(*  Title:      Pure/context.ML

    Author:     Markus Wenzel, TU Muenchen

Generic theory contexts with unique identity, arbitrarily typed data,

monotonic development graph and history support.  Generic proof

contexts with arbitrarily typed data.

Firm naming conventions:

   thy, thy', thy1, thy2: theory

   ctxt, ctxt', ctxt1, ctxt2: Proof.context

   context: Context.generic

*)

signature BASIC_CONTEXT =

sig

  type theory

  type theory_ref

  exception THEORY of string * theory list

  structure Proof: sig type context end

  structure Proof_Context:

  sig

    val theory_of: Proof.context -> theory

    val init_global: theory -> Proof.context

    val get_global: theory -> string -> Proof.context

  end

end;

signature CONTEXT =

sig

  include BASIC_CONTEXT

  (*theory context*)

  val timing: bool Unsynchronized.ref

  type pretty

  val parents_of: theory -> theory list

  val ancestors_of: theory -> theory list

  val theory_name: theory -> string

  val is_stale: theory -> bool

  val is_draft: theory -> bool

  val reject_draft: theory -> theory

  val PureN: string

  val display_names: theory -> string list

  val pretty_thy: theory -> Pretty.T

  val string_of_thy: theory -> string

  val pretty_abbrev_thy: theory -> Pretty.T

  val str_of_thy: theory -> string

  val get_theory: theory -> string -> theory

  val this_theory: theory -> string -> theory

  val deref: theory_ref -> theory

  val check_thy: theory -> theory_ref

  val eq_thy: theory * theory -> bool

  val subthy: theory * theory -> bool

  val joinable: theory * theory -> bool

  val merge: theory * theory -> theory

  val merge_refs: theory_ref * theory_ref -> theory_ref

  val copy_thy: theory -> theory

  val checkpoint_thy: theory -> theory

  val finish_thy: theory -> theory

  val begin_thy: (theory -> pretty) -> string -> theory list -> theory

  (*proof context*)

  val raw_transfer: theory -> Proof.context -> Proof.context

  (*generic context*)

  datatype generic = Theory of theory | Proof of Proof.context

  val cases: (theory -> 'a) -> (Proof.context -> 'a) -> generic -> 'a

  val mapping: (theory -> theory) -> (Proof.context -> Proof.context) -> generic -> generic

  val mapping_result: (theory -> 'a * theory) -> (Proof.context -> 'a * Proof.context) ->

    generic -> 'a * generic

  val the_theory: generic -> theory

  val the_proof: generic -> Proof.context

  val map_theory: (theory -> theory) -> generic -> generic

  val map_proof: (Proof.context -> Proof.context) -> generic -> generic

  val map_theory_result: (theory -> 'a * theory) -> generic -> 'a * generic

  val map_proof_result: (Proof.context -> 'a * Proof.context) -> generic -> 'a * generic

  val theory_map: (generic -> generic) -> theory -> theory

  val proof_map: (generic -> generic) -> Proof.context -> Proof.context

  val theory_of: generic -> theory  (*total*)

  val proof_of: generic -> Proof.context  (*total*)

  (*pretty printing context*)

  val pretty: Proof.context -> pretty

  val pretty_global: theory -> pretty

  val pretty_generic: generic -> pretty

  val pretty_context: (theory -> Proof.context) -> pretty -> Proof.context

  (*thread data*)

  val thread_data: unit -> generic option

  val the_thread_data: unit -> generic

  val set_thread_data: generic option -> unit

  val setmp_thread_data: generic option -> ('a -> 'b) -> 'a -> 'b

  val >> : (generic -> generic) -> unit

  val >>> : (generic -> 'a * generic) -> 'a

end;

signature PRIVATE_CONTEXT =

sig

  include CONTEXT

  structure Theory_Data:

