/**
* The basic method for splitting off a clause of a tree. This modifies the tree in place.
*
* @param tree The tree to split a clause from.
* @param toKeep The edge representing the clause to keep.
*/
static void splitToChildOfEdge(SemanticGraph tree, SemanticGraphEdge toKeep) {
Queue<IndexedWord> fringe = new LinkedList<>();
List<IndexedWord> nodesToRemove = new ArrayList<>();
// Find nodes to remove
// (from the root)
for (IndexedWord root : tree.getRoots()) {
nodesToRemove.add(root);
for (SemanticGraphEdge out : tree.outgoingEdgeIterable(root)) {
if (!out.equals(toKeep)) {
fringe.add(out.getDependent());
}
}
}
// (recursively)
while (!fringe.isEmpty()) {
IndexedWord node = fringe.poll();
nodesToRemove.add(node);
for (SemanticGraphEdge out : tree.outgoingEdgeIterable(node)) {
if (!out.equals(toKeep)) {
fringe.add(out.getDependent());
}
}
}
// Remove nodes
nodesToRemove.forEach(tree::removeVertex);
// Set new root
tree.setRoot(toKeep.getDependent());
}
/**
* A helper to add an entire subtree to a given dependency tree.
*
* @param toModify The tree to add the subtree to.
* @param root The root of the tree where we should be adding the subtree.
* @param rel The relation to add the subtree with.
* @param originalTree The orignal tree (i.e., {@link ClauseSplitterSearchProblem#tree}).
* @param subject The root of the clause to add.
* @param ignoredEdges The edges to ignore adding when adding this subtree.
*/
private static void addSubtree(
SemanticGraph toModify,
IndexedWord root,
String rel,
SemanticGraph originalTree,
IndexedWord subject,
Collection<SemanticGraphEdge> ignoredEdges) {
if (toModify.containsVertex(subject)) {
return; // This subtree already exists.
}
Queue<IndexedWord> fringe = new LinkedList<>();
Collection<IndexedWord> wordsToAdd = new ArrayList<>();
Collection<SemanticGraphEdge> edgesToAdd = new ArrayList<>();
// Search for subtree to add
for (SemanticGraphEdge edge : originalTree.outgoingEdgeIterable(subject)) {
if (!ignoredEdges.contains(edge)) {
if (toModify.containsVertex(edge.getDependent())) {
// Case: we're adding a subtree that's not disjoint from toModify. This is bad news.
return;
}
edgesToAdd.add(edge);
fringe.add(edge.getDependent());
}
}
while (!fringe.isEmpty()) {
IndexedWord node = fringe.poll();
wordsToAdd.add(node);
for (SemanticGraphEdge edge : originalTree.outgoingEdgeIterable(node)) {
if (!ignoredEdges.contains(edge)) {
if (toModify.containsVertex(edge.getDependent())) {
// Case: we're adding a subtree that's not disjoint from toModify. This is bad news.
return;
}
edgesToAdd.add(edge);
fringe.add(edge.getDependent());
}
}
}
// Add subtree
// (add subject)
toModify.addVertex(subject);
toModify.addEdge(
root,
subject,
GrammaticalRelation.valueOf(Language.English, rel),
Double.NEGATIVE_INFINITY,
false);
// (add nodes)
wordsToAdd.forEach(toModify::addVertex);
// (add edges)
for (SemanticGraphEdge edge : edgesToAdd) {
assert !toModify.incomingEdgeIterator(edge.getDependent()).hasNext();
toModify.addEdge(
edge.getGovernor(),
edge.getDependent(),
edge.getRelation(),
edge.getWeight(),
edge.isExtra());
}
}