Module BatInnerWeaktbl

Weak hash table library for OCaml, with an interface compatible with the standard Hashtbl module.

Generic interface
type ('a, 'b) t

The type of hash tables from type 'a to type 'b.

val create : int -> ('a, 'b) t

Weaktbl.create n creates a new, empty hash table, with initial size n. For best results, n should be on the order of the expected number of elements that will be in the table. The table grows as needed, so n is just an initial guess.

val clear : ('a, 'b) t -> unit

Empty a hash table.

val add : ('a, 'b) t -> 'a -> 'b -> unit

Weaktbl.add tbl x y adds a binding of x to y in table tbl. Previous bindings for x are not removed, but simply hidden. That is, after performing Weaktbl.remove tbl x, the previous binding for x, if any, is restored. (Same behavior as with association lists.)

val copy : ('a, 'b) t -> ('a, 'b) t

Return a copy of the given hashtable.

val find : ('a, 'b) t -> 'a -> 'b

Weaktbl.find tbl x returns the current binding of x in tbl, or raises Not_found if no such binding exists.

val find_all : ('a, 'b) t -> 'a -> 'b list

Weaktbl.find_all tbl x returns the list of all data associated with x in tbl. The current binding is returned first, then the previous bindings, in reverse order of introduction in the table.

val mem : ('a, 'b) t -> 'a -> bool

Weaktbl.mem tbl x checks if x is bound in tbl.

val remove : ('a, 'b) t -> 'a -> unit

Weaktbl.remove tbl x removes the current binding of x in tbl, restoring the previous binding if it exists. It does nothing if x is not bound in tbl.

val replace : ('a, 'b) t -> 'a -> 'b -> unit

Weaktbl.replace tbl x y replaces the current binding of x in tbl by a binding of x to y. If x is unbound in tbl, a binding of x to y is added to tbl. This is functionally equivalent to Weaktbl.remove tbl x followed by Weaktbl.add tbl x y.

val iter : ('a -> 'b -> unit) -> ('a, 'b) t -> unit

Weaktbl.iter f tbl applies f to all bindings in table tbl. f receives the key as first argument, and the associated value as second argument. Each binding is presented exactly once to f. The order in which the bindings are passed to f is unspecified. However, if the table contains several bindings for the same key, they are passed to f in reverse order of introduction, that is, the most recent binding is passed first.

val fold : ('a -> 'b -> 'c -> 'c) -> ('a, 'b) t -> 'c -> 'c

Weaktbl.fold f tbl init computes (f kN dN ... (f k1 d1 init)...), where k1 ... kN are the keys of all bindings in tbl, and d1 ... dN are the associated values. Each binding is presented exactly once to f. The order in which the bindings are passed to f is unspecified. However, if the table contains several bindings for the same key, they are passed to f in reverse order of introduction, that is, the most recent binding is passed first.

val length : ('a, 'b) t -> int

Weaktbl.length tbl returns the number of bindings in tbl. Multiple bindings are counted multiply, so Weaktbl.length gives the number of times Weaktbl.iter calls its first argument.

Functorial interface
module type HashedType = sig ... end
module type S = sig ... end

This is a subset of Hashtbl.S, kept as a separate interface to avoid compatibility issues when Hashtbl.S evolves.

module Make (H : HashedType) : S with type key = H.t

Functor building an implementation of the hashtable structure. The functor Weaktbl.Make returns a structure containing a type key of keys and a type 'a t of hash tables associating data of type 'a to keys of type key. The operations perform similarly to those of the generic interface, but use the hashing and equality functions specified in the functor argument H instead of generic equality and hashing.