(*  Title:      Pure/Thy/thy_info.ML

     Author:     Markus Wenzel, TU Muenchen

 Main part of theory loader database, including handling of theory and

 file dependencies.

 *)

 signature THY_INFO =

 sig

   datatype action = Update | Outdate | Remove

   val str_of_action: action -> string

   val add_hook: (action -> string -> unit) -> unit

   val get_names: unit -> string list

   val known_thy: string -> bool

   val check_known_thy: string -> bool

   val if_known_thy: (string -> unit) -> string -> unit

   val lookup_theory: string -> theory option

   val get_theory: string -> theory

   val the_theory: string -> theory -> theory

   val is_finished: string -> bool

   val master_directory: string -> Path.T

   val loaded_files: string -> Path.T list

   val get_parents: string -> string list

   val touch_thy: string -> unit

   val touch_child_thys: string -> unit

   val thy_ord: theory * theory -> order

   val remove_thy: string -> unit

   val kill_thy: string -> unit

   val provide_file: Path.T -> string -> unit

   val load_file: bool -> Path.T -> unit

   val exec_file: bool -> Path.T -> Context.generic -> Context.generic

   val use: string -> unit

   val time_use: string -> unit

   val use_thys: string list -> unit

   val use_thy: string -> unit

   val time_use_thy: string -> unit

   val begin_theory: string -> string list -> (Path.T * bool) list -> bool -> theory

   val end_theory: theory -> unit

   val register_thy: string -> unit

   val register_theory: theory -> unit

   val finish: unit -> unit

 end;

 structure Thy_Info: THY_INFO =

 struct

 (** theory loader actions and hooks **)

 datatype action = Update | Outdate | Remove;

 val str_of_action = fn Update => "Update" | Outdate => "Outdate" | Remove => "Remove";

 local

   val hooks = Unsynchronized.ref ([]: (action -> string -> unit) list);

 in

   fun add_hook f = CRITICAL (fn () => Unsynchronized.change hooks (cons f));

   fun perform action name = List.app (fn f => (try (fn () => f action name) (); ())) (! hooks);

 end;

 (** thy database **)

 (* messages *)

 fun loader_msg txt [] = "Theory loader: " ^ txt

   | loader_msg txt names = "Theory loader: " ^ txt ^ " " ^ commas_quote names;

 val show_path = space_implode " via " o map quote;

 fun cycle_msg names = loader_msg ("cyclic dependency of " ^ show_path names) [];

 (* derived graph operations *)

 fun add_deps name parents G = Graph.add_deps_acyclic (name, parents) G

   handle Graph.CYCLES namess => error (cat_lines (map cycle_msg namess));

 fun upd_deps name entry G =

   fold (fn parent => Graph.del_edge (parent, name)) (Graph.imm_preds G name) G

   |> Graph.map_node name (K entry);

 fun new_deps name parents entry G =

   (if can (Graph.get_node G) name then upd_deps name entry G else Graph.new_node (name, entry) G)

   |> add_deps name parents;

 (* thy database *)

 type deps =

   {update_time: int,                      (*symbolic time of update; negative value means outdated*)

     master: (Path.T * File.ident) option, (*master dependencies for thy file*)

     text: string list,                    (*source text for thy*)

     parents: string list,                 (*source specification of parents (partially qualified)*)

       (*auxiliary files: source path, physical path + identifier*)

     files: (Path.T * (Path.T * File.ident) option) list};

 fun make_deps update_time master text parents files : deps =

   {update_time = update_time, master = master, text = text, parents = parents, files = files};

 fun init_deps master text parents files =

   SOME (make_deps ~1 master text parents (map (rpair NONE) files));

 fun master_dir NONE = Path.current

   | master_dir (SOME (path, _)) = Path.dir path;

 fun master_dir' (d: deps option) = the_default Path.current (Option.map (master_dir o #master) d);

 fun master_dir'' d = the_default Path.current (Option.map master_dir' d);

 fun base_name s = Path.implode (Path.base (Path.explode s));

 type thy = deps option * theory option;

 local

   val database = Unsynchronized.ref (Graph.empty: thy Graph.T);

 in

   fun get_thys () = ! database;

   fun change_thys f = CRITICAL (fn () => Unsynchronized.change database f);

 end;

