(*  Title:      Tools/code/code_funcgr.ML

     Author:     Florian Haftmann, TU Muenchen

 Retrieving, normalizing and structuring code equations in graph

 with explicit dependencies.

 *)

 signature CODE_FUNCGR =

 sig

   type T

   val eqns: T -> string -> (thm * bool) list

   val typ: T -> string -> (string * sort) list * typ

   val all: T -> string list

   val pretty: theory -> T -> Pretty.T

   val make: theory -> string list

     -> ((sort -> sort) * Sorts.algebra) * T

   val eval_conv: theory

     -> (term -> term * (((sort -> sort) * Sorts.algebra) -> T -> thm)) -> cterm -> thm

   val eval_term: theory

     -> (term -> term * (((sort -> sort) * Sorts.algebra) -> T -> 'a)) -> term -> 'a

   val timing: bool ref

 end

 structure Code_Funcgr : CODE_FUNCGR =

 struct

 (** the graph type **)

 type T = (((string * sort) list * typ) * (thm * bool) list) Graph.T;

 fun eqns funcgr =

   these o Option.map snd o try (Graph.get_node funcgr);

 fun typ funcgr =

   fst o Graph.get_node funcgr;

 fun all funcgr = Graph.keys funcgr;

 fun pretty thy funcgr =

   AList.make (snd o Graph.get_node funcgr) (Graph.keys funcgr)

   |> (map o apfst) (Code_Unit.string_of_const thy)

   |> sort (string_ord o pairself fst)

   |> map (fn (s, thms) =>

        (Pretty.block o Pretty.fbreaks) (

          Pretty.str s

          :: map (Display.pretty_thm o fst) thms

        ))

   |> Pretty.chunks;

 (** generic combinators **)

 fun fold_consts f thms =

   thms

   |> maps (op :: o swap o apfst (snd o strip_comb) o Logic.dest_equals o Thm.plain_prop_of)

   |> (fold o fold_aterms) (fn Const c => f c | _ => I);

 fun consts_of (const, []) = []

   | consts_of (const, thms as _ :: _) = 

       let

         fun the_const (c, _) = if c = const then I else insert (op =) c

       in fold_consts the_const (map fst thms) [] end;

 fun insts_of thy algebra tys sorts =

   let

     fun class_relation (x, _) _ = x;

     fun type_constructor tyco xs class =

       (tyco, class) :: (maps o maps) fst xs;

     fun type_variable (TVar (_, sort)) = map (pair []) sort

       | type_variable (TFree (_, sort)) = map (pair []) sort;

     fun of_sort_deriv ty sort =

       Sorts.of_sort_derivation (Syntax.pp_global thy) algebra

         { class_relation = class_relation, type_constructor = type_constructor,

           type_variable = type_variable }

         (ty, sort) handle Sorts.CLASS_ERROR _ => [] (*permissive!*)

   in (flat o flat) (map2 of_sort_deriv tys sorts) end;

 fun meets_of thy algebra =

   let

     fun meet_of ty sort tab =

       Sorts.meet_sort algebra (ty, sort) tab

         handle Sorts.CLASS_ERROR _ => tab (*permissive!*);

   in fold2 meet_of end;

 (** graph algorithm **)

 val timing = ref false;

 local

 fun resort_thms thy algebra typ_of thms =

   let

     val cs = fold_consts (insert (op =)) thms [];

     fun meets (c, ty) = case typ_of c

        of SOME (vs, _) =>

             meets_of thy algebra (Sign.const_typargs thy (c, ty)) (map snd vs)

         | NONE => I;

     val tab = fold meets cs Vartab.empty;

   in map (Code_Unit.inst_thm thy tab) thms end;

 fun resort_eqnss thy algebra funcgr =

   let

     val typ_funcgr = try (fst o Graph.get_node funcgr);

     val resort_dep = (apsnd o burrow_fst) (resort_thms thy algebra typ_funcgr);

     fun resort_rec typ_of (c, []) = (true, (c, []))

       | resort_rec typ_of (c, thms as (thm, _) :: _) = if is_some (AxClass.inst_of_param thy c)

           then (true, (c, thms))

           else let

             val (_, (vs, ty)) = Code_Unit.head_eqn thy thm;

             val thms' as (thm', _) :: _ = burrow_fst (resort_thms thy algebra typ_of) thms

             val (_, (vs', ty')) = Code_Unit.head_eqn thy thm'; (*FIXME simplify check*)

