(*  Title:      Pure/codegen.ML

    Author:     Stefan Berghofer, TU Muenchen

Generic code generator.

*)

signature CODEGEN =

sig

  val quiet_mode : bool Unsynchronized.ref

  val message : string -> unit

  val mode : string list Unsynchronized.ref

  val margin : int Unsynchronized.ref

  val string_of : Pretty.T -> string

  val str : string -> Pretty.T

  datatype 'a mixfix =

      Arg

    | Ignore

    | Module

    | Pretty of Pretty.T

    | Quote of 'a;

  type deftab

  type node

  type codegr

  type 'a codegen

  val add_codegen: string -> term codegen -> theory -> theory

  val add_tycodegen: string -> typ codegen -> theory -> theory

  val add_preprocessor: (theory -> thm list -> thm list) -> theory -> theory

  val preprocess: theory -> thm list -> thm list

  val preprocess_term: theory -> term -> term

  val print_codegens: theory -> unit

  val generate_code: theory -> string list -> string -> (string * string) list ->

    (string * string) list * codegr

  val generate_code_i: theory -> string list -> string -> (string * term) list ->

    (string * string) list * codegr

  val assoc_const: string * (term mixfix list *

    (string * string) list) -> theory -> theory

  val assoc_const_i: (string * typ) * (term mixfix list *

    (string * string) list) -> theory -> theory

  val assoc_type: xstring * (typ mixfix list *

    (string * string) list) -> theory -> theory

  val get_assoc_code: theory -> string * typ ->

    (term mixfix list * (string * string) list) option

  val get_assoc_type: theory -> string ->

    (typ mixfix list * (string * string) list) option

  val codegen_error: codegr -> string -> string -> 'a

  val invoke_codegen: theory -> deftab -> string -> string -> bool ->

    term -> codegr -> Pretty.T * codegr

  val invoke_tycodegen: theory -> deftab -> string -> string -> bool ->

    typ -> codegr -> Pretty.T * codegr

  val mk_id: string -> string

  val mk_qual_id: string -> string * string -> string

  val mk_const_id: string -> string -> codegr -> (string * string) * codegr

  val get_const_id: codegr -> string -> string * string

  val mk_type_id: string -> string -> codegr -> (string * string) * codegr

  val get_type_id: codegr -> string -> string * string

  val thyname_of_type: theory -> string -> string

  val thyname_of_const: theory -> string -> string

  val rename_terms: term list -> term list

  val rename_term: term -> term

  val new_names: term -> string list -> string list

  val new_name: term -> string -> string

  val if_library: 'a -> 'a -> 'a

  val get_defn: theory -> deftab -> string -> typ ->

    ((typ * (string * thm)) * int option) option

  val is_instance: typ -> typ -> bool

  val parens: Pretty.T -> Pretty.T

  val mk_app: bool -> Pretty.T -> Pretty.T list -> Pretty.T

  val mk_tuple: Pretty.T list -> Pretty.T

  val mk_let: (Pretty.T * Pretty.T) list -> Pretty.T -> Pretty.T

  val eta_expand: term -> term list -> int -> term

  val strip_tname: string -> string

  val mk_type: bool -> typ -> Pretty.T

  val mk_term_of: codegr -> string -> bool -> typ -> Pretty.T

  val mk_gen: codegr -> string -> bool -> string list -> string -> typ -> Pretty.T

  val test_fn: (int -> term list option) Unsynchronized.ref

  val test_term: Proof.context -> term -> int -> term list option

  val eval_result: (unit -> term) Unsynchronized.ref

  val eval_term: theory -> term -> term

  val evaluation_conv: cterm -> thm

  val parse_mixfix: (string -> 'a) -> string -> 'a mixfix list

  val quotes_of: 'a mixfix list -> 'a list

  val num_args_of: 'a mixfix list -> int

  val replace_quotes: 'b list -> 'a mixfix list -> 'b mixfix list

  val mk_deftab: theory -> deftab

  val map_unfold: (simpset -> simpset) -> theory -> theory

  val add_unfold: thm -> theory -> theory

  val del_unfold: thm -> theory -> theory

  val get_node: codegr -> string -> node

  val add_edge: string * string -> codegr -> codegr

  val add_edge_acyclic: string * string -> codegr -> codegr

  val del_nodes: string list -> codegr -> codegr

  val map_node: string -> (node -> node) -> codegr -> codegr

  val new_node: string * node -> codegr -> codegr

  val setup: theory -> theory

end;

structure Codegen : CODEGEN =

struct

val quiet_mode = Unsynchronized.ref true;

fun message s = if !quiet_mode then () else writeln s;

val mode = Unsynchronized.ref ([] : string list);   (* FIXME proper functional argument *)

val margin = Unsynchronized.ref 80;

fun string_of p = (Pretty.string_of |>

  PrintMode.setmp [] |>

  Pretty.setmp_margin_CRITICAL (!margin)) p;

val str = PrintMode.setmp [] Pretty.str;

(**** Mixfix syntax ****)

datatype 'a mixfix =

    Arg

  | Ignore

  | Module

  | Pretty of Pretty.T

  | Quote of 'a;

fun is_arg Arg = true

  | is_arg Ignore = true

  | is_arg _ = false;

fun quotes_of [] = []

  | quotes_of (Quote q :: ms) = q :: quotes_of ms

  | quotes_of (_ :: ms) = quotes_of ms;

fun args_of [] xs = ([], xs)

  | args_of (Arg :: ms) (x :: xs) = apfst (cons x) (args_of ms xs)

  | args_of (Ignore :: ms) (_ :: xs) = args_of ms xs

  | args_of (_ :: ms) xs = args_of ms xs;

fun num_args_of x = length (filter is_arg x);

