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more flexible CCList.sublists_of_len

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This commit is contained in:
Simon Cruanes 2017-02-06 17:34:51 +01:00
parent fe2336bd3b
commit 1e9f5a9a21
2 changed files with 13 additions and 10 deletions
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15
src/core/CCList.ml
View file

@ -528,7 +528,7 @@ let take_drop n l = take n l, drop n l
l1 @ l2 = l ) l1 @ l2 = l )
*) *)
let sublists_of_len ?(drop_short=true) ?offset n l = let sublists_of_len ?(last=fun _ -> None) ?offset n l =
if n < 1 then invalid_arg "sublists_of_len: n must be > 0"; if n < 1 then invalid_arg "sublists_of_len: n must be > 0";
let offset = match offset with let offset = match offset with
| None -> n | None -> n
@ -538,11 +538,12 @@ let sublists_of_len ?(drop_short=true) ?offset n l =
(* add sub-lists of [l] to [acc] *) (* add sub-lists of [l] to [acc] *)
let rec aux acc l = let rec aux acc l =
let group = take n l in let group = take n l in
if List.length group < n if group=[] then acc (* this was the last group, we are done *)
then ( else if List.length group < n (* last group, with missing elements *)
(* this was the last group *) then match last group with
if drop_short || group=[] then acc else group :: acc | None -> acc
) else ( | Some group' -> group' :: acc
else (
let l' = drop offset l in let l' = drop offset l in
aux (group :: acc) l' (* continue *) aux (group :: acc) l' (* continue *)
) )
@ -556,7 +557,7 @@ let sublists_of_len ?(drop_short=true) ?offset n l =
[[1;2];[3;4]] (subs 2 ~offset:2 [1;2;3;4]) [[1;2];[3;4]] (subs 2 ~offset:2 [1;2;3;4])
[[1;2];[2;3]] (subs 2 ~offset:1 [1;2;3]) [[1;2];[2;3]] (subs 2 ~offset:1 [1;2;3])
[[1;2];[4;5]] (subs 2 ~offset:3 [1;2;3;4;5;6]) [[1;2];[4;5]] (subs 2 ~offset:3 [1;2;3;4;5;6])
[[1;2;3];[4]] (subs 3 ~drop_short:false [1;2;3;4]) [[1;2;3];[4]] (subs 3 ~last:CCOpt.return [1;2;3;4])
*) *)
let take_while p l = let take_while p l =

8
src/core/CCList.mli
View file

@ -96,7 +96,7 @@ val partition_map : ('a -> [<`Left of 'b | `Right of 'c | `Drop]) ->
@since 0.11 *) @since 0.11 *)
val sublists_of_len : val sublists_of_len :
?drop_short:bool -> ?last:('a list -> 'a list option) ->
?offset:int -> ?offset:int ->
int -> int ->
'a list -> 'a list ->
@ -104,11 +104,13 @@ val sublists_of_len :
(** [sublists_of_len n l] returns sub-lists of [l] that have length [n]. (** [sublists_of_len n l] returns sub-lists of [l] that have length [n].
By default, these sub-lists are non overlapping: By default, these sub-lists are non overlapping:
[sublists_of_len 2 [1;2;3;4;5;6]] returns [[1;2]; [3;4]; [5;6]] [sublists_of_len 2 [1;2;3;4;5;6]] returns [[1;2]; [3;4]; [5;6]]
@param drop_short if true, last elements are dropped if they do not
make a long enough list
@param offset the number of elements dropped between two consecutive @param offset the number of elements dropped between two consecutive
sub-lists. By default it is [n]. If [offset < n], the sub-lists sub-lists. By default it is [n]. If [offset < n], the sub-lists
will overlap; if [offset > n], some elements will not appear at all. will overlap; if [offset > n], some elements will not appear at all.
@param last if provided and the last group of elements [g] is such
that [length g < n], [last g] is called. If [last g = Some g'],
[g'] is appended; otherwise [g] is dropped.
If [last = CCOpt.return], it will simply keep the last group.
@raise Invalid_argument if [offset <= 0] or [n <= 0] @raise Invalid_argument if [offset <= 0] or [n <= 0]
@since NEXT_RELEASE *) @since NEXT_RELEASE *)