diff --git a/src/Pure/PIDE/command.ML b/src/Pure/PIDE/command.ML
--- a/src/Pure/PIDE/command.ML
+++ b/src/Pure/PIDE/command.ML
@@ -1,511 +1,516 @@
 (*  Title:      Pure/PIDE/command.ML
     Author:     Makarius
 
 Prover command execution: read -- eval -- print.
 *)
 
 signature COMMAND =
 sig
   type blob = {file_node: string, src_path: Path.T, content: (SHA1.digest * string list) option}
   val read_file: Path.T -> Position.T -> bool -> Path.T -> Token.file
   val read_thy: Toplevel.state -> theory
   val read: Keyword.keywords -> theory -> Path.T-> (unit -> theory) ->
     blob Exn.result list * int -> Token.T list -> Toplevel.transition
+  val read_span: Keyword.keywords -> Toplevel.state -> Path.T -> (unit -> theory) ->
+    Command_Span.span -> Toplevel.transition
   type eval
   val eval_command_id: eval -> Document_ID.command
   val eval_exec_id: eval -> Document_ID.exec
   val eval_eq: eval * eval -> bool
   val eval_running: eval -> bool
   val eval_finished: eval -> bool
   val eval_result_command: eval -> Toplevel.transition
   val eval_result_state: eval -> Toplevel.state
   val eval: Keyword.keywords -> Path.T -> (unit -> theory) ->
     blob Exn.result list * int -> Document_ID.command -> Token.T list -> eval -> eval
   type print
   type print_fn = Toplevel.transition -> Toplevel.state -> unit
   val print0: {pri: int, print_fn: print_fn} -> eval -> print
   val print: bool -> (string * string list) list -> Keyword.keywords -> string ->
     eval -> print list -> print list option
   val parallel_print: print -> bool
   type print_function =
     {keywords: Keyword.keywords, command_name: string, args: string list, exec_id: Document_ID.exec} ->
       {delay: Time.time option, pri: int, persistent: bool, strict: bool, print_fn: print_fn} option
   val print_function: string -> print_function -> unit
   val no_print_function: string -> unit
   type exec = eval * print list
   val init_exec: theory option -> exec
   val no_exec: exec
   val exec_ids: exec option -> Document_ID.exec list
   val exec: Document_ID.execution -> exec -> unit
   val exec_parallel_prints: Document_ID.execution -> Future.task list -> exec -> exec option
 end;
 
 structure Command: COMMAND =
 struct
 
 (** main phases of execution **)
 
 fun task_context group f =
   f
   |> Future.interruptible_task
   |> Future.task_context "Command.run_process" group;
 
 
 (* read *)
 
 type blob = {file_node: string, src_path: Path.T, content: (SHA1.digest * string list) option};
 
 fun read_file_node file_node master_dir pos delimited src_path =
   let
     val _ =
       if Context_Position.pide_reports ()
       then Position.report pos (Markup.language_path delimited) else ();
 
     fun read_file () =
       let
         val path = File.check_file (File.full_path master_dir src_path);
         val text = File.read path;
         val file_pos = Path.position path;
       in (text, file_pos) end;
 
     fun read_url () =
       let
         val text = Isabelle_System.download file_node;
         val file_pos = Position.file file_node;
       in (text, file_pos) end;
 
     val (text, file_pos) =
       (case try Url.explode file_node of
         NONE => read_file ()
       | SOME (Url.File _) => read_file ()
       | _ => read_url ());
 
     val lines = split_lines text;
     val digest = SHA1.digest text;
   in {src_path = src_path, lines = lines, digest = digest, pos = Position.copy_id pos file_pos} end
   handle ERROR msg => error (msg ^ Position.here pos);
 
 val read_file = read_file_node "";
 
 local
 
 fun blob_file src_path lines digest file_node =
   let
     val file_pos =
       Position.file file_node |>
       (case Position.get_id (Position.thread_data ()) of
         NONE => I
       | SOME exec_id => Position.put_id exec_id);
   in {src_path = src_path, lines = lines, digest = digest, pos = file_pos} end
 
 fun resolve_files master_dir (blobs, blobs_index) toks =
   (case Outer_Syntax.parse_spans toks of
     [Command_Span.Span (Command_Span.Command_Span _, _)] =>
       (case try (nth toks) blobs_index of
         SOME tok =>
           let
             val source = Token.input_of tok;
             val pos = Input.pos_of source;
             val delimited = Input.is_delimited source;
 
