src/Pure/term.scala

tuned whitespace;

/*  Title:      Pure/term.scala
    Author:     Makarius

Lambda terms, types, sorts.

Note: Isabelle/ML is the primary environment for logical operations.
*/

package isabelle


object Term
{
  /* types and terms */

  sealed case class Indexname(name: String, index: Int)
  {
    override def toString: String =
      if (index == -1) name
      else {
        val dot =
          Symbol.explode(name).reverse match {
            case _ :: s :: _ if s == Symbol.sub_decoded || s == Symbol.sub => false
            case c :: _ => Symbol.is_digit(c)
            case _ => true
          }
        if (dot) "?" + name + "." + index
        else if (index != 0) "?" + name + index
        else "?" + name
      }
  }

  type Sort = List[String]
  val dummyS: Sort = List("")

  sealed abstract class Typ
  case class Type(name: String, args: List[Typ] = Nil) extends Typ
  case class TFree(name: String, sort: Sort = dummyS) extends Typ
  case class TVar(name: Indexname, sort: Sort = dummyS) extends Typ
  val dummyT = Type("dummy")

  sealed abstract class Term
  case class Const(name: String, typargs: List[Typ]) extends Term
  case class Free(name: String, typ: Typ = dummyT) extends Term
  case class Var(name: Indexname, typ: Typ = dummyT) extends Term
  case class Bound(index: Int) extends Term
  case class Abs(name: String, typ: Typ = dummyT, body: Term) extends Term
  case class App(fun: Term, arg: Term) extends Term

  sealed abstract class Proof
  case object MinProof extends Proof
  case class PBound(index: Int) extends Proof
  case class Abst(name: String, typ: Typ, body: Proof) extends Proof
  case class AbsP(name: String, hyp: Term, body: Proof) extends Proof
  case class Appt(fun: Proof, arg: Term) extends Proof
  case class AppP(fun: Proof, arg: Proof) extends Proof
  case class Hyp(hyp: Term) extends Proof
  case class PAxm(name: String, types: List[Typ]) extends Proof
  case class OfClass(typ: Typ, cls: String) extends Proof
  case class Oracle(name: String, prop: Option[Term], types: List[Typ]) extends Proof
  case class PThm(serial: Long, theory_name: String, approximative_name: String, types: List[Typ])
    extends Proof


  /* Pure logic */

  def mk_type(ty: Typ): Term = Const(Pure_Thy.TYPE, List(ty))

  def const_of_class(c: String): String = c + "_class"

  def mk_of_sort(ty: Typ, s: Sort): List[Term] =
  {
    val t = mk_type(ty)
    s.map(c => App(Const(const_of_class(c), List(ty)), t))
  }



  /** cache **/

  def make_cache(initial_size: Int = 131071, max_string: Int = Integer.MAX_VALUE): Cache =
    new Cache(initial_size, max_string)

  class Cache private[Term](initial_size: Int, max_string: Int)
    extends isabelle.Cache(initial_size, max_string)
  {
    protected def cache_indexname(x: Indexname): Indexname =
      lookup(x) getOrElse store(Indexname(cache_string(x.name), x.index))

    protected def cache_sort(x: Sort): Sort =
      if (x == dummyS) dummyS
      else lookup(x) getOrElse store(x.map(cache_string(_)))

    protected def cache_typ(x: Typ): Typ =
    {
      if (x == dummyT) dummyT
      else
        lookup(x) match {
          case Some(y) => y
          case None =>
            x match {
              case Type(name, args) => store(Type(cache_string(name), cache_typs(args)))
              case TFree(name, sort) => store(TFree(cache_string(name), cache_sort(sort)))
              case TVar(name, sort) => store(TVar(cache_indexname(name), cache_sort(sort)))
            }
        }
    }

    protected def cache_typs(x: List[Typ]): List[Typ] =
    {
      if (x.isEmpty) Nil
      else {
        lookup(x) match {
          case Some(y) => y
          case None => store(x.map(cache_typ(_)))
        }
      }
    }

    protected def cache_term(x: Term): Term =
    {
      lookup(x) match {
        case Some(y) => y
        case None =>
          x match {
            case Const(name, typargs) => store(Const(cache_string(name), cache_typs(typargs)))
            case Free(name, typ) => store(Free(cache_string(name), cache_typ(typ)))
            case Var(name, typ) => store(Var(cache_indexname(name), cache_typ(typ)))
            case Bound(_) => store(x)
            case Abs(name, typ, body) =>
              store(Abs(cache_string(name), cache_typ(typ), cache_term(body)))
            case App(fun, arg) => store(App(cache_term(fun), cache_term(arg)))
          }
      }
    }

    protected def cache_proof(x: Proof): Proof =
    {
      if (x == MinProof) MinProof
      else {
        lookup(x) match {
          case Some(y) => y
          case None =>
            x match {
              case PBound(_) => store(x)
              case Abst(name, typ, body) =>
                store(Abst(cache_string(name), cache_typ(typ), cache_proof(body)))
              case AbsP(name, hyp, body) =>
                store(AbsP(cache_string(name), cache_term(hyp), cache_proof(body)))
              case Appt(fun, arg) => store(Appt(cache_proof(fun), cache_term(arg)))
              case AppP(fun, arg) => store(AppP(cache_proof(fun), cache_proof(arg)))
              case Hyp(hyp) => store(Hyp(cache_term(hyp)))
              case PAxm(name, types) => store(PAxm(cache_string(name), cache_typs(types)))
              case OfClass(typ, cls) => store(OfClass(cache_typ(typ), cache_string(cls)))
              case Oracle(name, prop, types) =>
                store(Oracle(cache_string(name), prop.map(cache_term(_)), cache_typs(types)))
              case PThm(serial, theory_name, name, types) =>
                store(PThm(serial, cache_string(theory_name), cache_string(name), cache_typs(types)))
            }
        }
      }
    }

    // main methods
    def indexname(x: Indexname): Indexname = synchronized { cache_indexname(x) }
    def sort(x: Sort): Sort = synchronized { cache_sort(x) }
    def typ(x: Typ): Typ = synchronized { cache_typ(x) }
    def term(x: Term): Term = synchronized { cache_term(x) }
    def proof(x: Proof): Proof = synchronized { cache_proof(x) }

    def position(x: Position.T): Position.T =
      synchronized { x.map({ case (a, b) => (cache_string(a), cache_string(b)) }) }
  }
}