  sig

    val declare: Position.T -> Any.T -> (Any.T -> Any.T) ->

      (pretty -> Any.T * Any.T -> Any.T) -> serial

    val get: serial -> (Any.T -> 'a) -> theory -> 'a

    val put: serial -> ('a -> Any.T) -> 'a -> theory -> theory

  end

  structure Proof_Data:

  sig

    val declare: (theory -> Any.T) -> serial

    val get: serial -> (Any.T -> 'a) -> Proof.context -> 'a

    val put: serial -> ('a -> Any.T) -> 'a -> Proof.context -> Proof.context

  end

end;

structure Context: PRIVATE_CONTEXT =

struct

(*** theory context ***)

(** theory data **)

(* data kinds and access methods *)

val timing = Unsynchronized.ref false;

(*private copy avoids potential conflict of table exceptions*)

structure Datatab = Table(type key = int val ord = int_ord);

datatype pretty = Pretty of Any.T;

local

type kind =

 {pos: Position.T,

  empty: Any.T,

  extend: Any.T -> Any.T,

  merge: pretty -> Any.T * Any.T -> Any.T};

val kinds = Synchronized.var "Theory_Data" (Datatab.empty: kind Datatab.table);

fun invoke name f k x =

  (case Datatab.lookup (Synchronized.value kinds) k of

    SOME kind =>

      if ! timing andalso name <> "" then

        Timing.cond_timeit true ("Theory_Data." ^ name ^ Position.here (#pos kind))

          (fn () => f kind x)

      else f kind x

  | NONE => raise Fail "Invalid theory data identifier");

in

fun invoke_empty k = invoke "" (K o #empty) k ();

val invoke_extend = invoke "extend" #extend;

fun invoke_merge pp = invoke "merge" (fn kind => #merge kind pp);

fun declare_theory_data pos empty extend merge =

  let

    val k = serial ();

    val kind = {pos = pos, empty = empty, extend = extend, merge = merge};

    val _ = Synchronized.change kinds (Datatab.update (k, kind));

  in k end;

val extend_data = Datatab.map invoke_extend;

fun merge_data pp = Datatab.join (invoke_merge pp) o pairself extend_data;

end;

(** datatype theory **)

datatype theory =

  Theory of

   (*identity*)

   {self: theory Unsynchronized.ref option,  (*dynamic self reference -- follows theory changes*)

    draft: bool,                  (*draft mode -- linear destructive changes*)

    id: serial,                   (*identifier*)

    ids: unit Inttab.table} *     (*cumulative identifiers of non-drafts -- symbolic body content*)

   (*data*)

   Any.T Datatab.table *       (*body content*)

   (*ancestry*)

   {parents: theory list,         (*immediate predecessors*)

    ancestors: theory list} *     (*all predecessors -- canonical reverse order*)

   (*history*)

   {name: string,                 (*official theory name*)

    stage: int};                  (*checkpoint counter*)

exception THEORY of string * theory list;

fun rep_theory (Theory args) = args;

val identity_of = #1 o rep_theory;

val data_of = #2 o rep_theory;

val ancestry_of = #3 o rep_theory;

val history_of = #4 o rep_theory;

fun make_identity self draft id ids = {self = self, draft = draft, id = id, ids = ids};

fun make_ancestry parents ancestors = {parents = parents, ancestors = ancestors};

fun make_history name stage = {name = name, stage = stage};

val the_self = the o #self o identity_of;

val parents_of = #parents o ancestry_of;

val ancestors_of = #ancestors o ancestry_of;

val theory_name = #name o history_of;

(* staleness *)

fun eq_id (i: int, j) = i = j;

fun is_stale

    (Theory ({self =

        SOME (Unsynchronized.ref (Theory ({id = id', ...}, _, _, _))), id, ...}, _, _, _)) =

      not (eq_id (id, id'))

  | is_stale (Theory ({self = NONE, ...}, _, _, _)) = true;

fun vitalize (thy as Theory ({self = SOME r, ...}, _, _, _)) = (r := thy; thy)

  | vitalize (thy as Theory ({self = NONE, draft, id, ids}, data, ancestry, history)) =

      let

        val r = Unsynchronized.ref thy;

        val thy' = Theory (make_identity (SOME r) draft id ids, data, ancestry, history);

      in r := thy'; thy' end;