(**** theory data ****)

(* preprocessed definition table *)

type deftab =

  (typ *              (* type of constant *)

    (string *         (* name of theory containing definition of constant *)

      thm))           (* definition theorem *)

  list Symtab.table;

(* code dependency graph *)

type nametab = (string * string) Symtab.table * unit Symtab.table;

fun merge_nametabs ((tab, used) : nametab, (tab', used')) =

  (Symtab.merge op = (tab, tab'), Symtab.merge op = (used, used'));

type node =

  (exn option *    (* slot for arbitrary data *)

   string *        (* name of structure containing piece of code *)

   string);        (* piece of code *)

type codegr =

  node Graph.T *

  (nametab *       (* table for assigned constant names *)

   nametab);       (* table for assigned type names *)

val emptygr : codegr = (Graph.empty,

  ((Symtab.empty, Symtab.empty), (Symtab.empty, Symtab.empty)));

(* type of code generators *)

type 'a codegen =

  theory ->    (* theory in which generate_code was called *)

  deftab ->    (* definition table (for efficiency) *)

  string ->    (* node name of caller (for recording dependencies) *)

  string ->    (* module name of caller (for modular code generation) *)

  bool ->      (* whether to parenthesize generated expression *)

  'a ->        (* item to generate code from *)

  codegr ->    (* code dependency graph *)

  (Pretty.T * codegr) option;

(* theory data *)

structure CodegenData = Theory_Data

(

  type T =

    {codegens : (string * term codegen) list,

     tycodegens : (string * typ codegen) list,

     consts : ((string * typ) * (term mixfix list * (string * string) list)) list,

     types : (string * (typ mixfix list * (string * string) list)) list,

     preprocs: (stamp * (theory -> thm list -> thm list)) list,

     modules: codegr Symtab.table};

  val empty =

    {codegens = [], tycodegens = [], consts = [], types = [],

     preprocs = [], modules = Symtab.empty};

  val extend = I;

  fun merge

    ({codegens = codegens1, tycodegens = tycodegens1,

      consts = consts1, types = types1,

      preprocs = preprocs1, modules = modules1} : T,

     {codegens = codegens2, tycodegens = tycodegens2,

      consts = consts2, types = types2,

      preprocs = preprocs2, modules = modules2}) : T =

    {codegens = AList.merge (op =) (K true) (codegens1, codegens2),

     tycodegens = AList.merge (op =) (K true) (tycodegens1, tycodegens2),

     consts = AList.merge (op =) (K true) (consts1, consts2),

     types = AList.merge (op =) (K true) (types1, types2),

     preprocs = AList.merge (op =) (K true) (preprocs1, preprocs2),

     modules = Symtab.merge (K true) (modules1, modules2)};

);

fun print_codegens thy =

  let val {codegens, tycodegens, ...} = CodegenData.get thy in

    Pretty.writeln (Pretty.chunks

      [Pretty.strs ("term code generators:" :: map fst codegens),

       Pretty.strs ("type code generators:" :: map fst tycodegens)])

  end;

(**** access modules ****)

fun get_modules thy = #modules (CodegenData.get thy);

fun map_modules f thy =

  let val {codegens, tycodegens, consts, types, preprocs, modules} =

    CodegenData.get thy;

  in CodegenData.put {codegens = codegens, tycodegens = tycodegens,

    consts = consts, types = types, preprocs = preprocs,

    modules = f modules} thy

  end;

(**** add new code generators to theory ****)

fun add_codegen name f thy =

  let val {codegens, tycodegens, consts, types, preprocs, modules} =

    CodegenData.get thy

  in (case AList.lookup (op =) codegens name of

      NONE => CodegenData.put {codegens = (name, f) :: codegens,

        tycodegens = tycodegens, consts = consts, types = types,

        preprocs = preprocs, modules = modules} thy

    | SOME _ => error ("Code generator " ^ name ^ " already declared"))

  end;

fun add_tycodegen name f thy =

  let val {codegens, tycodegens, consts, types, preprocs, modules} =

    CodegenData.get thy

  in (case AList.lookup (op =) tycodegens name of

      NONE => CodegenData.put {tycodegens = (name, f) :: tycodegens,

        codegens = codegens, consts = consts, types = types,

        preprocs = preprocs, modules = modules} thy

    | SOME _ => error ("Code generator " ^ name ^ " already declared"))

  end;

(**** preprocessors ****)

fun add_preprocessor p thy =

  let val {codegens, tycodegens, consts, types, preprocs, modules} =

    CodegenData.get thy

  in CodegenData.put {tycodegens = tycodegens,

    codegens = codegens, consts = consts, types = types,

    preprocs = (stamp (), p) :: preprocs,

    modules = modules} thy

  end;

fun preprocess thy =

  let val {preprocs, ...} = CodegenData.get thy

  in fold (fn (_, f) => f thy) preprocs end;

fun preprocess_term thy t =

  let

    val x = Free (Name.variant (OldTerm.add_term_names (t, [])) "x", fastype_of t);