             fun make_file (Exn.Res {file_node, src_path, content = NONE}) =
                   Exn.interruptible_capture (fn () =>
                     read_file_node file_node master_dir pos delimited src_path) ()
               | make_file (Exn.Res {file_node, src_path, content = SOME (digest, lines)}) =
                   (Position.report pos (Markup.language_path delimited);
                     Exn.Res (blob_file src_path lines digest file_node))
               | make_file (Exn.Exn e) = Exn.Exn e;
             val files = map make_file blobs;
           in
             toks |> map_index (fn (i, tok) =>
               if i = blobs_index then Token.put_files files tok else tok)
           end
       | NONE => toks)
   | _ => toks);
 
 fun reports_of_token keywords tok =
   let
     val malformed_symbols =
       Input.source_explode (Token.input_of tok)
       |> map_filter (fn (sym, pos) =>
           if Symbol.is_malformed sym
           then SOME ((pos, Markup.bad ()), "Malformed symbolic character") else NONE);
     val is_malformed = Token.is_error tok orelse not (null malformed_symbols);
     val reports = Token.reports keywords tok @ Token.completion_report tok @ malformed_symbols;
   in (is_malformed, reports) end;
 
 in
 
 fun read_thy st = Toplevel.theory_of st
   handle Toplevel.UNDEF => Pure_Syn.bootstrap_thy;
 
 fun read keywords thy master_dir init blobs_info span =
   let
     val command_reports = Outer_Syntax.command_reports thy;
 
     val core_range = Token.range_of (drop_suffix Token.is_ignored span);
     val pos =
       (case find_first Token.is_command span of
         SOME tok => Token.pos_of tok
       | NONE => #1 core_range);
 
     val token_reports = map (reports_of_token keywords) span;
     val _ = Position.reports_text (maps #2 token_reports @ maps command_reports span);
 
     val verbatim =
       span |> map_filter (fn tok =>
         if Token.kind_of tok = Token.Verbatim then SOME (Token.pos_of tok) else NONE);
     val _ =
       if null verbatim then ()
       else legacy_feature ("Old-style {* verbatim *} token -- use \<open>cartouche\<close> instead" ^
         Position.here_list verbatim);
   in
     if exists #1 token_reports then Toplevel.malformed pos "Malformed command syntax"
     else Outer_Syntax.parse_span thy init (resolve_files master_dir blobs_info span)
   end;
 
 end;
 
+fun read_span keywords st master_dir init =
+  Command_Span.content #> read keywords (read_thy st) master_dir init ([], ~1);
+
 
 (* eval *)
 
 type eval_state = {failed: bool, command: Toplevel.transition, state: Toplevel.state};
 
 fun init_eval_state opt_thy =
  {failed = false,
   command = Toplevel.empty,
   state =
     (case opt_thy of
       NONE => Toplevel.init_toplevel ()
     | SOME thy => Toplevel.theory_toplevel thy)};
 
 datatype eval =
   Eval of
     {command_id: Document_ID.command, exec_id: Document_ID.exec, eval_process: eval_state lazy};
 
 fun eval_command_id (Eval {command_id, ...}) = command_id;
 
 fun eval_exec_id (Eval {exec_id, ...}) = exec_id;
 val eval_eq = op = o apply2 eval_exec_id;
 
 val eval_running = Execution.is_running_exec o eval_exec_id;
 fun eval_finished (Eval {eval_process, ...}) = Lazy.is_finished eval_process;
 
 fun eval_result (Eval {eval_process, ...}) =
   Exn.release (Lazy.finished_result eval_process);
 
 val eval_result_command = #command o eval_result;
 val eval_result_state = #state o eval_result;
 
 local
 
 fun reset_state keywords tr st0 = Toplevel.setmp_thread_position tr (fn () =>
   let
     val name = Toplevel.name_of tr;
     val res =
       if Keyword.is_theory_body keywords name then Toplevel.reset_theory st0
       else if Keyword.is_proof keywords name then Toplevel.reset_proof st0
       else if Keyword.is_theory_end keywords name then
         (case Toplevel.reset_notepad st0 of
           NONE => Toplevel.reset_theory st0
         | some => some)
       else NONE;
   in
     (case res of
       NONE => st0
     | SOME st => (Output.error_message (Toplevel.type_error tr ^ " -- using reset state"); st))
   end) ();
 
 fun run keywords int tr st =
   if Future.proofs_enabled 1 andalso Keyword.is_diag keywords (Toplevel.name_of tr) then
     let
       val (tr1, tr2) = Toplevel.fork_presentation tr;
       val _ =
         Execution.fork {name = "Toplevel.diag", pos = Toplevel.pos_of tr, pri = ~1}
           (fn () => Toplevel.command_exception int tr1 st);
     in Toplevel.command_errors int tr2 st end
   else Toplevel.command_errors int tr st;
 
