wenzelm@38150: (*  Title:      Pure/PIDE/document.ML
wenzelm@38150:     Author:     Makarius
wenzelm@38150: 
wenzelm@38150: Document as collection of named nodes, each consisting of an editable
wenzelm@38418: list of commands, associated with asynchronous execution process.
wenzelm@38150: *)
wenzelm@38150: 
wenzelm@38150: signature DOCUMENT =
wenzelm@38150: sig
wenzelm@38363:   type id = int
wenzelm@38373:   type version_id = id
wenzelm@38363:   type command_id = id
wenzelm@38373:   type exec_id = id
wenzelm@38363:   val no_id: id
wenzelm@38419:   val new_id: unit -> id
wenzelm@38363:   val parse_id: string -> id
wenzelm@38363:   val print_id: id -> string
wenzelm@44185:   type node_header = (string * string list * (string * bool) list) Exn.result
wenzelm@44157:   datatype node_edit =
wenzelm@44185:     Clear |
wenzelm@44157:     Edits of (command_id option * command_id option) list |
wenzelm@44384:     Header of node_header |
wenzelm@44385:     Perspective of command_id list
wenzelm@44156:   type edit = string * node_edit
wenzelm@38418:   type state
wenzelm@38418:   val init_state: state
wenzelm@44197:   val join_commands: state -> unit
wenzelm@44301:   val cancel_execution: state -> Future.task list
wenzelm@38418:   val define_command: command_id -> string -> state -> state
wenzelm@44436:   val update_perspective: version_id -> version_id -> string -> command_id list -> state -> state
wenzelm@44157:   val edit: version_id -> version_id -> edit list -> state -> (command_id * exec_id) list * state
wenzelm@38418:   val execute: version_id -> state -> state
wenzelm@43713:   val state: unit -> state
wenzelm@43713:   val change_state: (state -> state) -> unit
wenzelm@38150: end;
wenzelm@38150: 
wenzelm@38150: structure Document: DOCUMENT =
wenzelm@38150: struct
wenzelm@38150: 
wenzelm@38150: (* unique identifiers *)
wenzelm@38150: 
wenzelm@38363: type id = int;
wenzelm@38373: type version_id = id;
wenzelm@38363: type command_id = id;
wenzelm@38373: type exec_id = id;
wenzelm@38355: 
wenzelm@38355: val no_id = 0;
wenzelm@40449: val new_id = Synchronized.counter ();
wenzelm@38418: 
wenzelm@38414: val parse_id = Markup.parse_int;
wenzelm@38414: val print_id = Markup.print_int;
wenzelm@38150: 
wenzelm@38418: fun err_dup kind id = error ("Duplicate " ^ kind ^ ": " ^ print_id id);
wenzelm@38418: fun err_undef kind id = error ("Undefined " ^ kind ^ ": " ^ print_id id);
wenzelm@38150: 
wenzelm@38418: 
wenzelm@38418: 
wenzelm@38418: (** document structure **)
wenzelm@38418: 
wenzelm@44185: type node_header = (string * string list * (string * bool) list) Exn.result;
wenzelm@44386: type perspective = (command_id -> bool) * command_id list; (*visible commands, canonical order*)
wenzelm@38448: structure Entries = Linear_Set(type key = command_id val ord = int_ord);
wenzelm@38448: 
wenzelm@43668: abstype node = Node of
wenzelm@44182:  {header: node_header,
wenzelm@44386:   perspective: perspective,
wenzelm@44180:   entries: exec_id option Entries.T,  (*command entries with excecutions*)
wenzelm@44197:   result: Toplevel.state lazy}
wenzelm@43668: and version = Version of node Graph.T  (*development graph wrt. static imports*)
wenzelm@38418: with
wenzelm@38418: 
wenzelm@44385: fun make_node (header, perspective, entries, result) =
wenzelm@44385:   Node {header = header, perspective = perspective, entries = entries, result = result};
wenzelm@43668: 
wenzelm@44385: fun map_node f (Node {header, perspective, entries, result}) =
wenzelm@44385:   make_node (f (header, perspective, entries, result));
wenzelm@38418: 
wenzelm@44386: val no_perspective: perspective = (K false, []);
wenzelm@44386: val no_print = Lazy.value ();
