src/Pure/PIDE/document.ML
author wenzelm
Wed Jul 23 13:01:30 2014 +0200 (2014-07-23)
changeset 57615 df1b3452d71c
parent 56801 8dd9df88f647
child 57616 50ab1db5c0fd
permissions -rw-r--r--
more explicit discrimination of empty nodes -- suppress from Theories panel;
     1 (*  Title:      Pure/PIDE/document.ML
     2     Author:     Makarius
     3 
     4 Document as collection of named nodes, each consisting of an editable
     5 list of commands, associated with asynchronous execution process.
     6 *)
     7 
     8 signature DOCUMENT =
     9 sig
    10   val timing: bool Unsynchronized.ref
    11   type node_header = string * Thy_Header.header * string list
    12   type overlay = Document_ID.command * (string * string list)
    13   datatype node_edit =
    14     Edits of (Document_ID.command option * Document_ID.command option) list |
    15     Deps of node_header |
    16     Perspective of bool * Document_ID.command list * overlay list
    17   type edit = string * node_edit
    18   type state
    19   val init_state: state
    20   val define_blob: string -> string -> state -> state
    21   type blob_digest = (string * string option) Exn.result
    22   val define_command: Document_ID.command -> string -> blob_digest list -> string ->
    23     state -> state
    24   val remove_versions: Document_ID.version list -> state -> state
    25   val start_execution: state -> state
    26   val update: Document_ID.version -> Document_ID.version -> edit list -> state ->
    27     Document_ID.exec list * (Document_ID.command * Document_ID.exec list) list * state
    28   val state: unit -> state
    29   val change_state: (state -> state) -> unit
    30 end;
    31 
    32 structure Document: DOCUMENT =
    33 struct
    34 
    35 val timing = Unsynchronized.ref false;
    36 fun timeit msg e = cond_timeit (! timing) msg e;
    37 
    38 
    39 
    40 (** document structure **)
    41 
    42 fun err_dup kind id = error ("Duplicate " ^ kind ^ ": " ^ Document_ID.print id);
    43 fun err_undef kind id = error ("Undefined " ^ kind ^ ": " ^ Document_ID.print id);
    44 
    45 type node_header = string * Thy_Header.header * string list;
    46 
    47 type perspective =
    48  {required: bool,  (*required node*)
    49   visible: Inttab.set,  (*visible commands*)
    50   visible_last: Document_ID.command option,  (*last visible command*)
    51   overlays: (string * string list) list Inttab.table};  (*command id -> print function with args*)
    52 
    53 structure Entries = Linear_Set(type key = Document_ID.command val ord = int_ord);
    54 
    55 abstype node = Node of
    56  {header: node_header,  (*master directory, theory header, errors*)
    57   perspective: perspective,  (*command perspective*)
    58   entries: Command.exec option Entries.T,  (*command entries with excecutions*)
    59   result: Command.eval option}  (*result of last execution*)
    60 and version = Version of node String_Graph.T  (*development graph wrt. static imports*)
    61 with
    62 
    63 fun make_node (header, perspective, entries, result) =
    64   Node {header = header, perspective = perspective, entries = entries, result = result};
    65 
    66 fun map_node f (Node {header, perspective, entries, result}) =
    67   make_node (f (header, perspective, entries, result));
    68 
    69 fun make_perspective (required, command_ids, overlays) : perspective =
    70  {required = required,
    71   visible = Inttab.make_set command_ids,
    72   visible_last = try List.last command_ids,
    73   overlays = Inttab.make_list overlays};
    74 
    75 val no_header = ("", Thy_Header.make ("", Position.none) [] [], []);
    76 val no_perspective = make_perspective (false, [], []);
    77 
    78 val empty_node = make_node (no_header, no_perspective, Entries.empty, NONE);
    79 
    80 fun is_no_perspective ({required, visible, visible_last, overlays}: perspective) =