 fun check_token_comments ctxt tok =
   (Thy_Output.check_comments ctxt (Input.source_explode (Token.input_of tok)); [])
     handle exn =>
       if Exn.is_interrupt exn then Exn.reraise exn
       else Runtime.exn_messages exn;
 
 fun check_span_comments ctxt span tr =
   Toplevel.setmp_thread_position tr (fn () => maps (check_token_comments ctxt) span) ();
 
 fun report tr m =
   Toplevel.setmp_thread_position tr (fn () => Output.report [Markup.markup_only m]) ();
 
 fun status tr m =
   Toplevel.setmp_thread_position tr (fn () => Output.status [Markup.markup_only m]) ();
 
 fun command_indent tr st =
   (case try Toplevel.proof_of st of
     SOME prf =>
       let val keywords = Thy_Header.get_keywords (Proof.theory_of prf) in
         if Keyword.command_kind keywords (Toplevel.name_of tr) = SOME Keyword.prf_script then
           (case try Proof.goal prf of
             SOME {goal, ...} =>
               let val n = Thm.nprems_of goal
               in if n > 1 then report tr (Markup.command_indent (n - 1)) else () end
           | NONE => ())
         else ()
       end
   | NONE => ());
 
 
 fun eval_state keywords span tr ({state, ...}: eval_state) =
   let
     val _ = Thread_Attributes.expose_interrupt ();
 
     val st = reset_state keywords tr state;
 
     val _ = command_indent tr st;
     val _ = status tr Markup.running;
     val (errs1, result) = run keywords true tr st;
     val errs2 =
       (case result of
         NONE => []
       | SOME st' => check_span_comments (Toplevel.presentation_context st') span tr);
     val errs = errs1 @ errs2;
     val _ = List.app (Future.error_message (Toplevel.pos_of tr)) errs;
   in
     (case result of
       NONE =>
         let
           val _ = status tr Markup.failed;
           val _ = status tr Markup.finished;
           val _ = if null errs then (status tr Markup.canceled; Exn.interrupt ()) else ();
         in {failed = true, command = tr, state = st} end
     | SOME st' =>
         let
           val _ =
             if Keyword.is_theory_end keywords (Toplevel.name_of tr) andalso
               can (Toplevel.end_theory Position.none) st'
             then status tr Markup.finalized else ();
           val _ = status tr Markup.finished;
         in {failed = false, command = tr, state = st'} end)
   end;
 
 in
 
 fun eval keywords master_dir init blobs_info command_id span eval0 =
   let
     val exec_id = Document_ID.make ();
     fun process () =
       let
         val eval_state0 = eval_result eval0;
         val thy = read_thy (#state eval_state0);
         val tr =
           Position.setmp_thread_data (Position.id_only (Document_ID.print exec_id))
             (fn () =>
               read keywords thy master_dir init blobs_info span |> Toplevel.exec_id exec_id) ();
       in eval_state keywords span tr eval_state0 end;
   in
     Eval {command_id = command_id, exec_id = exec_id,
       eval_process = Lazy.lazy_name "Command.eval" process}
   end;
 
 end;
 
 
 (* print *)
 
 datatype print = Print of
  {name: string, args: string list, delay: Time.time option, pri: int, persistent: bool,
   exec_id: Document_ID.exec, print_process: unit lazy};
 
 fun print_exec_id (Print {exec_id, ...}) = exec_id;
 val print_eq = op = o apply2 print_exec_id;
 
 type print_fn = Toplevel.transition -> Toplevel.state -> unit;
 
 type print_function =
   {keywords: Keyword.keywords, command_name: string, args: string list, exec_id: Document_ID.exec} ->
     {delay: Time.time option, pri: int, persistent: bool, strict: bool, print_fn: print_fn} option;
 
 local
 
 val print_functions =
   Synchronized.var "Command.print_functions" ([]: (string * print_function) list);
 
 fun print_error tr opt_context e =
   (Toplevel.setmp_thread_position tr o Runtime.controlled_execution opt_context) e ()
     handle exn =>
       if Exn.is_interrupt exn then Exn.reraise exn
       else List.app (Future.error_message (Toplevel.pos_of tr)) (Runtime.exn_messages exn);
 
 fun print_finished (Print {print_process, ...}) = Lazy.is_finished print_process;
 
 fun print_persistent (Print {persistent, ...}) = persistent;
 
 val overlay_ord = prod_ord string_ord (list_ord string_ord);
 
