From 799089659a3302c4435834865b8afdb2f8b6a7aa Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Wed, 21 Oct 2015 14:15:33 +0200
Subject: [PATCH] add `CCVector.find_map`

---
 src/core/CCVector.ml  | 21 ++++++++++++++++++++-
 src/core/CCVector.mli |  5 +++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/src/core/CCVector.ml b/src/core/CCVector.ml
index 2745f2b6..2254a04d 100644
--- a/src/core/CCVector.ml
+++ b/src/core/CCVector.ml
@@ -454,7 +454,9 @@ let find_exn p v =
   let n = v.size in
   let rec check i =
     if i = n then raise Not_found
-    else if p v.vec.(i) then v.vec.(i)
+    else
+      let x = v.vec.(i) in
+      if p x then x
     else check (i+1)
   in check 0
 
@@ -462,6 +464,23 @@ let find p v =
   try Some (find_exn p v)
   with Not_found -> None
 
+let find_map f v =
+  let n = v.size in
+  let rec search i =
+    if i=n then None
+    else match f v.vec.(i) with
+      | None -> search (i+1)
+      | Some _ as res -> res
+  in
+  search 0
+
+(*$Q
+  Q.(list small_int) (fun l -> \
+    let v = of_list l in \
+    let f x = x>30 && x < 35 in \
+    find_map (fun x -> if f x then Some x else None) v = find f v)
+*)
+
 let filter_map f v =
   let v' = create () in
   iter
diff --git a/src/core/CCVector.mli b/src/core/CCVector.mli
index 3c5976f8..26871405 100644
--- a/src/core/CCVector.mli
+++ b/src/core/CCVector.mli
@@ -164,6 +164,11 @@ val find_exn  : ('a -> bool) -> ('a,_) t -> 'a
 (** find an element that satisfies the predicate, or
     @raise Not_found if no element does *)
 
+val find_map : ('a -> 'b option) -> ('a,_) t -> 'b option
+(** [find_map f v] returns the first [Some y = f x] for [x] in [v],
+    or [None] if [f x = None] for each [x] in [v]
+    @since NEXT_RELEASE *)
+
 val filter_map : ('a -> 'b option) -> ('a,_) t -> ('b, 'mut) t
 (** Map elements with a function, possibly filtering some of them out *)