    81   not required andalso
    82   Inttab.is_empty visible andalso
    83   is_none visible_last andalso
    84   Inttab.is_empty overlays;
    85 
    86 fun is_empty_node (Node {header, perspective, entries, result}) =
    87   header = no_header andalso
    88   is_no_perspective perspective andalso
    89   Entries.is_empty entries andalso
    90   is_none result;
    91 
    92 
    93 (* basic components *)
    94 
    95 fun master_directory (Node {header = (master, _, _), ...}) =
    96   (case try Url.explode master of
    97     SOME (Url.File path) => path
    98   | _ => Path.current);
    99 
   100 fun set_header header =
   101   map_node (fn (_, perspective, entries, result) => (header, perspective, entries, result));
   102 
   103 fun get_header (Node {header = (master, header, errors), ...}) =
   104   if null errors then (master, header)
   105   else error (cat_lines errors);
   106 
   107 fun read_header node span =
   108   let
   109     val {name = (name, _), imports, keywords} = #2 (get_header node);
   110     val {name = (_, pos), imports = imports', ...} = Thy_Header.read_tokens span;
   111   in Thy_Header.make (name, pos) (map #1 imports ~~ map #2 imports') keywords end;
   112 
   113 fun get_perspective (Node {perspective, ...}) = perspective;
   114 fun set_perspective args =
   115   map_node (fn (header, _, entries, result) => (header, make_perspective args, entries, result));
   116 
   117 val required_node = #required o get_perspective;
   118 val visible_command = Inttab.defined o #visible o get_perspective;
   119 val visible_last = #visible_last o get_perspective;
   120 val visible_node = is_some o visible_last
   121 val overlays = Inttab.lookup_list o #overlays o get_perspective;
   122 
   123 fun map_entries f =
   124   map_node (fn (header, perspective, entries, result) => (header, perspective, f entries, result));
   125 fun get_entries (Node {entries, ...}) = entries;
   126 
   127 fun iterate_entries f = Entries.iterate NONE f o get_entries;
   128 fun iterate_entries_after start f (Node {entries, ...}) =
   129   (case Entries.get_after entries start of
   130     NONE => I
   131   | SOME id => Entries.iterate (SOME id) f entries);
   132 
   133 fun get_result (Node {result, ...}) = result;
   134 fun set_result result =
   135   map_node (fn (header, perspective, entries, _) => (header, perspective, entries, result));
   136 
   137 fun changed_result node node' =
   138   (case (get_result node, get_result node') of
   139     (SOME eval, SOME eval') => not (Command.eval_eq (eval, eval'))
   140   | (NONE, NONE) => false
   141   | _ => true);
   142 
   143 fun pending_result node =
   144   (case get_result node of
   145     SOME eval => not (Command.eval_finished eval)
   146   | NONE => false);
   147 
   148 fun get_node nodes name = String_Graph.get_node nodes name
   149   handle String_Graph.UNDEF _ => empty_node;
   150 fun default_node name = String_Graph.default_node (name, empty_node);
   151 fun update_node name f = default_node name #> String_Graph.map_node name f;
   152 
   153 
   154 (* node edits and associated executions *)
   155 
   156 type overlay = Document_ID.command * (string * string list);
   157 
   158 datatype node_edit =
   159   Edits of (Document_ID.command option * Document_ID.command option) list |
   160   Deps of node_header |
   161   Perspective of bool * Document_ID.command list * overlay list;
   162 
   163 type edit = string * node_edit;
   164 
   165 val after_entry = Entries.get_after o get_entries;
   166 
   167 fun lookup_entry node id =
   168   (case Entries.lookup (get_entries node) id of
   169     NONE => NONE
   170   | SOME (exec, _) => exec);
   171 
   172 fun the_entry node id =
   173   (case Entries.lookup (get_entries node) id of
   174     NONE => err_undef "command entry" id
   175   | SOME (exec, _) => exec);
   176 
