/**
* Compares two nodes for their unique order.
*
* @param node1 first node
* @param node2 node to be compared
* @return {@code 0} if the nodes are identical, or {@code 1}/{@code -1} if the first node appears
* after/before the second
*/
static int diff(final ANode node1, final ANode node2) {
// cache parents of first node
final ANodeList nl = new ANodeList();
for (ANode n = node1; n != null; n = n.parent()) {
if (n == node2) return 1;
nl.add(n);
}
// find lowest common ancestor
ANode c2 = node2;
LOOP:
for (ANode n = node2; (n = n.parent()) != null; ) {
final int is = nl.size();
for (int i = 1; i < is; i++) {
if (n == node1) return -1;
if (!nl.get(i).is(n)) continue;
// check which node appears as first LCA child
final ANode c1 = nl.get(i - 1);
final BasicNodeIter ir = n.children();
for (ANode c; (c = ir.next()) != null; ) {
if (c.is(c1)) return -1;
if (c.is(c2)) return 1;
}
break LOOP;
}
c2 = n;
}
// subtraction is used instead of comparison to support overflow of node id
return node1.id - node2.id < 0 ? -1 : 1;
}
@Override
protected ANodeList eval(final Iter[] iter) throws QueryException {
final ANodeList list = new ANodeList().check();
for (Item it; (it = iter[0].next()) != null; ) list.add(toNode(it));
final boolean db = list.dbnodes();
final int el = exprs.length;
for (int e = 1; e < el && !list.isEmpty(); e++) {
final Iter ir = iter[e];
for (Item it; (it = ir.next()) != null; ) {
final int i = list.indexOf(toNode(it), db);
if (i != -1) list.delete(i);
}
}
return list;
}
/**
* Adds children of a sub node.
*
* @param ch child nodes
* @param nb node cache
*/
static void addDesc(final BasicNodeIter ch, final ANodeList nb) {
for (ANode n; (n = ch.next()) != null; ) {
nb.add(n.finish());
addDesc(n.children(), nb);
}
}