From 9043add656177eeac1491a73d2f3ab92bec0013c Mon Sep 17 00:00:00 2001
From: Benjamin Barenblat <bbaren@debian.org>
Date: Sat, 29 Dec 2018 14:31:27 -0500
Subject: Imported Upstream version 8.8.2

---
 lib/util.ml | 49 +++++++++++++++++++++++++++++++++----------------
 1 file changed, 33 insertions(+), 16 deletions(-)

(limited to 'lib/util.ml')

diff --git a/lib/util.ml b/lib/util.ml
index 009dfbe1..7d7d380b 100644
--- a/lib/util.ml
+++ b/lib/util.ml
@@ -1,10 +1,12 @@
-(***********************************************************************)
-(*  v      *   The Coq Proof Assistant  /  The Coq Development Team    *)
-(* <O___,, *        INRIA-Rocquencourt  &  LRI-CNRS-Orsay              *)
-(*   \VV/  *************************************************************)
-(*    //   *      This file is distributed under the terms of the      *)
-(*         *       GNU Lesser General Public License Version 2.1       *)
-(***********************************************************************)
+(************************************************************************)
+(*         *   The Coq Proof Assistant / The Coq Development Team       *)
+(*  v      *   INRIA, CNRS and contributors - Copyright 1999-2018       *)
+(* <O___,, *       (see CREDITS file for the list of authors)           *)
+(*   \VV/  **************************************************************)
+(*    //   *    This file is distributed under the terms of the         *)
+(*         *     GNU Lesser General Public License Version 2.1          *)
+(*         *     (see LICENSE file for the text of the license)         *)
+(************************************************************************)
 
 (* Mapping under pairs *)
 
@@ -87,13 +89,17 @@ let matrix_transpose mat =
 
 let identity x = x
 
-(** Function composition: the mathematical [∘] operator.
+(** Left-to-right function composition:
+    
+    [f1 %> f2] is [fun x -> f2 (f1 x)].
 
-    So [g % f] is a synonym for [fun x -> g (f x)].
+    [f1 %> f2 %> f3] is [fun x -> f3 (f2 (f1 x))].
 
-    Also because [%] is right-associative, [h % g % f] means [fun x -> h (g (f x))].
- *)
-let (%) f g x = f (g x)
+    [f1 %> f2 %> f3 %> f4] is [fun x -> f4 (f3 (f2 (f1 x)))]
+
+    etc.
+*)
+let (%>) f g x = g (f x)
 
 let const x _ = x
 
@@ -132,6 +138,8 @@ type ('a, 'b) union = ('a, 'b) CSig.union = Inl of 'a | Inr of 'b
 type 'a until = 'a CSig.until = Stop of 'a | Cont of 'a
 type ('a, 'b) eq = ('a, 'b) CSig.eq = Refl : ('a, 'a) eq
 
+let sym : type a b. (a, b) eq -> (b, a) eq = fun Refl -> Refl
+
 module Union =
 struct
   let map f g = function
@@ -157,11 +165,20 @@ let iraise = Exninfo.iraise
 
 let open_utf8_file_in fname =
   let is_bom s =
-    Int.equal (Char.code s.[0]) 0xEF &&
-    Int.equal (Char.code s.[1]) 0xBB &&
-    Int.equal (Char.code s.[2]) 0xBF
+    Int.equal (Char.code (Bytes.get s 0)) 0xEF &&
+    Int.equal (Char.code (Bytes.get s 1)) 0xBB &&
+    Int.equal (Char.code (Bytes.get s 2)) 0xBF
   in
   let in_chan = open_in fname in
-  let s = "   " in
+  let s = Bytes.make 3 ' ' in
   if input in_chan s 0 3 < 3 || not (is_bom s) then seek_in in_chan 0;
   in_chan
+
+(** A trick which can typically be used to store on the fly the
+   computation of values in the "when" clause of a "match" then
+   retrieve the evaluated result in the r.h.s of the clause *)
+
+let set_temporary_memory () =
+  let a = ref None in
+  (fun x -> assert (!a = None); a := Some x; x),
+  (fun () -> match !a with Some x -> x | None -> assert false)
-- 
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