   177 fun the_default_entry node (SOME id) = (id, the_default Command.no_exec (the_entry node id))
   178   | the_default_entry _ NONE = (Document_ID.none, Command.no_exec);
   179 
   180 fun assign_entry (command_id, exec) node =
   181   if is_none (Entries.lookup (get_entries node) command_id) then node
   182   else map_entries (Entries.update (command_id, exec)) node;
   183 
   184 fun reset_after id entries =
   185   (case Entries.get_after entries id of
   186     NONE => entries
   187   | SOME next => Entries.update (next, NONE) entries);
   188 
   189 val edit_node = map_entries o fold
   190   (fn (id, SOME id2) => Entries.insert_after id (id2, NONE)
   191     | (id, NONE) => Entries.delete_after id #> reset_after id);
   192 
   193 
   194 (* version operations *)
   195 
   196 val empty_version = Version String_Graph.empty;
   197 
   198 fun nodes_of (Version nodes) = nodes;
   199 val node_of = get_node o nodes_of;
   200 
   201 fun cycle_msg names = "Cyclic dependency of " ^ space_implode " via " (map quote names);
   202 
   203 fun edit_nodes (name, node_edit) (Version nodes) =
   204   Version
   205     (case node_edit of
   206       Edits edits => update_node name (edit_node edits) nodes
   207     | Deps (master, header, errors) =>
   208         let
   209           val imports = map fst (#imports header);
   210           val errors1 =
   211             (Thy_Header.define_keywords header; errors)
   212               handle ERROR msg => errors @ [msg];
   213           val nodes1 = nodes
   214             |> default_node name
   215             |> fold default_node imports;
   216           val nodes2 = nodes1
   217             |> String_Graph.Keys.fold
   218                 (fn dep => String_Graph.del_edge (dep, name)) (String_Graph.imm_preds nodes1 name);
   219           val (nodes3, errors2) =
   220             (String_Graph.add_deps_acyclic (name, imports) nodes2, errors1)
   221               handle String_Graph.CYCLES cs => (nodes2, errors1 @ map cycle_msg cs);
   222         in String_Graph.map_node name (set_header (master, header, errors2)) nodes3 end
   223     | Perspective perspective => update_node name (set_perspective perspective) nodes);
   224 
   225 fun put_node (name, node) (Version nodes) =
   226   Version (update_node name (K node) nodes);
   227 
   228 end;
   229 
   230 
   231 
   232 (** main state -- document structure and execution process **)
   233 
   234 type blob_digest = (string * string option) Exn.result;  (*file node name, raw digest*)
   235 
   236 type execution =
   237  {version_id: Document_ID.version,  (*static version id*)
   238   execution_id: Document_ID.execution,  (*dynamic execution id*)
   239   delay_request: unit future,  (*pending event timer request*)
   240   frontier: Future.task Symtab.table};  (*node name -> running execution task*)
   241 
   242 val no_execution: execution =
   243   {version_id = Document_ID.none, execution_id = Document_ID.none,
   244    delay_request = Future.value (), frontier = Symtab.empty};
   245 
   246 fun new_execution version_id delay_request frontier : execution =
   247   {version_id = version_id, execution_id = Execution.start (),
   248    delay_request = delay_request, frontier = frontier};
   249 
   250 abstype state = State of
   251  {versions: version Inttab.table,  (*version id -> document content*)
   252   blobs: (SHA1.digest * string list) Symtab.table,  (*raw digest -> digest, lines*)
   253   commands: (string * blob_digest list * Token.T list lazy) Inttab.table,
   254     (*command id -> name, inlined files, command span*)
   255   execution: execution}  (*current execution process*)
   256 with
   257 
   258 fun make_state (versions, blobs, commands, execution) =
   259   State {versions = versions, blobs = blobs, commands = commands, execution = execution};
   260 
   261 fun map_state f (State {versions, blobs, commands, execution}) =