wenzelm@44386: val no_result = Lazy.value Toplevel.toplevel;
wenzelm@44386: 
wenzelm@44386: val empty_node =
wenzelm@44386:   make_node (Exn.Exn (ERROR "Bad theory header"), no_perspective, Entries.empty, no_result);
wenzelm@44386: 
wenzelm@44386: val clear_node =
wenzelm@44386:   map_node (fn (header, _, _, _) => (header, no_perspective, Entries.empty, no_result));
wenzelm@44386: 
wenzelm@44386: 
wenzelm@44386: (* basic components *)
wenzelm@44386: 
wenzelm@44180: fun get_header (Node {header, ...}) = header;
wenzelm@44385: fun set_header header =
wenzelm@44385:   map_node (fn (_, perspective, entries, result) => (header, perspective, entries, result));
wenzelm@44180: 
wenzelm@44385: fun get_perspective (Node {perspective, ...}) = perspective;
wenzelm@44385: fun set_perspective perspective =
wenzelm@44386:   let val pred = Inttab.defined (Inttab.make (map (rpair ()) perspective)) in
wenzelm@44386:     map_node (fn (header, _, entries, result) => (header, (pred, perspective), entries, result))
wenzelm@44386:   end;
wenzelm@44385: 
wenzelm@44385: fun map_entries f (Node {header, perspective, entries, result}) =
wenzelm@44385:   make_node (header, perspective, f entries, result);
wenzelm@43668: fun fold_entries start f (Node {entries, ...}) = Entries.fold start f entries;
wenzelm@43668: fun first_entry start P (Node {entries, ...}) = Entries.get_first start P entries;
wenzelm@43668: 
wenzelm@44386: fun get_theory pos (Node {result, ...}) = Toplevel.end_theory pos (Lazy.force result);
wenzelm@44385: fun set_result result =
wenzelm@44385:   map_node (fn (header, perspective, entries, _) => (header, perspective, entries, result));
wenzelm@44180: 
wenzelm@44185: fun get_node nodes name = Graph.get_node nodes name handle Graph.UNDEF _ => empty_node;
wenzelm@44202: fun default_node name = Graph.default_node (name, empty_node);
wenzelm@44202: fun update_node name f = default_node name #> Graph.map_node name f;
wenzelm@38418: 
wenzelm@38418: 
wenzelm@38448: (* node edits and associated executions *)
wenzelm@38150: 
wenzelm@44157: datatype node_edit =
wenzelm@44185:   Clear |
wenzelm@44157:   Edits of (command_id option * command_id option) list |
wenzelm@44384:   Header of node_header |
wenzelm@44385:   Perspective of command_id list;
wenzelm@44157: 
wenzelm@44156: type edit = string * node_edit;
wenzelm@38448: 
wenzelm@43668: fun the_entry (Node {entries, ...}) id =
wenzelm@38448:   (case Entries.lookup entries id of
wenzelm@38448:     NONE => err_undef "command entry" id
wenzelm@38448:   | SOME entry => entry);
wenzelm@38150: 
wenzelm@43668: fun update_entry (id, exec_id) =
wenzelm@43668:   map_entries (Entries.update (id, SOME exec_id));
wenzelm@38418: 
wenzelm@38448: fun reset_after id entries =
wenzelm@38448:   (case Entries.get_after entries id of
wenzelm@38448:     NONE => entries
wenzelm@38448:   | SOME next => Entries.update (next, NONE) entries);
wenzelm@38448: 
wenzelm@43668: val edit_node = map_entries o fold
wenzelm@43668:   (fn (id, SOME id2) => Entries.insert_after id (id2, NONE)
wenzelm@43668:     | (id, NONE) => Entries.delete_after id #> reset_after id);
wenzelm@38418: 
wenzelm@38418: 
wenzelm@38418: (* version operations *)
wenzelm@38418: 
wenzelm@44185: val empty_version = Version Graph.empty;
wenzelm@44185: 
wenzelm@38418: fun nodes_of (Version nodes) = nodes;
wenzelm@44185: val node_of = get_node o nodes_of;
wenzelm@38418: 
wenzelm@44185: fun cycle_msg names = "Cyclic dependency of " ^ space_implode " via " (map quote names);
wenzelm@44180: 
wenzelm@44202: fun touch_descendants name nodes =
wenzelm@44202:   fold (fn desc => desc <> name ? update_node desc (map_entries (reset_after NONE)))
wenzelm@44202:     (Graph.all_succs nodes [name]) nodes;