    (* fake definition *)

    val eq = Skip_Proof.make_thm thy (Logic.mk_equals (x, t));

    fun err () = error "preprocess_term: bad preprocessor"

  in case map prop_of (preprocess thy [eq]) of

      [Const ("==", _) $ x' $ t'] => if x = x' then t' else err ()

    | _ => err ()

  end;

structure UnfoldData = Theory_Data

(

  type T = simpset;

  val empty = empty_ss;

  val extend = I;

  val merge = merge_ss;

);

val map_unfold = UnfoldData.map;

val add_unfold = map_unfold o MetaSimplifier.add_simp;

val del_unfold = map_unfold o MetaSimplifier.del_simp;

fun unfold_preprocessor thy =

  let val ss = Simplifier.theory_context thy (UnfoldData.get thy)

  in map (Thm.transfer thy #> Simplifier.full_simplify ss) end;

(**** associate constants with target language code ****)

fun gen_assoc_const prep_const (raw_const, syn) thy =

  let

    val {codegens, tycodegens, consts, types, preprocs, modules} =

      CodegenData.get thy;

    val (cname, T) = prep_const thy raw_const;

  in

    if num_args_of (fst syn) > length (binder_types T) then

      error ("More arguments than in corresponding type of " ^ cname)

    else case AList.lookup (op =) consts (cname, T) of

      NONE => CodegenData.put {codegens = codegens,

        tycodegens = tycodegens,

        consts = ((cname, T), syn) :: consts,

        types = types, preprocs = preprocs,

        modules = modules} thy

    | SOME _ => error ("Constant " ^ cname ^ " already associated with code")

  end;

val assoc_const_i = gen_assoc_const (K I);

val assoc_const = gen_assoc_const Code.read_bare_const;

(**** associate types with target language types ****)

fun assoc_type (s, syn) thy =

  let

    val {codegens, tycodegens, consts, types, preprocs, modules} =

      CodegenData.get thy;

    val tc = Sign.intern_type thy s;

  in

    case Symtab.lookup (snd (#types (Type.rep_tsig (Sign.tsig_of thy)))) tc of

      SOME (Type.LogicalType i) =>

        if num_args_of (fst syn) > i then

          error ("More arguments than corresponding type constructor " ^ s)

        else

          (case AList.lookup (op =) types tc of

            NONE => CodegenData.put {codegens = codegens,

              tycodegens = tycodegens, consts = consts,

              types = (tc, syn) :: types,

              preprocs = preprocs, modules = modules} thy

          | SOME _ => error ("Type " ^ tc ^ " already associated with code"))

    | _ => error ("Not a type constructor: " ^ s)

  end;

fun get_assoc_type thy = AList.lookup (op =) ((#types o CodegenData.get) thy);

(**** make valid ML identifiers ****)

fun is_ascii_letdig x = Symbol.is_ascii_letter x orelse

  Symbol.is_ascii_digit x orelse Symbol.is_ascii_quasi x;

fun dest_sym s = (case split_last (snd (take_prefix (fn c => c = "\\") (explode s))) of

    ("<" :: "^" :: xs, ">") => (true, implode xs)

  | ("<" :: xs, ">") => (false, implode xs)

  | _ => sys_error "dest_sym");

fun mk_id s = if s = "" then "" else

  let

    fun check_str [] = []

      | check_str xs = (case take_prefix is_ascii_letdig xs of

          ([], " " :: zs) => check_str zs

        | ([], z :: zs) =>

          if size z = 1 then string_of_int (ord z) :: check_str zs

          else (case dest_sym z of

              (true, "isub") => check_str zs

            | (true, "isup") => "" :: check_str zs

            | (ctrl, s') => (if ctrl then "ctrl_" ^ s' else s') :: check_str zs)

        | (ys, zs) => implode ys :: check_str zs);

    val s' = space_implode "_" (maps (check_str o Symbol.explode) (Long_Name.explode s))

  in

    if Symbol.is_ascii_letter (hd (explode s')) then s' else "id_" ^ s'

  end;

fun mk_long_id (p as (tab, used)) module s =

  let

    fun find_name [] = sys_error "mk_long_id"

      | find_name (ys :: yss) =

          let

            val s' = Long_Name.implode ys

            val s'' = Long_Name.append module s'

          in case Symtab.lookup used s'' of

              NONE => ((module, s'),

                (Symtab.update_new (s, (module, s')) tab,

                 Symtab.update_new (s'', ()) used))

            | SOME _ => find_name yss

          end

  in case Symtab.lookup tab s of

      NONE => find_name (Library.suffixes1 (Long_Name.explode s))

    | SOME name => (name, p)

  end;

(* module:  module name for caller                                        *)

(* module': module name for callee                                        *)

(* if caller and callee reside in different modules, use qualified access *)

fun mk_qual_id module (module', s) =

  if module = module' orelse module' = "" then s else module' ^ "." ^ s;

fun mk_const_id module cname (gr, (tab1, tab2)) =

  let

    val ((module, s), tab1') = mk_long_id tab1 module cname

    val s' = mk_id s;

    val s'' = if ML_Syntax.is_reserved s' then s' ^ "_const" else s'

  in (((module, s'')), (gr, (tab1', tab2))) end;

fun get_const_id (gr, (tab1, tab2)) cname =

  case Symtab.lookup (fst tab1) cname of

    NONE => error ("get_const_id: no such constant: " ^ quote cname)

  | SOME (module, s) =>

      let

        val s' = mk_id s;

        val s'' = if ML_Syntax.is_reserved s' then s' ^ "_const" else s'