   262   make_state (f (versions, blobs, commands, execution));
   263 
   264 val init_state =
   265   make_state (Inttab.make [(Document_ID.none, empty_version)],
   266     Symtab.empty, Inttab.empty, no_execution);
   267 
   268 
   269 (* document versions *)
   270 
   271 fun define_version version_id version =
   272   map_state (fn (versions, blobs, commands, {delay_request, frontier, ...}) =>
   273     let
   274       val versions' = Inttab.update_new (version_id, version) versions
   275         handle Inttab.DUP dup => err_dup "document version" dup;
   276       val execution' = new_execution version_id delay_request frontier;
   277     in (versions', blobs, commands, execution') end);
   278 
   279 fun the_version (State {versions, ...}) version_id =
   280   (case Inttab.lookup versions version_id of
   281     NONE => err_undef "document version" version_id
   282   | SOME version => version);
   283 
   284 fun delete_version version_id versions =
   285   Inttab.delete version_id versions
   286     handle Inttab.UNDEF _ => err_undef "document version" version_id;
   287 
   288 
   289 (* inlined files *)
   290 
   291 fun define_blob digest text =
   292   map_state (fn (versions, blobs, commands, execution) =>
   293     let
   294       val sha1_digest = SHA1.digest text;
   295       val _ =
   296         digest = SHA1.rep sha1_digest orelse
   297           error ("Ill-defined blob: bad SHA1 digest " ^ digest ^ " vs. " ^ SHA1.rep sha1_digest);
   298       val blobs' = Symtab.update (digest, (sha1_digest, split_lines text)) blobs;
   299     in (versions, blobs', commands, execution) end);
   300 
   301 fun the_blob (State {blobs, ...}) digest =
   302   (case Symtab.lookup blobs digest of
   303     NONE => error ("Undefined blob: " ^ digest)
   304   | SOME content => content);
   305 
   306 fun resolve_blob state (blob_digest: blob_digest) =
   307   blob_digest |> Exn.map_result (fn (file_node, raw_digest) =>
   308     (file_node, Option.map (the_blob state) raw_digest));
   309 
   310 
   311 (* commands *)
   312 
   313 fun define_command command_id name command_blobs text =
   314   map_state (fn (versions, blobs, commands, execution) =>
   315     let
   316       val id = Document_ID.print command_id;
   317       val span =
   318         Lazy.lazy (fn () =>
   319           Position.setmp_thread_data (Position.id_only id)
   320             (fn () => Thy_Syntax.parse_tokens (Keyword.get_lexicons ()) (Position.id id) text) ());
   321       val _ =
   322         Position.setmp_thread_data (Position.id_only id)
   323           (fn () => Output.status (Markup.markup_only Markup.accepted)) ();
   324       val commands' =
   325         Inttab.update_new (command_id, (name, command_blobs, span)) commands
   326           handle Inttab.DUP dup => err_dup "command" dup;
   327     in (versions, blobs, commands', execution) end);
   328 
   329 fun the_command (State {commands, ...}) command_id =
   330   (case Inttab.lookup commands command_id of
   331     NONE => err_undef "command" command_id
   332   | SOME command => command);
   333 
   334 val the_command_name = #1 oo the_command;
   335 
   336 end;
   337 
   338 
   339 (* remove_versions *)
   340 
   341 fun remove_versions version_ids state = state |> map_state (fn (versions, _, _, execution) =>
   342   let
   343     val _ =
   344       member (op =) version_ids (#version_id execution) andalso
   345         error ("Attempt to remove execution version " ^ Document_ID.print (#version_id execution));
   346 
   347     val versions' = fold delete_version version_ids versions;
   348     val commands' =
   349       (versions', Inttab.empty) |->
   350         Inttab.fold (fn (_, version) => nodes_of version |>
   351           String_Graph.fold (fn (_, (node, _)) => node |>
   352             iterate_entries (fn ((_, command_id), _) =>
