package edu.stanford.nlp.parser.lexparser;
import java.util.*;
import edu.stanford.nlp.ling.CoreLabel;
import edu.stanford.nlp.ling.LabelFactory;
import edu.stanford.nlp.trees.LabeledScoredTreeFactory;
import edu.stanford.nlp.trees.Tree;
import edu.stanford.nlp.trees.TreeFactory;
import edu.stanford.nlp.trees.TreeTransformer;
/** Debinarizes a binary tree from the parser.
* Node values with a '@' in them anywhere are assumed to be inserted
* nodes for the purpose of binarization, and are removed.
* The code also removes the last child of the root node, assuming
* that it is an inserted dependency root.
*/
public class Debinarizer implements TreeTransformer {
private final TreeFactory tf;
private final boolean forceCNF;
private final TreeTransformer boundaryRemover;
protected Tree transformTreeHelper(Tree t) {
if (t.isLeaf()) {
Tree leaf = tf.newLeaf(t.label());
leaf.setScore(t.score());
return leaf;
}
List<Tree> newChildren = new ArrayList<Tree>();
for (int childNum = 0, numKids = t.numChildren(); childNum < numKids; childNum++) {
Tree child = t.getChild(childNum);
Tree newChild = transformTreeHelper(child);
if ((!newChild.isLeaf()) && newChild.label().value().indexOf('@') >= 0) {
newChildren.addAll(newChild.getChildrenAsList());
} else {
newChildren.add(newChild);
}
}
Tree node = tf.newTreeNode(t.label(), newChildren);
node.setScore(t.score());
return node;
}
@Override
public Tree transformTree(Tree t) {
Tree result = transformTreeHelper(t);
if (forceCNF) {
result = new CNFTransformers.FromCNFTransformer().transformTree(result);
}
return boundaryRemover.transformTree(result);
}
public Debinarizer(boolean forceCNF) {
this(forceCNF, CoreLabel.factory());
}
public Debinarizer(boolean forceCNF, LabelFactory lf) {
this.forceCNF = forceCNF;
tf = new LabeledScoredTreeFactory(lf);
boundaryRemover = new BoundaryRemover();
}
} // end class Debinarizer