src/Pure/context.ML

 (*  Title:      Pure/context.ML
     ID:         $Id$
     Author:     Markus Wenzel, TU Muenchen
 
 Generic theory contexts with unique identity, arbitrarily typed data,
-linear and graph development.  Implicit ML theory context.
+graph-based development.  Implicit theory context in ML.
 *)
 
 signature BASIC_CONTEXT =
 sig
   type theory

 end;
 
 signature CONTEXT =
 sig
   include BASIC_CONTEXT
+  exception DATA_FAIL of exn * string
   (*theory context*)
+  val theory_name: theory -> string
   val parents_of: theory -> theory list
   val ancestors_of: theory -> theory list
   val is_stale: theory -> bool
   val ProtoPureN: string
   val PureN: string
   val CPureN: string
   val draftN: string
-  val is_draft: theory -> bool
   val exists_name: string -> theory -> bool
   val names_of: theory -> string list
   val pretty_thy: theory -> Pretty.T
   val string_of_thy: theory -> string
   val pprint_thy: theory -> pprint_args -> unit
   val pretty_abbrev_thy: theory -> Pretty.T
   val str_of_thy: theory -> string
   val check_thy: string -> theory -> theory
   val eq_thy: theory * theory -> bool
   val subthy: theory * theory -> bool
+  val merge: theory * theory -> theory                     (*exception TERM*)
+  val merge_refs: theory_ref * theory_ref -> theory_ref    (*exception TERM*)
   val self_ref: theory -> theory_ref
   val deref: theory_ref -> theory
-  exception DATA_FAIL of exn * string
-  val theory_data: theory -> string list
-  val print_all_data: theory -> unit
   val copy_thy: theory -> theory
   val checkpoint_thy: theory -> theory
-  val pre_pure: theory
-  val merge: theory * theory -> theory                     (*exception TERM*)
-  val merge_refs: theory_ref * theory_ref -> theory_ref    (*exception TERM*)
-  val theory_name: theory -> string
-  val begin_theory: (theory -> Pretty.pp) -> string -> theory list -> theory
-  val end_theory: theory -> theory
-
-  (*ML context*)
+  val finish_thy: theory -> theory
+  val theory_data: theory -> string list
+  val pre_pure_thy: theory
+  val begin_thy: (theory -> Pretty.pp) -> string -> theory list -> theory
+  (*ML theory context*)
   val get_context: unit -> theory option
   val set_context: theory option -> unit
   val reset_context: unit -> unit
   val setmp: theory option -> ('a -> 'b) -> 'a -> 'b
   val pass: theory option -> ('a -> 'b) -> 'a -> 'b * theory option

 signature PRIVATE_CONTEXT =
 sig
   include CONTEXT
   structure TheoryData:
   sig
-    val declare: string -> Object.T -> (Object.T -> Object.T) ->
-      (Object.T -> Object.T) -> (Pretty.pp -> Object.T * Object.T -> Object.T) ->
-      (theory -> Object.T -> unit) -> serial
+    val declare: string -> Object.T -> (Object.T -> Object.T) -> (Object.T -> Object.T) ->
+      (Pretty.pp -> Object.T * Object.T -> Object.T) -> serial
     val init: serial -> theory -> theory
-    val print: serial -> theory -> unit
     val get: serial -> (Object.T -> 'a) -> theory -> 'a
     val put: serial -> ('a -> Object.T) -> 'a -> theory -> theory
-  end;
+  end
 end;
 
