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.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>atom_chars/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_atom_chars_2 extends Predicate {
/**
*
*/
private static final long serialVersionUID = 1723238089996762455L;
private final static SymbolTerm Nil = SymbolTerm.makeSymbol("[]");
private Term arg1, arg2;
public PRED_atom_chars_2(Term a1, Term a2, Predicate cont) {
arg1 = a1;
arg2 = a2;
this.cont = cont;
}
public PRED_atom_chars_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 "atom_chars(" + arg1 + "," + arg2 + ")";
}
@Override
public Predicate exec(Prolog engine) {
engine.setB0();
Term a1, a2;
a1 = arg1;
a2 = arg2;
a1 = a1.dereference();
a2 = a2.dereference();
if (a1.isVariable()) { // atom_chars(-Atom, +CharList)
if (a2.isNil()) {
if (!a1.unify(SymbolTerm.makeSymbol(""), engine.trail)) {
return engine.fail();
}
return cont;
} else if (a2.isVariable()) {
throw new PInstantiationException(this, 2);
} else if (!a2.isList()) {
throw new IllegalTypeException(this, 2, "list", a2);
}
StringBuffer sb = new StringBuffer();
Term x = a2;
while (!x.isNil()) {
if (x.isVariable()) {
throw new PInstantiationException(this, 2);
}
if (!x.isList()) {
throw new IllegalTypeException(this, 2, "list", a2);
}
Term car = ((ListTerm) x).car().dereference();
if (car.isVariable()) {
throw new PInstantiationException(this, 2);
}
if (!car.isSymbol() || ((SymbolTerm) car).name().length() != 1) {
throw new IllegalTypeException(this, 2, "character", a2);
}
sb.append(((SymbolTerm) car).name());
x = ((ListTerm) x).cdr().dereference();
}
if (!a1.unify(SymbolTerm.makeSymbol(sb.toString()), engine.trail)) {
return engine.fail();
}
return cont;
} else if (a2.isNil() || a2.isVariable() || a2.isList()) { // atom_chars(+Atom,
// ?CharList)
if (!a1.isSymbol()) {
throw new IllegalTypeException(this, 1, "atom", a1);
}
String s = ((SymbolTerm) a1).name();
Term x = Nil;
for (int i = s.length(); i > 0; i--) {
x = new ListTerm(SymbolTerm.makeSymbol(s.substring(i - 1, i)),
x);
}
if (!a2.unify(x, engine.trail)) {
return engine.fail();
}
return cont;
} else {
return engine.fail();
}
}
}