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Stanford CoreNLP provides a set of natural language analysis tools which can take raw English language text input and give the base forms of words, their parts of speech, whether they are names of companies, people, etc., normalize dates, times, and numeric quantities, mark up the structure of sentences in terms of phrases and word dependencies, and indicate which noun phrases refer to the same entities. It provides the foundational building blocks for higher level text understanding applications.

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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;
    }
  }
}