 (* access thy graph *)

 fun thy_graph f x = f (get_thys ()) x;

 fun get_names () = Graph.topological_order (get_thys ());

 (* access thy *)

 fun lookup_thy name =

   SOME (thy_graph Graph.get_node name) handle Graph.UNDEF _ => NONE;

 val known_thy = is_some o lookup_thy;

 fun check_known_thy name = known_thy name orelse (warning ("Unknown theory " ^ quote name); false);

 fun if_known_thy f name = if check_known_thy name then f name else ();

 fun get_thy name =

   (case lookup_thy name of

     SOME thy => thy

   | NONE => error (loader_msg "nothing known about theory" [name]));

 fun change_thy name f = CRITICAL (fn () =>

   (get_thy name; change_thys (Graph.map_node name f)));

 (* access deps *)

 val lookup_deps = Option.map #1 o lookup_thy;

 val get_deps = #1 o get_thy;

 fun change_deps name f = change_thy name (fn (deps, x) => (f deps, x));

 val is_finished = is_none o get_deps;

 val master_directory = master_dir' o get_deps;

 fun loaded_files name =

   (case get_deps name of

     NONE => []

   | SOME {master, files, ...} =>

       (case master of SOME (thy_path, _) => [thy_path] | NONE => []) @

       (map_filter (Option.map #1 o #2) files));

 fun get_parents name =

   thy_graph Graph.imm_preds name handle Graph.UNDEF _ =>

     error (loader_msg "nothing known about theory" [name]);

 (* access theory *)

 fun lookup_theory name =

   (case lookup_thy name of

     SOME (_, SOME thy) => SOME thy

   | _ => NONE);

 fun get_theory name =

   (case lookup_theory name of

     SOME theory => theory

   | _ => error (loader_msg "undefined theory entry for" [name]));

 fun the_theory name thy =

   if Context.theory_name thy = name then thy

   else get_theory name;

 (** thy operations **)

 (* check state *)

 fun check_unfinished fail name =

   if known_thy name andalso is_finished name then

     fail (loader_msg "cannot update finished theory" [name])

   else ();

 fun check_files name =

   let

     val files = (case get_deps name of SOME {files, ...} => files | NONE => []);

     val missing_files = map_filter (fn (path, NONE) => SOME (Path.implode path) | _ => NONE) files;

     val _ = null missing_files orelse

       error (loader_msg "unresolved dependencies of theory" [name] ^

         " on file(s): " ^ commas_quote missing_files);

   in () end;

 (* maintain update_time *)

 local

 fun is_outdated name =

   (case lookup_deps name of

     SOME (SOME {update_time, ...}) => update_time < 0

   | _ => false);

 fun unfinished name =

   if is_finished name then (warning (loader_msg "tried to touch finished theory" [name]); NONE)

   else SOME name;

 in

 fun outdate_thy name =

   if is_finished name orelse is_outdated name then ()

   else CRITICAL (fn () =>

    (change_deps name (Option.map (fn {master, text, parents, files, ...} =>

     make_deps ~1 master text parents files)); perform Outdate name));

 fun touch_thys names =

   List.app outdate_thy (thy_graph Graph.all_succs (map_filter unfinished names));

 fun touch_thy name = touch_thys [name];

 fun touch_child_thys name = touch_thys (thy_graph Graph.imm_succs name);

 end;

 (* management data *)

 structure Management_Data = Theory_Data

 (

   type T =

     Task_Queue.group option *   (*worker thread group*)

     int;                        (*abstract update time*)

   val empty = (NONE, 0);

   fun extend _ = empty;

   fun merge _ = empty;

 );

 val thy_ord = int_ord o pairself (#2 o Management_Data.get);