(* draft mode *)

val is_draft = #draft o identity_of;

fun reject_draft thy =

  if is_draft thy then

    raise THEORY ("Illegal draft theory -- stable checkpoint required", [thy])

  else thy;

(* names *)

val PureN = "Pure";

val draftN = "#";

val finished = ~1;

fun display_names thy =

  let

    val draft = if is_draft thy then [draftN] else [];

    val {stage, ...} = history_of thy;

    val name =

      if stage = finished then theory_name thy

      else theory_name thy ^ ":" ^ string_of_int stage;

    val ancestor_names = map theory_name (ancestors_of thy);

    val stale = if is_stale thy then ["!"] else [];

  in rev (stale @ draft @ [name] @ ancestor_names) end;

val pretty_thy = Pretty.str_list "{" "}" o display_names;

val string_of_thy = Pretty.string_of o pretty_thy;

fun pretty_abbrev_thy thy =

  let

    val names = display_names thy;

    val n = length names;

    val abbrev = if n > 5 then "..." :: List.drop (names, n - 5) else names;

  in Pretty.str_list "{" "}" abbrev end;

val str_of_thy = Pretty.str_of o pretty_abbrev_thy;

fun get_theory thy name =

  if theory_name thy <> name then

    (case find_first (fn thy' => theory_name thy' = name) (ancestors_of thy) of

      SOME thy' => thy'

    | NONE => error ("Unknown ancestor theory " ^ quote name))

  else if #stage (history_of thy) = finished then thy

  else error ("Unfinished theory " ^ quote name);

fun this_theory thy name =

  if theory_name thy = name then thy

  else get_theory thy name;

(* theory references *)

(*theory_ref provides a safe way to store dynamic references to a

  theory in external data structures -- a plain theory value would

  become stale as the self reference moves on*)

datatype theory_ref = Theory_Ref of theory Unsynchronized.ref;

fun deref (Theory_Ref (Unsynchronized.ref thy)) = thy;

fun check_thy thy =  (*thread-safe version*)

  let val thy_ref = Theory_Ref (the_self thy) in

    if is_stale thy then error ("Stale theory encountered:\n" ^ string_of_thy thy)

    else thy_ref

  end;

(* build ids *)

fun insert_id draft id ids =

  if draft then ids

  else Inttab.update (id, ()) ids;

fun merge_ids

    (Theory ({draft = draft1, id = id1, ids = ids1, ...}, _, _, _))

    (Theory ({draft = draft2, id = id2, ids = ids2, ...}, _, _, _)) =

  Inttab.merge (K true) (ids1, ids2)

  |> insert_id draft1 id1

  |> insert_id draft2 id2;

(* equality and inclusion *)

val eq_thy = eq_id o pairself (#id o identity_of);

fun proper_subthy (Theory ({id, ...}, _, _, _), Theory ({ids, ...}, _, _, _)) =

  Inttab.defined ids id;

fun subthy thys = eq_thy thys orelse proper_subthy thys;

fun joinable (thy1, thy2) = subthy (thy1, thy2) orelse subthy (thy2, thy1);

(* consistent ancestors *)

fun eq_thy_consistent (thy1, thy2) =

  eq_thy (thy1, thy2) orelse

    (theory_name thy1 = theory_name thy2 andalso

      raise THEORY ("Duplicate theory name", [thy1, thy2]));

fun extend_ancestors thy thys =

  if member eq_thy_consistent thys thy then

    raise THEORY ("Duplicate theory node", thy :: thys)

  else thy :: thys;

val merge_ancestors = merge eq_thy_consistent;