      in (module, s'') end;

fun mk_type_id module tyname (gr, (tab1, tab2)) =

  let

    val ((module, s), tab2') = mk_long_id tab2 module tyname

    val s' = mk_id s;

    val s'' = if ML_Syntax.is_reserved s' then s' ^ "_type" else s'

  in ((module, s''), (gr, (tab1, tab2'))) end;

fun get_type_id (gr, (tab1, tab2)) tyname =

  case Symtab.lookup (fst tab2) tyname of

    NONE => error ("get_type_id: no such type: " ^ quote tyname)

  | SOME (module, s) =>

      let

        val s' = mk_id s;

        val s'' = if ML_Syntax.is_reserved s' then s' ^ "_type" else s'

      in (module, s'') end;

fun get_type_id' f tab tyname = apsnd f (get_type_id tab tyname);

fun get_node (gr, x) k = Graph.get_node gr k;

fun add_edge e (gr, x) = (Graph.add_edge e gr, x);

fun add_edge_acyclic e (gr, x) = (Graph.add_edge_acyclic e gr, x);

fun del_nodes ks (gr, x) = (Graph.del_nodes ks gr, x);

fun map_node k f (gr, x) = (Graph.map_node k f gr, x);

fun new_node p (gr, x) = (Graph.new_node p gr, x);

fun thyname_of_type thy = #theory_name o Name_Space.the_entry (Sign.type_space thy);

fun thyname_of_const thy = #theory_name o Name_Space.the_entry (Sign.const_space thy);

fun rename_terms ts =

  let

    val names = List.foldr OldTerm.add_term_names

      (map (fst o fst) (rev (fold Term.add_vars ts []))) ts;

    val reserved = filter ML_Syntax.is_reserved names;

    val (illegal, alt_names) = split_list (map_filter (fn s =>

      let val s' = mk_id s in if s = s' then NONE else SOME (s, s') end) names)

    val ps = (reserved @ illegal) ~~

      Name.variant_list names (map (suffix "'") reserved @ alt_names);

    fun rename_id s = AList.lookup (op =) ps s |> the_default s;

    fun rename (Var ((a, i), T)) = Var ((rename_id a, i), T)

      | rename (Free (a, T)) = Free (rename_id a, T)

      | rename (Abs (s, T, t)) = Abs (s, T, rename t)

      | rename (t $ u) = rename t $ rename u

      | rename t = t;

  in

    map rename ts

  end;

val rename_term = hd o rename_terms o single;

(**** retrieve definition of constant ****)

fun is_instance T1 T2 =

  Type.raw_instance (T1, if null (OldTerm.typ_tfrees T2) then T2 else Logic.varifyT T2);

fun get_assoc_code thy (s, T) = Option.map snd (find_first (fn ((s', T'), _) =>

  s = s' andalso is_instance T T') (#consts (CodegenData.get thy)));

fun get_aux_code xs = map_filter (fn (m, code) =>

  if m = "" orelse member (op =) (!mode) m then SOME code else NONE) xs;

fun dest_prim_def t =

  let

    val (lhs, rhs) = Logic.dest_equals t;

    val (c, args) = strip_comb lhs;

    val (s, T) = dest_Const c

  in if forall is_Var args then SOME (s, (T, (args, rhs))) else NONE

  end handle TERM _ => NONE;

fun mk_deftab thy =

  let

    val axmss = map (fn thy' => (Context.theory_name thy', Theory.axiom_table thy'))

      (thy :: Theory.ancestors_of thy);

    fun add_def thyname (name, t) = (case dest_prim_def t of

        NONE => I

      | SOME (s, (T, _)) => Symtab.map_default (s, [])

          (cons (T, (thyname, Thm.axiom thy name))));

  in

    fold (fn (thyname, axms) => Symtab.fold (add_def thyname) axms) axmss Symtab.empty

  end;

fun prep_prim_def thy thm =

  let

    val prop = case preprocess thy [thm]

     of [thm'] => Thm.prop_of thm'

      | _ => error "mk_deftab: bad preprocessor"

  in ((Option.map o apsnd o apsnd)

    (fn (args, rhs) => split_last (rename_terms (args @ [rhs]))) o dest_prim_def) prop

  end;

fun get_defn thy defs s T = (case Symtab.lookup defs s of

    NONE => NONE

  | SOME ds =>

      let val i = find_index (is_instance T o fst) ds

      in if i >= 0 then

          SOME (nth ds i, if length ds = 1 then NONE else SOME i)

        else NONE

      end);

(**** invoke suitable code generator for term / type ****)

fun codegen_error (gr, _) dep s =

  error (s ^ "\nrequired by:\n" ^ commas (Graph.all_succs gr [dep]));

fun invoke_codegen thy defs dep module brack t gr = (case get_first

   (fn (_, f) => f thy defs dep module brack t gr) (#codegens (CodegenData.get thy)) of

      NONE => codegen_error gr dep ("Unable to generate code for term:\n" ^

        Syntax.string_of_term_global thy t)

    | SOME x => x);

fun invoke_tycodegen thy defs dep module brack T gr = (case get_first

   (fn (_, f) => f thy defs dep module brack T gr ) (#tycodegens (CodegenData.get thy)) of

      NONE => codegen_error gr dep ("Unable to generate code for type:\n" ^

        Syntax.string_of_typ_global thy T)

    | SOME x => x);

