package jp.ac.kobe_u.cs.prolog.builtin;
import java.util.Arrays;
import jp.ac.kobe_u.cs.prolog.lang.IllegalTypeException;
import jp.ac.kobe_u.cs.prolog.lang.JavaException;
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.SymbolTerm;
import jp.ac.kobe_u.cs.prolog.lang.Term;
/**
* <code>sort/2</code><br>
*
* @author Mutsunori Banbara (banbara@kobe-u.ac.jp)
* @author Naoyuki Tamura (tamura@kobe-u.ac.jp)
* @version 1.1
*/
public class PRED_sort_2 extends Predicate {
/**
*
*/
private static final long serialVersionUID = 5057211905293366446L;
private final static SymbolTerm Nil = SymbolTerm.makeSymbol("[]");
private Term arg1, arg2;
public PRED_sort_2(Term a1, Term a2, Predicate cont) {
arg1 = a1;
arg2 = a2;
this.cont = cont;
}
public PRED_sort_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 "sort(" + arg1 + "," + arg2 + ")";
}
@Override
public Predicate exec(Prolog engine) {
engine.setB0();
Term a1, a2;
a1 = arg1;
a2 = arg2;
int len;
Term tmp, tmp2;
Term[] list;
a1 = a1.dereference();
if (a1.isVariable()) {
throw new PInstantiationException(this, 1);
} else if (a1.equals(Nil)) {
if (!a2.unify(Nil, engine.trail)) {
return engine.fail();
}
return cont;
} else if (!a1.isList()) {
throw new IllegalTypeException(this, 1, "list", a1);
}
len = ((ListTerm) a1).length();
list = new Term[len];
tmp = a1;
for (int i = 0; i < len; i++) {
if (!tmp.isList()) {
throw new IllegalTypeException(this, 1, "list", a1);
}
list[i] = ((ListTerm) tmp).car().dereference();
tmp = ((ListTerm) tmp).cdr().dereference();
}
if (!tmp.equals(Nil)) {
throw new PInstantiationException(this, 1);
}
try {
Arrays.sort(list);
} catch (ClassCastException e) {
throw new JavaException(this, 1, e);
}
tmp = Nil;
tmp2 = null;
for (int i = list.length - 1; i >= 0; i--) {
if (!list[i].equals(tmp2)) {
tmp = new ListTerm(list[i], tmp);
}
tmp2 = list[i];
}
if (!a2.unify(tmp, engine.trail)) {
return engine.fail();
}
return cont;
}
}