 structure Context: PRIVATE_CONTEXT =
 struct
 
 (*** theory context ***)
+
+(** theory data **)
+
+(* data kinds and access methods *)
+
+exception DATA_FAIL of exn * string;
+
+local
+
+type kind =
+ {name: string,
+  empty: Object.T,
+  copy: Object.T -> Object.T,
+  extend: Object.T -> Object.T,
+  merge: Pretty.pp -> Object.T * Object.T -> Object.T};
+
+val kinds = ref (Inttab.empty: kind Inttab.table);
+
+fun invoke meth_name meth_fn k =
+  (case Inttab.lookup (! kinds, k) of
+    SOME kind => meth_fn kind |> transform_failure (fn exn =>
+      DATA_FAIL (exn, "Theory data method " ^ #name kind ^ "." ^ meth_name ^ " failed"))
+  | NONE => sys_error ("Invalid theory data identifier " ^ string_of_int k));
+
+in
+
+fun invoke_name k    = invoke "name" (K o #name) k ();
+fun invoke_empty k   = invoke "empty" (K o #empty) k ();
+val invoke_copy      = invoke "copy" #copy;
+val invoke_extend    = invoke "extend" #extend;
+fun invoke_merge pp  = invoke "merge" (fn kind => #merge kind pp);
+
+fun declare_theory_data name e cp ext mrg =
+  let
+    val k = serial ();
+    val kind = {name = name, empty = e, copy = cp, extend = ext, merge = mrg};
+    val _ = conditional (Inttab.exists (equal name o #name o #2) (! kinds)) (fn () =>
+      warning ("Duplicate declaration of theory data " ^ quote name));
+    val _ = kinds := Inttab.update ((k, kind), ! kinds);
+  in k end;
+
+val copy_data = Inttab.map' invoke_copy;
+val extend_data = Inttab.map' invoke_extend;
+fun merge_data pp = Inttab.join (SOME oo invoke_merge pp) o pairself extend_data;
+
+end;
+
+
+
+(** datatype theory **)
 
 datatype theory =
   Theory of
   (*identity*)
-   {self: theory ref option,
-    id: serial * string,
-    ids: string Inttab.table} *
+   {self: theory ref option,            (*dynamic self reference -- follows theory changes*)
+    id: serial * string,                (*identifier of this theory*)
+    ids: string Inttab.table,           (*identifiers of ancestors*)
+    iids: string Inttab.table} *        (*identifiers of intermediate checkpoints*)
   (*data*)
-  Object.T Inttab.table *
+  Object.T Inttab.table *               (*record of arbitrarily typed data*)
+  (*ancestry of graph development*)
+   {parents: theory list,               (*immediate predecessors*)
+    ancestors: theory list} *           (*all predecessors*)
   (*history of linear development*)
-   {name: string,
-    version: int,
-    intermediates: theory list} *
-  (*ancestry of graph development*)
-   {parents: theory list,
-    ancestors: theory list};
+   {name: string,                       (*prospective name of finished theory*)
+    version: int,                       (*checkpoint counter*)
+    intermediates: theory list};        (*intermediate checkpoints*)
 
 exception THEORY of string * theory list;
 
 fun rep_theory (Theory args) = args;
 
 val identity_of = #1 o rep_theory;
 val data_of     = #2 o rep_theory;
-val history_of  = #3 o rep_theory;
-val ancestry_of = #4 o rep_theory;
-
-fun make_identity self id ids = {self = self, id = id, ids = ids};
+val ancestry_of = #3 o rep_theory;
+val history_of  = #4 o rep_theory;
+
+fun make_identity self id ids iids = {self = self, id = id, ids = ids, iids = iids};
+fun make_ancestry parents ancestors = {parents = parents, ancestors = ancestors};
 fun make_history name vers ints = {name = name, version = vers, intermediates = ints};
-fun make_ancestry parents ancestors = {parents = parents, ancestors = ancestors};
 
 val parents_of = #parents o ancestry_of;
 val ancestors_of = #ancestors o ancestry_of;
-
-
-
-(** theory identity **)
+val theory_name = #name o history_of;
+
 
 (* staleness *)
 
 fun eq_id ((i: int, _), (j, _)) = i = j;
 

     (Theory ({self = SOME (ref (Theory ({id = id', ...}, _, _, _))), id, ...}, _, _, _)) =
       not (eq_id (id, id'))
   | is_stale (Theory ({self = NONE, ...}, _, _, _)) = true;
 
 fun vitalize (thy as Theory ({self = SOME r, ...}, _, _, _)) = (r := thy; thy)
-  | vitalize (thy as Theory ({self = NONE, id, ids}, data, history, ancestry)) =
+  | vitalize (thy as Theory ({self = NONE, id, ids, iids}, data, ancestry, history)) =
       let
         val r = ref thy;
-        val thy' = Theory (make_identity (SOME r) id ids, data, history, ancestry);
+        val thy' = Theory (make_identity (SOME r) id ids iids, data, ancestry, history);
       in r := thy'; thy' end;
 