(**** code generator for mixfix expressions ****)

fun parens p = Pretty.block [str "(", p, str ")"];

fun pretty_fn [] p = [p]

  | pretty_fn (x::xs) p = str ("fn " ^ x ^ " =>") ::

      Pretty.brk 1 :: pretty_fn xs p;

fun pretty_mixfix _ _ [] [] _ = []

  | pretty_mixfix module module' (Arg :: ms) (p :: ps) qs =

      p :: pretty_mixfix module module' ms ps qs

  | pretty_mixfix module module' (Ignore :: ms) ps qs =

      pretty_mixfix module module' ms ps qs

  | pretty_mixfix module module' (Module :: ms) ps qs =

      (if module <> module'

       then cons (str (module' ^ ".")) else I)

      (pretty_mixfix module module' ms ps qs)

  | pretty_mixfix module module' (Pretty p :: ms) ps qs =

      p :: pretty_mixfix module module' ms ps qs

  | pretty_mixfix module module' (Quote _ :: ms) ps (q :: qs) =

      q :: pretty_mixfix module module' ms ps qs;

fun replace_quotes [] [] = []

  | replace_quotes xs (Arg :: ms) =

      Arg :: replace_quotes xs ms

  | replace_quotes xs (Ignore :: ms) =

      Ignore :: replace_quotes xs ms

  | replace_quotes xs (Module :: ms) =

      Module :: replace_quotes xs ms

  | replace_quotes xs (Pretty p :: ms) =

      Pretty p :: replace_quotes xs ms

  | replace_quotes (x::xs) (Quote _ :: ms) =

      Quote x :: replace_quotes xs ms;

(**** default code generators ****)

fun eta_expand t ts i =

  let

    val k = length ts;

    val Ts = drop k (binder_types (fastype_of t));

    val j = i - k

  in

    List.foldr (fn (T, t) => Abs ("x", T, t))

      (list_comb (t, ts @ map Bound (j-1 downto 0))) (take j Ts)

  end;

fun mk_app _ p [] = p

  | mk_app brack p ps = if brack then

       Pretty.block (str "(" ::

         separate (Pretty.brk 1) (p :: ps) @ [str ")"])

     else Pretty.block (separate (Pretty.brk 1) (p :: ps));

fun new_names t xs = Name.variant_list

  (union (op =) (map (fst o fst o dest_Var) (OldTerm.term_vars t))

    (OldTerm.add_term_names (t, ML_Syntax.reserved_names))) (map mk_id xs);

fun new_name t x = hd (new_names t [x]);

fun if_library x y = if member (op =) (!mode) "library" then x else y;

fun default_codegen thy defs dep module brack t gr =

  let

    val (u, ts) = strip_comb t;

    fun codegens brack = fold_map (invoke_codegen thy defs dep module brack)

  in (case u of

      Var ((s, i), T) =>

        let

          val (ps, gr') = codegens true ts gr;

          val (_, gr'') = invoke_tycodegen thy defs dep module false T gr'

        in SOME (mk_app brack (str (s ^

           (if i=0 then "" else string_of_int i))) ps, gr'')

        end

    | Free (s, T) =>

        let

          val (ps, gr') = codegens true ts gr;

          val (_, gr'') = invoke_tycodegen thy defs dep module false T gr'

        in SOME (mk_app brack (str s) ps, gr'') end

    | Const (s, T) =>

      (case get_assoc_code thy (s, T) of

         SOME (ms, aux) =>

           let val i = num_args_of ms

           in if length ts < i then

               default_codegen thy defs dep module brack (eta_expand u ts i) gr 

             else

               let

                 val (ts1, ts2) = args_of ms ts;

                 val (ps1, gr1) = codegens false ts1 gr;

                 val (ps2, gr2) = codegens true ts2 gr1;

                 val (ps3, gr3) = codegens false (quotes_of ms) gr2;

                 val (_, gr4) = invoke_tycodegen thy defs dep module false

                   (funpow (length ts) (hd o tl o snd o dest_Type) T) gr3;

                 val (module', suffix) = (case get_defn thy defs s T of

                     NONE => (if_library (thyname_of_const thy s) module, "")

                   | SOME ((U, (module', _)), NONE) =>

                       (if_library module' module, "")

                   | SOME ((U, (module', _)), SOME i) =>

                       (if_library module' module, " def" ^ string_of_int i));

                 val node_id = s ^ suffix;

                 fun p module' = mk_app brack (Pretty.block

                   (pretty_mixfix module module' ms ps1 ps3)) ps2

               in SOME (case try (get_node gr4) node_id of

                   NONE => (case get_aux_code aux of

                       [] => (p module, gr4)

                     | xs => (p module', add_edge (node_id, dep) (new_node

                         (node_id, (NONE, module', cat_lines xs ^ "\n")) gr4)))

                 | SOME (_, module'', _) =>

                     (p module'', add_edge (node_id, dep) gr4))

               end

           end

       | NONE => (case get_defn thy defs s T of

           NONE => NONE

         | SOME ((U, (thyname, thm)), k) => (case prep_prim_def thy thm

            of SOME (_, (_, (args, rhs))) => let

               val module' = if_library thyname module;

               val suffix = (case k of NONE => "" | SOME i => " def" ^ string_of_int i);

               val node_id = s ^ suffix;

               val ((ps, def_id), gr') = gr |> codegens true ts

                 ||>> mk_const_id module' (s ^ suffix);

               val p = mk_app brack (str (mk_qual_id module def_id)) ps

             in SOME (case try (get_node gr') node_id of

                 NONE =>

                   let

                     val _ = message ("expanding definition of " ^ s);

                     val (Ts, _) = strip_type U;

                     val (args', rhs') =

                       if not (null args) orelse null Ts then (args, rhs) else

                         let val v = Free (new_name rhs "x", hd Ts)

