+(* Copyright (C) 2004, HELM Team.
+ *
+ * This file is part of HELM, an Hypertextual, Electronic
+ * Library of Mathematics, developed at the Computer Science
+ * Department, University of Bologna, Italy.
+ *
+ * HELM is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * HELM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with HELM; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ *
+ * For details, see the HELM World-Wide-Web page,
+ * http://helm.cs.unibo.it/
+ *)
+
+(** Stateful handling of proof status *)
+
+exception No_goal_left
+exception Uri_redefinition
+
+ (** can't undo/redo one or more actions *)
+exception History_failure
+
+type event = [ `Proof_changed | `Proof_completed ]
+
+ (** Proof observer. First callback argument is Some extended_status
+ * when a 'real 'change of the proof happened and None when Proof_changed event
+ * was triggered by a time travel by the means of undo/redo actions. Embedded
+ * status is the status _before_ the current change. Second status is the
+ * status reached _after_ the current change. *)
+type 'a observer =
+ (ProofEngineTypes.status * 'a) option -> (ProofEngineTypes.status * 'a) ->
+ unit
+
+ (** needed to detach previously attached observers *)
+type observer_id
+
+ (** tactic application failed. @see apply_tactic *)
+exception Tactic_failure of exn
+
+ (** one or more observers failed. @see apply_tactic *)
+exception Observer_failures of (observer_id * exn) list
+
+ (** failure while updating internal data (: 'a). @see apply_tactic *)
+exception Data_failure of exn
+
+(** {2 OO interface} *)
+
+class ['a] status:
+ ?uri:UriManager.uri ->
+ typ:Cic.term -> ?body:Cic.term -> ?metasenv:Cic.metasenv ->
+ (ProofEngineTypes.proof * ProofEngineTypes.goal option -> 'a) ->
+ (ProofEngineTypes.status * 'a -> ProofEngineTypes.status -> 'a) ->
+ unit ->
+ object
+
+ method proof: ProofEngineTypes.proof
+ method metasenv: Cic.metasenv
+ method body: Cic.term
+ method typ: Cic.term
+
+ (** goal -> conjecture
+ * @raise CicUtil.Meta_not_found *)
+ method conjecture: int -> Cic.conjecture
+
+ method proof_completed: bool
+ method goal: int (** @raise No_goal_left *)
+ method set_goal: int -> unit (** @raise No_goal_left *)
+
+ method uri: UriManager.uri option
+ method set_uri: UriManager.uri -> unit (** @raise Uri_redefinition *)
+
+ (** @raise Tactic_failure
+ * @raise Observer_failures
+ * @raise Data_failure
+ *
+ * In case of tactic failure, internal status is left unchanged.
+ * In case of observer failures internal status will be changed and is
+ * granted that all observer will be invoked collecting their failures.
+ * In case of data failure, internal status is left unchanged (rolling back
+ * last tactic application if needed)
+ *)
+ method apply_tactic: ProofEngineTypes.tactic -> unit
+
+ method undo: ?steps:int -> unit -> unit
+ method redo: ?steps:int -> unit -> unit
+
+ method attach_observer:
+ ?interested_in:(event list) -> 'a observer -> observer_id
+
+ method detach_observer: observer_id -> unit
+
+ end
+
+val trivial_status:
+ ?uri:UriManager.uri ->
+ typ:Cic.term -> ?body:Cic.term -> ?metasenv:Cic.metasenv ->
+ unit ->
+ unit status
+