wenzelm@44202: 
wenzelm@44157: fun edit_nodes (name, node_edit) (Version nodes) =
wenzelm@44157:   Version
wenzelm@44436:     (case node_edit of
wenzelm@44436:       Clear =>
wenzelm@44436:         nodes
wenzelm@44436:         |> update_node name clear_node
wenzelm@44436:         |> touch_descendants name
wenzelm@44436:     | Edits edits =>
wenzelm@44436:         nodes
wenzelm@44436:         |> update_node name (edit_node edits)
wenzelm@44436:         |> touch_descendants name
wenzelm@44436:     | Header header =>
wenzelm@44436:         let
wenzelm@44436:           val parents = (case header of Exn.Res (_, parents, _) => parents | _ => []);
wenzelm@44436:           val nodes1 = nodes
wenzelm@44436:             |> default_node name
wenzelm@44436:             |> fold default_node parents;
wenzelm@44436:           val nodes2 = nodes1
wenzelm@44436:             |> Graph.Keys.fold
wenzelm@44436:                 (fn dep => Graph.del_edge (dep, name)) (Graph.imm_preds nodes1 name);
wenzelm@44436:           val (header', nodes3) =
wenzelm@44436:             (header, Graph.add_deps_acyclic (name, parents) nodes2)
wenzelm@44436:               handle Graph.CYCLES cs => (Exn.Exn (ERROR (cat_lines (map cycle_msg cs))), nodes2);
wenzelm@44436:         in Graph.map_node name (set_header header') nodes3 end
wenzelm@44436:         |> touch_descendants name
wenzelm@44436:     | Perspective perspective =>
wenzelm@44436:         update_node name (set_perspective perspective) nodes);
wenzelm@38418: 
wenzelm@44222: fun put_node (name, node) (Version nodes) =
wenzelm@44222:   Version (update_node name (K node) nodes);
wenzelm@38418: 
wenzelm@38150: end;
wenzelm@38150: 
wenzelm@38418: 
wenzelm@38418: 
wenzelm@38418: (** global state -- document structure and execution process **)
wenzelm@38418: 
wenzelm@38418: abstype state = State of
wenzelm@40398:  {versions: version Inttab.table,  (*version_id -> document content*)
wenzelm@38421:   commands: Toplevel.transition future Inttab.table,  (*command_id -> transition (future parsing)*)
wenzelm@44386:   execs: (command_id * (Toplevel.state * unit lazy) lazy) Inttab.table,
wenzelm@44386:     (*exec_id -> command_id with eval/print process*)
wenzelm@44300:   execution: Future.group}  (*global execution process*)
wenzelm@38418: with
wenzelm@38418: 
wenzelm@38418: fun make_state (versions, commands, execs, execution) =
wenzelm@38418:   State {versions = versions, commands = commands, execs = execs, execution = execution};
wenzelm@38418: 
wenzelm@38418: fun map_state f (State {versions, commands, execs, execution}) =
wenzelm@38418:   make_state (f (versions, commands, execs, execution));
wenzelm@38418: 
wenzelm@38418: val init_state =
wenzelm@38418:   make_state (Inttab.make [(no_id, empty_version)],
wenzelm@38449:     Inttab.make [(no_id, Future.value Toplevel.empty)],
wenzelm@44386:     Inttab.make [(no_id, (no_id, Lazy.value (Toplevel.toplevel, no_print)))],
wenzelm@44300:     Future.new_group NONE);
wenzelm@38418: 
wenzelm@38418: 
wenzelm@38418: (* document versions *)
wenzelm@38418: 
wenzelm@38418: fun define_version (id: version_id) version =
wenzelm@38418:   map_state (fn (versions, commands, execs, execution) =>
wenzelm@38418:     let val versions' = Inttab.update_new (id, version) versions
wenzelm@38418:       handle Inttab.DUP dup => err_dup "document version" dup
wenzelm@38418:     in (versions', commands, execs, execution) end);
wenzelm@38418: 
wenzelm@38418: fun the_version (State {versions, ...}) (id: version_id) =
wenzelm@38418:   (case Inttab.lookup versions id of
wenzelm@38418:     NONE => err_undef "document version" id
wenzelm@38418:   | SOME version => version);
wenzelm@38418: 
wenzelm@38418: 