                         in ([v], betapply (rhs, v)) end;

                     val (p', gr1) = invoke_codegen thy defs node_id module' false

                       rhs' (add_edge (node_id, dep)

                          (new_node (node_id, (NONE, "", "")) gr'));

                     val (xs, gr2) = codegens false args' gr1;

                     val (_, gr3) = invoke_tycodegen thy defs dep module false T gr2;

                     val (ty, gr4) = invoke_tycodegen thy defs node_id module' false U gr3;

                   in (p, map_node node_id (K (NONE, module', string_of

                       (Pretty.block (separate (Pretty.brk 1)

                         (if null args' then

                            [str ("val " ^ snd def_id ^ " :"), ty]

                          else str ("fun " ^ snd def_id) :: xs) @

                        [str " =", Pretty.brk 1, p', str ";"])) ^ "\n\n")) gr4)

                   end

               | SOME _ => (p, add_edge (node_id, dep) gr'))

             end

             | NONE => NONE)))

    | Abs _ =>

      let

        val (bs, Ts) = ListPair.unzip (strip_abs_vars u);

        val t = strip_abs_body u

        val bs' = new_names t bs;

        val (ps, gr1) = codegens true ts gr;

        val (p, gr2) = invoke_codegen thy defs dep module false

          (subst_bounds (map Free (rev (bs' ~~ Ts)), t)) gr1;

      in

        SOME (mk_app brack (Pretty.block (str "(" :: pretty_fn bs' p @

          [str ")"])) ps, gr2)

      end

    | _ => NONE)

  end;

fun default_tycodegen thy defs dep module brack (TVar ((s, i), _)) gr =

      SOME (str (s ^ (if i = 0 then "" else string_of_int i)), gr)

  | default_tycodegen thy defs dep module brack (TFree (s, _)) gr =

      SOME (str s, gr)

  | default_tycodegen thy defs dep module brack (Type (s, Ts)) gr =

      (case AList.lookup (op =) ((#types o CodegenData.get) thy) s of

         NONE => NONE

       | SOME (ms, aux) =>

           let

             val (ps, gr') = fold_map

               (invoke_tycodegen thy defs dep module false)

               (fst (args_of ms Ts)) gr;

             val (qs, gr'') = fold_map

               (invoke_tycodegen thy defs dep module false)

               (quotes_of ms) gr';

             val module' = if_library (thyname_of_type thy s) module;

             val node_id = s ^ " (type)";

             fun p module' = Pretty.block (pretty_mixfix module module' ms ps qs)

           in SOME (case try (get_node gr'') node_id of

               NONE => (case get_aux_code aux of

                   [] => (p module', gr'')

                 | xs => (p module', snd (mk_type_id module' s

                       (add_edge (node_id, dep) (new_node (node_id,

                         (NONE, module', cat_lines xs ^ "\n")) gr'')))))

             | SOME (_, module'', _) =>

                 (p module'', add_edge (node_id, dep) gr''))

           end);

fun mk_tuple [p] = p

  | mk_tuple ps = Pretty.block (str "(" ::

      flat (separate [str ",", Pretty.brk 1] (map single ps)) @ [str ")"]);

fun mk_let bindings body =

  Pretty.blk (0, [str "let", Pretty.brk 1,

    Pretty.blk (0, separate Pretty.fbrk (map (fn (pat, rhs) =>

      Pretty.block [str "val ", pat, str " =", Pretty.brk 1,

      rhs, str ";"]) bindings)),

    Pretty.brk 1, str "in", Pretty.brk 1, body,

    Pretty.brk 1, str "end"]);

fun mk_struct name s = "structure " ^ name ^ " =\nstruct\n\n" ^ s ^ "end;\n";

fun add_to_module name s = AList.map_entry (op =) (name : string) (suffix s);

fun output_code gr module xs =

  let

    val code = map_filter (fn s =>

      let val c as (_, module', _) = Graph.get_node gr s

      in if module = "" orelse module = module' then SOME (s, c) else NONE end)

        (rev (Graph.all_preds gr xs));

    fun string_of_cycle (a :: b :: cs) =

          let val SOME (x, y) = get_first (fn (x, (_, a', _)) =>

            if a = a' then Option.map (pair x)

              (find_first ((fn (_, b', _) => b' = b) o Graph.get_node gr)

                (Graph.imm_succs gr x))

            else NONE) code

          in x ^ " called by " ^ y ^ "\n" ^ string_of_cycle (b :: cs) end

      | string_of_cycle _ = ""

  in

    if module = "" then

      let

        val modules = distinct (op =) (map (#2 o snd) code);

        val mod_gr = fold_rev Graph.add_edge_acyclic

          (maps (fn (s, (_, module, _)) => map (pair module)

            (filter_out (fn s => s = module) (map (#2 o Graph.get_node gr)

              (Graph.imm_succs gr s)))) code)

          (fold_rev (Graph.new_node o rpair ()) modules Graph.empty);

        val modules' =

          rev (Graph.all_preds mod_gr (map (#2 o Graph.get_node gr) xs))

      in

        List.foldl (fn ((_, (_, module, s)), ms) => add_to_module module s ms)