 
 (* names *)
 

 
 val draftN = "#";
 fun draft_id (_, name) = (name = draftN);
 val is_draft = draft_id o #id o identity_of;
 
-fun exists_name name (Theory ({id, ids, ...}, _, _, _)) =
-  name = #2 id orelse Inttab.exists (equal name o #2) ids;
-
-fun names_of (Theory ({id, ids, ...}, _, _, _)) =
-  map #2 (Inttab.dest ids @ [id]);
+fun exists_name name (Theory ({id, ids, iids, ...}, _, _, _)) =
+  name = #2 id orelse
+  Inttab.exists (equal name o #2) ids orelse
+  Inttab.exists (equal name o #2) iids;
+
+fun names_of (Theory ({id, ids, iids, ...}, _, _, _)) =
+  rev (#2 id :: Inttab.fold (cons o #2) iids (Inttab.fold (cons o #2) ids []));
 
 fun pretty_thy thy =
   Pretty.str_list "{" "}" (names_of thy @ (if is_stale thy then ["!"] else []));
 
 val string_of_thy = Pretty.string_of o pretty_thy;

 
 (* consistency *)
 
 fun check_thy pos thy =
   if is_stale thy then
-    raise TERM ("Stale theory encountered (see " ^ pos ^ "):\n" ^ string_of_thy thy, [])
+    raise TERM ("Stale theory encountered (in " ^ pos ^ "):\n" ^ string_of_thy thy, [])
   else thy;
 
-fun check_insert id ids =
+fun check_ins id ids =
   if draft_id id orelse is_some (Inttab.lookup (ids, #1 id)) then ids
   else if Inttab.exists (equal (#2 id) o #2) ids then
     raise TERM ("Different versions of theory component " ^ quote (#2 id), [])
   else Inttab.update (id, ids);
 
-fun check_merge thy1 thy2 =
-  let
-    val {id = id1, ids = ids1, ...} = identity_of thy1;
-    val {id = id2, ids = ids2, ...} = identity_of thy2;
-  in check_insert id2 (Inttab.fold check_insert ids2 (check_insert id1 ids1)) end;
-
-
-(* equality and inclusion *)
+fun check_insert intermediate id (ids, iids) =
+  let val ids' = check_ins id ids and iids' = check_ins id iids
+  in if intermediate then (ids, iids') else (ids', iids) end;
+
+fun check_merge
+    (Theory ({id = id1, ids = ids1, iids = iids1, ...}, _, _, history1))
+    (Theory ({id = id2, ids = ids2, iids = iids2, ...}, _, _, history2)) =
+  (Inttab.fold check_ins ids2 ids1, Inttab.fold check_ins iids2 iids1)
+  |> check_insert (#version history1 > 0) id1
+  |> check_insert (#version history2 > 0) id2;
+
+
+(* theory references *)
+
+(*theory_ref provides a safe way to store dynamic references to a
+  theory -- a plain theory value would become stale as the self
+  reference moves on*)
+
+datatype theory_ref = TheoryRef of theory ref;
+
+val self_ref = TheoryRef o the o #self o identity_of o check_thy "Context.self_ref";
+fun deref (TheoryRef (ref thy)) = thy;
+
+
+(* equality and inclusion *)  (* FIXME proper_subthy; no subthy_internal *)
 
 local
 
-fun exists_ids (Theory ({id, ids, ...}, _, _, _)) (i, _) =
-  i = #1 id orelse is_some (Inttab.lookup (ids, i));
+fun exists_ids (Theory ({id, ids, iids, ...}, _, _, _)) (i, _) =
+  i = #1 id orelse
+  is_some (Inttab.lookup (ids, i)) orelse
+  is_some (Inttab.lookup (iids, i));
 
 fun member_ids (Theory ({id, ...}, _, _, _), thy) = exists_ids thy id;
 