 fun make_print (name, args) {delay, pri, persistent, strict, print_fn} eval =
   let
     val exec_id = Document_ID.make ();
     fun process () =
       let
         val {failed, command, state = st', ...} = eval_result eval;
         val tr = Toplevel.exec_id exec_id command;
         val opt_context = try Toplevel.generic_theory_of st';
       in
         if failed andalso strict then ()
         else print_error tr opt_context (fn () => print_fn tr st')
       end;
   in
     Print {
       name = name, args = args, delay = delay, pri = pri, persistent = persistent,
       exec_id = exec_id, print_process = Lazy.lazy_name "Command.print" process}
   end;
 
 fun bad_print name_args exn =
   make_print name_args {delay = NONE, pri = 0, persistent = false,
     strict = false, print_fn = fn _ => fn _ => Exn.reraise exn};
 
 in
 
 fun print0 {pri, print_fn} =
   make_print ("", [serial_string ()])
     {delay = NONE, pri = pri, persistent = true, strict = true, print_fn = print_fn};
 
 fun print command_visible command_overlays keywords command_name eval old_prints =
   let
     val print_functions = Synchronized.value print_functions;
 
     fun new_print (name, args) get_pr =
       let
         val params =
          {keywords = keywords,
           command_name = command_name,
           args = args,
           exec_id = eval_exec_id eval};
       in
         (case Exn.capture (Runtime.controlled_execution NONE get_pr) params of
           Exn.Res NONE => NONE
         | Exn.Res (SOME pr) => SOME (make_print (name, args) pr eval)
         | Exn.Exn exn => SOME (bad_print (name, args) exn eval))
       end;
 
     fun get_print (name, args) =
       (case find_first (fn Print print => (#name print, #args print) = (name, args)) old_prints of
         NONE =>
           (case AList.lookup (op =) print_functions name of
             NONE =>
               SOME (bad_print (name, args) (ERROR ("Missing print function " ^ quote name)) eval)
           | SOME get_pr => new_print (name, args) get_pr)
       | some => some);
 
     val retained_prints =
       filter (fn print => print_finished print andalso print_persistent print) old_prints;
     val visible_prints =
       if command_visible then
         fold (fn (name, _) => cons (name, [])) print_functions command_overlays
         |> sort_distinct overlay_ord
         |> map_filter get_print
       else [];
     val new_prints = visible_prints @ retained_prints;
   in
     if eq_list print_eq (old_prints, new_prints) then NONE else SOME new_prints
   end;
 
 fun parallel_print (Print {pri, ...}) =
   pri <= 0 orelse (Future.enabled () andalso Options.default_bool "parallel_print");
 
 fun print_function name f =
   Synchronized.change print_functions (fn funs =>
    (if name = "" then error "Unnamed print function" else ();
     if not (AList.defined (op =) funs name) then ()
     else warning ("Redefining command print function: " ^ quote name);
     AList.update (op =) (name, f) funs));
 
 fun no_print_function name =
   Synchronized.change print_functions (filter_out (equal name o #1));
 
 end;
 
 val _ =
   print_function "Execution.print"
     (fn {args, exec_id, ...} =>
       if null args then
         SOME {delay = NONE, pri = Task_Queue.urgent_pri + 2, persistent = false, strict = false,
           print_fn = fn _ => fn _ => Execution.fork_prints exec_id}
       else NONE);
 
 val _ =
   print_function "print_state"
     (fn {keywords, command_name, ...} =>
       if Options.default_bool "editor_output_state" andalso Keyword.is_printed keywords command_name
       then
         SOME {delay = NONE, pri = Task_Queue.urgent_pri + 1, persistent = false, strict = false,
           print_fn = fn _ => fn st =>
             if Toplevel.is_proof st then Output.state (Toplevel.string_of_state st)
             else ()}
       else NONE);
 
 
 (* combined execution *)
 
 type exec = eval * print list;
 
 fun init_exec opt_thy : exec =
   (Eval
     {command_id = Document_ID.none, exec_id = Document_ID.none,
       eval_process = Lazy.value (init_eval_state opt_thy)}, []);
 
 val no_exec = init_exec NONE;
 
 fun exec_ids NONE = []
   | exec_ids (SOME (eval, prints)) = eval_exec_id eval :: map print_exec_id prints;
 
 local
 
 fun run_process execution_id exec_id process =
   let val group = Future.worker_subgroup () in
     if Execution.running execution_id exec_id [group] then
       ignore (task_context group (fn () => Lazy.force_result {strict = true} process) ())
     else ()
   end;
 
 fun ignore_process process =
   Lazy.is_running process orelse Lazy.is_finished process;
 
