@Override
public Iter iter(final QueryContext ctx) throws QueryException {
final Iter iter = ctx.iter(expr);
final Item it = iter.next();
if (it == null) {
if (type.mayBeZero()) return Empty.ITER;
throw XPEMPTY.thrw(input, desc());
}
if (type.zeroOrOne()) {
if (iter.next() != null) NOTREATS.thrw(input, desc(), type);
if (!it.type.instance(type.type)) NOTREAT.thrw(input, desc(), type, it.type);
return it.iter();
}
return new Iter() {
Item i = it;
@Override
public Item next() throws QueryException {
if (i == null) return null;
if (!i.type.instance(type.type)) NOTREAT.thrw(input, desc(), type, i.type);
final Item ii = i;
i = iter.next();
return ii;
}
};
}
@Override
public Iter iter(final QueryContext ctx) throws QueryException {
switch (def) {
case ERROR:
final int al = expr.length;
if (al == 0) FUNERR1.thrw(input);
String code = FUNERR1.code();
String msg = FUNERR1.desc;
final Item it = expr[0].item(ctx, input);
if (it == null) {
if (al == 1) XPEMPTY.thrw(input, desc());
} else {
code = Token.string(((QNm) checkType(it, AtomType.QNM)).ln());
}
if (al > 1) msg = Token.string(checkEStr(expr[1], ctx));
final Value val = al > 2 ? expr[2].value(ctx) : null;
final QueryException ex = new QueryException(input, code, val, msg);
throw ex;
case TRACE:
return new Iter() {
final Iter ir = expr[0].iter(ctx);
final byte[] s = checkEStr(expr[1], ctx);
@Override
public Item next() throws QueryException {
final Item i = ir.next();
if (i != null) {
final TokenBuilder tb = new TokenBuilder(s);
if (s.length != 0) tb.add(": ");
tb.add(i.toString());
// if GUI is used, or if user is no admin, trace info is cached
if (Prop.gui || !ctx.context.user.perm(User.ADMIN)) {
ctx.evalInfo(tb.finish());
} else {
Util.errln(tb);
}
}
return i;
}
};
case ENVARS:
final ItemCache ic = new ItemCache();
for (final Object k : System.getenv().keySet().toArray()) {
ic.add(Str.get(k));
}
return ic;
default:
return super.iter(ctx);
}
}
@Override
public Value value(final QueryContext ctx) throws QueryException {
final Value val = ctx.value(expr);
final long len = val.size();
if (len == 0) {
if (type.mayBeZero()) return val;
throw XPEMPTY.thrw(input, desc());
}
if (type.zeroOrOne()) {
if (len > 1) throw NOTREATS.thrw(input, desc(), type);
final Item it = val.itemAt(0);
if (!it.type.instance(type.type)) NOTREAT.thrw(input, desc(), type, it.type);
return it;
}
for (long i = 0; i < len; i++) {
final Item it = val.itemAt(i);
if (!it.type.instance(type.type)) NOTREAT.thrw(input, desc(), type, it.type);
}
return val;
}
/**
* Checks if the specified item is an empty sequence; if yes, throws an exception.
*
* @param it item to be checked
* @return specified item
* @throws QueryException query exception
*/
public final Item checkEmpty(final Item it) throws QueryException {
if (it == null) XPEMPTY.thrw(input, desc());
return it;
}