Ajout de Hashtbl.fold (PR#195)

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@3544 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

stdlib/hashtbl.ml

@@ -141,6 +141,20 @@ let iter f h =
     do_bucket d.(i)
   done
 
+let fold f h init =
+  let rec do_bucket b accu =
+    match b with
+      Empty ->
+        accu
+    | Cons(k, d, rest) ->
+        do_bucket rest (f k d accu) in
+  let d = h.data in
+  let accu = ref init in
+  for i = 0 to Array.length d - 1 do
+    accu := do_bucket d.(i) !accu
+  done;
+  !accu
+
 (* Functorial interface *)
 
 module type HashedType =
@@ -163,6 +177,7 @@ module type S =
     val replace : 'a t -> key -> 'a -> unit
     val mem : 'a t -> key -> bool
     val iter: (key -> 'a -> unit) -> 'a t -> unit
+    val fold: f:(key:key -> data:'a -> 'b -> 'b) -> 'a t -> init:'b -> 'b
   end
 
 module Make(H: HashedType): (S with type key = H.t) =
@@ -243,6 +258,6 @@ module Make(H: HashedType): (S with type key = H.t) =
           H.equal k key || mem_in_bucket rest in
       mem_in_bucket h.data.((H.hash key) mod (Array.length h.data))
 
-
     let iter = iter
+    let fold = fold
   end

stdlib/hashtbl.mli

@@ -70,6 +70,15 @@ val iter : f:(key:'a -> data:'b -> unit) -> ('a, 'b) t -> unit
            [f] is unspecified. Each binding is presented exactly once
            to [f]. *)
 
+val fold : f:(key:'a -> data:'b -> 'c -> 'c) -> ('a, 'b) t -> init:'c -> 'c
+        (* [Hashtbl.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.
+           The order in which the bindings are passed to
+           [f] is unspecified. Each binding is presented exactly once
+           to [f]. *)
+
 (*** Functorial interface *)
 
 module type HashedType =
@@ -104,6 +113,7 @@ module type S =
     val replace : 'a t -> key:key -> data:'a -> unit
     val mem: 'a t -> key -> bool
     val iter: f:(key:key -> data:'a -> unit) -> 'a t -> unit
+    val fold: f:(key:key -> data:'a -> 'b -> 'b) -> 'a t -> init:'b -> 'b
   end
 
 module Make(H: HashedType): (S with type key = H.t)