   353               SOME o Inttab.insert (K true) (command_id, the_command state command_id))));
   354     val blobs' =
   355       (commands', Symtab.empty) |->
   356         Inttab.fold (fn (_, (_, blobs, _)) => blobs |>
   357           fold (fn Exn.Res (_, SOME b) => Symtab.update (b, the_blob state b) | _ => I));
   358 
   359   in (versions', blobs', commands', execution) end);
   360 
   361 
   362 (* document execution *)
   363 
   364 fun start_execution state = state |> map_state (fn (versions, blobs, commands, execution) =>
   365   timeit "Document.start_execution" (fn () =>
   366     let
   367       val {version_id, execution_id, delay_request, frontier} = execution;
   368 
   369       val delay = seconds (Options.default_real "editor_execution_delay");
   370 
   371       val _ = Future.cancel delay_request;
   372       val delay_request' = Event_Timer.future (Time.+ (Time.now (), delay));
   373 
   374       val new_tasks =
   375         nodes_of (the_version state version_id) |> String_Graph.schedule
   376           (fn deps => fn (name, node) =>
   377             if visible_node node orelse pending_result node then
   378               let
   379                 val more_deps =
   380                   Future.task_of delay_request' :: the_list (Symtab.lookup frontier name);
   381                 fun body () =
   382                   iterate_entries (fn (_, opt_exec) => fn () =>
   383                     (case opt_exec of
   384                       SOME exec =>
   385                         if Execution.is_running execution_id
   386                         then SOME (Command.exec execution_id exec)
   387                         else NONE
   388                     | NONE => NONE)) node ()
   389                   handle exn => if Exn.is_interrupt exn then () (*sic!*) else reraise exn;
   390                 val future =
   391                   (singleton o Future.forks)
   392                     {name = "theory:" ^ name, group = SOME (Future.new_group NONE),
   393                       deps = more_deps @ map #2 (maps #2 deps),
   394                       pri = 0, interrupts = false} body;
   395               in [(name, Future.task_of future)] end
   396             else []);
   397       val frontier' = (fold o fold) Symtab.update new_tasks frontier;
   398       val execution' =
   399         {version_id = version_id, execution_id = execution_id,
   400          delay_request = delay_request', frontier = frontier'};
   401     in (versions, blobs, commands, execution') end));
   402 
   403 
   404 
   405 (** document update **)
   406 
   407 (* exec state assignment *)
   408 
   409 type assign_update = Command.exec option Inttab.table;  (*command id -> exec*)
   410 
   411 val assign_update_empty: assign_update = Inttab.empty;
   412 fun assign_update_defined (tab: assign_update) command_id = Inttab.defined tab command_id;
   413 fun assign_update_apply (tab: assign_update) node = Inttab.fold assign_entry tab node;
   414 
   415 fun assign_update_new upd (tab: assign_update) =
   416   Inttab.update_new upd tab
   417     handle Inttab.DUP dup => err_dup "exec state assignment" dup;
   418 
   419 fun assign_update_result (tab: assign_update) =
   420   Inttab.fold (fn (command_id, exec) => cons (command_id, Command.exec_ids exec)) tab [];
   421 
   422 
   423 (* update *)
   424 
   425 local
   426 
   427 fun make_required nodes =
   428   let
   429     fun all_preds P =
   430       String_Graph.fold (fn (a, (node, _)) => P node ? cons a) nodes []
   431       |> String_Graph.all_preds nodes
   432       |> Symtab.make_set;
   433 
   434     val all_visible = all_preds visible_node;
   435     val all_required = all_preds required_node;
   436   in
   437     Symtab.fold (fn (a, ()) =>
   438       exists (Symtab.defined all_visible) (String_Graph.immediate_succs nodes a) ?
