From 2dc830735ecb42fb5840534afe2453e026238411 Mon Sep 17 00:00:00 2001
From: Jules Villard <jul@fb.com>
Date: Tue, 28 Jul 2020 03:51:36 -0700
Subject: [PATCH] [istd] refactor of ImperativeUnionFind to expose [find_opt]
 later

Summary: I think this does the same thing as before.

Reviewed By: skcho

Differential Revision: D22576002

fbshipit-source-id: 8317dd82e
---
 infer/src/istd/ImperativeUnionFind.ml | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/infer/src/istd/ImperativeUnionFind.ml b/infer/src/istd/ImperativeUnionFind.ml
index 24d475472..7a478e921 100644
--- a/infer/src/istd/ImperativeUnionFind.ml
+++ b/infer/src/istd/ImperativeUnionFind.ml
@@ -57,15 +57,18 @@ module Make (Set : Set) = struct
 
     let is_a_repr (t : t) e = not (H.mem t e)
 
-    let rec find (t : t) e : Repr.t =
-      match H.find_opt t e with
-      | None ->
-          Repr.of_elt e
-      | Some r ->
-          let r' = find t (r :> Set.elt) in
-          if not (phys_equal r r') then H.replace t e r' ;
-          r'
-
+    let rec find_opt (t : t) e : Repr.t option =
+      H.find_opt t e
+      |> Option.map ~f:(fun (r : Repr.t) ->
+             match find_opt t (r :> Set.elt) with
+             | None ->
+                 r
+             | Some r' ->
+                 if not (phys_equal r r') then H.replace t e r' ;
+                 r' )
+
+
+    let find (t : t) e : Repr.t = match find_opt t e with Some r -> r | None -> Repr.of_elt e
 
     let merge (t : t) ~(from : Repr.t) ~(to_ : Repr.t) = H.replace t (from :> Set.elt) to_
   end