(* trivial merge *)

fun merge (thy1, thy2) =

  if eq_thy (thy1, thy2) then thy1

  else if proper_subthy (thy2, thy1) then thy1

  else if proper_subthy (thy1, thy2) then thy2

  else error (cat_lines ["Attempt to perform non-trivial merge of theories:",

    str_of_thy thy1, str_of_thy thy2]);

fun merge_refs (ref1, ref2) =

  if ref1 = ref2 then ref1

  else check_thy (merge (deref ref1, deref ref2));

(** build theories **)

(* primitives *)

local

  val lock = Mutex.mutex ();

in

  fun SYNCHRONIZED e = Simple_Thread.synchronized "theory" lock e;

end;

fun create_thy self draft ids data ancestry history =

  let val identity = make_identity self draft (serial ()) ids;

  in vitalize (Theory (identity, data, ancestry, history)) end;

fun change_thy draft' f thy =

  let

    val Theory ({self, draft, id, ids}, data, ancestry, history) = thy;

    val (self', data', ancestry') =

      if draft then (self, data, ancestry)    (*destructive change!*)

      else if #stage history > 0

      then (NONE, data, ancestry)

      else (NONE, extend_data data, make_ancestry [thy] (extend_ancestors thy (ancestors_of thy)));

    val ids' = insert_id draft id ids;

    val data'' = f data';

    val thy' = SYNCHRONIZED (fn () =>

      (check_thy thy; create_thy self' draft' ids' data'' ancestry' history));

  in thy' end;

val name_thy = change_thy false I;

val extend_thy = change_thy true I;

val modify_thy = change_thy true;

fun copy_thy thy =

  let

    val Theory ({draft, id, ids, ...}, data, ancestry, history) = thy;

    val ids' = insert_id draft id ids;

    val thy' = SYNCHRONIZED (fn () =>

      (check_thy thy; create_thy NONE true ids' data ancestry history));

  in thy' end;

val pre_pure_thy = create_thy NONE true Inttab.empty

  Datatab.empty (make_ancestry [] []) (make_history PureN 0);

(* named theory nodes *)

fun merge_thys pp (thy1, thy2) =

  let

    val ids = merge_ids thy1 thy2;

    val data = merge_data (pp thy1) (data_of thy1, data_of thy2);

    val ancestry = make_ancestry [] [];

    val history = make_history "" 0;

    val thy' = SYNCHRONIZED (fn () =>

     (check_thy thy1; check_thy thy2; create_thy NONE true ids data ancestry history));

  in thy' end;

fun maximal_thys thys =

  thys |> filter_out (fn thy => exists (fn thy' => proper_subthy (thy, thy')) thys);

fun begin_thy pp name imports =

  if name = "" orelse name = draftN then error ("Bad theory name: " ^ quote name)

  else

    let

      val parents = maximal_thys (distinct eq_thy imports);

      val ancestors =

        Library.foldl merge_ancestors ([], map ancestors_of parents)

        |> fold extend_ancestors parents;

      val Theory ({ids, ...}, data, _, _) =

        (case parents of

          [] => error "Missing theory imports"

        | [thy] => extend_thy thy

        | thy :: thys => Library.foldl (merge_thys pp) (thy, thys));

      val ancestry = make_ancestry parents ancestors;

      val history = make_history name 0;

      val thy' = SYNCHRONIZED (fn () =>

        (map check_thy imports; create_thy NONE true ids data ancestry history));

    in thy' end;

(* history stages *)

fun history_stage f thy =

  let

    val {name, stage} = history_of thy;

    val _ = stage = finished andalso raise THEORY ("Theory already finished", [thy]);

    val history' = make_history name (f stage);

    val thy' as Theory (identity', data', ancestry', _) = name_thy thy;

    val thy'' = SYNCHRONIZED (fn () =>

      (check_thy thy'; vitalize (Theory (identity', data', ancestry', history'))));

  in thy'' end;

fun checkpoint_thy thy =

  if is_draft thy then history_stage (fn stage => stage + 1) thy

  else thy;

val finish_thy = history_stage (fn _ => finished);

