# File specification_package.ML

    (*  Title:      HOL/Tools/specification_package.ML
        ID:         $Id: specification_package.ML,v 1.21 2005/09/14 08:24:39 haftmann Exp $
        Author:     Sebastian Skalberg, TU Muenchen

    Package for defining constants by specification.
    *)

    signature SPECIFICATION_PACKAGE =
    sig
      val quiet_mode: bool ref
      val add_specification_i: string option -> (bstring * xstring * bool) list ->
        theory attribute
    end

    structure SpecificationPackage : SPECIFICATION_PACKAGE =
    struct

    (* messages *)

    val quiet_mode = ref false
    fun message s = if ! quiet_mode then () else writeln s

    local
        val _ = Goal "[| Ex P ; c == Eps P |] ==> P c"
        val _ = by (Asm_simp_tac 1)
        val _ = by (rtac (thm "someI_ex") 1)
        val _ = ba 1
    in
    val helper = Goals.result()
    end

    (* Actual code *)

    local
        fun mk_definitional [] arg = arg
          | mk_definitional ((thname,cname,covld)::cos) (thy,thm) =
            case HOLogic.dest_Trueprop (concl_of thm) of
                Const("Ex",_) $ P =>
                let
                    val ctype = domain_type (type_of P)
                    val cname_full = Sign.intern_const (sign_of thy) cname
                    val cdefname = if thname = ""
                                   then Thm.def_name (Sign.base_name cname)
                                   else thname
                    val def_eq = Logic.mk_equals (Const(cname_full,ctype),
                                                  HOLogic.choice_const ctype $  P)
                    val (thy',thms) = PureThy.add_defs_i covld [((cdefname,def_eq),[])] thy
                    val thm' = [thm,hd thms] MRS helper
                in
                    mk_definitional cos (thy',thm')
                end
              | _ => raise THM ("Internal error: Bad specification theorem",0,[thm])

        fun mk_axiomatic axname cos arg =
            let
                fun process [] (thy,tm) =
                    let
                        val (thy',thms) = PureThy.add_axioms_i [((axname,HOLogic.mk_Trueprop tm),[])] thy
                    in
                        (thy',hd thms)
                    end
                  | process ((thname,cname,covld)::cos) (thy,tm) =
                    case tm of
                        Const("Ex",_) $ P =>
                        let
                            val ctype = domain_type (type_of P)
                            val cname_full = Sign.intern_const (sign_of thy) cname
                            val cdefname = if thname = ""
                                           then Thm.def_name (Sign.base_name cname)
                                           else thname
                            val co = Const(cname_full,ctype)
                            val thy' = Theory.add_finals_i covld [co] thy
                            val tm' = case P of
                                          Abs(_, _, bodt) => subst_bound (co, bodt)
                                        | _ => P $ co
                        in
                            process cos (thy',tm')
                        end
                      | _ => raise TERM ("Internal error: Bad specification theorem",[tm])
            in
                process cos arg
            end

    in
    fun proc_exprop axiomatic cos arg =
        case axiomatic of
            SOME axname => mk_axiomatic axname cos (apsnd (HOLogic.dest_Trueprop o concl_of) arg)
          | NONE => mk_definitional cos arg
    end

    fun add_specification_i axiomatic cos arg =
        arg |> apsnd freezeT
            |> proc_exprop axiomatic cos
            |> apsnd standard

    (* Collect all intances of constants in term *)

    fun collect_consts (        t $ u,tms) = collect_consts (u,collect_consts (t,tms))
      | collect_consts (   Abs(_,_,t),tms) = collect_consts (t,tms)
      | collect_consts (tm as Const _,tms) = gen_ins (op aconv) (tm,tms)
      | collect_consts (            _,tms) = tms

    (* Complementing Type.varify... *)

    fun unvarify t fmap =
        let
            val fmap' = map Library.swap fmap
            fun unthaw (f as (a, S)) =
                (case AList.lookup (op =) fmap' a of
                     NONE => TVar f
                   | SOME (b, _) => TFree (b, S))
        in
            map_term_types (map_type_tvar unthaw) t
        end

    (* The syntactic meddling needed to setup add_specification for work *)

    fun process_spec axiomatic cos alt_props thy =
        let
            fun zip3 [] [] [] = []
              | zip3 (x::xs) (y::ys) (z::zs) = (x,y,z)::zip3 xs ys zs
              | zip3 _ _ _ = error "SpecificationPackage.process_spec internal error"

            fun myfoldr f [x] = x
              | myfoldr f (x::xs) = f (x,myfoldr f xs)
              | myfoldr f [] = error "SpecificationPackage.process_spec internal error"

            val sg = sign_of thy
            fun typ_equiv t u = Sign.typ_instance sg (t,u) andalso Sign.typ_instance sg (u,t);

            val cprops = map (Thm.read_cterm sg o rpair Term.propT o snd) alt_props
            val ss = empty_ss setmksimps single addsimps [thm "HOL.atomize_imp",thm "HOL.atomize_all"]
            val rew_imps = map (Simplifier.full_rewrite ss) cprops
            val props' = map (HOLogic.dest_Trueprop o term_of o snd o dest_equals o cprop_of) rew_imps

            fun proc_single prop =
                let
                    val frees = Term.term_frees prop
                    val tsig = Sign.tsig_of (sign_of thy)
                    val _ = assert (forall (fn v => Type.of_sort tsig (type_of v,HOLogic.typeS)) frees)
                                   "Specificaton: Only free variables of sort 'type' allowed"
                    val prop_closed = foldr (fn ((vname,T),prop) => HOLogic.mk_all (vname,T,prop)) prop (map dest_Free frees)
                in
                    (prop_closed,frees)
                end

