a way that affects the hash. If this is the case, you can use CachedHash::invalidate_hash to invalidate the hash manually.

Structs

CachedHash

For a type T, CachedHash wraps T and implements Hash in a way that caches T’s hash value. The first time the hash is computed, it is stored and returned on subsequent calls. When the stored value is accessed mutably the hash is invalidated and needs to be recomputed again. CachedHash implements Deref and DerefMut so it can be used as a drop-in replacement for T.