(* theory data *)

structure Theory_Data =

struct

val declare = declare_theory_data;

fun get k dest thy =

  (case Datatab.lookup (data_of thy) k of

    SOME x => x

  | NONE => invoke_empty k) |> dest;

fun put k mk x = modify_thy (Datatab.update (k, mk x));

end;

(*** proof context ***)

(* datatype Proof.context *)

structure Proof =

struct

  datatype context = Context of Any.T Datatab.table * theory_ref;

end;

fun theory_of_proof (Proof.Context (_, thy_ref)) = deref thy_ref;

fun data_of_proof (Proof.Context (data, _)) = data;

fun map_prf f (Proof.Context (data, thy_ref)) = Proof.Context (f data, thy_ref);

(* proof data kinds *)

local

val kinds = Synchronized.var "Proof_Data" (Datatab.empty: (theory -> Any.T) Datatab.table);

fun invoke_init k =

  (case Datatab.lookup (Synchronized.value kinds) k of

    SOME init => init

  | NONE => raise Fail "Invalid proof data identifier");

fun init_data thy =

  Datatab.map (fn k => fn _ => invoke_init k thy) (Synchronized.value kinds);

fun init_new_data data thy =

  Datatab.merge (K true) (data, init_data thy);

in

fun raw_transfer thy' (Proof.Context (data, thy_ref)) =

  let

    val thy = deref thy_ref;

    val _ = subthy (thy, thy') orelse error "transfer proof context: not a super theory";

    val _ = check_thy thy;

    val data' = init_new_data data thy';

    val thy_ref' = check_thy thy';

  in Proof.Context (data', thy_ref') end;

structure Proof_Context =

struct

  val theory_of = theory_of_proof;

  fun init_global thy = Proof.Context (init_data thy, check_thy thy);

  fun get_global thy name = init_global (get_theory thy name);

end;

structure Proof_Data =

struct

fun declare init =

  let

    val k = serial ();

    val _ = Synchronized.change kinds (Datatab.update (k, init));

  in k end;

fun get k dest prf =

  dest (case Datatab.lookup (data_of_proof prf) k of

    SOME x => x

  | NONE => invoke_init k (Proof_Context.theory_of prf));   (*adhoc value*)

fun put k mk x = map_prf (Datatab.update (k, mk x));

end;

end;

(*** generic context ***)

datatype generic = Theory of theory | Proof of Proof.context;

fun cases f _ (Theory thy) = f thy

  | cases _ g (Proof prf) = g prf;

fun mapping f g = cases (Theory o f) (Proof o g);

fun mapping_result f g = cases (apsnd Theory o f) (apsnd Proof o g);

val the_theory = cases I (fn _ => error "Ill-typed context: theory expected");

val the_proof = cases (fn _ => error "Ill-typed context: proof expected") I;

fun map_theory f = Theory o f o the_theory;

fun map_proof f = Proof o f o the_proof;

fun map_theory_result f = apsnd Theory o f o the_theory;

fun map_proof_result f = apsnd Proof o f o the_proof;

fun theory_map f = the_theory o f o Theory;

fun proof_map f = the_proof o f o Proof;

val theory_of = cases I Proof_Context.theory_of;

val proof_of = cases Proof_Context.init_global I;

(* pretty printing context *)

exception PRETTY of generic;

val pretty_generic = Pretty o PRETTY;

val pretty = pretty_generic o Proof;

val pretty_global = pretty_generic o Theory;

fun pretty_context init (Pretty (PRETTY context)) = cases init I context;