wenzelm@38418: (* commands *)
wenzelm@38418: 
wenzelm@38418: fun define_command (id: command_id) text =
wenzelm@38418:   map_state (fn (versions, commands, execs, execution) =>
wenzelm@38418:     let
wenzelm@38418:       val id_string = print_id id;
wenzelm@44302:       val tr =
wenzelm@44302:         Future.fork_pri 2 (fn () =>
wenzelm@44302:           Position.setmp_thread_data (Position.id_only id_string)
wenzelm@44302:             (fn () => Outer_Syntax.prepare_command (Position.id id_string) text) ());
wenzelm@38418:       val commands' =
wenzelm@38421:         Inttab.update_new (id, tr) commands
wenzelm@38418:           handle Inttab.DUP dup => err_dup "command" dup;
wenzelm@38418:     in (versions, commands', execs, execution) end);
wenzelm@38418: 
wenzelm@38418: fun the_command (State {commands, ...}) (id: command_id) =
wenzelm@38418:   (case Inttab.lookup commands id of
wenzelm@38418:     NONE => err_undef "command" id
wenzelm@38418:   | SOME tr => tr);
wenzelm@38418: 
wenzelm@38421: fun join_commands (State {commands, ...}) =
wenzelm@38421:   Inttab.fold (fn (_, tr) => fn () => ignore (Future.join_result tr)) commands ();
wenzelm@38421: 
wenzelm@38418: 
wenzelm@38418: (* command executions *)
wenzelm@38418: 
wenzelm@44197: fun define_exec (exec_id, exec) =
wenzelm@38418:   map_state (fn (versions, commands, execs, execution) =>
wenzelm@44197:     let val execs' = Inttab.update_new (exec_id, exec) execs
wenzelm@38418:       handle Inttab.DUP dup => err_dup "command execution" dup
wenzelm@38418:     in (versions, commands, execs', execution) end);
wenzelm@38418: 
wenzelm@44197: fun the_exec (State {execs, ...}) exec_id =
wenzelm@44197:   (case Inttab.lookup execs exec_id of
wenzelm@44197:     NONE => err_undef "command execution" exec_id
wenzelm@38418:   | SOME exec => exec);
wenzelm@38418: 
wenzelm@41634: 
wenzelm@41634: (* document execution *)
wenzelm@41634: 
wenzelm@44299: fun cancel_execution (State {execution, ...}) = Future.cancel_group execution;
wenzelm@41634: 
wenzelm@38418: end;
wenzelm@38418: 
wenzelm@38418: 
wenzelm@38418: 
wenzelm@38888: (* toplevel transactions *)
wenzelm@38888: 
wenzelm@38888: local
wenzelm@38888: 
wenzelm@40391: fun timing tr t = Toplevel.status tr (Markup.timing t);
wenzelm@40391: 
wenzelm@38888: fun proof_status tr st =
wenzelm@38888:   (case try Toplevel.proof_of st of
wenzelm@38888:     SOME prf => Toplevel.status tr (Proof.status_markup prf)
wenzelm@38888:   | NONE => ());
wenzelm@38888: 
wenzelm@44386: fun print_state tr st =
wenzelm@44386:   (Lazy.lazy o Toplevel.setmp_thread_position tr)
wenzelm@44386:     (fn () => Toplevel.print_state false st);
wenzelm@38888: 
wenzelm@40390: fun run int tr st =
wenzelm@40390:   (case Toplevel.transition int tr st of
wenzelm@40390:     SOME (st', NONE) => ([], SOME st')
wenzelm@44271:   | SOME (_, SOME (exn, _)) =>
wenzelm@44271:       (case ML_Compiler.exn_messages exn of
wenzelm@40390:         [] => Exn.interrupt ()
wenzelm@40390:       | errs => (errs, NONE))
wenzelm@44270:   | NONE => ([(serial (), ML_Compiler.exn_message Runtime.TERMINATE)], NONE));
wenzelm@40390: 
wenzelm@38888: in
wenzelm@38888: 
wenzelm@44199: fun run_command tr st =
wenzelm@44185:   let
wenzelm@44199:     val is_init = Toplevel.is_init tr;
wenzelm@44185:     val is_proof = Keyword.is_proof (Toplevel.name_of tr);
wenzelm@44185:     val do_print = not is_init andalso (Toplevel.print_of tr orelse is_proof);
wenzelm@44185: 
wenzelm@44185:     val start = Timing.start ();
wenzelm@44185:     val (errs, result) =
wenzelm@44185:       if Toplevel.is_toplevel st andalso not is_init then ([], SOME st)
wenzelm@44185:       else run (is_init orelse is_proof) (Toplevel.set_print false tr) st;