          (map (rpair "") modules') code

      end handle Graph.CYCLES (cs :: _) =>

        error ("Cyclic dependency of modules:\n" ^ commas cs ^

          "\n" ^ string_of_cycle cs)

    else [(module, implode (map (#3 o snd) code))]

  end;

fun gen_generate_code prep_term thy modules module xs =

  let

    val _ = (module <> "" orelse

        member (op =) (!mode) "library" andalso forall (fn (s, _) => s = "") xs)

      orelse error "missing module name";

    val graphs = get_modules thy;

    val defs = mk_deftab thy;

    val gr = new_node ("<Top>", (NONE, module, ""))

      (List.foldl (fn ((gr, (tab1, tab2)), (gr', (tab1', tab2'))) =>

        (Graph.merge (fn ((_, module, _), (_, module', _)) =>

           module = module') (gr, gr'),

         (merge_nametabs (tab1, tab1'), merge_nametabs (tab2, tab2')))) emptygr

           (map (fn s => case Symtab.lookup graphs s of

                NONE => error ("Undefined code module: " ^ s)

              | SOME gr => gr) modules))

      handle Graph.DUP k => error ("Duplicate code for " ^ k);

    fun expand (t as Abs _) = t

      | expand t = (case fastype_of t of

          Type ("fun", [T, U]) => Abs ("x", T, t $ Bound 0) | _ => t);

    val (ps, gr') = fold_map (fn (s, t) => fn gr => apfst (pair s)

      (invoke_codegen thy defs "<Top>" module false t gr))

        (map (apsnd (expand o preprocess_term thy o prep_term thy)) xs) gr;

    val code = map_filter

      (fn ("", _) => NONE

        | (s', p) => SOME (string_of (Pretty.block

          [str ("val " ^ s' ^ " ="), Pretty.brk 1, p, str ";"]))) ps;

    val code' = space_implode "\n\n" code ^ "\n\n";

    val code'' =

      map_filter (fn (name, s) =>

          if member (op =) (!mode) "library" andalso name = module andalso null code

          then NONE

          else SOME (name, mk_struct name s))

        ((if null code then I

          else add_to_module module code')

           (output_code (fst gr') (if_library "" module) ["<Top>"]))

  in

    (code'', del_nodes ["<Top>"] gr')

  end;

val generate_code_i = gen_generate_code Sign.cert_term;

val generate_code =

  gen_generate_code (Syntax.read_term o ProofContext.allow_dummies o ProofContext.init);

(**** Reflection ****)

val strip_tname = implode o tl o explode;

fun pretty_list xs = Pretty.block (str "[" ::

  flat (separate [str ",", Pretty.brk 1] (map single xs)) @

  [str "]"]);

fun mk_type p (TVar ((s, i), _)) = str

      (strip_tname s ^ (if i = 0 then "" else string_of_int i) ^ "T")

  | mk_type p (TFree (s, _)) = str (strip_tname s ^ "T")

  | mk_type p (Type (s, Ts)) = (if p then parens else I) (Pretty.block

      [str "Type", Pretty.brk 1, str ("(\"" ^ s ^ "\","),

       Pretty.brk 1, pretty_list (map (mk_type false) Ts), str ")"]);

fun mk_term_of gr module p (TVar ((s, i), _)) = str

      (strip_tname s ^ (if i = 0 then "" else string_of_int i) ^ "F")

  | mk_term_of gr module p (TFree (s, _)) = str (strip_tname s ^ "F")

  | mk_term_of gr module p (Type (s, Ts)) = (if p then parens else I)

      (Pretty.block (separate (Pretty.brk 1)

        (str (mk_qual_id module

          (get_type_id' (fn s' => "term_of_" ^ s') gr s)) ::

        maps (fn T =>

          [mk_term_of gr module true T, mk_type true T]) Ts)));

(**** Test data generators ****)

fun mk_gen gr module p xs a (TVar ((s, i), _)) = str

      (strip_tname s ^ (if i = 0 then "" else string_of_int i) ^ "G")

  | mk_gen gr module p xs a (TFree (s, _)) = str (strip_tname s ^ "G")

  | mk_gen gr module p xs a (Type (tyc as (s, Ts))) = (if p then parens else I)

      (Pretty.block (separate (Pretty.brk 1)

        (str (mk_qual_id module (get_type_id' (fn s' => "gen_" ^ s') gr s) ^

          (if member (op =) xs s then "'" else "")) ::

         (case tyc of

            ("fun", [T, U]) =>

              [mk_term_of gr module true T, mk_type true T,

               mk_gen gr module true xs a U, mk_type true U]

          | _ => maps (fn T =>

              [mk_gen gr module true xs a T, mk_type true T]) Ts) @

         (if member (op =) xs s then [str a] else []))));

val test_fn : (int -> term list option) Unsynchronized.ref =

  Unsynchronized.ref (fn _ => NONE);

fun test_term ctxt t =

  let

    val thy = ProofContext.theory_of ctxt;

    val (code, gr) = setmp_CRITICAL mode ["term_of", "test"]