 (* pending proofs *)

 fun join_thy name =

   (case lookup_theory name of

     NONE => ()

   | SOME thy => PureThy.join_proofs thy);

 fun cancel_thy name =

   (case lookup_theory name of

     NONE => ()

   | SOME thy =>

       (case #1 (Management_Data.get thy) of

         NONE => ()

       | SOME group => Future.cancel_group group));

 (* remove theory *)

 fun remove_thy name =

   if is_finished name then error (loader_msg "cannot remove finished theory" [name])

   else

     let

       val succs = thy_graph Graph.all_succs [name];

       val _ = List.app cancel_thy succs;

       val _ = priority (loader_msg "removing" succs);

       val _ = CRITICAL (fn () =>

         (List.app (perform Remove) succs; change_thys (Graph.del_nodes succs)));

     in () end;

 val kill_thy = if_known_thy remove_thy;

 (* load_file *)

 local

 fun provide path name info (SOME {update_time, master, text, parents, files}) =

      (if AList.defined (op =) files path then ()

       else warning (loader_msg "undeclared dependency of theory" [name] ^

         " on file: " ^ quote (Path.implode path));

       SOME (make_deps update_time master text parents

         (AList.update (op =) (path, SOME info) files)))

   | provide _ _ _ NONE = NONE;

 fun run_file path =

   (case Option.map (Context.theory_name o Context.the_theory) (Context.thread_data ()) of

     NONE => (Thy_Load.load_ml Path.current path; ())

   | SOME name =>

       (case lookup_deps name of

         SOME deps =>

           change_deps name (provide path name (Thy_Load.load_ml (master_dir' deps) path))

       | NONE => (Thy_Load.load_ml Path.current path; ())));

 in

 fun provide_file path name =

   let

     val dir = master_directory name;

     val _ = check_unfinished error name;

   in

     (case Thy_Load.check_file dir path of

       SOME path_info => change_deps name (provide path name path_info)

     | NONE => error ("Could not find file " ^ quote (Path.implode path)))

   end;

 fun load_file time path =

   if time then

     let val name = Path.implode path in

       timeit (fn () =>

        (priority ("\n**** Starting file " ^ quote name ^ " ****");

         run_file path;

         priority ("**** Finished file " ^ quote name ^ " ****\n")))

     end

   else run_file path;

 fun exec_file time path = ML_Context.exec (fn () => load_file time path);

 val use = load_file false o Path.explode;

 val time_use = load_file true o Path.explode;

 end;

 (* load_thy *)

 fun required_by _ [] = ""

   | required_by s initiators = s ^ "(required by " ^ show_path (rev initiators) ^ ")";

 fun load_thy time upd_time initiators name =

   let

     val _ = priority ("Loading theory " ^ quote name ^ required_by " " initiators);

     val (pos, text, _) =

       (case get_deps name of

         SOME {master = SOME (master_path, _), text as _ :: _, files, ...} =>

           (Path.position master_path, text, files)

       | _ => error (loader_msg "corrupted dependency information" [name]));

     val _ = touch_thy name;

     val _ = CRITICAL (fn () =>

       change_deps name (Option.map (fn {master, text, parents, files, ...} =>

         make_deps upd_time master text parents files)));

     val after_load = Outer_Syntax.load_thy name pos text (time orelse ! Output.timing);

     val _ =

       CRITICAL (fn () =>

        (change_deps name

           (Option.map (fn {update_time, master, parents, files, ...} =>

             make_deps update_time master [] parents files));

         perform Update name));

   in after_load end;

 (* scheduling loader tasks *)

 datatype task = Task of (unit -> unit -> unit) | Finished | Running;

 fun task_finished Finished = true | task_finished _ = false;

 local

 fun schedule_futures task_graph = uninterruptible (fn _ => fn () =>

   let

     val tasks = Graph.topological_order task_graph |> map_filter (fn name =>

       (case Graph.get_node task_graph name of Task body => SOME (name, body) | _ => NONE));

     val par_proofs = ! parallel_proofs >= 1;

     fun fork (name, body) tab =

       let

         val deps = Graph.imm_preds task_graph name

           |> map_filter (fn parent =>

             (case Symtab.lookup tab parent of SOME future => SOME (parent, future) | NONE => NONE));