 fun run_eval execution_id (Eval {exec_id, eval_process, ...}) =
   if Lazy.is_finished eval_process then ()
   else run_process execution_id exec_id eval_process;
 
 fun fork_print execution_id deps (Print {name, delay, pri, exec_id, print_process, ...}) =
   let
     val group = Future.worker_subgroup ();
     fun fork () =
       ignore ((singleton o Future.forks)
         {name = name, group = SOME group, deps = deps, pri = pri, interrupts = true}
         (fn () =>
           if ignore_process print_process then ()
           else run_process execution_id exec_id print_process));
   in
     (case delay of
       NONE => fork ()
     | SOME d => ignore (Event_Timer.request {physical = true} (Time.now () + d) fork))
   end;
 
 fun run_print execution_id (print as Print {exec_id, print_process, ...}) =
   if ignore_process print_process then ()
   else if parallel_print print then fork_print execution_id [] print
   else run_process execution_id exec_id print_process;
 
 in
 
 fun exec execution_id (eval, prints) =
   (run_eval execution_id eval; List.app (run_print execution_id) prints);
 
 fun exec_parallel_prints execution_id deps (exec as (Eval {eval_process, ...}, prints)) =
   if Lazy.is_finished eval_process
   then (List.app (fork_print execution_id deps) prints; NONE)
   else SOME exec;
 
 end;
 
 end;
diff --git a/src/Pure/Thy/thy_info.ML b/src/Pure/Thy/thy_info.ML
--- a/src/Pure/Thy/thy_info.ML
+++ b/src/Pure/Thy/thy_info.ML
@@ -1,468 +1,467 @@
 (*  Title:      Pure/Thy/thy_info.ML
     Author:     Makarius
 
 Global theory info database, with auto-loading according to theory and
 file dependencies, and presentation of theory documents.
 *)
 
 signature THY_INFO =
 sig
   type presentation_context =
     {options: Options.T, file_pos: Position.T, adjust_pos: Position.T -> Position.T,
       segments: Thy_Output.segment list}
   val adjust_pos_properties: presentation_context -> Position.T -> Properties.T
   val apply_presentation: presentation_context -> theory -> unit
   val add_presentation: (presentation_context -> theory -> unit) -> theory -> theory
   val get_names: unit -> string list
   val lookup_theory: string -> theory option
   val get_theory: string -> theory
   val master_directory: string -> Path.T
   val remove_thy: string -> unit
   val use_theories: Options.T -> string -> (string * Position.T) list -> unit
   val use_thy: string -> unit
   val script_thy: Position.T -> string -> theory -> theory
   val register_thy: theory -> unit
   val finish: unit -> unit
 end;
 
 structure Thy_Info: THY_INFO =
 struct
 
 (** theory presentation **)
 
 (* artefact names *)
 
 fun document_name ext thy =
   Path.explode_binding0 ("document/" ^ Context.theory_name thy ^ "." ^ ext);
 
 val document_tex_name = document_name "tex";
 
 
 (* hook for consolidated theory *)
 
 type presentation_context =
   {options: Options.T, file_pos: Position.T, adjust_pos: Position.T -> Position.T,
     segments: Thy_Output.segment list};
 
 fun adjust_pos_properties (context: presentation_context) pos =
   Position.offset_properties_of (#adjust_pos context pos) @ Position.id_properties_of pos;
 
 structure Presentation = Theory_Data
 (
   type T = ((presentation_context -> theory -> unit) * stamp) list;
   val empty = [];
   val extend = I;
   fun merge data : T = Library.merge (eq_snd op =) data;
 );
 
 fun apply_presentation (context: presentation_context) thy =
   ignore (Presentation.get thy |> Par_List.map (fn (f, _) => f context thy));
 
 fun add_presentation f = Presentation.map (cons (f, stamp ()));
 
 val _ =
   Theory.setup (add_presentation (fn {options, file_pos, segments, ...} => fn thy =>
     if exists (Toplevel.is_skipped_proof o #state) segments then ()
     else
       let
         val body = Thy_Output.present_thy options thy segments;
       in
         if Options.string options "document" = "false" then ()
         else
           let
             val thy_name = Context.theory_name thy;
             val document_tex_name = document_tex_name thy;
 
             val latex = Latex.isabelle_body thy_name body;
             val output = [Latex.output_text latex, Latex.output_positions file_pos latex];
           in Export.export thy document_tex_name (XML.blob output) end
       end));
 
 
 
 (** thy database **)
 
 (* messages *)
 
 val show_path = space_implode " via " o map quote;
 
 fun cycle_msg names = "Cyclic dependency of " ^ show_path names;
 