           in (Sign.typ_equiv thy (ty, ty'), (c, thms')) end;

     fun resort_recs eqnss =

       let

         fun typ_of c = case these (AList.lookup (op =) eqnss c)

          of (thm, _) :: _ => (SOME o snd o Code_Unit.head_eqn thy) thm

           | [] => NONE;

         val (unchangeds, eqnss') = split_list (map (resort_rec typ_of) eqnss);

         val unchanged = fold (fn x => fn y => x andalso y) unchangeds true;

       in (unchanged, eqnss') end;

     fun resort_rec_until eqnss =

       let

         val (unchanged, eqnss') = resort_recs eqnss;

       in if unchanged then eqnss' else resort_rec_until eqnss' end;

   in map resort_dep #> resort_rec_until end;

 fun instances_of thy algebra insts =

   let

     val thy_classes = (#classes o Sorts.rep_algebra o Sign.classes_of) thy;

     fun all_classparams tyco class =

       these (try (#params o AxClass.get_info thy) class)

       |> map_filter (fn (c, _) => try (AxClass.param_of_inst thy) (c, tyco))

   in

     Symtab.empty

     |> fold (fn (tyco, class) =>

         Symtab.map_default (tyco, []) (insert (op =) class)) insts

     |> (fn tab => Symtab.fold (fn (tyco, classes) => append (maps (all_classparams tyco)

          (Graph.all_succs thy_classes classes))) tab [])

   end;

 fun instances_of_consts thy algebra funcgr consts =

   let

     fun inst (cexpr as (c, ty)) = insts_of thy algebra

       (Sign.const_typargs thy (c, ty)) ((map snd o fst) (typ funcgr c));

   in

     []

     |> fold (fold (insert (op =)) o inst) consts

     |> instances_of thy algebra

   end;

 fun ensure_const' thy algebra funcgr const auxgr =

   if can (Graph.get_node funcgr) const

     then (NONE, auxgr)

   else if can (Graph.get_node auxgr) const

     then (SOME const, auxgr)

   else if is_some (Code.get_datatype_of_constr thy const) then

     auxgr

     |> Graph.new_node (const, [])

     |> pair (SOME const)

   else let

     val thms = Code.these_eqns thy const

       |> burrow_fst (Code_Unit.norm_args thy)

       |> burrow_fst (Code_Unit.norm_varnames thy Code_Name.purify_tvar Code_Name.purify_var);

     val rhs = consts_of (const, thms);

   in

     auxgr

     |> Graph.new_node (const, thms)

     |> fold_map (ensure_const thy algebra funcgr) rhs

     |-> (fn rhs' => fold (fn SOME const' => Graph.add_edge (const, const')

                            | NONE => I) rhs')

     |> pair (SOME const)

   end

 and ensure_const thy algebra funcgr const =

   let

     val timeap = if !timing

       then Output.timeap_msg ("time for " ^ Code_Unit.string_of_const thy const)

       else I;

   in timeap (ensure_const' thy algebra funcgr const) end;

 fun merge_eqnss thy algebra raw_eqnss funcgr =

   let

     val eqnss = raw_eqnss

       |> resort_eqnss thy algebra funcgr

       |> filter_out (can (Graph.get_node funcgr) o fst);

     fun typ_eqn c [] = Code.default_typscheme thy c

       | typ_eqn c (thms as (thm, _) :: _) = (snd o Code_Unit.head_eqn thy) thm;

     fun add_eqns (const, thms) =

       Graph.new_node (const, (typ_eqn const thms, thms));

     fun add_deps (eqns as (const, thms)) funcgr =

       let

         val deps = consts_of eqns;

         val insts = instances_of_consts thy algebra funcgr

           (fold_consts (insert (op =)) (map fst thms) []);

       in

         funcgr

         |> ensure_consts thy algebra insts

         |> fold (curry Graph.add_edge const) deps

         |> fold (curry Graph.add_edge const) insts

        end;

   in

     funcgr

     |> fold add_eqns eqnss

     |> fold add_deps eqnss

   end

 and ensure_consts thy algebra cs funcgr =

   let

     val auxgr = Graph.empty

       |> fold (snd oo ensure_const thy algebra funcgr) cs;

   in

     funcgr

     |> fold (merge_eqnss thy algebra)

          (map (AList.make (Graph.get_node auxgr))

