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+(***********************************************************************)
+(* 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 *)
+(***********************************************************************)
+
+(** Enriched exceptions have an additional field at the end of their usual data
+ containing a pair composed of the distinguishing [token] and the backtrace
+ information. We discriminate the token by pointer equality. *)
+
+module Store = Store.Make(struct end)
+
+type 'a t = 'a Store.field
+
+type info = Store.t
+
+type iexn = exn * info
+
+let make = Store.field
+let add = Store.set
+let get = Store.get
+let null = Store.empty
+
+exception Unique
+
+let dummy = (Unique, Store.empty)
+
+let current : (int * iexn) list ref = ref []
+(** List associating to each thread id the latest exception raised by an
+ instrumented raise (i.e. {!raise} from this module). It is shared between
+ threads, so we must take care of this when modifying it.
+
+ Invariants: all index keys are unique in the list.
+*)
+
+let lock = Mutex.create ()
+
+let rec remove_assoc (i : int) = function
+| [] -> []
+| (j, v) :: rem as l ->
+ if i = j then rem
+ else
+ let ans = remove_assoc i rem in
+ if rem == ans then l
+ else (j, v) :: ans
+
+let rec find_and_remove_assoc (i : int) = function
+| [] -> dummy, []
+| (j, v) :: rem as l ->
+ if i = j then (v, rem)
+ else
+ let (r, ans) = find_and_remove_assoc i rem in
+ if rem == ans then (r, l)
+ else (r, (j, v) :: ans)
+
+let iraise e =
+ let () = Mutex.lock lock in
+ let id = Thread.id (Thread.self ()) in
+ let () = current := (id, e) :: remove_assoc id !current in
+ let () = Mutex.unlock lock in
+ raise (fst e)
+
+let raise ?info e = match info with
+| None ->
+ let () = Mutex.lock lock in
+ let id = Thread.id (Thread.self ()) in
+ let () = current := remove_assoc id !current in
+ let () = Mutex.unlock lock in
+ raise e
+| Some i ->
+ let () = Mutex.lock lock in
+ let id = Thread.id (Thread.self ()) in
+ let () = current := (id, (e, i)) :: remove_assoc id !current in
+ let () = Mutex.unlock lock in
+ raise e
+
+let find_and_remove () =
+ let () = Mutex.lock lock in
+ let id = Thread.id (Thread.self ()) in
+ let (v, l) = find_and_remove_assoc id !current in
+ let () = current := l in
+ let () = Mutex.unlock lock in
+ v
+
+let info e =
+ let (src, data) = find_and_remove () in
+ if src == e then
+ (** Slightly unsound, some exceptions may not be unique up to pointer
+ equality. Though, it should be quite exceptional to be in a situation
+ where the following holds:
+
+ 1. An argument-free exception is raised through the enriched {!raise};
+ 2. It is not captured by any enriched with-clause (which would reset
+ the current data);
+ 3. The same exception is raised through the standard raise, accessing
+ the wrong data.
+ . *)
+ data
+ else
+ (** Mismatch: the raised exception is not the one stored, either because the
+ previous raise was not instrumented, or because something went wrong. *)
+ Store.empty