public boolean next() throws IOException {
if (firstTime) {
initList(true);
listToQueue(); // initialize queue
firstTime = false;
} else if (more) {
more = min().next(); // trigger further scanning
if (more) queue.adjustTop(); // maintain queue
}
while (more) {
boolean queueStale = false;
if (min().doc() != max.doc()) { // maintain list
queueToList();
queueStale = true;
}
// skip to doc w/ all clauses
while (more && first.doc() < last.doc()) {
more = first.skipTo(last.doc()); // skip first upto last
firstToLast(); // and move it to the end
queueStale = true;
}
if (!more) return false;
// found doc w/ all clauses
if (queueStale) { // maintain the queue
listToQueue();
queueStale = false;
}
if (atMatch()) return true;
// trigger further scanning
if (inOrder && checkSlop()) {
/* There is a non ordered match within slop and an ordered match is needed. */
more = firstNonOrderedNextToPartialList();
if (more) {
partialListToQueue();
}
} else {
more = min().next();
if (more) {
queue.adjustTop(); // maintain queue
}
}
}
return false; // no more matches
}
public boolean skipTo(int target) throws IOException {
if (firstTime) { // initialize
initList(false);
for (SpansCell cell = first; more && cell != null; cell = cell.next) {
more = cell.skipTo(target); // skip all
}
if (more) {
listToQueue();
}
firstTime = false;
} else { // normal case
while (more && min().doc() < target) { // skip as needed
more = min().skipTo(target);
if (more) queue.adjustTop();
}
}
if (more) {
if (atMatch()) // at a match?
return true;
return next(); // no, scan
}
return false;
}
private boolean firstNonOrderedNextToPartialList() throws IOException {
/* Creates a partial list consisting of first non ordered and earlier.
* Returns first non ordered .next().
*/
last = first = null;
int orderedIndex = 0;
while (queue.top() != null) {
SpansCell cell = (SpansCell) queue.pop();
addToList(cell);
if (cell.index == orderedIndex) {
orderedIndex++;
} else {
return cell.next();
// FIXME: continue here, rename to eg. checkOrderedMatch():
// when checkSlop() and not ordered, repeat cell.next().
// when checkSlop() and ordered, add to list and repeat queue.pop()
// without checkSlop(): no match, rebuild the queue from the partial list.
// When queue is empty and checkSlop() and ordered there is a match.
}
}
throw new RuntimeException("Unexpected: ordered");
}
private void partialListToQueue() {
for (SpansCell cell = first; cell != null; cell = cell.next) {
queue.put(cell); // add to queue from list
}
}
private void listToQueue() {
queue.clear(); // rebuild queue
partialListToQueue();
}
private void queueToList() {
last = first = null;
while (queue.top() != null) {
addToList((SpansCell) queue.pop());
}
}
private SpansCell min() {
return (SpansCell) queue.top();
}