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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.
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.
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 (removed) binding may still count towards the size bound for some time.
fold f c init
folds the function f
and value init
over the bindings of c
from newest to oldest.
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.
fold_oldest_first
is like fold
but in reversed order: oldest elements of c
first. This function has the same limitation as fold
.
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
. The order of the traversal is unspecified.
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.
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.
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.
filter c f
removes all the bindings (k, v)
such that f k v = false
.
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 : Hashtbl.HashedType with type t = key