package tezos-crypto

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A Mutable structure akin to a hash-table, but with a size bound. Note that, different caches have different policies towards the size bounds: some uphold the bound strictly, some treat the bound as a suggestion. In addition, some caches count their elements somewhat sloppily.

In general, the caches of ringo are intended to be used in settings that do not require strict, by-the-number, extremely-predictable behaviors.

See Ringo (or Functors) for more information.


module H : Stdlib.Hashtbl.HashedType


type key = H.t

The type of keys on which values in the cache are indexed.

type 'a t

The type of caches holding bindings from key to 'a

val create : int -> 'a t

create n creates a cache with a size-bound of n. Remember that the size-bound is not upheld strictly by all caches.

val replace : 'a t -> key -> 'a -> unit

replace c k v binds the key k to the value v in the cache c. This may or may not cause another binding to be removed from the cache, depending on the number of bindings already present in the cache c, the size-bound of the cache c, and the policy of the cache c towards its size-bound.

If k is already bound to a value in c, the previous binding disappears and is replaced by the new binding to v.

Note that in caches with a Sloppy accounting policy, the old binding is erased but may still count towards the size bound for some time. In other words: apart for size bound consideration, the following sequences of operations are indistinguishable: replace c k v; replace c k u replace c k v; remove c k; replace c k u

val fold : (key -> 'a -> 'b -> 'b) -> 'a t -> 'b -> 'b

fold f c init folds the function f and value init over the bindings of c.

Note that for caches with a Weak overflow policy, this function may fold over a subset of the bindings of c. See Ringo (or Functors) for more details.

val fold_v : ('a -> 'b -> 'b) -> 'a t -> 'b -> 'b

fold_v f c init folds the function f and value init over the values held by the bindings of c.

It is less powerful than fold in that it does not grant access to the bindings' keys, but it does fold over all the values bound in c, even when the c has a Weak overflow policy.

val find_opt : 'a t -> key -> 'a option

find_opt c k is Some v if k is bound to v in c. It is None otherwise.

Note that the in caches with a non-FIFO replacement policy, this may have a side effect on the k-to-v binding. Specifically, in those caches, it might make it less likely to be removed when supernumerary bindings are inserted.

val remove : 'a t -> key -> unit

remove c k removes the binding from k in c. If k is not bound in c, it does nothing.

Note that in caches with a Sloppy accounting policy, removed bindings can still count towards the size bound for some time.

val length : 'a t -> int

length c is the number of bindings held by c.

val capacity : 'a t -> int

capacity c is the number of bindings c can hold: capacity (create n) = n

val clear : 'a t -> unit

clear c removes all bindings from c.

module H : Stdlib.Hashtbl.HashedType with type t = key

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