src/HOL/Tools/SMT/smt_datatypes.ML

re-implemented support for datatypes (including records and typedefs);
added test cases for datatypes, records and typedefs

(*  Title:      HOL/Tools/SMT/smt_datatypes.ML
    Author:     Sascha Boehme, TU Muenchen

Collector functions for common type declarations and their representation
as algebraic datatypes.
*)

signature SMT_DATATYPES =
sig
  val add_decls: typ ->
    (typ * (term * term list) list) list list * Proof.context ->
    (typ * (term * term list) list) list list * Proof.context
end

structure SMT_Datatypes: SMT_DATATYPES =
struct

val lhs_head_of = Term.head_of o fst o Logic.dest_equals o Thm.prop_of

fun mk_selectors T Ts ctxt =
  let
    val (sels, ctxt') =
      Variable.variant_fixes (replicate (length Ts) "select") ctxt
  in (map2 (fn n => fn U => Free (n, T --> U)) sels Ts, ctxt') end


(* datatype declarations *)

fun get_datatype_decl ({descr, ...} : Datatype.info) n Ts ctxt =
  let
    fun get_vars (_, (m, vs, _)) = if m = n then SOME vs else NONE
    val vars = the (get_first get_vars descr) ~~ Ts
    val lookup_var = the o AList.lookup (op =) vars

    val dTs = map (apsnd (fn (m, vs, _) => Type (m, map lookup_var vs))) descr
    val lookup_typ = the o AList.lookup (op =) dTs

    fun typ_of (dt as Datatype.DtTFree _) = lookup_var dt
      | typ_of (Datatype.DtType (n, dts)) = Type (n, map typ_of dts)
      | typ_of (Datatype.DtRec i) = lookup_typ i

    fun mk_constr T (m, dts) ctxt =
      let
        val Ts = map typ_of dts
        val constr = Const (m, Ts ---> T)
        val (selects, ctxt') = mk_selectors T Ts ctxt
      in ((constr, selects), ctxt') end

    fun mk_decl (i, (_, _, constrs)) ctxt =
      let
        val T = lookup_typ i
        val (css, ctxt') = fold_map (mk_constr T) constrs ctxt
      in ((T, css), ctxt') end

  in fold_map mk_decl descr ctxt end


(* record declarations *)

val record_name_of = Long_Name.implode o fst o split_last o Long_Name.explode

fun get_record_decl ({ext_def, ...} : Record.info) T ctxt =
  let
    val (con, _) = Term.dest_Const (lhs_head_of ext_def)
    val (fields, more) = Record.get_extT_fields (ProofContext.theory_of ctxt) T
    val fieldTs = map snd fields @ [snd more]

    val constr = Const (con, fieldTs ---> T)
    val (selects, ctxt') = mk_selectors T fieldTs ctxt
  in ((T, [(constr, selects)]), ctxt') end


(* typedef declarations *)

fun get_typedef_decl (info : Typedef.info) T Ts =
  let
    val ({Abs_name, Rep_name, abs_type, rep_type, ...}, _) = info

    val env = snd (Term.dest_Type abs_type) ~~ Ts
    val instT = Term.map_atyps (perhaps (AList.lookup (op =) env))

    val constr = Const (Abs_name, instT (rep_type --> abs_type))
    val select = Const (Rep_name, instT (abs_type --> rep_type))
  in (T, [(constr, [select])]) end


(* collection of declarations *)

fun declared declss T = exists (exists (equal T o fst)) declss

fun get_decls T n Ts ctxt =
  let val thy = ProofContext.theory_of ctxt
  in
    (case Datatype.get_info thy n of
      SOME info => get_datatype_decl info n Ts ctxt
    | NONE =>
        (case Record.get_info thy (record_name_of n) of
          SOME info => get_record_decl info T ctxt |>> single
        | NONE =>
            (case Typedef.get_info ctxt n of
              [] => ([], ctxt)
            | info :: _ => ([get_typedef_decl info T Ts], ctxt))))
  end

fun add_decls T (declss, ctxt) =
  let
    fun add (TFree _) = I
      | add (TVar _) = I
      | add (T as Type (@{type_name fun}, _)) =
          fold add (Term.body_type T :: Term.binder_types T)
      | add @{typ bool} = I
      | add (T as Type (n, Ts)) = (fn (dss, ctxt1) =>
          if declared declss T orelse declared dss T then (dss, ctxt1)
          else if SMT_Builtin.is_builtin_typ_ext ctxt1 T then (dss, ctxt1)
          else
            (case get_decls T n Ts ctxt1 of
              ([], _) => (dss, ctxt1)
            | (ds, ctxt2) =>
                let
                  val constrTs =
                    maps (map (snd o Term.dest_Const o fst) o snd) ds
                  val Us = fold (union (op =) o Term.binder_types) constrTs []
            in fold add Us (ds :: dss, ctxt2) end))
  in add T ([], ctxt) |>> append declss end

end