wenzelm@44185:     val _ = timing tr (Timing.result start);
wenzelm@44185:     val _ = List.app (Toplevel.error_msg tr) errs;
wenzelm@44185:   in
wenzelm@44185:     (case result of
wenzelm@44386:       NONE => (Toplevel.status tr Markup.failed; (st, no_print))
wenzelm@44185:     | SOME st' =>
wenzelm@44185:        (Toplevel.status tr Markup.finished;
wenzelm@44185:         proof_status tr st';
wenzelm@44386:         (st', if do_print then print_state tr st' else no_print)))
wenzelm@44185:   end;
wenzelm@38888: 
wenzelm@38888: end;
wenzelm@38888: 
wenzelm@38888: 
wenzelm@38888: 
wenzelm@38888: 
wenzelm@38418: (** editing **)
wenzelm@38418: 
wenzelm@44436: (* perspective *)
wenzelm@44436: 
wenzelm@44436: fun update_perspective (old_id: version_id) (new_id: version_id) name perspective state =
wenzelm@44436:   let
wenzelm@44436:     val old_version = the_version state old_id;
wenzelm@44436:     val _ = Time.now ();  (* FIXME odd workaround for polyml-5.4.0/x86_64 -- needed? *)
wenzelm@44436:     val new_version = edit_nodes (name, Perspective perspective) old_version;
wenzelm@44436:   in define_version new_id new_version state end;
wenzelm@44436: 
wenzelm@44436: 
wenzelm@38418: (* edit *)
wenzelm@38418: 
wenzelm@38418: local
wenzelm@38418: 
wenzelm@38448: fun is_changed node' ((_, id), exec) =
wenzelm@38418:   (case try (the_entry node') id of
wenzelm@38418:     NONE => true
wenzelm@38448:   | SOME exec' => exec' <> exec);
wenzelm@38418: 
wenzelm@44435: fun init_theory deps (name, node) =
wenzelm@44435:   let
wenzelm@44435:     val (thy_name, imports, uses) = Exn.release (get_header node);
wenzelm@44435:     (* FIXME provide files via Scala layer *)
wenzelm@44435:     val (dir, files) =
wenzelm@44435:       if ML_System.platform_is_cygwin then (Path.current, [])
wenzelm@44435:       else (Path.dir (Path.explode name), map (apfst Path.explode) uses);
wenzelm@44435: 
wenzelm@44435:     val parents =
wenzelm@44435:       imports |> map (fn import =>
wenzelm@44435:         (case Thy_Info.lookup_theory import of
wenzelm@44435:           SOME thy => thy
wenzelm@44435:         | NONE =>
wenzelm@44435:             get_theory (Position.file_only import)
wenzelm@44435:               (#2 (Future.join (the (AList.lookup (op =) deps import))))));
wenzelm@44435:   in Thy_Load.begin_theory dir thy_name imports files parents end;
wenzelm@44435: 
wenzelm@44199: fun new_exec (command_id, command) (assigns, execs, exec) =
wenzelm@38418:   let
wenzelm@38419:     val exec_id' = new_id ();
wenzelm@44386:     val exec' = exec |> Lazy.map (fn (st, _) =>
wenzelm@44386:       let val tr = Toplevel.put_id (print_id exec_id') (Future.join command)
wenzelm@44386:       in run_command tr st end);
wenzelm@44386:   in ((command_id, exec_id') :: assigns, (exec_id', (command_id, exec')) :: execs, exec') end;
wenzelm@38418: 
wenzelm@38418: in
wenzelm@38418: 
wenzelm@44157: fun edit (old_id: version_id) (new_id: version_id) edits state =
wenzelm@38418:   let
wenzelm@38418:     val old_version = the_version state old_id;
wenzelm@44180:     val _ = Time.now ();  (* FIXME odd workaround for polyml-5.4.0/x86_64 *)
wenzelm@44222:     val new_version = fold edit_nodes edits old_version;
wenzelm@38418: 
wenzelm@44197:     val updates =
wenzelm@44197:       nodes_of new_version |> Graph.schedule
wenzelm@44199:         (fn deps => fn (name, node) =>
wenzelm@44197:           (case first_entry NONE (is_changed (node_of old_version name)) node of
wenzelm@44201:             NONE => Future.value (([], [], []), node)
wenzelm@44197:           | SOME ((prev, id), _) =>
wenzelm@44197:               let
wenzelm@44435:                 fun init () = init_theory deps (name, node);
