Move towards standard functions.
(* Title: HOL/recfun_codegen.ML
ID: $Id$
Author: Stefan Berghofer, TU Muenchen
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 CodegenArgs =
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' Drule.eq_thm_prop;
fun print _ _ = ();
end;
structure CodegenData = TheoryDataFun(CodegenArgs);
val prop_of = #prop o rep_thm;
val dest_eqn = HOLogic.dest_eq o HOLogic.dest_Trueprop;
val lhs_of = fst o dest_eqn o prop_of;
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 tab = CodegenData.get thy;
val (s, _) = const_of (prop_of thm);
in
if Pattern.pattern (lhs_of thm) then
(CodegenData.put (Symtab.update ((s,
thm :: getOpt (Symtab.lookup (tab, s), [])), tab)) thy, thm)
else (warn thm; p)
end handle TERM _ => (warn thm; p);
fun del (p as (thy, thm)) =
let
val tab = CodegenData.get thy;
val (s, _) = const_of (prop_of thm);
in case Symtab.lookup (tab, s) of
NONE => p
| SOME thms => (CodegenData.put (Symtab.update ((s,
gen_rem eq_thm (thms, thm)), tab)) thy, thm)
end handle TERM _ => (warn thm; p);
fun del_redundant thy eqs [] = eqs
| del_redundant thy eqs (eq :: eqs') =
let
val tsig = Sign.tsig_of (sign_of thy);
val matches = curry
(Pattern.matches tsig o pairself lhs_of)
in del_redundant thy (eq :: eqs) (filter_out (matches eq) eqs') end;
fun get_equations thy (s, T) =
(case Symtab.lookup (CodegenData.get thy, s) of
NONE => []
| SOME thms => preprocess thy (del_redundant thy []
(List.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 Library.foldl (cycle g) (x :: xs, List.concat (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)
(List.concat (map (get_equations thy) cs));
val (gr3, fundef') = mk_fundef "" "fun "
(Graph.add_edge (dname, dep)
(Library.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 as (s, T)), ts) => (case (get_equations thy p, get_assoc_code thy s T) of
([], _) => NONE
| (_, SOME _) => NONE
| (eqns, NONE) =>
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 =
[CodegenData.init,
add_codegen "recfun" recfun_codegen,
add_attribute "" (Args.del |-- Scan.succeed del || Scan.succeed add)];
end;