package edu.stanford.nlp.trees;
/**
* Tree normalizer for cleaning up labels and preserving the whole node label,
* the grammatical function and category information from the label, or only
* the category information. Only normalization occurs on nonterminals.
* @author Anna Rafferty
*
*/
public class GrammaticalFunctionTreeNormalizer extends TreeNormalizer {
private static final long serialVersionUID = -2270472762938163327L;
/** How to clean up node labels: 0 = do nothing, 1 = keep category and
* function, 2 = just category.
*/
private final int nodeCleanup;
private final String root;
protected final TreebankLanguagePack tlp;
public GrammaticalFunctionTreeNormalizer(TreebankLanguagePack tlp, int nodeCleanup) {
this.tlp = tlp;
this.nodeCleanup = nodeCleanup;
root = tlp.startSymbol();
}
/**
* Normalizes a nonterminal contents.
* This implementation strips functional tags, etc. and interns the
* nonterminal.
*/
@Override
public String normalizeNonterminal(String category) {
return cleanUpLabel(category).intern();
}
/**
* Remove things like hyphened functional tags and equals from the
* end of a node label.
*/
protected String cleanUpLabel(String label) {
if (label == null) {
return root;
} else if (nodeCleanup == 1) {
return tlp.categoryAndFunction(label);
} else if (nodeCleanup == 2) {
return tlp.basicCategory(label);
} else {
return label;
}
}
}