package jp.ac.kobe_u.cs.prolog.builtin;
import jp.ac.kobe_u.cs.prolog.lang.IllegalTypeException;
import jp.ac.kobe_u.cs.prolog.lang.IntegerTerm;
import jp.ac.kobe_u.cs.prolog.lang.ListTerm;
import jp.ac.kobe_u.cs.prolog.lang.PInstantiationException;
import jp.ac.kobe_u.cs.prolog.lang.Predicate;
import jp.ac.kobe_u.cs.prolog.lang.Prolog;
import jp.ac.kobe_u.cs.prolog.lang.RepresentationException;
import jp.ac.kobe_u.cs.prolog.lang.StructureTerm;
import jp.ac.kobe_u.cs.prolog.lang.SymbolTerm;
import jp.ac.kobe_u.cs.prolog.lang.Term;
/**
* <code>'$get_instances'/2</code><br>
*
* @author Mutsunori Banbara (banbara@kobe-u.ac.jp)
* @author Naoyuki Tamura (tamura@kobe-u.ac.jp)
* @version 1.1
*/
class PRED_$get_instances_2 extends Predicate {
/**
*
*/
private static final long serialVersionUID = -3085864832865167853L;
private Term arg1, arg2;
private final static SymbolTerm COMMA = SymbolTerm.makeSymbol(",", 2);
public PRED_$get_instances_2(Term a1, Term a2, Predicate cont) {
arg1 = a1;
arg2 = a2;
this.cont = cont;
}
public PRED_$get_instances_2() {
}
@Override
public void setArgument(Term[] args, Predicate cont) {
arg1 = args[0];
arg2 = args[1];
this.cont = cont;
}
@Override
public int arity() {
return 2;
}
@Override
public String toString() {
return "$get_instances(" + arg1 + "," + arg2 + ")";
}
@Override
public Predicate exec(Prolog engine) {
engine.setB0();
Term a1, a2;
a1 = arg1;
a2 = arg2;
a1 = a1.dereference();
if (a1.isNil()) {
return engine.fail();
}
if (!a1.isList()) {
throw new IllegalTypeException(this, 1, "list", a1);
}
Term x = Prolog.Nil;
Term tmp = a1;
while (!tmp.isNil()) {
if (!tmp.isList()) {
throw new IllegalTypeException(this, 1, "list", a1);
}
Term car = ((ListTerm) tmp).car().dereference();
if (car.isVariable()) {
throw new PInstantiationException(this, 1);
}
if (!car.isInteger()) {
throw new RepresentationException(this, 1, "integer");
}
// car is an integer
int i = ((IntegerTerm) car).intValue();
Term e = engine.internalDB.get(i);
if (e != null) {
Term[] arg = { e, car };
x = new ListTerm(new StructureTerm(COMMA, arg), x);
}
// else {
// System.out.println("index " + i + " is deleted.");
// }
// if (e == null)
// throw new SystemException("invalid index");
// Term[] arg = {e, car};
// x = new ListTerm(new StructureTerm(COMMA, arg), x);
tmp = ((ListTerm) tmp).cdr().dereference();
}
if (!a2.unify(x, engine.trail)) {
return engine.fail();
}
return cont;
}
}