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-rw-r--r--clib/cList.ml14
1 files changed, 14 insertions, 0 deletions
diff --git a/clib/cList.ml b/clib/cList.ml
index 0ef7c3d8b..627a3e3e0 100644
--- a/clib/cList.ml
+++ b/clib/cList.ml
@@ -62,6 +62,7 @@ sig
val fold_right_and_left :
('a -> 'b -> 'b list -> 'a) -> 'b list -> 'a -> 'a
val fold_left3 : ('a -> 'b -> 'c -> 'd -> 'a) -> 'a -> 'b list -> 'c list -> 'd list -> 'a
+ val fold_left2_set : exn -> ('a -> 'b -> 'c -> 'b list -> 'c list -> 'a) -> 'a -> 'b list -> 'c list -> 'a
val for_all_i : (int -> 'a -> bool) -> int -> 'a list -> bool
val except : 'a eq -> 'a -> 'a list -> 'a list
val remove : 'a eq -> 'a -> 'a list -> 'a list
@@ -472,6 +473,19 @@ let fold_right_and_left f l hd =
| a::l -> let hd = aux (a::tl) l in f hd a tl
in aux [] l
+(* Match sets as lists according to a matching function, also folding a side effect *)
+let rec fold_left2_set e f x l1 l2 =
+ match l1 with
+ | a1::l1 ->
+ let rec find seen = function
+ | [] -> raise e
+ | a2::l2 ->
+ try fold_left2_set e f (f x a1 a2 l1 l2) l1 (List.rev_append seen l2)
+ with e' when e' = e -> find (a2::seen) l2 in
+ find [] l2
+ | [] ->
+ if l2 = [] then x else raise e
+
let iteri f l = fold_left_i (fun i _ x -> f i x) 0 () l
let for_all_i p =