From d5c9c90b9760bd51136f0ccbb041f8697ad0a081 Mon Sep 17 00:00:00 2001
From: Théo Zimmermann
Date: Sat, 21 Jul 2018 20:25:27 +0200
Subject: Add support for focusing on named goals using brackets.

---
 clib/cList.ml  | 3 +++
 clib/cList.mli | 4 ++++
 2 files changed, 7 insertions(+)

(limited to 'clib')

diff --git a/clib/cList.ml b/clib/cList.ml
index de42886dcb..dc59ff2970 100644
--- a/clib/cList.ml
+++ b/clib/cList.ml
@@ -60,6 +60,7 @@ sig
   val extend : bool list -> 'a -> 'a list -> 'a list
   val count : ('a -> bool) -> 'a list -> int
   val index : 'a eq -> 'a -> 'a list -> int
+  val safe_index : 'a eq -> 'a -> 'a list -> int option
   val index0 : 'a eq -> 'a -> 'a list -> int
   val fold_left_until : ('c -> 'a -> 'c CSig.until) -> 'c -> 'a list -> 'c
   val fold_right_i :  (int -> 'a -> 'b -> 'b) -> int -> 'a list -> 'b -> 'b
@@ -538,6 +539,8 @@ let rec index_f f x l n = match l with
 
 let index f x l = index_f f x l 1
 
+let safe_index f x l = try Some (index f x l) with Not_found -> None
+
 let index0 f x l = index_f f x l 0
 
 (** {6 Folding} *)
diff --git a/clib/cList.mli b/clib/cList.mli
index 42fae5ed39..ed468cb977 100644
--- a/clib/cList.mli
+++ b/clib/cList.mli
@@ -155,6 +155,10 @@ sig
   val index : 'a eq -> 'a -> 'a list -> int
   (** [index] returns the 1st index of an element in a list (counting from 1). *)
 
+  val safe_index : 'a eq -> 'a -> 'a list -> int option
+  (** [safe_index] returns the 1st index of an element in a list (counting from 1)
+      and None otherwise. *)
+
   val index0 : 'a eq -> 'a -> 'a list -> int
   (** [index0] behaves as [index] except that it starts counting at 0. *)
 
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