-fun subset_ids (Theory ({id, ids, ...}, _, _, _), thy) =
-  exists_ids thy id andalso Inttab.forall (exists_ids thy) ids;
+fun subset_ids (Theory ({id, ids, iids, ...}, _, _, _), thy) =
+  exists_ids thy id andalso
+  Inttab.forall (exists_ids thy) ids andalso
+  Inttab.forall (exists_ids thy) iids;
 
 in
 
 val eq_thy = eq_id o pairself (#id o identity_of o check_thy "Context.eq_thy");
 fun subthy thys = eq_thy thys orelse member_ids thys;
 fun subthy_internal thys = eq_thy thys orelse subset_ids thys;
 
 end;
-
-
-(* external references *)
-
-datatype theory_ref = TheoryRef of theory ref;
-
-val self_ref = TheoryRef o the o #self o identity_of o check_thy "Context.self_ref";
-fun deref (TheoryRef (ref thy)) = thy;
-
-
-
-(** theory data **)
-
-(* data kinds and access methods *)
-
-exception DATA_FAIL of exn * string;
-
-local
-
-type kind =
- {name: string,
-  empty: Object.T,
-  copy: Object.T -> Object.T,
-  extend: Object.T -> Object.T,
-  merge: Pretty.pp -> Object.T * Object.T -> Object.T,
-  print: theory -> Object.T -> unit};
-
-val kinds = ref (Inttab.empty: kind Inttab.table);
-
-fun invoke meth_name meth_fn k =
-  (case Inttab.lookup (! kinds, k) of
-    SOME kind => meth_fn kind |> transform_failure (fn exn =>
-      DATA_FAIL (exn, "Theory data method " ^ #name kind ^ "." ^ meth_name ^ " failed"))
-  | NONE => sys_error ("Invalid theory data identifier " ^ string_of_int k));
-
-in
-
-fun invoke_name k    = invoke "name" (K o #name) k ();
-fun invoke_empty k   = invoke "empty" (K o #empty) k ();
-val invoke_copy      = invoke "copy" #copy;
-val invoke_extend    = invoke "extend" #extend;
-fun invoke_merge pp  = invoke "merge" (fn kind => #merge kind pp);
-fun invoke_print thy = invoke "print" (fn kind => #print kind thy);
-
-fun declare name e cp ext mrg prt =
-  let
-    val k = serial ();
-    val kind = {name = name, empty = e, copy = cp, extend = ext, merge = mrg, print = prt};
-    val _ = conditional (Inttab.exists (equal name o #name o #2) (! kinds)) (fn () =>
-      warning ("Duplicate declaration of theory data " ^ quote name));
-    val _ = kinds := Inttab.update ((k, kind), ! kinds);
-  in k end;
-
-val copy_data = Inttab.map' invoke_copy;
-val extend_data = Inttab.map' invoke_extend;
-fun merge_data pp = Inttab.join (SOME oo invoke_merge pp) o pairself extend_data;
-
-fun theory_data thy =
-  map invoke_name (Inttab.keys (data_of thy))
-  |> map (rpair ()) |> Symtab.make_multi |> Symtab.dest
-  |> map (apsnd length)
-  |> map (fn (name, 1) => name | (name, n) => name ^ enclose "[" "]" (string_of_int n));
-
-fun print_all_data thy =
-  List.app (uncurry (invoke_print thy)) (Inttab.dest (data_of thy));
-
-end;
-
-
-
-(** build theories **)
-
-(* primitives *)
-
-fun create_thy name self id ids data history ancestry =
-  let
-    val ids' = check_insert id ids;
-    val id' = (serial (), name);
-    val _ = check_insert id' ids';
-    val identity' = make_identity self id' ids';
-  in vitalize (Theory (identity', data, history, ancestry)) end;
-
-fun copy_thy (thy as Theory ({id, ids, ...}, data, history, ancestry)) =
-  let val _ = check_thy "Context.copy_thy" thy;
-  in create_thy draftN NONE id ids (copy_data data) history ancestry end;
-
-fun change_thy name f (thy as Theory ({self, id, ids}, data, history, ancestry)) =
-  let
-    val _ = check_thy "Context.change_thy" thy;
-    val (self', data', ancestry') =
-      if is_draft thy then (self, data, ancestry)
-      else (NONE, extend_data data, make_ancestry [thy] (thy :: #ancestors ancestry));
-  in create_thy name self' id ids (f data') history ancestry' end;
-
-fun name_thy name = change_thy name I;
-val map_thy = change_thy draftN;
-val extend_thy = map_thy I;
-
-fun checkpoint_thy thy =
-  if not (is_draft thy) then thy
-  else
-    let
-      val {name, version, intermediates} = history_of thy;
-      val thy' as Theory (identity', data', _, ancestry') =
-        name_thy (name ^ ":" ^ string_of_int version) thy;
-      val history' = make_history name (version + 1) (thy' :: intermediates);
-    in vitalize (Theory (identity', data', history', ancestry')) end;
-
-
-(* theory data *)
-
-structure TheoryData =
-struct
-
-val declare = declare;
-
-fun get k dest thy =
-  (case Inttab.lookup (data_of thy, k) of
-    SOME x => (dest x handle Match =>
-      error ("Failed to access theory data " ^ quote (invoke_name k)))
-  | NONE => error ("Uninitialized theory data " ^ quote (invoke_name k)));
-
-fun print k thy = invoke_print thy k (get k I thy);
-fun put k mk x = map_thy (curry Inttab.update (k, mk x));
-fun init k = put k I (invoke_empty k);
-
-end;
-
-
-(* pre_pure *)
-
-val pre_pure = create_thy draftN NONE (serial (), draftN) Inttab.empty
-  Inttab.empty (make_history ProtoPureN 0 []) (make_ancestry [] []);
 
