/**
* AbstractDbIterator.readNext implementation. Iterates over tuples from the child operator,
* applying the predicate to them and returning those that pass the predicate (i.e. for which the
* Predicate.filter() returns true.)
*
* @return The next tuple that passes the filter, or null if there are no more tuples
* @see Predicate#filter
*/
protected Tuple fetchNext()
throws NoSuchElementException, TransactionAbortedException, DbException {
try {
Tuple cur_tuple = m_child.next();
while (true) {
if (m_predicate.filter(cur_tuple)) {
return cur_tuple;
}
cur_tuple = m_child.next();
}
} catch (NoSuchElementException e) {
return null;
}
}
/**
* Operator.readNext implementation. Iterates over tuples from the child operator, applying the
* predicate to them and returning those that pass the predicate (i.e. for which the
* Predicate.filter() returns true.)
*
* @return The next tuple that passes the filter, or null if there are no more tuples
* @see Predicate#filter
*/
protected Tuple fetchNext()
throws NoSuchElementException, TransactionAbortedException, DbException {
// some code goes here
// DONE?
while (_child.hasNext()) {
Tuple t = _child.next();
if (_p.filter(t)) return t;
}
return null;
}
/**
* AbstractDbIterator.readNext implementation. Iterates over tuples from the child operator,
* applying the predicate to them and returning those that pass the predicate (i.e. for which the
* Predicate.filter() returns true.)
*
* @return The next tuple that passes the filter, or null if there are no more tuples
* @see Predicate#filter
*/
protected Tuple readNext()
throws NoSuchElementException, TransactionAbortedException, DbException {
Tuple t;
for (; ; ) {
t = null;
if (!child.hasNext()) {
break;
} else {
t = child.next();
if (p.filter(t)) {
System.out.println();
break;
}
}
}
return t;
}