From bc4089316632cb11f0ae7a07559c92b94cf16e75 Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Wed, 11 Jun 2014 21:54:01 +0200
Subject: [PATCH] CCList.filter

---
 core/CCList.ml  | 13 +++++++++++++
 core/CCList.mli |  3 +++
 2 files changed, 16 insertions(+)

diff --git a/core/CCList.ml b/core/CCList.ml
index f6eac495..1eb68c32 100644
--- a/core/CCList.ml
+++ b/core/CCList.ml
@@ -61,6 +61,19 @@ let append l1 l2 =
 
 let (@) = append
 
+let filter p l =
+  let rec direct i p l = match l with
+    | [] -> []
+    | _ when i=0 -> safe p l []
+    | x::l' when not (p x) -> direct i p l'
+    | x::l' -> x :: direct (i-1) p l'
+  and safe p l acc = match l with
+    | [] -> List.rev acc
+    | x::l' when not (p x) -> safe p l' acc
+    | x::l' -> safe p l' (x::acc)
+  in
+  direct _direct_depth p l
+
 let fold_right f l acc =
   let rec direct i f l acc = match l with
     | [] -> acc
diff --git a/core/CCList.mli b/core/CCList.mli
index f06284f1..0d0901c5 100644
--- a/core/CCList.mli
+++ b/core/CCList.mli
@@ -36,6 +36,9 @@ val append : 'a t -> 'a t -> 'a t
 
 val (@) : 'a t -> 'a t -> 'a t
 
+val filter : ('a -> bool) -> 'a t -> 'a t
+(** Safe version of {!List.filter} *)
+
 val fold_right : ('a -> 'b -> 'b) -> 'a t -> 'b -> 'b
 (** Safe version of [fold_right] *)