   439         Symtab.update (a, ())) all_visible all_required
   440   end;
   441 
   442 fun loaded_theory name =
   443   (case try (unsuffix ".thy") name of
   444     SOME a => get_first Thy_Info.lookup_theory [a, Long_Name.base_name a]
   445   | NONE => NONE);
   446 
   447 fun init_theory deps node span =
   448   let
   449     val master_dir = master_directory node;
   450     val header = read_header node span;
   451     val imports = #imports header;
   452     val parents =
   453       imports |> map (fn (import, _) =>
   454         (case loaded_theory import of
   455           SOME thy => thy
   456         | NONE =>
   457             Toplevel.end_theory (Position.file_only import)
   458               (case get_result (snd (the (AList.lookup (op =) deps import))) of
   459                 NONE => Toplevel.toplevel
   460               | SOME eval => Command.eval_result_state eval)));
   461     val _ = Position.reports (map #2 imports ~~ map Theory.get_markup parents);
   462   in Resources.begin_theory master_dir header parents end;
   463 
   464 fun check_theory full name node =
   465   is_some (loaded_theory name) orelse
   466   can get_header node andalso (not full orelse is_some (get_result node));
   467 
   468 fun last_common state node_required node0 node =
   469   let
   470     fun update_flags prev (visible, initial) =
   471       let
   472         val visible' = visible andalso prev <> visible_last node;
   473         val initial' = initial andalso
   474           (case prev of
   475             NONE => true
   476           | SOME command_id => not (Keyword.is_theory_begin (the_command_name state command_id)));
   477       in (visible', initial') end;
   478 
   479     fun get_common ((prev, command_id), opt_exec) (_, ok, flags, assign_update) =
   480       if ok then
   481         let
   482           val flags' as (visible', _) = update_flags prev flags;
   483           val ok' =
   484             (case (lookup_entry node0 command_id, opt_exec) of
   485               (SOME (eval0, _), SOME (eval, _)) =>
   486                 Command.eval_eq (eval0, eval) andalso
   487                   (visible' orelse node_required orelse Command.eval_running eval)
   488             | _ => false);
   489           val assign_update' = assign_update |> ok' ?
   490             (case opt_exec of
   491               SOME (eval, prints) =>
   492                 let
   493                   val command_visible = visible_command node command_id;
   494                   val command_overlays = overlays node command_id;
   495                   val command_name = the_command_name state command_id;
   496                 in
   497                   (case Command.print command_visible command_overlays command_name eval prints of
   498                     SOME prints' => assign_update_new (command_id, SOME (eval, prints'))
   499                   | NONE => I)
   500                 end
   501             | NONE => I);
   502         in SOME (prev, ok', flags', assign_update') end
   503       else NONE;
   504     val (common, ok, flags, assign_update') =
   505       iterate_entries get_common node (NONE, true, (true, true), assign_update_empty);
   506     val (common', flags') =
   507       if ok then
   508         let val last = Entries.get_after (get_entries node) common
   509         in (last, update_flags last flags) end
   510       else (common, flags);
   511   in (assign_update', common', flags') end;
   512 
   513 fun illegal_init _ = error "Illegal theory header after end of theory";
   514 
   515 fun new_exec state node proper_init command_id' (assign_update, command_exec, init) =
   516   if not proper_init andalso is_none init then NONE
   517   else
   518     let
   519       val (_, (eval, _)) = command_exec;
   520 
   521       val command_visible = visible_command node command_id';
   522       val command_overlays = overlays node command_id';
   523       val (command_name, blob_digests, span0) = the_command state command_id';
   524       val blobs = map (resolve_blob state) blob_digests;
   525       val span = Lazy.force span0;
   526 
   527       val eval' =
   528         Command.eval (fn () => the_default illegal_init init span)
   529           (master_directory node) blobs span eval;
   530       val prints' = perhaps (Command.print command_visible command_overlays command_name eval') [];
   531       val exec' = (eval', prints');
   532 
   533       val assign_update' = assign_update_new (command_id', SOME exec') assign_update;
   534       val init' = if Keyword.is_theory_begin command_name then NONE else init;
   535     in SOME (assign_update', (command_id', (eval', prints')), init') end;
   536 
   537 fun removed_execs node0 (command_id, exec_ids) =
   538   subtract (op =) exec_ids (Command.exec_ids (lookup_entry node0 command_id));
   539 
   540 in
   541 