 
 (* trivial merge *)
 
 fun merge (thy1, thy2) =

       str_of_thy thy1, str_of_thy thy2], []));
 
 fun merge_refs (ref1, ref2) = self_ref (merge (deref ref1, deref ref2));
 
 
-(* non-trivial merge *)
-
-fun merge_internal pp (thy1, thy2) =
+
+(** build theories **)
+
+(* primitives *)
+
+fun create_thy name self id ids iids data ancestry history =
+  let
+    val intermediate = #version history > 0;
+    val (ids', iids') = check_insert intermediate id (ids, iids);
+    val id' = (serial (), name);
+    val _ = check_insert intermediate id' (ids', iids');
+    val identity' = make_identity self id' ids' iids';
+  in vitalize (Theory (identity', data, ancestry, history)) end;
+
+fun change_thy name f (thy as Theory ({self, id, ids, iids}, data, ancestry, history)) =
+  let
+    val _ = check_thy "Context.change_thy" thy;
+    val (self', data', ancestry') =
+      if is_draft thy then (self, data, ancestry)    (*destructive change!*)
+      else if #version history > 0
+      then (NONE, copy_data data, ancestry)
+      else (NONE, extend_data data, make_ancestry [thy] (thy :: #ancestors ancestry));
+    val data'' = f data';
+  in create_thy name self' id ids iids data'' ancestry' history end;
+
+fun name_thy name = change_thy name I;
+val modify_thy = change_thy draftN;
+val extend_thy = modify_thy I;
+
+fun copy_thy (thy as Theory ({id, ids, iids, ...}, data, ancestry, history)) =
+  (check_thy "Context.copy_thy" thy;
+    create_thy draftN NONE id ids iids (copy_data data) ancestry history);
+
+val pre_pure_thy = create_thy draftN NONE (serial (), draftN) Inttab.empty Inttab.empty
+  Inttab.empty (make_ancestry [] []) (make_history ProtoPureN 0 []);
+
+
+(* named theory nodes *)
+
+fun merge_thys pp (thy1, thy2) =
   if subthy_internal (thy2, thy1) then thy1
   else if subthy_internal (thy1, thy2) then thy2
   else if exists_name CPureN thy1 <> exists_name CPureN thy2 then
     error "Cannot merge Pure and CPure developments"
   else
     let
-      val ids = check_merge thy1 thy2;
+      val (ids, iids) = check_merge thy1 thy2;
       val data = merge_data (pp thy1) (data_of thy1, data_of thy2);
+      val ancestry = make_ancestry [] [];
       val history = make_history "" 0 [];
-      val ancestry = make_ancestry [] [];
-    in create_thy draftN NONE (serial (), draftN) ids data history ancestry end;
-
-
-(* named theory nodes *)
-
-val theory_name = #name o history_of;
-
-fun begin_theory pp name imports =
-  if name = draftN then
-    error ("Illegal theory name: " ^ quote draftN)
-  else if exists is_draft imports then
-    error "Attempt to import draft theories"
+    in create_thy draftN NONE (serial (), draftN) ids iids data ancestry history end;
+
+fun begin_thy pp name imports =
+  if name = draftN then error ("Illegal theory name: " ^ quote draftN)
   else
     let
-      val parents = gen_distinct eq_thy imports;
+      val parents = gen_distinct eq_thy imports;  (* FIXME maximals *)
       val ancestors = gen_distinct eq_thy (parents @ List.concat (map ancestors_of parents));
-      val Theory ({id, ids, ...}, data, _, _) =
+      val Theory ({id, ids, iids, ...}, data, _, _) =
         (case parents of
           [] => error "No parent theories"