            val props'' = map proc_single props'
            val frees = map snd props''
            val prop  = myfoldr HOLogic.mk_conj (map fst props'')
            val cprop = cterm_of sg (HOLogic.mk_Trueprop prop)

            val (prop_thawed,vmap) = Type.varify (prop,[])
            val thawed_prop_consts = collect_consts (prop_thawed,[])
            val (altcos,overloaded) = Library.split_list cos
            val (names,sconsts) = Library.split_list altcos
            val consts = map (term_of o Thm.read_cterm sg o rpair TypeInfer.logicT) sconsts
            val _ = assert (not (Library.exists (not o Term.is_Const) consts))
                           "Specification: Non-constant found as parameter"

            fun proc_const c =
                let
                    val c' = fst (Type.varify (c,[]))
                    val (cname,ctyp) = dest_Const c'
                in
                    case List.filter (fn t => let val (name,typ) = dest_Const t
                                         in name = cname andalso typ_equiv typ ctyp
                                         end) thawed_prop_consts of
                        [] => error ("Specification: No suitable instances of constant \"" ^ (Sign.string_of_term sg c) ^ "\" found")
                      | [cf] => unvarify cf vmap
                      | _ => error ("Specification: Several variations of \"" ^ (Sign.string_of_term sg c) ^ "\" found (try applying explicit type constraints)")
                end
            val proc_consts = map proc_const consts
            fun mk_exist (c,prop) =
                let
                    val T = type_of c
                    val cname = Sign.base_name (fst (dest_Const c))
                    val vname = if Syntax.is_identifier cname
                                then cname
                                else "x"
                in
                    HOLogic.exists_const T $ Abs(vname,T,Term.abstract_over (c,prop))
                end
            val ex_prop = foldr mk_exist prop proc_consts
            val cnames = map (fst o dest_Const) proc_consts
            fun post_process (arg as (thy,thm)) =
                let
                    fun inst_all sg (thm,v) =
                        let
                            val cv = cterm_of sg v
                            val cT = ctyp_of_term cv
                            val spec' = instantiate' [SOME cT] [NONE,SOME cv] spec
                        in
                            thm RS spec'
                        end
                    fun remove_alls frees thm = Library.foldl (inst_all (sign_of_thm thm)) (thm,frees)
                    fun process_single ((name,atts),rew_imp,frees) args =
                        let
                            fun undo_imps thm =
                                equal_elim (symmetric rew_imp) thm

                            fun apply_atts arg = Thm.apply_attributes (arg,map (Attrib.global_attribute thy) atts)
                            fun add_final (arg as (thy,thm)) =
                                if name = ""
                                then arg
                                else (writeln ("  " ^ name ^ ": " ^ (string_of_thm thm));
                                      PureThy.store_thm((name,thm),[]) thy)
                        in
                            args |> apsnd (remove_alls frees)
                                 |> apsnd undo_imps
                                 |> apsnd standard
                                 |> apply_atts
                                 |> add_final
                        end

                    fun process_all [proc_arg] args =
                        process_single proc_arg args
                      | process_all (proc_arg::rest) (thy,thm) =
                        let
                            val single_th = thm RS conjunct1
                            val rest_th   = thm RS conjunct2
                            val (thy',_)  = process_single proc_arg (thy,single_th)
                        in
                            process_all rest (thy',rest_th)
                        end
                      | process_all [] _ = error "SpecificationPackage.process_spec internal error"
                    val alt_names = map fst alt_props
                    val _ = if exists (fn(name,_) => not (name = "")) alt_names
                            then writeln "specification"
                            else ()
                in
                    arg |> apsnd freezeT
                        |> process_all (zip3 alt_names rew_imps frees)
                end
        in
          IsarThy.theorem_i Drule.internalK
            ("", [add_specification_i axiomatic (zip3 names cnames overloaded), post_process])
            (HOLogic.mk_Trueprop ex_prop, ([], [])) thy
        end

    (* outer syntax *)

    local structure P = OuterParse and K = OuterKeyword in

    val opt_name = Scan.optional (P.name --| P.$$$ ":") ""
    val opt_overloaded = P.opt_keyword "overloaded";

    val specification_decl =
      P.$$$ "(" |-- Scan.repeat1 (opt_name -- P.term -- opt_overloaded) --| P.$$$ ")" --
              Scan.repeat1 (P.opt_thm_name ":" -- P.prop)

    val specificationP =
      OuterSyntax.command "specification" "define constants by specification" K.thy_goal
        (specification_decl >> (fn (cos,alt_props) =>
                                   Toplevel.print o (Toplevel.theory_to_proof
                                                         (process_spec NONE cos alt_props))))

    val ax_specification_decl =
        P.name --
        (P.$$$ "(" |-- Scan.repeat1 (opt_name -- P.term -- opt_overloaded) --| P.$$$ ")" --
               Scan.repeat1 (P.opt_thm_name ":" -- P.prop))

    val ax_specificationP =
      OuterSyntax.command "ax_specification" "define constants by specification" K.thy_goal
        (ax_specification_decl >> (fn (axname,(cos,alt_props)) =>
                                   Toplevel.print o (Toplevel.theory_to_proof
                                                         (process_spec (SOME axname) cos alt_props))))

    val _ = OuterSyntax.add_parsers [specificationP,ax_specificationP]

    end

    end