   542 fun update old_version_id new_version_id edits state =
   543   let
   544     val old_version = the_version state old_version_id;
   545     val new_version = timeit "Document.edit_nodes" (fn () => fold edit_nodes edits old_version);
   546 
   547     val nodes = nodes_of new_version;
   548     val required = make_required nodes;
   549     val required0 = make_required (nodes_of old_version);
   550     val edited = fold (fn (name, _) => Symtab.update (name, ())) edits Symtab.empty;
   551 
   552     val updated = timeit "Document.update" (fn () =>
   553       nodes |> String_Graph.schedule
   554         (fn deps => fn (name, node) =>
   555           (singleton o Future.forks)
   556             {name = "Document.update", group = NONE,
   557               deps = map (Future.task_of o #2) deps, pri = 1, interrupts = false}
   558             (fn () => timeit ("Document.update " ^ name) (fn () =>
   559               let
   560                 val imports = map (apsnd Future.join) deps;
   561                 val imports_result_changed = exists (#4 o #1 o #2) imports;
   562                 val node_required = Symtab.defined required name;
   563               in
   564                 if Symtab.defined edited name orelse visible_node node orelse
   565                   imports_result_changed orelse Symtab.defined required0 name <> node_required
   566                 then
   567                   let
   568                     val node0 = node_of old_version name;
   569                     val init = init_theory imports node;
   570                     val proper_init =
   571                       check_theory false name node andalso
   572                       forall (fn (name, (_, node)) => check_theory true name node) imports;
   573 
   574                     val (print_execs, common, (still_visible, initial)) =
   575                       if imports_result_changed then (assign_update_empty, NONE, (true, true))
   576                       else last_common state node_required node0 node;
   577                     val common_command_exec = the_default_entry node common;
   578 
   579                     val (updated_execs, (command_id', (eval', _)), _) =
   580                       (print_execs, common_command_exec, if initial then SOME init else NONE)
   581                       |> (still_visible orelse node_required) ?
   582                         iterate_entries_after common
   583                           (fn ((prev, id), _) => fn res =>
   584                             if not node_required andalso prev = visible_last node then NONE
   585                             else new_exec state node proper_init id res) node;
   586 
   587                     val assigned_execs =
   588                       (node0, updated_execs) |-> iterate_entries_after common
   589                         (fn ((_, command_id0), exec0) => fn res =>
   590                           if is_none exec0 then NONE
   591                           else if assign_update_defined updated_execs command_id0 then SOME res
   592                           else SOME (assign_update_new (command_id0, NONE) res));
   593 
   594                     val last_exec =
   595                       if command_id' = Document_ID.none then NONE else SOME command_id';
   596                     val result =
   597                       if is_none last_exec orelse is_some (after_entry node last_exec) then NONE
   598                       else SOME eval';
   599 
   600                     val assign_update = assign_update_result assigned_execs;
   601                     val removed = maps (removed_execs node0) assign_update;
   602                     val _ = List.app Execution.cancel removed;
   603 
   604                     val node' = node
   605                       |> assign_update_apply assigned_execs
   606                       |> set_result result;
   607                     val assigned_node = SOME (name, node');
   608                     val result_changed = changed_result node0 node';
   609                   in ((removed, assign_update, assigned_node, result_changed), node') end
   610                 else (([], [], NONE, false), node)
   611               end)))
   612       |> Future.joins |> map #1);
   613 
   614     val removed = maps #1 updated;
   615     val assign_update = maps #2 updated;
   616     val assigned_nodes = map_filter #3 updated;
   617 
   618     val state' = state
   619       |> define_version new_version_id (fold put_node assigned_nodes new_version);
   620 
   621   in (removed, assign_update, state') end;
   622 
   623 end;
   624 
   625 
   626 
   627 (** global state **)
   628 
   629 val global_state = Synchronized.var "Document.global_state" init_state;
   630 
   631 fun state () = Synchronized.value global_state;
   632 val change_state = Synchronized.change global_state;
   633 
   634 end;
   635