/** returns true iff <code>head</code> (transitively) heads <code>node</code> */
public static boolean heads(Tree head, Tree node, HeadFinder hf) {
if (node.isLeaf()) {
return false;
} else {
return heads(head, hf.determineHead(node), hf);
}
}
/**
* returns the maximal projection of <code>head</code> in <code>root</code> given a {@link
* HeadFinder}
*/
public static Tree maximalProjection(Tree head, Tree root, HeadFinder hf) {
Tree projection = head;
if (projection == root) {
return root;
}
Tree parent = projection.parent(root);
while (hf.determineHead(parent) == projection) {
projection = parent;
if (projection == root) {
return root;
}
parent = projection.parent(root);
}
return projection;
}
/* applies a TreeVisitor to all projections (including the node itself) of a node in a Tree.
* Does nothing if head is not in root.
* @return the maximal projection of head in root.
*/
public static Tree applyToProjections(TreeVisitor v, Tree head, Tree root, HeadFinder hf) {
Tree projection = head;
Tree parent = projection.parent(root);
if (parent == null && projection != root) {
return null;
}
v.visitTree(projection);
if (projection == root) {
return root;
}
while (hf.determineHead(parent) == projection) {
projection = parent;
v.visitTree(projection);
if (projection == root) {
return root;
}
parent = projection.parent(root);
}
return projection;
}