(* Title: HOL/Tools/TFL/dcterm.ML
ID: $Id$
Author: Konrad Slind, Cambridge University Computer Laboratory
Copyright 1997 University of Cambridge
*)
(*---------------------------------------------------------------------------
* Derived efficient cterm destructors.
*---------------------------------------------------------------------------*)
signature DCTERM =
sig
val dest_comb: cterm -> cterm * cterm
val dest_abs: string option -> cterm -> cterm * cterm
val capply: cterm -> cterm -> cterm
val cabs: cterm -> cterm -> cterm
val mk_conj: cterm * cterm -> cterm
val mk_disj: cterm * cterm -> cterm
val mk_exists: cterm * cterm -> cterm
val dest_conj: cterm -> cterm * cterm
val dest_const: cterm -> {Name: string, Ty: typ}
val dest_disj: cterm -> cterm * cterm
val dest_eq: cterm -> cterm * cterm
val dest_exists: cterm -> cterm * cterm
val dest_forall: cterm -> cterm * cterm
val dest_imp: cterm -> cterm * cterm
val dest_let: cterm -> cterm * cterm
val dest_neg: cterm -> cterm
val dest_pair: cterm -> cterm * cterm
val dest_var: cterm -> {Name:string, Ty:typ}
val is_conj: cterm -> bool
val is_cons: cterm -> bool
val is_disj: cterm -> bool
val is_eq: cterm -> bool
val is_exists: cterm -> bool
val is_forall: cterm -> bool
val is_imp: cterm -> bool
val is_let: cterm -> bool
val is_neg: cterm -> bool
val is_pair: cterm -> bool
val list_mk_disj: cterm list -> cterm
val strip_abs: cterm -> cterm list * cterm
val strip_comb: cterm -> cterm * cterm list
val strip_disj: cterm -> cterm list
val strip_exists: cterm -> cterm list * cterm
val strip_forall: cterm -> cterm list * cterm
val strip_imp: cterm -> cterm list * cterm
val drop_prop: cterm -> cterm
val mk_prop: cterm -> cterm
end;
structure Dcterm: DCTERM =
struct
structure U = Utils;
fun ERR func mesg = U.ERR {module = "Dcterm", func = func, mesg = mesg};
fun dest_comb t = Thm.dest_comb t
handle CTERM (msg, _) => raise ERR "dest_comb" msg;
fun dest_abs a t = Thm.dest_abs a t
handle CTERM (msg, _) => raise ERR "dest_abs" msg;
fun capply t u = Thm.capply t u
handle CTERM (msg, _) => raise ERR "capply" msg;
fun cabs a t = Thm.cabs a t
handle CTERM (msg, _) => raise ERR "cabs" msg;
(*---------------------------------------------------------------------------
* Some simple constructor functions.
*---------------------------------------------------------------------------*)
val mk_hol_const = Thm.cterm_of @{theory HOL} o Const;
fun mk_exists (r as (Bvar, Body)) =
let val ty = #T(rep_cterm Bvar)
val c = mk_hol_const("Ex", (ty --> HOLogic.boolT) --> HOLogic.boolT)
in capply c (uncurry cabs r) end;
local val c = mk_hol_const("op &", HOLogic.boolT --> HOLogic.boolT --> HOLogic.boolT)
in fun mk_conj(conj1,conj2) = capply (capply c conj1) conj2
end;
local val c = mk_hol_const("op |", HOLogic.boolT --> HOLogic.boolT --> HOLogic.boolT)
in fun mk_disj(disj1,disj2) = capply (capply c disj1) disj2
end;
(*---------------------------------------------------------------------------
* The primitives.
*---------------------------------------------------------------------------*)
fun dest_const ctm =
(case #t(rep_cterm ctm)
of Const(s,ty) => {Name = s, Ty = ty}
| _ => raise ERR "dest_const" "not a constant");
fun dest_var ctm =
(case #t(rep_cterm ctm)
of Var((s,i),ty) => {Name=s, Ty=ty}
| Free(s,ty) => {Name=s, Ty=ty}
| _ => raise ERR "dest_var" "not a variable");
(*---------------------------------------------------------------------------
* Derived destructor operations.
*---------------------------------------------------------------------------*)
fun dest_monop expected tm =
let
fun err () = raise ERR "dest_monop" ("Not a(n) " ^ quote expected);
val (c, N) = dest_comb tm handle U.ERR _ => err ();
val name = #Name (dest_const c handle U.ERR _ => err ());
in if name = expected then N else err () end;
fun dest_binop expected tm =
let
fun err () = raise ERR "dest_binop" ("Not a(n) " ^ quote expected);
val (M, N) = dest_comb tm handle U.ERR _ => err ()
in (dest_monop expected M, N) handle U.ERR _ => err () end;
fun dest_binder expected tm =
dest_abs NONE (dest_monop expected tm)
handle U.ERR _ => raise ERR "dest_binder" ("Not a(n) " ^ quote expected);
val dest_neg = dest_monop "not"
val dest_pair = dest_binop "Pair";
val dest_eq = dest_binop "op ="
val dest_imp = dest_binop "op -->"
val dest_conj = dest_binop "op &"
val dest_disj = dest_binop "op |"
val dest_cons = dest_binop "Cons"
val dest_let = Library.swap o dest_binop "Let";
val dest_select = dest_binder "Hilbert_Choice.Eps"
val dest_exists = dest_binder "Ex"
val dest_forall = dest_binder "All"
(* Query routines *)
val is_eq = can dest_eq
val is_imp = can dest_imp
val is_select = can dest_select
val is_forall = can dest_forall
val is_exists = can dest_exists
val is_neg = can dest_neg
val is_conj = can dest_conj
val is_disj = can dest_disj
val is_pair = can dest_pair
val is_let = can dest_let
val is_cons = can dest_cons
(*---------------------------------------------------------------------------
* Iterated creation.
*---------------------------------------------------------------------------*)
val list_mk_disj = U.end_itlist (fn d1 => fn tm => mk_disj (d1, tm));
(*---------------------------------------------------------------------------
* Iterated destruction. (To the "right" in a term.)
*---------------------------------------------------------------------------*)
fun strip break tm =
let fun dest (p as (ctm,accum)) =
let val (M,N) = break ctm
in dest (N, M::accum)
end handle U.ERR _ => p
in dest (tm,[])
end;
fun rev2swap (x,l) = (rev l, x);
val strip_comb = strip (Library.swap o dest_comb) (* Goes to the "left" *)
val strip_imp = rev2swap o strip dest_imp
val strip_abs = rev2swap o strip (dest_abs NONE)
val strip_forall = rev2swap o strip dest_forall
val strip_exists = rev2swap o strip dest_exists
val strip_disj = rev o (op::) o strip dest_disj
(*---------------------------------------------------------------------------
* Going into and out of prop
*---------------------------------------------------------------------------*)
fun mk_prop ctm =
let
val thy = Thm.theory_of_cterm ctm;
val t = Thm.term_of ctm;
in
if can HOLogic.dest_Trueprop t then ctm
else Thm.cterm_of thy (HOLogic.mk_Trueprop t)
end
handle TYPE (msg, _, _) => raise ERR "mk_prop" msg
| TERM (msg, _) => raise ERR "mk_prop" msg;
fun drop_prop ctm = dest_monop "Trueprop" ctm handle U.ERR _ => ctm;
end;