         fun failed (parent, future) = if can Future.join future then NONE else SOME parent;

         val future = Future.fork_deps (map #2 deps) (fn () =>

           (case map_filter failed deps of

             [] => body ()

           | bad => error (loader_msg

               ("failed to load " ^ quote name ^ " (unresolved " ^ commas_quote bad ^ ")") [])));

         val future' =

           if par_proofs then future

           else Future.map (fn after_load => (after_load (); fn () => ())) future;

       in Symtab.update (name, future') tab end;

     val futures = fold fork tasks Symtab.empty;

     val failed = tasks |> maps (fn (name, _) =>

       let

         val after_load = Future.join (the (Symtab.lookup futures name));

         val _ = join_thy name;

         val _ = after_load ();

       in [] end handle exn => [(name, exn)]) |> rev;

     val _ = List.app (kill_thy o #1) failed;

     val _ = Exn.release_all (map (Exn.Exn o #2) failed);

   in () end) ();

 fun schedule_seq tasks =

   Graph.topological_order tasks

   |> List.app (fn name =>

     (case Graph.get_node tasks name of

       Task body =>

         let val after_load = body ()

         in after_load () handle exn => (kill_thy name; reraise exn) end

     | _ => ()));

 in

 fun schedule_tasks tasks =

   if not (Multithreading.enabled ()) then schedule_seq tasks

   else if Multithreading.self_critical () then

      (warning (loader_msg "no multithreading within critical section" []);

       schedule_seq tasks)

   else schedule_futures tasks;

 end;

 (* require_thy -- checking database entries wrt. the file-system *)

 local

 fun check_ml master (src_path, info) =

   let val info' =

     (case info of NONE => NONE

     | SOME (_, id) =>

         (case Thy_Load.check_ml (master_dir master) src_path of NONE => NONE

         | SOME (path', id') => if id <> id' then NONE else SOME (path', id')))

   in (src_path, info') end;

 fun check_deps dir name =

   (case lookup_deps name of

     SOME NONE => (true, NONE, get_parents name)

   | NONE =>

       let val {master, text, imports = parents, uses = files} = Thy_Load.deps_thy dir name

       in (false, init_deps (SOME master) text parents files, parents) end

   | SOME (SOME {update_time, master, text, parents, files}) =>

       let

         val (thy_path, thy_id) = Thy_Load.check_thy dir name;

         val master' = SOME (thy_path, thy_id);

       in

         if Option.map #2 master <> SOME thy_id then

           let val {text = text', imports = parents', uses = files', ...} =

             Thy_Load.deps_thy dir name;

           in (false, init_deps master' text' parents' files', parents') end

         else

           let

             val files' = map (check_ml master') files;

             val current = update_time >= 0 andalso can get_theory name

               andalso forall (is_some o snd) files';

             val update_time' = if current then update_time else ~1;

             val deps' = SOME (make_deps update_time' master' text parents files');

           in (current, deps', parents) end

       end);

 fun read_text (SOME {update_time, master = master as SOME (path, _), text = _, parents, files}) =

   SOME (make_deps update_time master (explode (File.read path)) parents files);

 in

 fun require_thys time initiators dir strs tasks =

       fold_map (require_thy time initiators dir) strs tasks |>> forall I

 and require_thy time initiators dir str tasks =

   let

     val path = Path.expand (Path.explode str);

     val name = Path.implode (Path.base path);

     val dir' = Path.append dir (Path.dir path);

     val _ = member (op =) initiators name andalso error (cycle_msg initiators);

   in

     (case try (Graph.get_node tasks) name of

       SOME task => (task_finished task, tasks)

     | NONE =>

         let

           val (current, deps, parents) = check_deps dir' name

             handle ERROR msg => cat_error msg

               (loader_msg "the error(s) above occurred while examining theory" [name] ^

                 required_by "\n" initiators);

           val parent_names = map base_name parents;

           val (parents_current, tasks_graph') =

             require_thys time (name :: initiators)

               (Path.append dir (master_dir' deps)) parents tasks;

           val all_current = current andalso parents_current;

           val _ = if not all_current andalso known_thy name then outdate_thy name else ();

           val entry =

             if all_current then (deps, SOME (get_theory name))

             else (read_text deps, NONE);

           val _ = change_thys (new_deps name parent_names entry);

           val upd_time = serial ();

           val tasks_graph'' = tasks_graph' |> new_deps name parent_names

            (if all_current then Finished

             else Task (fn () => load_thy time upd_time initiators name));

         in (all_current, tasks_graph'') end)

   end;

 end;

 (* use_thy etc. *)

 local

 fun gen_use_thy' req dir arg =

   schedule_tasks (snd (req [] dir arg Graph.empty));

 fun gen_use_thy req str =

   let val name = base_name str in

     check_unfinished warning name;

     gen_use_thy' req Path.current str

   end;

 in

 val use_thys_dir = gen_use_thy' (require_thys false);

 val use_thys = use_thys_dir Path.current;

 val use_thy = gen_use_thy (require_thy false);

 val time_use_thy = gen_use_thy (require_thy true);

 end;

 (* begin / end theory *)

 fun begin_theory name parents uses int =

   let

     val parent_names = map base_name parents;

     val dir = master_dir'' (lookup_deps name);

     val _ = check_unfinished error name;

     val _ = if int then use_thys_dir dir parents else ();

     val theory = Theory.begin_theory name (map get_theory parent_names);

     val deps =

       if known_thy name then get_deps name

       else init_deps NONE [] parents (map #1 uses);

     val _ = change_thys (new_deps name parent_names (deps, NONE));

     val update_time = (case deps of NONE => 0 | SOME {update_time, ...} => update_time);

     val update_time = if update_time > 0 then update_time else serial ();

     val theory' = theory

       |> Management_Data.put (Future.worker_group (), update_time)

       |> Present.begin_theory update_time dir uses;

     val uses_now = map_filter (fn (x, true) => SOME x | _ => NONE) uses;

     val theory'' =

       fold (fn x => Context.theory_map (exec_file false x) o Theory.checkpoint) uses_now theory';

   in theory'' end;

 fun end_theory theory =

   let

     val name = Context.theory_name theory;

     val _ = check_files name;

     val theory' = Theory.end_theory theory;

     val _ = change_thy name (fn (deps, _) => (deps, SOME theory'));

   in () end;

 (* register existing theories *)

 fun register_thy name =

   let

     val _ = priority ("Registering theory " ^ quote name);

     val thy = get_theory name;

     val _ = map get_theory (get_parents name);

     val _ = check_unfinished error name;

     val _ = touch_thy name;

     val master = #master (Thy_Load.deps_thy Path.current name);

     val upd_time = #2 (Management_Data.get thy);

   in

     CRITICAL (fn () =>

      (change_deps name (Option.map

        (fn {parents, files, ...} => make_deps upd_time (SOME master) [] parents files));

       perform Update name))

   end;

 fun register_theory theory =

   let

     val name = Context.theory_name theory;

     val parents = Theory.parents_of theory;

     val parent_names = map Context.theory_name parents;

     fun err txt bads =

       error (loader_msg txt bads ^ "\ncannot register theory " ^ quote name);

     val nonfinished = filter_out is_finished parent_names;

     fun get_variant (x, y_name) =

       if Theory.eq_thy (x, get_theory y_name) then NONE

       else SOME y_name;

     val variants = map_filter get_variant (parents ~~ parent_names);

     fun register G =

       (Graph.new_node (name, (NONE, SOME theory)) G

         handle Graph.DUP _ => err "duplicate theory entry" [])

       |> add_deps name parent_names;

   in

     if not (null nonfinished) then err "non-finished parent theories" nonfinished

     else if not (null variants) then err "different versions of parent theories" variants

     else CRITICAL (fn () => (change_thys register; perform Update name))

   end;

 (* finish all theories *)

 fun finish () = change_thys (Graph.map_nodes (fn (_, entry) => (NONE, entry)));

 end;