--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Tools/recfun_codegen.ML Mon Dec 10 15:32:10 2001 +0100
@@ -0,0 +1,146 @@
+(* Title: HOL/recfun_codegen.ML
+ ID: $Id$
+ Author: Stefan Berghofer, TU Muenchen
+ License: GPL (GNU GENERAL PUBLIC LICENSE)
+
+Code generator for recursive functions.
+*)
+
+signature RECFUN_CODEGEN =
+sig
+ val add: theory attribute
+ val setup: (theory -> theory) list
+end;
+
+structure RecfunCodegen : RECFUN_CODEGEN =
+struct
+
+open Codegen;
+
+structure RecfunArgs =
+struct
+ val name = "HOL/recfun_codegen";
+ type T = thm list Symtab.table;
+ val empty = Symtab.empty;
+ val copy = I;
+ val prep_ext = I;
+ val merge = Symtab.merge_multi eq_thm;
+ fun print _ _ = ();
+end;
+
+structure RecfunData = TheoryDataFun(RecfunArgs);
+
+val prop_of = #prop o rep_thm;
+val dest_eqn = HOLogic.dest_eq o HOLogic.dest_Trueprop;
+val const_of = dest_Const o head_of o fst o dest_eqn;
+
+fun warn thm = warning ("RecfunCodegen: Not a proper equation:\n" ^
+ string_of_thm thm);
+
+fun add (p as (thy, thm)) =
+ let
+ val tsig = Sign.tsig_of (sign_of thy);
+ val tab = RecfunData.get thy;
+ val (s, _) = const_of (prop_of thm);
+
+ val matches = curry
+ (Pattern.matches tsig o pairself (fst o dest_eqn o prop_of));
+
+ in (RecfunData.put (Symtab.update ((s,
+ filter_out (matches thm) (if_none (Symtab.lookup (tab, s)) []) @ [thm]),
+ tab)) thy, thm)
+ end handle TERM _ => (warn thm; p) | Pattern.Pattern => (warn thm; p);
+
+fun get_equations thy (s, T) =
+ (case Symtab.lookup (RecfunData.get thy, s) of
+ None => []
+ | Some thms => filter (fn thm => is_instance thy T
+ (snd (const_of (prop_of thm)))) thms);
+
+fun mk_poly_id thy (s, T) = mk_const_id (sign_of thy) s ^
+ (case get_defn thy s T of
+ Some (_, Some i) => "_def" ^ string_of_int i
+ | _ => "");
+
+exception EQN of string * typ * string;
+
+fun cycle g (xs, x) =
+ if x mem xs then xs
+ else foldl (cycle g) (x :: xs, flat (Graph.find_paths g (x, x)));
+
+fun add_rec_funs thy gr dep eqs =
+ let
+ fun dest_eq t =
+ (mk_poly_id thy (const_of t), dest_eqn (rename_term t));
+ val eqs' = map dest_eq eqs;
+ val (dname, _) :: _ = eqs';
+ val (s, T) = const_of (hd eqs);
+
+ fun mk_fundef fname prfx gr [] = (gr, [])
+ | mk_fundef fname prfx gr ((fname', (lhs, rhs)) :: xs) =
+ let
+ val (gr1, pl) = invoke_codegen thy dname false (gr, lhs);
+ val (gr2, pr) = invoke_codegen thy dname false (gr1, rhs);
+ val (gr3, rest) = mk_fundef fname' "and " gr2 xs
+ in
+ (gr3, Pretty.blk (4, [Pretty.str (if fname = fname' then " | " else prfx),
+ pl, Pretty.str " =", Pretty.brk 1, pr]) :: rest)
+ end;
+
+ fun put_code fundef = Graph.map_node dname
+ (K (Some (EQN ("", dummyT, dname)), Pretty.string_of (Pretty.blk (0,
+ separate Pretty.fbrk fundef @ [Pretty.str ";"])) ^ "\n\n"));
+
+ in
+ (case try (Graph.get_node gr) dname of
+ None =>
+ let
+ val gr1 = Graph.add_edge (dname, dep)
+ (Graph.new_node (dname, (Some (EQN (s, T, "")), "")) gr);
+ val (gr2, fundef) = mk_fundef "" "fun " gr1 eqs';
+ val xs = cycle gr2 ([], dname);
+ val cs = map (fn x => case Graph.get_node gr2 x of
+ (Some (EQN (s, T, _)), _) => (s, T)
+ | _ => error ("RecfunCodegen: illegal cyclic dependencies:\n" ^
+ implode (separate ", " xs))) xs
+ in (case xs of
+ [_] => put_code fundef gr2
+ | _ =>
+ if not (dep mem xs) then
+ let
+ val eqs'' = map (dest_eq o prop_of)
+ (flat (map (get_equations thy) cs));
+ val (gr3, fundef') = mk_fundef "" "fun "
+ (Graph.add_edge (dname, dep)
+ (foldr (uncurry Graph.new_node) (map (fn k =>
+ (k, (Some (EQN ("", dummyT, dname)), ""))) xs,
+ Graph.del_nodes xs gr2))) eqs''
+ in put_code fundef' gr3 end
+ else gr2)
+ end
+ | Some (Some (EQN (_, _, s)), _) =>
+ if s = "" then
+ if dname = dep then gr else Graph.add_edge (dname, dep) gr
+ else if s = dep then gr else Graph.add_edge (s, dep) gr)
+ end;
+
+fun recfun_codegen thy gr dep brack t = (case strip_comb t of
+ (Const p, ts) => (case get_equations thy p of
+ [] => None
+ | eqns =>
+ let val (gr', ps) = foldl_map (invoke_codegen thy dep true) (gr, ts)
+ in
+ Some (add_rec_funs thy gr' dep (map prop_of eqns),
+ mk_app brack (Pretty.str (mk_poly_id thy p)) ps)
+ end)
+ | _ => None);
+
+
+val setup =
+ [RecfunData.init,
+ add_codegen "recfun" recfun_codegen,
+ Attrib.add_attributes [("code",
+ (Attrib.no_args add, Attrib.no_args Attrib.undef_local_attribute),
+ "declare equations to be used for code generation")]];
+
+end;