 
 (* derived graph operations *)
 
 fun add_deps name parents G = String_Graph.add_deps_acyclic (name, parents) G
   handle String_Graph.CYCLES namess => error (cat_lines (map cycle_msg namess));
 
 fun new_entry name parents entry =
   String_Graph.new_node (name, entry) #> add_deps name parents;
 
 
 (* global thys *)
 
 type deps =
  {master: (Path.T * SHA1.digest),  (*master dependencies for thy file*)
   imports: (string * Position.T) list};  (*source specification of imports (partially qualified)*)
 
 fun make_deps master imports : deps = {master = master, imports = imports};
 
 fun master_dir_deps (d: deps option) =
   the_default Path.current (Option.map (Path.dir o #1 o #master) d);
 
 local
   val global_thys =
     Synchronized.var "Thy_Info.thys"
       (String_Graph.empty: (deps option * theory option) String_Graph.T);
 in
   fun get_thys () = Synchronized.value global_thys;
   fun change_thys f = Synchronized.change global_thys f;
 end;
 
 fun get_names () = String_Graph.topological_order (get_thys ());
 
 
 (* access thy *)
 
 fun lookup thys name = try (String_Graph.get_node thys) name;
 fun lookup_thy name = lookup (get_thys ()) name;
 
 fun get thys name =
   (case lookup thys name of
     SOME thy => thy
   | NONE => error ("Theory loader: nothing known about theory " ^ quote name));
 
 fun get_thy name = get (get_thys ()) name;
 
 
 (* access deps *)
 
 val lookup_deps = Option.map #1 o lookup_thy;
 
 val master_directory = master_dir_deps o #1 o get_thy;
 
 
 (* access theory *)
 
 fun lookup_theory name =
   (case lookup_thy name of
     SOME (_, SOME theory) => SOME theory
   | _ => NONE);
 
 fun get_theory name =
   (case lookup_theory name of
     SOME theory => theory
   | _ => error ("Theory loader: undefined entry for theory " ^ quote name));
 
 val get_imports = Resources.imports_of o get_theory;
 
 
 
 (** thy operations **)
 
 (* remove *)
 
 fun remove name thys =
   (case lookup thys name of
     NONE => thys
   | SOME (NONE, _) => error ("Cannot update finished theory " ^ quote name)
   | SOME _ =>
       let
         val succs = String_Graph.all_succs thys [name];
         val _ = writeln ("Theory loader: removing " ^ commas_quote succs);
       in fold String_Graph.del_node succs thys end);
 
 val remove_thy = change_thys o remove;
 
 
 (* update *)
 
 fun update deps theory thys =
   let
     val name = Context.theory_long_name theory;
     val parents = map Context.theory_long_name (Theory.parents_of theory);
 
     val thys' = remove name thys;
     val _ = map (get thys') parents;
   in new_entry name parents (SOME deps, SOME theory) thys' end;
 
 fun update_thy deps theory = change_thys (update deps theory);
 
 
 (* scheduling loader tasks *)
 
 datatype result =
   Result of {theory: theory, exec_id: Document_ID.exec,
     present: unit -> unit, commit: unit -> unit, weight: int};
 
 fun theory_result theory =
   Result {theory = theory, exec_id = Document_ID.none, present = I, commit = I, weight = 0};
 
 fun result_theory (Result {theory, ...}) = theory;
 fun result_present (Result {present, ...}) = present;
 fun result_commit (Result {commit, ...}) = commit;
 fun result_ord (Result {weight = i, ...}, Result {weight = j, ...}) = int_ord (j, i);
 
 fun join_theory (Result {theory, exec_id, ...}) =
   let
     val _ = Execution.join [exec_id];
     val res = Exn.capture Thm.consolidate_theory theory;
     val exns = maps Task_Queue.group_status (Execution.peek exec_id);
   in res :: map Exn.Exn exns end;
 
 datatype task =
   Task of string list * (theory list -> result) |
   Finished of theory;
 
 fun task_finished (Task _) = false
   | task_finished (Finished _) = true;
 
 fun task_parents deps (parents: string list) = map (the o AList.lookup (op =) deps) parents;
 
 val schedule_seq =
   String_Graph.schedule (fn deps => fn (_, task) =>
     (case task of
       Task (parents, body) =>
         let
           val result = body (task_parents deps parents);
           val _ = Par_Exn.release_all (join_theory result);
           val _ = result_present result ();
           val _ = result_commit result ();
         in result_theory result end
     | Finished thy => thy)) #> ignore;
 
 val schedule_futures = Thread_Attributes.uninterruptible (fn _ => fn tasks =>
   let
     val futures = tasks
       |> String_Graph.schedule (fn deps => fn (name, task) =>
         (case task of
           Task (parents, body) =>
             (singleton o Future.forks)
               {name = "theory:" ^ name, group = NONE,
                 deps = map (Future.task_of o #2) deps, pri = 0, interrupts = true}
               (fn () =>
                 (case filter (not o can Future.join o #2) deps of
                   [] => body (map (result_theory o Future.join) (task_parents deps parents))
                 | bad =>
                     error
                       ("Failed to load theory " ^ quote name ^
                         " (unresolved " ^ commas_quote (map #1 bad) ^ ")")))
         | Finished theory => Future.value (theory_result theory)));
 
     val results1 = futures
       |> maps (fn future =>
           (case Future.join_result future of
             Exn.Res result => join_theory result
           | Exn.Exn exn => [Exn.Exn exn]));
 
     val results2 = futures
       |> map_filter (Exn.get_res o Future.join_result)
       |> sort result_ord
       |> Par_List.map (fn result => Exn.capture (result_present result) ());
 
     (* FIXME more precise commit order (!?) *)
     val results3 = futures
       |> map (fn future => Exn.capture (fn () => result_commit (Future.join future) ()) ());
 
     (* FIXME avoid global Execution.reset (!??) *)
     val results4 = map Exn.Exn (maps Task_Queue.group_status (Execution.reset ()));
 
     val _ = Par_Exn.release_all (results1 @ results2 @ results3 @ results4);
   in () end);
 
 
 (* eval theory *)
 
 fun excursion keywords master_dir init elements =
   let
-    fun prepare_span st span =
-      Command_Span.content span
-      |> Command.read keywords (Command.read_thy st) master_dir init ([], ~1)
-      |> (fn tr => Toplevel.timing (Resources.last_timing tr) tr);
+    fun prepare_span st =
+      Command.read_span keywords st master_dir init
+      #> (fn tr => Toplevel.timing (Resources.last_timing tr) tr);
 
     fun element_result span_elem (st, _) =
       let
         val elem = Thy_Element.map_element (prepare_span st) span_elem;
         val (results, st') = Toplevel.element_result keywords elem st;
         val pos' = Toplevel.pos_of (Thy_Element.last_element elem);
       in (results, (st', pos')) end;
 
     val (results, (end_state, end_pos)) =
       fold_map element_result elements (Toplevel.init_toplevel (), Position.none);
 
     val thy = Toplevel.end_theory end_pos end_state;
   in (results, thy) end;
 
 fun eval_thy options master_dir header text_pos text parents =
   let
     val (name, _) = #name header;
     val keywords =
       fold (curry Keyword.merge_keywords o Thy_Header.get_keywords) parents
         (Keyword.add_keywords (#keywords header) Keyword.empty_keywords);
 
     val spans = Outer_Syntax.parse_spans (Token.explode keywords text_pos text);
     val elements = Thy_Element.parse_elements keywords spans;
 
     fun init () = Resources.begin_theory master_dir header parents;
     val (results, thy) =
       cond_timeit true ("theory " ^ quote name)
         (fn () => excursion keywords master_dir init elements);
 
     fun present () =
       let
         val segments = (spans ~~ maps Toplevel.join_results results)
           |> map (fn (span, (tr, st')) => {span = span, command = tr, state = st'});
         val context: presentation_context =
           {options = options, file_pos = text_pos, adjust_pos = I, segments = segments};
       in apply_presentation context thy end;
   in (thy, present, size text) end;
 
 
 (* require_thy -- checking database entries wrt. the file-system *)
 
 local
 
 fun required_by _ [] = ""
   | required_by s initiators = s ^ "(required by " ^ show_path (rev initiators) ^ ")";
 
 fun load_thy options initiators deps text (name, pos) keywords parents =
   let
     val exec_id = Document_ID.make ();
     val id = Document_ID.print exec_id;
     val _ =
       Execution.running Document_ID.none exec_id [] orelse
         raise Fail ("Failed to register execution: " ^ id);
 
     val {master = (thy_path, _), imports} = deps;
     val dir = Path.dir thy_path;
     val header = Thy_Header.make (name, pos) imports keywords;
     val _ =
       (imports ~~ parents) |> List.app (fn ((_, pos), thy) =>
         Context_Position.reports_global thy [(pos, Theory.get_markup thy)]);
 
     val text_pos = Position.put_id id (Path.position thy_path);
     val text_props = Position.properties_of text_pos;
 
     val _ = remove_thy name;
     val _ = writeln ("Loading theory " ^ quote name ^ required_by " " initiators);
     val _ = Output.try_protocol_message (Markup.loading_theory name @ text_props) (XML.blob [text]);
 