wenzelm@44199:                 fun get_command id =
wenzelm@44199:                   (id, the_command state id |> Future.map (Toplevel.modify_init init));
wenzelm@44201:               in
wenzelm@44302:                 (singleton o Future.forks)
wenzelm@44302:                   {name = "Document.edit", group = NONE,
wenzelm@44302:                     deps = map (Future.task_of o #2) deps, pri = 2, interrupts = false}
wenzelm@44201:                   (fn () =>
wenzelm@44201:                     let
wenzelm@44201:                       val prev_exec =
wenzelm@44201:                         (case prev of
wenzelm@44201:                           NONE => no_id
wenzelm@44201:                         | SOME prev_id => the_default no_id (the_entry node prev_id));
wenzelm@44386:                       val (assigns, execs, last_exec) =
wenzelm@44201:                         fold_entries (SOME id) (new_exec o get_command o #2 o #1)
wenzelm@44386:                           node ([], [], #2 (the_exec state prev_exec));
wenzelm@44201:                       val node' = node
wenzelm@44201:                         |> fold update_entry assigns
wenzelm@44386:                         |> set_result (Lazy.map #1 last_exec);
wenzelm@44201:                     in ((assigns, execs, [(name, node')]), node') end)
wenzelm@44201:               end))
wenzelm@44330:       |> Future.joins |> map #1;
wenzelm@38418: 
wenzelm@44197:     val state' = state
wenzelm@44197:       |> fold (fold define_exec o #2) updates
wenzelm@44197:       |> define_version new_id (fold (fold put_node o #3) updates new_version);
wenzelm@38421: 
wenzelm@44197:   in (maps #1 (rev updates), state') end;
wenzelm@38418: 
wenzelm@38418: end;
wenzelm@38418: 
wenzelm@38418: 
wenzelm@38418: (* execute *)
wenzelm@38418: 
wenzelm@38418: fun execute version_id state =
wenzelm@41673:   state |> map_state (fn (versions, commands, execs, _) =>
wenzelm@38418:     let
wenzelm@38418:       val version = the_version state version_id;
wenzelm@38418: 
wenzelm@44386:       fun force_exec _ NONE = ()
wenzelm@44386:         | force_exec node (SOME exec_id) =
wenzelm@44386:             let
wenzelm@44386:               val (command_id, exec) = the_exec state exec_id;
wenzelm@44386:               val (_, print) = Lazy.force exec;
wenzelm@44386:               val perspective = get_perspective node;
wenzelm@44386:               val _ =
wenzelm@44386:                 if #1 (get_perspective node) command_id orelse true  (* FIXME *)
wenzelm@44386:                 then ignore (Lazy.future Future.default_params print)
wenzelm@44386:                 else ();
wenzelm@44386:             in () end;
wenzelm@38418: 
wenzelm@44300:       val execution = Future.new_group NONE;
wenzelm@44299:       val _ =
wenzelm@44201:         nodes_of version |> Graph.schedule
wenzelm@44201:           (fn deps => fn (name, node) =>
wenzelm@44302:             (singleton o Future.forks)
wenzelm@44302:               {name = "theory:" ^ name, group = SOME (Future.new_group (SOME execution)),
wenzelm@44302:                 deps = map (Future.task_of o #2) deps, pri = 1, interrupts = true}
wenzelm@44386:               (fold_entries NONE (fn (_, exec) => fn () => force_exec node exec) node));
wenzelm@40520: 
wenzelm@44299:     in (versions, commands, execs, execution) end);
wenzelm@38418: 
wenzelm@43713: 
wenzelm@43713: 
wenzelm@43713: (** global state **)
wenzelm@43713: 
wenzelm@43713: val global_state = Synchronized.var "Document" init_state;
wenzelm@43713: 
wenzelm@43713: fun state () = Synchronized.value global_state;
wenzelm@43713: val change_state = Synchronized.change global_state;
wenzelm@43713: 
wenzelm@38418: end;
wenzelm@38418: