(*  Title:      Pure/Isar/toplevel.ML

    ID:         $Id$

    Author:     Markus Wenzel, TU Muenchen

The Isabelle/Isar toplevel.

*)

signature TOPLEVEL =

sig

  datatype node = Theory of theory | Proof of ProofHistory.T

  type state

  val toplevel: state

  val prompt_state_default: state -> string

  val prompt_state_fn: (state -> string) ref

  val print_state_default: state -> unit

  val print_state_fn: (state -> unit) ref

  val print_state: state -> unit

  exception UNDEF

  val node_history_of: state -> node History.T

  val node_of: state -> node

  val node_case: (theory -> 'a) -> (Proof.state -> 'a) -> state -> 'a

  val theory_of: state -> theory

  val sign_of: state -> Sign.sg

  val proof_of: state -> Proof.state

  type transition

  exception TERMINATE

  exception RESTART

  val undo_limit: bool -> int option

  val empty: transition

  val name: string -> transition -> transition

  val position: Position.T -> transition -> transition

  val interactive: bool -> transition -> transition

  val print: transition -> transition

  val reset: transition -> transition

  val init: (bool -> state -> node) -> (node -> unit) -> (node -> unit) -> transition -> transition

  val exit: transition -> transition

  val kill: transition -> transition

  val keep: (state -> unit) -> transition -> transition

  val history: (node History.T -> node History.T) -> transition -> transition

  val imperative: (unit -> unit) -> transition -> transition

  val init_theory: (bool -> theory) -> (theory -> unit) -> (theory -> unit)

    -> transition -> transition

  val theory: (theory -> theory) -> transition -> transition

  val theory_to_proof: (bool -> theory -> ProofHistory.T) -> transition -> transition

  val proof: (ProofHistory.T -> ProofHistory.T) -> transition -> transition

  val proof': (bool -> ProofHistory.T -> ProofHistory.T) -> transition -> transition

  val proof_to_theory: (ProofHistory.T -> theory) -> transition -> transition

  val trace: bool ref

  val exn_message: exn -> string

  val apply: bool -> transition -> state -> (state * (exn * string) option) option

  val excursion: transition list -> unit

  val excursion_error: transition list -> unit

  val set_state: state -> unit

  val get_state: unit -> state

  val exn: unit -> (exn * string) option

  val >> : transition -> bool

  type isar

  val loop: isar -> unit

end;

structure Toplevel: TOPLEVEL =

struct

(** toplevel state **)

(* datatype node *)

datatype node =

  Theory of theory |

  Proof of ProofHistory.T;

fun str_of_node (Theory _) = "in theory mode"

  | str_of_node (Proof _) = "in proof mode";

fun print_node (Theory thy) = Pretty.writeln (Pretty.block

      [Pretty.str "Theory:", Pretty.brk 1, Pretty.str (PureThy.get_name thy),

        Pretty.str " =", Pretty.brk 1, Display.pretty_theory thy])

  | print_node (Proof prf) =

      (writeln ("Proof: step #" ^ string_of_int (ProofHistory.position prf));

        Proof.print_state (ProofHistory.current prf));

(* datatype state *)

datatype state = State of (node History.T * ((node -> unit) * (node -> unit))) list;

val toplevel = State [];

fun str_of_state (State []) = "at top level"

  | str_of_state (State ((node, _) :: _)) = str_of_node (History.current node);

(* prompt_state hook *)

fun prompt_state_default (State nodes) =

  let val len = length nodes

  in (if len < 2 then "" else string_of_int len) ^ Source.default_prompt end;

val prompt_state_fn = ref prompt_state_default;

fun prompt_state state = ! prompt_state_fn state;

(* print_state hook *)

fun print_topnode (State []) = ()

  | print_topnode (State ((node, _) :: _)) = print_node (History.current node);

fun print_state_default state =

  let val ref (begin_state, end_state, _) = Goals.current_goals_markers in

    if begin_state = "" then () else writeln begin_state;

    print_topnode state;

    if end_state = "" then () else writeln end_state

  end;

val print_state_fn = ref print_state_default;

fun print_state state = ! print_state_fn state;

(* top node *)

exception UNDEF;

fun node_history_of (State []) = raise UNDEF

  | node_history_of (State ((node, _) :: _)) = node;

val node_of = History.current o node_history_of;

fun node_case f g state =

  (case node_of state of

    Theory thy => f thy

  | Proof prf => g (ProofHistory.current prf));

val theory_of = node_case I Proof.theory_of;

val sign_of = Theory.sign_of o theory_of;

val proof_of = node_case (fn _ => raise UNDEF) I;

(** toplevel transitions **)

exception TERMINATE;

exception RESTART;

exception EXCURSION_FAIL of exn * string;

exception FAILURE of state * exn;

(* recovery from stale signatures *)

(*note: proof commands should be non-destructive!*)

local

fun is_stale state = Sign.is_stale (sign_of state) handle UNDEF => false;

fun checkpoint_node true (Theory thy) = Theory (PureThy.checkpoint thy)

  | checkpoint_node _ node = node;

fun copy_node true (Theory thy) = Theory (Theory.copy thy)

  | copy_node _ node = node;

fun interruptible f x =

  let val y = ref (None: node History.T option);

  in exhibit_interrupt (fn () => y := Some (f x)) (); the (! y) end;

val rollback = ERROR_MESSAGE "Stale signature encountered after succesful execution!";

fun return (result, None) = result

  | return (result, Some exn) = raise FAILURE (result, exn);

in

fun node_trans _ _ _ (State []) = raise UNDEF

  | node_trans int hist f (State ((node, term) :: nodes)) =

      let

        fun mk_state nd = State ((nd, term) :: nodes);

        val cont_node = History.map (checkpoint_node int) node;

        val back_node = History.map (copy_node int) cont_node;

        val trans = if hist then History.apply_copy (copy_node int) else History.map;

        val (result, opt_exn) =

          (mk_state (transform_error (interruptible (trans (f int))) cont_node), None)

            handle exn => (mk_state cont_node, Some exn);

      in

        if is_stale result then return (mk_state back_node, Some (if_none opt_exn rollback))

        else return (result, opt_exn)

      end;

fun check_stale state =

  if not (is_stale state) then ()

  else warning "Stale signature encountered!  Should restart current theory.";

end;

(* primitive transitions *)

(*Important note: recovery from stale signatures is provided only for

  theory-level operations via MapCurrent and AppCurrent.  Other node

  or state operations should not touch signatures at all.

  Also note that interrupts are enabled for Keep, MapCurrent, and

  AppCurrent only.*)

datatype trans =

  Reset |                                       (*empty toplevel*)

  Init of (bool -> state -> node) * ((node -> unit) * (node -> unit)) |

    (*push node; provide exit/kill operation*)

  Exit |                                        (*pop node*)

  Kill |                                        (*abort node*)

  Keep of state -> unit |                       (*peek at state*)

  History of node History.T -> node History.T | (*history operation (undo etc.)*)

  MapCurrent of bool -> node -> node |          (*change node, bypassing history*)

  AppCurrent of bool -> node -> node;           (*change node, recording history*)

fun undo_limit int = if int then None else Some 0;

local

fun apply_tr _ Reset _ = toplevel

  | apply_tr int (Init (f, term)) (state as State nodes) =

      State ((History.init (undo_limit int) (f int state), term) :: nodes)

  | apply_tr _ Exit (State []) = raise UNDEF

  | apply_tr _ Exit (State ((node, (exit, _)):: nodes)) =

      (exit (History.current node); State nodes)

  | apply_tr _ Kill (State []) = raise UNDEF

  | apply_tr _ Kill (State ((node, (_, kill)) :: nodes)) =

      (kill (History.current node); State nodes)

  | apply_tr _ (Keep f) state = (exhibit_interrupt f state; state)

  | apply_tr _ (History _) (State []) = raise UNDEF

  | apply_tr _ (History f) (State ((node, term) :: nodes)) = State ((f node, term) :: nodes)

  | apply_tr int (MapCurrent f) state = node_trans int false f state

  | apply_tr int (AppCurrent f) state = node_trans int true f state;

fun apply_union _ [] state = raise FAILURE (state, UNDEF)

  | apply_union int (tr :: trs) state =

      transform_error (apply_tr int tr) state

        handle UNDEF => apply_union int trs state

          | FAILURE (alt_state, UNDEF) => apply_union int trs alt_state

          | exn as FAILURE _ => raise exn

          | exn => raise FAILURE (state, exn);

in

fun apply_trans int trs state = (apply_union int trs state, None)

  handle FAILURE (alt_state, exn) => (alt_state, Some exn) | exn => (state, Some exn);

end;

(* datatype transition *)

datatype transition = Transition of

 {name: string,

  pos: Position.T,

  int_only: bool,

  print: bool,

  trans: trans list};

fun make_transition (name, pos, int_only, print, trans) =

  Transition {name = name, pos = pos, int_only = int_only, print = print, trans = trans};

fun map_transition f (Transition {name, pos, int_only, print, trans}) =

  make_transition (f (name, pos, int_only, print, trans));

val empty = make_transition ("<unknown>", Position.none, false, false, []);

(* diagnostics *)

fun str_of_transition (Transition {name, pos, ...}) = quote name ^ Position.str_of pos;

fun command_msg msg tr = msg ^ "command " ^ str_of_transition tr;

fun at_command tr = command_msg "At " tr ^ ".";

fun type_error tr state =

  ERROR_MESSAGE (command_msg "Illegal application of " tr ^ " " ^ str_of_state state);

(* modify transitions *)

fun name nm = map_transition

  (fn (_, pos, int_only, print, trans) => (nm, pos, int_only, print, trans));

fun position pos = map_transition

  (fn (name, _, int_only, print, trans) => (name, pos, int_only, print, trans));

fun interactive int_only = map_transition

  (fn (name, pos, _, print, trans) => (name, pos, int_only, print, trans));

val print = map_transition

  (fn (name, pos, int_only, _, trans) => (name, pos, int_only, true, trans));

fun add_trans tr = map_transition

  (fn (name, pos, int_only, print, trans) => (name, pos, int_only, print, trans @ [tr]));

(* build transitions *)

val reset = add_trans Reset;

fun init f exit kill = add_trans (Init (f, (exit, kill)));

val exit = add_trans Exit;

val kill = add_trans Kill;

val keep = add_trans o Keep;

val history = add_trans o History;

val map_current = add_trans o MapCurrent;

val app_current = add_trans o AppCurrent;

fun imperative f = keep (fn _ => f ());

fun init_theory f exit kill =

  init (fn int => fn _ => Theory (f int))

    (fn Theory thy => exit thy | _ => raise UNDEF)

    (fn Theory thy => kill thy | _ => raise UNDEF);

fun theory f = app_current (fn _ => (fn Theory thy => Theory (f thy) | _ => raise UNDEF));

fun theory_to_proof f =

  app_current (fn int => (fn Theory thy => Proof (f int thy) | _ => raise UNDEF));

fun proof' f = map_current (fn int => (fn Proof prf => Proof (f int prf) | _ => raise UNDEF));

val proof = proof' o K;

fun proof_to_theory f = map_current (fn _ => (fn Proof prf => Theory (f prf) | _ => raise UNDEF));

(** toplevel transactions **)

val trace = ref false;

(* print exceptions *)

fun raised name = "exception " ^ name ^ " raised";

fun raised_msg name msg = raised name ^ ": " ^ msg;

fun exn_message TERMINATE = "Exit."

  | exn_message RESTART = "Restart."

  | exn_message (EXCURSION_FAIL (exn, msg)) = cat_lines [exn_message exn, msg]

  | exn_message Interrupt = "Interrupt."

  | exn_message ERROR = "ERROR."

  | exn_message (ERROR_MESSAGE msg) = msg

  | exn_message (THEORY (msg, _)) = msg

  | exn_message (ProofContext.CONTEXT (msg, _)) = msg

  | exn_message (Proof.STATE (msg, _)) = msg

  | exn_message (ProofHistory.FAIL msg) = msg

  | exn_message (Attrib.ATTRIB_FAIL info) = fail_message "attribute" info

  | exn_message (Method.METHOD_FAIL info) = fail_message "method" info

  | exn_message (Syntax.AST (msg, _)) = raised_msg "AST" msg

  | exn_message (TYPE (msg, _, _)) = raised_msg "TYPE" msg

  | exn_message (TERM (msg, _)) = raised_msg "TERM" msg

  | exn_message (THM (msg, _, _)) = raised_msg "THM" msg

  | exn_message Library.OPTION = raised "Library.OPTION"

  | exn_message (Library.LIST msg) = raised_msg "Library.LIST" msg

  | exn_message exn = General.exnMessage exn

and fail_message kind ((name, pos), exn) =

  "Error in " ^ kind ^ " " ^ name ^ Position.str_of pos ^ ":\n" ^ exn_message exn;

fun print_exn None = ()

  | print_exn (Some (exn, s)) = error_msg (cat_lines [exn_message exn, s]);

(* apply transitions *)

local

fun app int (tr as Transition {trans, int_only, print, ...}) state =

  let

    val _ =

      if int orelse not int_only then ()

      else warning (command_msg "Executing interactive-only " tr);

    val (result, opt_exn) =

      (if ! trace then (writeln (command_msg "" tr); timeap) else I) (apply_trans int trans) state;

    val _ = if int andalso print then print_state result else ();

  in (result, apsome (fn UNDEF => type_error tr state | exn => exn) opt_exn) end;

in

fun apply int tr st =

  (case app int tr st of

    (_, Some TERMINATE) => None

  | (_, Some RESTART) => Some (toplevel, None)

  | (state', Some (EXCURSION_FAIL exn_info)) => Some (state', Some exn_info)

  | (state', Some exn) => Some (state', Some (exn, at_command tr))

  | (state', None) => Some (state', None));

end;

(* excursion: toplevel -- apply transformers -- toplevel *)

local

fun excur [] x = x

  | excur (tr :: trs) x =

      (case apply false tr x of

        Some (x', None) => excur trs x'

      | Some (x', Some exn_info) => raise EXCURSION_FAIL exn_info

      | None => raise EXCURSION_FAIL (TERMINATE, at_command tr));

in

fun excursion trs =

  (case excur trs (State []) of

    State [] => ()

  | _ => raise ERROR_MESSAGE "Open block(s) pending at end of input");

fun excursion_error trs =

  excursion trs handle exn => error (exn_message exn);

end;

(** interactive transformations **)

(* the global state reference *)

val global_state = ref (toplevel, None: (exn * string) option);

fun set_state state = global_state := (state, None);

fun get_state () = fst (! global_state);

fun exn () = snd (! global_state);

(* the Isar source of transitions *)

type isar =

  (transition, (transition option,

    (OuterLex.token, (OuterLex.token,

      Position.T * (Symbol.symbol, (string, unit) Source.source) Source.source)

          Source.source) Source.source) Source.source) Source.source;

fun transform_interrupt_isar f x =

  let val y = ref (None: (transition * isar) option option);

  in exhibit_interrupt (fn () => y := Some (f x)) (); the (! y) end;

fun get_interruptible src =

  Some (transform_interrupt_isar Source.get_single src)

    handle Interrupt => None;

(* apply transformers to global state *)

nonfix >>;

fun >> tr =

  (case apply true tr (get_state ()) of

    None => false

  | Some (state', exn_info) =>

      (global_state := (state', exn_info);

        check_stale state'; print_exn exn_info;

        true));

fun raw_loop src =

  (case get_interruptible (Source.set_prompt (prompt_state (get_state ())) src) of

    None => (writeln "\nInterrupt."; raw_loop src)

  | Some None => ()

  | Some (Some (tr, src')) => if >> tr then raw_loop src' else ());

fun loop src = mask_interrupt raw_loop src;

end;