     val timing_start = Timing.start ();
 
     val (theory, present, weight) =
       eval_thy options dir header text_pos text
         (if name = Context.PureN then [Context.the_global_context ()] else parents);
 
     val timing_result = Timing.result timing_start;
     val timing_props = [Markup.theory_timing, (Markup.nameN, name)];
     val _  = Output.try_protocol_message (timing_props @ Markup.timing_properties timing_result) []
 
     fun commit () = update_thy deps theory;
   in
     Result {theory = theory, exec_id = exec_id, present = present, commit = commit, weight = weight}
   end;
 
 fun check_thy_deps dir name =
   (case lookup_deps name of
     SOME NONE => (true, NONE, Position.none, get_imports name, [])
   | NONE =>
       let val {master, text, theory_pos, imports, keywords} = Resources.check_thy dir name
       in (false, SOME (make_deps master imports, text), theory_pos, imports, keywords) end
   | SOME (SOME {master, ...}) =>
       let
         val {master = master', text = text', theory_pos = theory_pos', imports = imports',
           keywords = keywords'} = Resources.check_thy dir name;
         val deps' = SOME (make_deps master' imports', text');
         val current =
           #2 master = #2 master' andalso
             (case lookup_theory name of
               NONE => false
             | SOME theory => Resources.loaded_files_current theory);
       in (current, deps', theory_pos', imports', keywords') end);
 
 in
 
 fun require_thys options initiators qualifier dir strs tasks =
       fold_map (require_thy options initiators qualifier dir) strs tasks |>> forall I
 and require_thy options initiators qualifier dir (s, require_pos) tasks =
   let
     val {master_dir, theory_name, ...} = Resources.import_name qualifier dir s;
   in
     (case try (String_Graph.get_node tasks) theory_name of
       SOME task => (task_finished task, tasks)
     | NONE =>
         let
           val _ = member (op =) initiators theory_name andalso error (cycle_msg initiators);
 
           val (current, deps, theory_pos, imports, keywords) = check_thy_deps master_dir theory_name
             handle ERROR msg =>
               cat_error msg
                 ("The error(s) above occurred for theory " ^ quote theory_name ^
                   Position.here require_pos ^ required_by "\n" initiators);
 
           val qualifier' = Resources.theory_qualifier theory_name;
           val dir' = dir + master_dir_deps (Option.map #1 deps);
 
           val parents = map (#theory_name o Resources.import_name qualifier' dir' o #1) imports;
           val (parents_current, tasks') =
             require_thys options (theory_name :: initiators) qualifier' dir' imports tasks;
 
           val all_current = current andalso parents_current;
           val task =
             if all_current then Finished (get_theory theory_name)
             else
               (case deps of
                 NONE => raise Fail "Malformed deps"
               | SOME (dep, text) =>
                   Task (parents,
                     load_thy options initiators dep text (theory_name, theory_pos) keywords));
 
           val tasks'' = new_entry theory_name parents task tasks';
         in (all_current, tasks'') end)
   end;
 
 end;
 
 
 (* use theories *)
 
 fun use_theories options qualifier imports =
   let val (_, tasks) = require_thys options [] qualifier Path.current imports String_Graph.empty
   in if Multithreading.max_threads () > 1 then schedule_futures tasks else schedule_seq tasks end;
 
 fun use_thy name =
   use_theories (Options.default ()) Resources.default_qualifier [(name, Position.none)];
 
 
 (* toplevel scripting -- without maintaining database *)
 
 fun script_thy pos txt thy =
   let
     val trs = Outer_Syntax.parse_text thy (K thy) pos txt;
     val end_pos = if null trs then pos else Toplevel.pos_of (List.last trs);
     val end_state = fold (Toplevel.command_exception true) trs (Toplevel.init_toplevel ());
   in Toplevel.end_theory end_pos end_state end;
 
 
 (* register theory *)
 
 fun register_thy theory =
   let
     val name = Context.theory_long_name theory;
     val {master, ...} = Resources.check_thy (Resources.master_directory theory) name;
     val imports = Resources.imports_of theory;
   in
     change_thys (fn thys =>
       let
         val thys' = remove name thys;
         val _ = writeln ("Registering theory " ^ quote name);
       in update (make_deps master imports) theory thys' end)
   end;
 
 
 (* finish all theories *)
 
 fun finish () = change_thys (String_Graph.map (fn _ => fn (_, entry) => (NONE, entry)));
 
 end;
 
 fun use_thy name = Runtime.toplevel_program (fn () => Thy_Info.use_thy name);