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package jp.ac.kobe_u.cs.prolog.builtin;
import jp.ac.kobe_u.cs.prolog.lang.*;
/**
* <code>atom_codes/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_codes_2 extends Predicate.P2 {
private static final SymbolTerm Nil = SymbolTerm.makeSymbol("[]");
public PRED_atom_codes_2(Term a1, Term a2, Operation cont) {
arg1 = a1;
arg2 = a2;
this.cont = cont;
}
public Operation exec(Prolog engine) {
engine.setB0();
Term a1, a2;
a1 = arg1;
a2 = arg2;
a1 = a1.dereference();
a2 = a2.dereference();
if (a1.isVariable()) { // atom_codes(-Atom, +CharCodeList)
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.isInteger())
throw new RepresentationException(this, 2, "character_code");
// car is an integer
int i = ((IntegerTerm)car).intValue();
if (! Character.isDefined((char)i))
throw new RepresentationException(this, 2, "character_code");
sb.append((char)i);
x = ((ListTerm)x).cdr().dereference();
}
if (! a1.unify(SymbolTerm.makeSymbol(sb.toString()), engine.trail))
return engine.fail();
return cont;
} else { // atom_codes(+Atom, ?CharCodeList)
if (! a1.isSymbol())
throw new IllegalTypeException(this, 1, "atom", a1);
char[] chars = ((SymbolTerm)a1).name().toCharArray();
Term x = Nil;
for (int i=chars.length; i>0; i--) {
x = new ListTerm(new IntegerTerm((int)chars[i-1]), x);
}
if(! a2.unify(x, engine.trail))
return engine.fail();
return cont;
}
}
}
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