From 6a5b186d2b53cf2c3e3a7ed5c238d26367a9df96 Mon Sep 17 00:00:00 2001
From: gareuselesinge
Date: Fri, 30 Aug 2013 12:20:10 +0000
Subject: recdef: restore old semantics (pre STM)

The Stm commit switched from an home made handling of failures to
a with_state_protection.  This was wrong, since in case of success
the global state has to be left altered.

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16746 85f007b7-540e-0410-9357-904b9bb8a0f7
---
 lib/future.ml  | 5 +++++
 lib/future.mli | 2 ++
 2 files changed, 7 insertions(+)

(limited to 'lib')

diff --git a/lib/future.ml b/lib/future.ml
index 1e9cada513..d8f7b3a947 100644
--- a/lib/future.ml
+++ b/lib/future.ml
@@ -111,6 +111,11 @@ let purify f x =
     v
   with e -> let e = Errors.push e in !unfreeze state; raise e
 
+let transactify f x =
+  let state = !freeze () in
+  try f x
+  with e -> let e = Errors.push e in !unfreeze state; raise e
+
 let purify_future f x =
   match !x with
   | Val _ | Exn _ | Delegated | Dropped -> f x
diff --git a/lib/future.mli b/lib/future.mli
index 39be0c1806..f07d325e03 100644
--- a/lib/future.mli
+++ b/lib/future.mli
@@ -59,4 +59,6 @@ val set_freeze : (unit -> Dyn.t) -> (Dyn.t -> unit) -> unit
 
 (* Once set_freeze is called we can purify a computation *)
 val purify : ('a -> 'b) -> 'a -> 'b
+(* And also let a function alter the state but backtrack if it raises exn *)
+val transactify : ('a -> 'b) -> 'a -> 'b
 
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