/**
* Generic (model-independent) method to determine the relative position of two node in document
* order. The nodes must be in the same tree.
*
* @param first The first node
* @param second The second node, whose position is to be compared with the first node
* @return -1 if this node precedes the other node, +1 if it follows the other node, or 0 if they
* are the same node. (In this case, isSameNode() will always return true, and the two nodes
* will produce the same result for generateId())
*/
public static int compareOrder(SiblingCountingNode first, SiblingCountingNode second) {
NodeInfo ow = second;
// are they the same node?
if (first.isSameNode(second)) {
return 0;
}
// are they siblings (common case)
if (first.getParent().isSameNode(second.getParent())) {
return first.getSiblingPosition() - second.getSiblingPosition();
}
// find the depths of both nodes in the tree
int depth1 = 0;
int depth2 = 0;
NodeInfo p1 = first;
NodeInfo p2 = second;
while (p1 != null) {
depth1++;
p1 = p1.getParent();
}
while (p2 != null) {
depth2++;
p2 = p2.getParent();
}
// move up one branch of the tree so we have two nodes on the same level
p1 = first;
while (depth1 > depth2) {
p1 = p1.getParent();
if (p1.isSameNode(second)) {
return +1;
}
depth1--;
}
p2 = ow;
while (depth2 > depth1) {
p2 = p2.getParent();
if (p2.isSameNode(first)) {
return -1;
}
depth2--;
}
// now move up both branches in sync until we find a common parent
while (true) {
NodeInfo par1 = p1.getParent();
NodeInfo par2 = p2.getParent();
if (par1 == null || par2 == null) {
throw new NullPointerException("DOM tree compare - internal error");
}
if (par1.isSameNode(par2)) {
return ((SiblingCountingNode) p1).getSiblingPosition()
- ((SiblingCountingNode) p2).getSiblingPosition();
}
p1 = par1;
p2 = par2;
}
}
/**
* Get a character string that uniquely identifies this node and that collates nodes into document
* order
*
* @return a string. The string is always interned so keys can be compared using "==".
*/
public static String getSequentialKey(SiblingCountingNode node) {
// TODO: this was designed so it could be used for sorting nodes into document
// order, but is not currently used that way.
StringBuffer key = new StringBuffer();
while (!(node instanceof DocumentInfo)) {
key.insert(0, alphaKey(node.getSiblingPosition()));
node = (SiblingCountingNode) node.getParent();
}
key.insert(0, "w" + node.getDocumentNumber());
return key.toString().intern();
}