-        | thy :: thys => extend_thy (Library.foldl (merge_internal pp) (thy, thys)));
+        | thy :: thys => extend_thy (Library.foldl (merge_thys pp) (thy, thys)));
+      val ancestry = make_ancestry parents ancestors;
       val history = make_history name 0 [];
-      val ancestry = make_ancestry parents ancestors;
-    in create_thy draftN NONE id ids data history ancestry end;
-
-fun end_theory thy =
-  thy
-(*|> purge_thy  FIXME *)
-  |> name_thy (theory_name thy);
-
-
-
-
-(*** ML theory context ***)
+    in create_thy draftN NONE id ids iids data ancestry history end;
+
+
+(* undoable checkpoints *)
+
+fun checkpoint_thy thy =
+  if not (is_draft thy) then thy
+  else
+    let
+      val {name, version, intermediates} = history_of thy;
+      val thy' as Theory (identity', data', ancestry', _) =
+        name_thy (name ^ ":" ^ string_of_int version) thy;
+      val history' = make_history name (version + 1) (thy' :: intermediates);
+    in vitalize (Theory (identity', data', ancestry', history')) end;
+
+fun finish_thy thy =
+  let
+    val {name, version, intermediates} = history_of thy;
+    val rs = map (the o #self o identity_of o check_thy "Context.finish_thy") intermediates;
+    val thy' as Theory ({self, id, ids, ...}, data', ancestry', _) = name_thy name thy;
+    val identity' = make_identity self id ids Inttab.empty;
+    val history' = make_history name 0 [];
+    val thy'' = vitalize (Theory (identity', data', ancestry', history'));
+  in List.app (fn r => r := thy'') rs; thy'' end;
+
+
+(* theory data *)
+
+fun theory_data thy =
+  map invoke_name (Inttab.keys (data_of thy))
+  |> map (rpair ()) |> Symtab.make_multi |> Symtab.dest
+  |> map (apsnd length)
+  |> map (fn (name, 1) => name | (name, n) => name ^ enclose "[" "]" (string_of_int n));
+
+structure TheoryData =
+struct
+
+val declare = declare_theory_data;
+
+fun get k dest thy =
+  (case Inttab.lookup (data_of thy, k) of
+    SOME x => (dest x handle Match =>
+      error ("Failed to access theory data " ^ quote (invoke_name k)))
+  | NONE => error ("Uninitialized theory data " ^ quote (invoke_name k)));
+
+fun put k mk x = modify_thy (curry Inttab.update (k, mk x));
+fun init k = put k I (invoke_empty k);
+
+end;
+
+
+
+(** ML theory context **)
 
 local
   val current_theory = ref (NONE: theory option);
 in
   fun get_context () = ! current_theory;

 sig
   type T
   val init: theory -> theory
   val print: theory -> unit
   val get: theory -> T
+  val get_sg: theory -> T    (*obsolete*)
   val put: T -> theory -> theory
   val map: (T -> T) -> theory -> theory
 end;
 
 functor TheoryDataFun(Data: THEORY_DATA_ARGS): THEORY_DATA =

 
 val kind = TheoryData.declare Data.name
   (Data Data.empty)
   (fn Data x => Data (Data.copy x))
   (fn Data x => Data (Data.extend x))
-  (fn pp => fn (Data x1, Data x2) => Data (Data.merge pp (x1, x2)))
-  (fn thy => fn Data x => Data.print thy x);
+  (fn pp => fn (Data x1, Data x2) => Data (Data.merge pp (x1, x2)));
 
 val init = TheoryData.init kind;
-val print = TheoryData.print kind;
 val get = TheoryData.get kind (fn Data x => x);
-val get_sg = get;    (*obsolete*)
+val get_sg = get;
+fun print thy = Data.print thy (get thy);
 val put = TheoryData.put kind Data;
 fun map f thy = put (f (get thy)) thy;
 
 end;