From e9b9ed1d9252edcbd9bf531a850f2f9a65bfdd00 Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Fri, 22 Sep 2017 17:52:24 +0200
Subject: [PATCH] add `CCRef.swap`

---
 src/core/CCRef.ml  | 5 +++++
 src/core/CCRef.mli | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/src/core/CCRef.ml b/src/core/CCRef.ml
index 5fb260b0..44eab344 100644
--- a/src/core/CCRef.ml
+++ b/src/core/CCRef.ml
@@ -32,6 +32,11 @@ let compare f r1 r2 = f !r1 !r2
 
 let equal f r1 r2 = f !r1 !r2
 
+let swap a b =
+  let x = !a in
+  a := !b;
+  b := x
+
 let to_list r = [!r]
 let to_seq r yield = yield !r
 
diff --git a/src/core/CCRef.mli b/src/core/CCRef.mli
index 4a488600..ed7fc05a 100644
--- a/src/core/CCRef.mli
+++ b/src/core/CCRef.mli
@@ -31,6 +31,10 @@ val get_then_incr : int t -> int
 (** [get_then_incr r] increments [r] and returns its old value, think [r++]
     @since 0.17 *)
 
+val swap : 'a t -> 'a t -> unit
+(** Swap values.
+    @since NEXT_RELEASE *)
+
 val compare : 'a ord -> 'a t ord
 
 val equal : 'a eq -> 'a t eq