(* Title: HOL/recfun_codegen.ML
ID: $Id$
Author: Stefan Berghofer, TU Muenchen
Code generator for recursive functions.
*)
signature RECFUN_CODEGEN =
sig
val add: string option -> attribute
val del: attribute
val get_thm_equations: theory -> string * typ -> (thm list * typ) option
val setup: theory -> theory
end;
structure RecfunCodegen : RECFUN_CODEGEN =
struct
open Codegen;
structure CodegenData = TheoryDataFun
(struct
val name = "HOL/recfun_codegen";
type T = (thm * string option) list Symtab.table;
val empty = Symtab.empty;
val copy = I;
val extend = I;
fun merge _ = Symtab.merge_list (Drule.eq_thm_prop o pairself fst);
fun print _ _ = ();
end);
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 optmod = Thm.declaration_attribute (fn thm => Context.map_theory
let
fun add thm =
if Pattern.pattern (lhs_of thm) then
CodegenData.map
(Symtab.update_list ((fst o const_of o prop_of) thm, (thm, optmod)))
else tap (fn _ => warn thm)
handle TERM _ => tap (fn _ => warn thm);
in
add thm
#> CodegenTheorems.add_fun thm
end);
fun del_thm thm thy =
let
val tab = CodegenData.get thy;
val (s, _) = const_of (prop_of thm);
in case Symtab.lookup tab s of
NONE => thy
| SOME thms =>
CodegenData.put (Symtab.update (s, gen_rem (eq_thm o apfst fst) (thms, thm)) tab) thy
end handle TERM _ => (warn thm; thy);
val del = Thm.declaration_attribute
(fn thm => Context.map_theory (del_thm thm #> CodegenTheorems.del_fun thm))
fun del_redundant thy eqs [] = eqs
| del_redundant thy eqs (eq :: eqs') =
let
val matches = curry
(Pattern.matches thy o pairself (lhs_of o fst))
in del_redundant thy (eq :: eqs) (filter_out (matches eq) eqs') end;
fun get_equations thy defs (s, T) =
(case Symtab.lookup (CodegenData.get thy) s of
NONE => ([], "")
| SOME thms =>
let val thms' = del_redundant thy []
(List.filter (fn (thm, _) => is_instance thy T
(snd (const_of (prop_of thm)))) thms)
in if null thms' then ([], "")
else (preprocess thy (map fst thms'),
case snd (snd (split_last thms')) of
NONE => (case get_defn thy defs s T of
NONE => thyname_of_const s thy
| SOME ((_, (thyname, _)), _) => thyname)
| SOME thyname => thyname)
end);
fun get_thm_equations thy (c, ty) =
Symtab.lookup (CodegenData.get thy) c
|> Option.map (fn thms =>
List.filter (fn (thm, _) => is_instance thy ty ((snd o const_of o prop_of) thm)) thms
|> del_redundant thy [])
|> Option.mapPartial (fn thms => if null thms then NONE else SOME thms)
|> Option.map (fn thms =>
(preprocess thy (map fst thms),
(snd o const_of o prop_of o fst o hd) thms))
|> (Option.map o apfst o map) (fn thm => thm RS HOL.eq_reflection);
fun mk_suffix thy defs (s, T) = (case get_defn thy defs 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.irreducible_paths (fst g) (x, x)));
fun add_rec_funs thy defs gr dep eqs module =
let
fun dest_eq t = (fst (const_of t) ^ mk_suffix thy defs (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 module fname prfx gr [] = (gr, [])
| mk_fundef module fname prfx gr ((fname', (lhs, rhs)) :: xs) =
let
val (gr1, pl) = invoke_codegen thy defs dname module false (gr, lhs);
val (gr2, pr) = invoke_codegen thy defs dname module false (gr1, rhs);
val (gr3, rest) = mk_fundef module 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 module fundef = map_node dname
(K (SOME (EQN ("", dummyT, dname)), module, Pretty.string_of (Pretty.blk (0,
separate Pretty.fbrk fundef @ [Pretty.str ";"])) ^ "\n\n"));
in
(case try (get_node gr) dname of
NONE =>
let
val gr1 = add_edge (dname, dep)
(new_node (dname, (SOME (EQN (s, T, "")), module, "")) gr);
val (gr2, fundef) = mk_fundef module "" "fun " gr1 eqs';
val xs = cycle gr2 ([], dname);
val cs = map (fn x => case 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 module fundef gr2, module)
| _ =>
if not (dep mem xs) then
let
val thmss as (_, thyname) :: _ = map (get_equations thy defs) cs;
val module' = if_library thyname module;
val eqs'' = map (dest_eq o prop_of) (List.concat (map fst thmss));
val (gr3, fundef') = mk_fundef module' "" "fun "
(add_edge (dname, dep)
(foldr (uncurry new_node) (del_nodes xs gr2)
(map (fn k =>
(k, (SOME (EQN ("", dummyT, dname)), module', ""))) xs))) eqs''
in (put_code module' fundef' gr3, module') end
else (gr2, module))
end
| SOME (SOME (EQN (_, _, s)), module', _) =>
(if s = "" then
if dname = dep then gr else add_edge (dname, dep) gr
else if s = dep then gr else add_edge (s, dep) gr,
module'))
end;
fun recfun_codegen thy defs gr dep module brack t = (case strip_comb t of
(Const (p as (s, T)), ts) => (case (get_equations thy defs p, get_assoc_code thy s T) of
(([], _), _) => NONE
| (_, SOME _) => NONE
| ((eqns, thyname), NONE) =>
let
val module' = if_library thyname module;
val (gr', ps) = foldl_map
(invoke_codegen thy defs dep module true) (gr, ts);
val suffix = mk_suffix thy defs p;
val (gr'', module'') =
add_rec_funs thy defs gr' dep (map prop_of eqns) module';
val (gr''', fname) = mk_const_id module'' (s ^ suffix) gr''
in
SOME (gr''', mk_app brack (Pretty.str (mk_qual_id module fname)) ps)
end)
| _ => NONE);
val setup =
CodegenData.init #>
add_codegen "recfun" recfun_codegen #>
add_attribute ""
(Args.del |-- Scan.succeed del
|| Scan.option (Args.$$$ "target" |-- Args.colon |-- Args.name) >> add);
end;