(** thread data **)

local val tag = Universal.tag () : generic option Universal.tag in

fun thread_data () =

  (case Thread.getLocal tag of

    SOME (SOME context) => SOME context

  | _ => NONE);

fun the_thread_data () =

  (case thread_data () of

    SOME context => context

  | _ => error "Unknown context");

fun set_thread_data context = Thread.setLocal (tag, context);

fun setmp_thread_data context = Library.setmp_thread_data tag (thread_data ()) context;

end;

fun >>> f =

  let

    val (res, context') = f (the_thread_data ());

    val _ = set_thread_data (SOME context');

  in res end;

nonfix >>;

fun >> f = >>> (fn context => ((), f context));

val _ = set_thread_data (SOME (Theory pre_pure_thy));

end;

structure Basic_Context: BASIC_CONTEXT = Context;

open Basic_Context;

(*** type-safe interfaces for data declarations ***)

(** theory data **)

signature THEORY_DATA_PP_ARGS =

sig

  type T

  val empty: T

  val extend: T -> T

  val merge: Context.pretty -> T * T -> T

end;

signature THEORY_DATA_ARGS =

sig

  type T

  val empty: T

  val extend: T -> T

  val merge: T * T -> T

end;

signature THEORY_DATA =

sig

  type T

  val get: theory -> T

  val put: T -> theory -> theory

  val map: (T -> T) -> theory -> theory

end;

functor Theory_Data_PP(Data: THEORY_DATA_PP_ARGS): THEORY_DATA =

struct

type T = Data.T;

exception Data of T;

val kind =

  Context.Theory_Data.declare

    (Position.thread_data ())

    (Data Data.empty)

    (fn Data x => Data (Data.extend x))

    (fn pp => fn (Data x1, Data x2) => Data (Data.merge pp (x1, x2)));

val get = Context.Theory_Data.get kind (fn Data x => x);

val put = Context.Theory_Data.put kind Data;

fun map f thy = put (f (get thy)) thy;

end;

functor Theory_Data(Data: THEORY_DATA_ARGS): THEORY_DATA =

  Theory_Data_PP

  (

    type T = Data.T;

    val empty = Data.empty;

    val extend = Data.extend;

    fun merge _ = Data.merge;

  );

(** proof data **)

signature PROOF_DATA_ARGS =

sig

  type T

  val init: theory -> T

end;

signature PROOF_DATA =

sig

  type T

  val get: Proof.context -> T

  val put: T -> Proof.context -> Proof.context

  val map: (T -> T) -> Proof.context -> Proof.context

end;

functor Proof_Data(Data: PROOF_DATA_ARGS): PROOF_DATA =

struct

type T = Data.T;

exception Data of T;

val kind = Context.Proof_Data.declare (Data o Data.init);

val get = Context.Proof_Data.get kind (fn Data x => x);

val put = Context.Proof_Data.put kind Data;

fun map f prf = put (f (get prf)) prf;

end;

(** generic data **)

signature GENERIC_DATA_ARGS =

sig

  type T

  val empty: T

  val extend: T -> T

  val merge: T * T -> T

end;

signature GENERIC_DATA =

sig

  type T

  val get: Context.generic -> T

  val put: T -> Context.generic -> Context.generic

  val map: (T -> T) -> Context.generic -> Context.generic

end;

functor Generic_Data(Data: GENERIC_DATA_ARGS): GENERIC_DATA =

struct

structure Thy_Data = Theory_Data(Data);

structure Prf_Data = Proof_Data(type T = Data.T val init = Thy_Data.get);

type T = Data.T;

fun get (Context.Theory thy) = Thy_Data.get thy

  | get (Context.Proof prf) = Prf_Data.get prf;

fun put x (Context.Theory thy) = Context.Theory (Thy_Data.put x thy)

  | put x (Context.Proof prf) = Context.Proof (Prf_Data.put x prf);

fun map f ctxt = put (f (get ctxt)) ctxt;

end;

(*hide private interface*)

structure Context: CONTEXT = Context;