          (rev (Graph.strong_conn auxgr)))

   end;

 in

 (** retrieval interfaces **)

 val ensure_consts = ensure_consts;

 fun proto_eval thy cterm_of evaluator_lift evaluator proto_ct funcgr =

   let

     val ct = cterm_of proto_ct;

     val _ = Sign.no_vars (Syntax.pp_global thy) (Thm.term_of ct);

     val _ = Term.fold_types (Type.no_tvars #> K I) (Thm.term_of ct) ();

     fun consts_of t =

       fold_aterms (fn Const c_ty => cons c_ty | _ => I) t [];

     val algebra = Code.coregular_algebra thy;

     val thm = Code.preprocess_conv thy ct;

     val ct' = Thm.rhs_of thm;

     val t' = Thm.term_of ct';

     val consts = map fst (consts_of t');

     val funcgr' = ensure_consts thy algebra consts funcgr;

     val (t'', evaluator_funcgr) = evaluator t';

     val consts' = consts_of t'';

     val dicts = instances_of_consts thy algebra funcgr' consts';

     val funcgr'' = ensure_consts thy algebra dicts funcgr';

   in (evaluator_lift (evaluator_funcgr (Code.operational_algebra thy)) thm funcgr'', funcgr'') end;

 fun proto_eval_conv thy =

   let

     fun evaluator_lift evaluator thm1 funcgr =

       let

         val thm2 = evaluator funcgr;

         val thm3 = Code.postprocess_conv thy (Thm.rhs_of thm2);

       in

         Thm.transitive thm1 (Thm.transitive thm2 thm3) handle THM _ =>

           error ("could not construct evaluation proof:\n"

           ^ (cat_lines o map Display.string_of_thm) [thm1, thm2, thm3])

       end;

   in proto_eval thy I evaluator_lift end;

 fun proto_eval_term thy =

   let

     fun evaluator_lift evaluator _ funcgr = evaluator funcgr;

   in proto_eval thy (Thm.cterm_of thy) evaluator_lift end;

 end; (*local*)

 structure Funcgr = CodeDataFun

 (

   type T = T;

   val empty = Graph.empty;

   fun purge _ cs funcgr =

     Graph.del_nodes ((Graph.all_preds funcgr 

       o filter (can (Graph.get_node funcgr))) cs) funcgr;

 );

 fun make thy =

   pair (Code.operational_algebra thy)

   o Funcgr.change thy o ensure_consts thy (Code.coregular_algebra thy);

 fun eval_conv thy f =

   fst o Funcgr.change_yield thy o proto_eval_conv thy f;

 fun eval_term thy f =

   fst o Funcgr.change_yield thy o proto_eval_term thy f;

 (** diagnostic commands **)

 fun code_depgr thy consts =

   let

     val (_, gr) = make thy consts;

     val select = Graph.all_succs gr consts;

   in

     gr

     |> not (null consts) ? Graph.subgraph (member (op =) select) 

     |> Graph.map_nodes ((apsnd o map o apfst) (AxClass.overload thy))

   end;

 fun code_thms thy = Pretty.writeln o pretty thy o code_depgr thy;

 fun code_deps thy consts =

   let

     val gr = code_depgr thy consts;

     fun mk_entry (const, (_, (_, parents))) =

       let

         val name = Code_Unit.string_of_const thy const;

         val nameparents = map (Code_Unit.string_of_const thy) parents;

       in { name = name, ID = name, dir = "", unfold = true,

         path = "", parents = nameparents }

       end;

     val prgr = Graph.fold ((fn x => fn xs => xs @ [x]) o mk_entry) gr [];

   in Present.display_graph prgr end;

 local

 structure P = OuterParse

 and K = OuterKeyword

 fun code_thms_cmd thy = code_thms thy o op @ o Code_Name.read_const_exprs thy;

 fun code_deps_cmd thy = code_deps thy o op @ o Code_Name.read_const_exprs thy;

 in

 val _ =

   OuterSyntax.improper_command "code_thms" "print system of defining equations for code" OuterKeyword.diag

     (Scan.repeat P.term_group

       >> (fn cs => Toplevel.no_timing o Toplevel.unknown_theory

         o Toplevel.keep ((fn thy => code_thms_cmd thy cs) o Toplevel.theory_of)));

 val _ =

   OuterSyntax.improper_command "code_deps" "visualize dependencies of defining equations for code" OuterKeyword.diag

     (Scan.repeat P.term_group

       >> (fn cs => Toplevel.no_timing o Toplevel.unknown_theory

         o Toplevel.keep ((fn thy => code_deps_cmd thy cs) o Toplevel.theory_of)));

 end;

 end; (*struct*)