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(* Title: Pure/Tools/codegen_func.ML
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ID: $Id$
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Author: Florian Haftmann, TU Muenchen
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Basic handling of defining equations ("func"s) for code generator framework.
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*)
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signature CODEGEN_FUNC =
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sig
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val assert_rew: thm -> thm
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val mk_rew: thm -> thm list
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val assert_func: thm -> thm
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val mk_func: thm -> (CodegenConsts.const * thm) list
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val mk_head: thm -> CodegenConsts.const * thm
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val dest_func: thm -> (string * typ) * term list
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val typ_func: thm -> typ
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val inst_thm: sort Vartab.table -> thm -> thm
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val expand_eta: int -> thm -> thm
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val rewrite_func: thm list -> thm -> thm
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end;
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structure CodegenFunc : CODEGEN_FUNC =
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struct
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fun lift_thm_thy f thm = f (Thm.theory_of_thm thm) thm;
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fun bad_thm msg thm =
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error (msg ^ ": " ^ string_of_thm thm);
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(* making rewrite theorems *)
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fun assert_rew thm =
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let
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val thy = Thm.theory_of_thm thm;
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val (lhs, rhs) = (Logic.dest_equals o Thm.prop_of) thm;
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fun vars_of t = fold_aterms
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(fn Var (v, _) => insert (op =) v
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| Free _ => bad_thm "Illegal free variable in rewrite theorem" thm
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| _ => I) t [];
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fun tvars_of t = fold_term_types
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(fn _ => fold_atyps (fn TVar (v, _) => insert (op =) v
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| TFree _ => bad_thm "Illegal free type variable in rewrite theorem" thm)) t [];
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val lhs_vs = vars_of lhs;
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val rhs_vs = vars_of rhs;
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val lhs_tvs = tvars_of lhs;
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val rhs_tvs = tvars_of lhs;
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val _ = if null (subtract (op =) lhs_vs rhs_vs)
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then ()
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else bad_thm "Free variables on right hand side of rewrite theorems" thm
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val _ = if null (subtract (op =) lhs_tvs rhs_tvs)
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then ()
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else bad_thm "Free type variables on right hand side of rewrite theorems" thm
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in thm end;
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fun mk_rew thm =
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let
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val thy = Thm.theory_of_thm thm;
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val thms = (#mk o #mk_rews o snd o MetaSimplifier.rep_ss o Simplifier.simpset_of) thy thm;
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in
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map assert_rew thms
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end;
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(* making defining equations *)
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val typ_func = lift_thm_thy (fn thy => snd o dest_Const o fst o strip_comb
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o fst o Logic.dest_equals o ObjectLogic.drop_judgment thy o Drule.plain_prop_of);
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val dest_func = lift_thm_thy (fn thy => apfst dest_Const o strip_comb
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o fst o Logic.dest_equals o ObjectLogic.drop_judgment thy o Drule.plain_prop_of
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o Drule.fconv_rule Drule.beta_eta_conversion);
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val mk_head = lift_thm_thy (fn thy => fn thm =>
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((CodegenConsts.norm_of_typ thy o fst o dest_func) thm, thm));
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fun assert_func thm = case try dest_func thm
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of SOME (c_ty as (c, ty), args) =>
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let
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val thy = Thm.theory_of_thm thm;
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val _ =
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if has_duplicates (op =)
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((fold o fold_aterms) (fn Var (v, _) => cons v
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| _ => I
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) args [])
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then bad_thm "Repeated variables on left hand side of defining equation" thm
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else ()
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fun no_abs (Abs _) = bad_thm "Abstraction on left hand side of defining equation" thm
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| no_abs (t1 $ t2) = (no_abs t1; no_abs t2)
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| no_abs _ = ();
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val _ = map no_abs args;
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in thm end
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| NONE => bad_thm "Not a defining equation" thm;
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val mk_func = map (mk_head o assert_func) o mk_rew;
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(* utilities *)
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fun inst_thm tvars' thm =
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let
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val thy = Thm.theory_of_thm thm;
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val tvars = (Term.add_tvars o Thm.prop_of) thm [];
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fun mk_inst (tvar as (v, _)) = case Vartab.lookup tvars' v
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of SOME sort => SOME (pairself (Thm.ctyp_of thy o TVar) (tvar, (v, sort)))
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| NONE => NONE;
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val insts = map_filter mk_inst tvars;
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in Thm.instantiate (insts, []) thm end;
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fun expand_eta k thm =
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let
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val thy = Thm.theory_of_thm thm;
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val (lhs, rhs) = (Logic.dest_equals o Drule.plain_prop_of) thm;
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val (head, args) = strip_comb lhs;
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val l = if k = ~1
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then (length o fst o strip_abs) rhs
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else Int.max (0, k - length args);
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val used = Name.make_context (map (fst o fst) (Term.add_vars lhs []));
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fun get_name _ 0 used = ([], used)
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| get_name (Abs (v, ty, t)) k used =
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used
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|> Name.variants [v]
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||>> get_name t (k - 1)
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|>> (fn ([v'], vs') => (v', ty) :: vs')
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| get_name t k used =
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let
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val (tys, _) = (strip_type o fastype_of) t
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in case tys
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of [] => raise TERM ("expand_eta", [t])
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| ty :: _ =>
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used
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|> Name.variants [""]
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|-> (fn [v] => get_name (t $ Var ((v, 0), ty)) (k - 1)
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#>> (fn vs' => (v, ty) :: vs'))
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end;
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val (vs, _) = get_name rhs l used;
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val vs_refl = map (fn (v, ty) => Thm.reflexive (Thm.cterm_of thy (Var ((v, 0), ty)))) vs;
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in
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fold (fn refl => fn thm => Thm.combination thm refl) vs_refl thm
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end;
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fun rewrite_func rewrites thm =
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let
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val rewrite = MetaSimplifier.rewrite false rewrites;
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val (ct_eq, [ct_lhs, ct_rhs]) = (Drule.strip_comb o Thm.cprop_of) thm;
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val Const ("==", _) = Thm.term_of ct_eq;
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val (ct_f, ct_args) = Drule.strip_comb ct_lhs;
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val rhs' = rewrite ct_rhs;
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val args' = map rewrite ct_args;
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val lhs' = Thm.symmetric (fold (fn th1 => fn th2 => Thm.combination th2 th1)
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args' (Thm.reflexive ct_f));
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in Thm.transitive (Thm.transitive lhs' thm) rhs' end;
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end;
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