      (generate_code_i thy [] "Generated") [("testf", t)];

    val Ts = map snd (fst (strip_abs t));

    val args = map_index (fn (i, T) => ("arg" ^ string_of_int i, T)) Ts;

    val s = "structure TestTerm =\nstruct\n\n" ^

      cat_lines (map snd code) ^

      "\nopen Generated;\n\n" ^ string_of

        (Pretty.block [str "val () = Codegen.test_fn :=",

          Pretty.brk 1, str ("(fn i =>"), Pretty.brk 1,

          mk_let (map (fn (s, T) =>

              (mk_tuple [str s, str (s ^ "_t")],

               Pretty.block [mk_gen gr "Generated" false [] "" T, Pretty.brk 1,

                 str "i"])) args)

            (Pretty.block [str "if ",

              mk_app false (str "testf") (map (str o fst) args),

              Pretty.brk 1, str "then NONE",

              Pretty.brk 1, str "else ",

              Pretty.block [str "SOME ", Pretty.block (str "[" ::

                Pretty.commas (map (fn (s, _) => str (s ^ "_t ()")) args) @

                  [str "]"])]]),

          str ");"]) ^

      "\n\nend;\n";

    val _ = ML_Context.eval_in (SOME ctxt) false Position.none s;

  in ! test_fn end;

(**** Evaluator for terms ****)

val eval_result = Unsynchronized.ref (fn () => Bound 0);

fun eval_term thy t =

  let

    val ctxt = ProofContext.init thy;

    val e =

      let

        val _ = (null (Term.add_tvars t []) andalso null (Term.add_tfrees t [])) orelse

          error "Term to be evaluated contains type variables";

        val _ = (null (Term.add_vars t []) andalso null (Term.add_frees t [])) orelse

          error "Term to be evaluated contains variables";

        val (code, gr) = setmp_CRITICAL mode ["term_of"]

          (generate_code_i thy [] "Generated")

          [("result", Abs ("x", TFree ("'a", []), t))];

        val s = "structure EvalTerm =\nstruct\n\n" ^

          cat_lines (map snd code) ^

          "\nopen Generated;\n\n" ^ string_of

            (Pretty.block [str "val () = Codegen.eval_result := (fn () =>",

              Pretty.brk 1,

              mk_app false (mk_term_of gr "Generated" false (fastype_of t))

                [str "(result ())"],

              str ");"]) ^

          "\n\nend;\n";

        val _ = NAMED_CRITICAL "codegen" (fn () =>   (* FIXME ??? *)

          ML_Context.eval_in (SOME ctxt) false Position.none s);

      in !eval_result end;

  in e () end;

val (_, evaluation_conv) = Context.>>> (Context.map_theory_result

  (Thm.add_oracle (Binding.name "evaluation", fn ct =>

    let

      val thy = Thm.theory_of_cterm ct;

      val t = Thm.term_of ct;

    in Thm.cterm_of thy (Logic.mk_equals (t, eval_term thy t)) end)));

(**** Interface ****)

fun parse_mixfix rd s =

  (case Scan.finite Symbol.stopper (Scan.repeat

     (   $$ "_" >> K Arg

      || $$ "?" >> K Ignore

      || $$ "\\<module>" >> K Module

      || $$ "/" |-- Scan.repeat ($$ " ") >> (Pretty o Pretty.brk o length)

      || $$ "{" |-- $$ "*" |-- Scan.repeat1

           (   $$ "'" |-- Scan.one Symbol.is_regular

            || Scan.unless ($$ "*" -- $$ "}") (Scan.one Symbol.is_regular)) --|

         $$ "*" --| $$ "}" >> (Quote o rd o implode)

      || Scan.repeat1

           (   $$ "'" |-- Scan.one Symbol.is_regular

            || Scan.unless ($$ "_" || $$ "?" || $$ "\\<module>" || $$ "/" || $$ "{" |-- $$ "*")

                 (Scan.one Symbol.is_regular)) >> (Pretty o str o implode)))

       (Symbol.explode s) of

     (p, []) => p

   | _ => error ("Malformed annotation: " ^ quote s));

structure P = OuterParse and K = OuterKeyword;

val _ = List.app OuterKeyword.keyword ["attach", "file", "contains"];

fun strip_whitespace s = implode (fst (take_suffix (fn c => c = "\n" orelse c = " ")

  (snd (take_prefix (fn c => c = "\n" orelse c = " ") (explode s))))) ^ "\n";

val parse_attach = Scan.repeat (P.$$$ "attach" |--

  Scan.optional (P.$$$ "(" |-- P.xname --| P.$$$ ")") "" --

    (P.verbatim >> strip_whitespace));

val _ =

  OuterSyntax.command "types_code"

  "associate types with target language types" K.thy_decl

    (Scan.repeat1 (P.xname --| P.$$$ "(" -- P.string --| P.$$$ ")" -- parse_attach) >>

     (fn xs => Toplevel.theory (fn thy => fold (assoc_type o

       (fn ((name, mfx), aux) => (name, (parse_mixfix

         (Syntax.read_typ_global thy) mfx, aux)))) xs thy)));

val _ =

  OuterSyntax.command "consts_code"

  "associate constants with target language code" K.thy_decl

    (Scan.repeat1

       (P.term --|

        P.$$$ "(" -- P.string --| P.$$$ ")" -- parse_attach) >>

     (fn xs => Toplevel.theory (fn thy => fold (assoc_const o

       (fn ((const, mfx), aux) =>

         (const, (parse_mixfix (Syntax.read_term_global thy) mfx, aux)))) xs thy)));

fun parse_code lib =

  Scan.optional (P.$$$ "(" |-- P.enum "," P.xname --| P.$$$ ")") (!mode) --