a few more functions in CCVector, including in-place filtering

and efficient non-order-preserving removal

core/CCVector.ml

@@ -42,6 +42,8 @@ type ('a,'mut) t = {
   mutable vec : 'a array;
 }
 
+type 'a vector = ('a, rw) t
+
 let freeze v = {
   size=v.size;
   vec=v.vec;
@@ -145,6 +147,14 @@ let set v i x =
   if i < 0 || i >= v.size then failwith "Vector.set";
   Array.unsafe_set v.vec i x
 
+let remove v i =
+  if i < 0 || i >= v.size then failwith "Vector.remove";
+  (* if v.(i) not the last element, then put last element at index i *)
+  if i < v.size - 1
+    then v.vec.(i) <- v.vec.(v.size - 1);
+  (* remove one element *)
+  v.size <- v.size - 1
+
 let append_seq a seq =
   seq (fun x -> push a x)
 
@@ -251,6 +261,20 @@ let map f v =
     vec=Array.map f v.vec
   }
 
+let filter' p v =
+  let i = ref (v.size - 1) in
+  while !i >= 0 do
+    if not (p v.vec.(! i))
+      (* remove i-th item! *)
+      then remove v !i;
+    decr i
+  done
+
+(*$T
+  let v = 1 -- 10 in filter' (fun x->x<4) v; \
+   to_list v |> List.sort Pervasives.compare = [1;2;3]
+*)
+
 let filter p v =
   if _empty_array v
   then create ()
@@ -377,7 +401,7 @@ let of_seq ?(init=create ()) seq =
 
 let to_seq v k = iter k v
 
-let slice v start len =
+let slice_seq v start len =
   assert (start >= 0 && len >= 0);
   fun k ->
     assert (start+len < v.size);
@@ -387,9 +411,11 @@ let slice v start len =
     done
 
 (*$T
-  slice (of_list [0;1;2;3;4]) 1 3 |> CCList.of_seq = [1;2;3]
+  slice_seq (of_list [0;1;2;3;4]) 1 3 |> CCList.of_seq = [1;2;3]
 *)
 
+let slice v = (v.vec, 0, v.size)
+
 let (--) i j =
   if i>j
     then init (i-j+1) (fun k -> i-k)

core/CCVector.mli

@@ -34,6 +34,9 @@ type ('a, 'mut) t
 (** the type of a vector of elements of type ['a], with
     a mutability flat ['mut] *)
 
+type 'a vector = ('a, rw) t
+(** Type synonym: a ['a vector] is mutable. *)
+
 type 'a sequence = ('a -> unit) -> unit
 type 'a klist = unit -> [`Nil | `Cons of 'a * 'a klist]
 type 'a gen = unit -> 'a option
@@ -110,10 +113,10 @@ val sort : ('a -> 'a -> int) -> ('a, _) t -> ('a, 'mut) t
 (** Sort the vector *)
 
 val sort' : ('a -> 'a -> int) -> ('a, rw) t -> unit
-(** sort the vector in place*)
+(** Sort the vector in place *)
 
 val uniq_sort : ('a -> 'a -> int) -> ('a, rw) t -> unit
-(** sort the array and remove duplicates in place*)
+(** Sort the array and remove duplicates, in place*)
 
 val iter : ('a -> unit) -> ('a,_) t -> unit
 (** iterate on the vector *)
@@ -127,6 +130,10 @@ val map : ('a -> 'b) -> ('a,_) t -> ('b, 'mut) t
 val filter : ('a -> bool) -> ('a,_) t -> ('a, 'mut) t
 (** filter elements from vector *)
 
+val filter' : ('a -> bool) -> ('a, rw) t -> unit
+(** Filter elements in place. Does {b NOT} preserve the order
+    of the elements. *)
+
 val fold : ('b -> 'a -> 'b) -> 'b -> ('a,_) t -> 'b
 (** fold on elements of the vector *)
 
@@ -164,6 +171,10 @@ val set : ('a, rw) t -> int -> 'a -> unit
 (** access element, or
     @raise Failure if bad index *)
 
+val remove : ('a, rw) t -> int -> unit
+(** Remove the [n-th] element of the vector. Does {b NOT} preserve the order
+    of the elements (might swap with the last element) *)
+
 val rev : ('a,_) t -> ('a, 'mut) t
 (** Reverse the vector *)
 
@@ -196,8 +207,12 @@ val of_seq : ?init:('a,rw) t -> 'a sequence -> ('a, rw) t
 
 val to_seq : ('a,_) t -> 'a sequence
 
-val slice : ('a,_) t -> int -> int -> 'a sequence
-(** [slice v start len] is the sequence of elements from [v.(start)]
+val slice : ('a,rw) t -> ('a array * int * int)
+(** Vector as an array slice. By doing it we expose the internal array, so
+    be careful! *)
+
+val slice_seq : ('a,_) t -> int -> int -> 'a sequence
+(** [slice_seq v start len] is the sequence of elements from [v.(start)]
     to [v.(start+len-1)]. *)
 
 val of_klist : ?init:('a, rw) t -> 'a klist -> ('a, rw) t