package jp.ac.kobe_u.cs.prolog.builtin;
import java.io.IOException;
import java.io.PushbackReader;
import jp.ac.kobe_u.cs.prolog.lang.ExistenceException;
import jp.ac.kobe_u.cs.prolog.lang.IllegalDomainException;
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.JavaObjectTerm;
import jp.ac.kobe_u.cs.prolog.lang.PInstantiationException;
import jp.ac.kobe_u.cs.prolog.lang.PermissionException;
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.Term;
import jp.ac.kobe_u.cs.prolog.lang.TermException;
/**
* <code>get/2</code><br>
*
* @author Mutsunori Banbara (banbara@kobe-u.ac.jp)
* @author Naoyuki Tamura (tamura@kobe-u.ac.jp)
* @version 1.0
*/
public class PRED_get_2 extends Predicate {
/**
*
*/
private static final long serialVersionUID = -180234271645268922L;
private final static IntegerTerm INT_EOF = new IntegerTerm(-1);
private Term arg1, arg2;
public PRED_get_2(Term a1, Term a2, Predicate cont) {
arg1 = a1;
arg2 = a2;
this.cont = cont;
}
public PRED_get_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(" + arg1 + "," + arg2 + ")";
}
@Override
public Predicate exec(Prolog engine) {
engine.setB0();
Term a1, a2;
a1 = arg1;
a2 = arg2;
Object stream = null;
// Char
a2 = a2.dereference();
if (!a2.isVariable()) {
if (!a2.isInteger()) {
throw new IllegalTypeException(this, 2, "integer", a2);
}
int n = ((IntegerTerm) a2).intValue();
if (n != -1 && !Character.isDefined(n)) {
throw new RepresentationException(this, 2, "in_character_code");
}
}
// S_or_a
a1 = a1.dereference();
if (a1.isVariable()) {
throw new PInstantiationException(this, 1);
} else if (a1.isSymbol()) {
if (!engine.getStreamManager().containsKey(a1)) {
throw new ExistenceException(this, 1, "stream", a1, "");
}
stream = ((JavaObjectTerm) engine.getStreamManager().get(a1))
.object();
} else if (a1.isJavaObject()) {
stream = ((JavaObjectTerm) a1).object();
} else {
throw new IllegalDomainException(this, 1, "stream_or_alias", a1);
}
if (!(stream instanceof PushbackReader)) {
throw new PermissionException(this, "input", "stream", a1, "");
}
// read a non-blank single character
try {
PushbackReader in = (PushbackReader) stream;
int c = in.read();
while (Character.isWhitespace((char) c)) {
c = in.read();
}
if (c < 0) { // EOF
if (!a2.unify(INT_EOF, engine.trail)) {
return engine.fail();
}
return cont;
}
if (!Character.isDefined(c)) {
throw new RepresentationException(this, 0, "character");
}
if (!a2.unify(new IntegerTerm(c), engine.trail)) {
return engine.fail();
}
return cont;
} catch (IOException e) {
throw new TermException(new JavaObjectTerm(e));
}
}
}