From 9bb280e35321982191c2dce26eaef0ea1b221be6 Mon Sep 17 00:00:00 2001
From: Yotam Barnoy <yotambarnoy@gmail.com>
Date: Mon, 21 Feb 2022 18:42:16 +0200
Subject: [PATCH 1/2] CCVector: add insert

---
 src/core/CCVector.ml  | 18 ++++++++++++++++++
 src/core/CCVector.mli |  6 ++++++
 2 files changed, 24 insertions(+)

diff --git a/src/core/CCVector.ml b/src/core/CCVector.ml
index 719ea85e..40e6198a 100644
--- a/src/core/CCVector.ml
+++ b/src/core/CCVector.ml
@@ -345,6 +345,24 @@ let remove_unordered v i =
     to_list v1 = (List.sort CCInt.compare (to_list v2)))
 *)
 
+let insert v i x =
+  (* Note that we can insert at i=v.size *)
+  if i < 0 || i > v.size then invalid_arg "CCVector.insert";
+  if v.size = Array.length v.vec
+  then grow_with_ v ~filler:x;
+  (* Shift the following elements, then put the element at i *)
+  Array.blit v.vec i v.vec (i+1) (v.size - i);
+  v.vec.(i) <- x;
+  v.size <- v.size + 1
+
+(*$T
+  let v = (1 -- 5) in insert v 3 9; to_list v = [1;2;3;9;4;5]
+  let v = create () in insert v 0 2; to_list v = [2]
+  let v = (1 -- 3) in remove_and_shift v 1; insert v 1 5; to_list v = [1;5;3]
+  let v = (1 -- 3) in remove_and_shift v 0; insert v 2 5; to_list v = [2;3;5]
+  let v = (1 -- 3) in insert v 3 5; to_list v = [1;2;3;5]
+*)
+
 let[@inline] append_iter a i = i (fun x -> push a x)
 
 let append_seq a seq = Seq.iter (fun x -> push a x) seq
diff --git a/src/core/CCVector.mli b/src/core/CCVector.mli
index c631a721..08221d73 100644
--- a/src/core/CCVector.mli
+++ b/src/core/CCVector.mli
@@ -277,6 +277,12 @@ val remove_unordered : ('a, rw) t -> int -> unit
     (might swap with the last element).
     See {!remove_and_shift} if you want to keep the ordering. *)
 
+val insert : ('a, rw) t -> int -> 'a -> unit
+(** [insert v i x] insert the given element at index i.
+    Elements at location [i] and later are first shifted over in linear time before inserting [x].
+    Preserve the order of elements in [v].
+    @since 3.7 *)
+
 val rev : ('a,_) t -> ('a, 'mut) t
 (** Reverse the vector. *)
 

From 408c14fac7076678bad0239915b109aaa666d75b Mon Sep 17 00:00:00 2001
From: Yotam Barnoy <yotambarnoy@gmail.com>
Date: Mon, 21 Feb 2022 18:50:19 +0200
Subject: [PATCH 2/2] CCVector.insert: check if there's a need to blit

Co-authored-by: Simon Cruanes <simon.cruanes.2007@m4x.org>
---
 src/core/CCVector.ml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/core/CCVector.ml b/src/core/CCVector.ml
index 40e6198a..29f9a01c 100644
--- a/src/core/CCVector.ml
+++ b/src/core/CCVector.ml
@@ -351,7 +351,7 @@ let insert v i x =
   if v.size = Array.length v.vec
   then grow_with_ v ~filler:x;
   (* Shift the following elements, then put the element at i *)
-  Array.blit v.vec i v.vec (i+1) (v.size - i);
+  if i < v.size then Array.blit v.vec i v.vec (i+1) (v.size - i);
   v.vec.(i) <- x;
   v.size <- v.size + 1