package aches

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Set(RA)(O)(H) is a [SET] indexed by [H] and governed by [RA] and [O].

A Mutable structure akin to a set, 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 Vache are intended to be used in settings that do not require strict, by-the-number, extremely-predictable behaviors.

See Vache (or Functors) for more information.


module O : OVERFLOW


type elt = H.t

The type of values held by the cache.

type t

The type of caches holding values of type elt.

val create : int -> t

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

val add : t -> elt -> unit

add c v adds the value v to the cache c. This may or may not cause another element to be removed from the cache, depending on the number of elements already present in the cache c, the size-bound of the cache c, and the policy of the cache c towards its size-bound.

Note that after the add c v call returns, v is the most recent element in the cache. This is true whether or not the element was already in the cache before the call. This is true for whichever replacement policy (see Vache.replacement) the cache has.

If v is already present in c, and the accounting policy of the cache is Sloppy, the element may or may not count twice towards the size bound for some time. On the other hand, if the cache accounting is Precise then the element v only counts once. See Vache.accounting for more details.

val fold : (elt -> 'a -> 'a) -> t -> 'a -> 'a

fold f c init folds the function f and value init over the elements of c from newest to oldest.

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

val fold_oldest_first : (elt -> 'a -> 'a) -> t -> 'a -> 'a

fold_oldest_first is like fold but in reversed order: oldest elements of c first. This function has the same limitation as fold.

val mem : t -> elt -> bool

mem c v is true if v is present in c. It is false otherwise.

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

val remove : t -> elt -> unit

remove c v removes the element v from c. If v is not present in c, it does nothing.

Note that in caches with a Sloppy accounting policy, removed elements can still count towards the size bound for some time. On the other hand, if the cache's accounting policy is Precise then the element immediately stops counting towards the size bound.

val length : t -> int

length c is the number of elements present in c.

val capacity : t -> int

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

val clear : t -> unit

clear c removes all elements from c.


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