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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.international.tuebadz;

import java.util.ArrayList;
import java.util.List;

import edu.stanford.nlp.trees.Tree;
import edu.stanford.nlp.trees.TreeFactory;
import edu.stanford.nlp.trees.TreeNormalizer;
import edu.stanford.nlp.trees.TreebankLanguagePack;


/**
 * Tree normalizer for the TueBaDZ treebank.
 *
 * (An adaptation of Roger Levy's NegraPennTreeNormalizer.)
 *
 * @author Wolfgang Maier ([email protected])
 */
public class TueBaDZPennTreeNormalizer extends TreeNormalizer {

  /** 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;
  private List tns = new ArrayList<>();

  public String rootSymbol() {
    return root;
  }

//  public TueBaDZPennTreeNormalizer() {
//    this(new TueBaDZLanguagePack(), 0);
//  }

  public TueBaDZPennTreeNormalizer(TreebankLanguagePack tlp, int nodeCleanup) {
    this.tlp = tlp;
    this.nodeCleanup = nodeCleanup;
    root = tlp.startSymbol();
  }
  
  public TueBaDZPennTreeNormalizer(TreebankLanguagePack tlp, int nodeCleanup, List tns) {
    this.tlp = tlp;
    this.nodeCleanup = nodeCleanup;
    root = tlp.startSymbol();
    this.tns.addAll(tns);
  }

  /**
   * Normalizes a leaf contents.
   * This implementation interns the leaf.
   */
  @Override
  public String normalizeTerminal(String leaf) {
    // We could unquote * and / with backslash \ in front of them
    return leaf.intern();
  }


  /**
   * 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;
    }
  }


  /**
   * Normalize a whole tree.
   * TueBa-D/Z adaptation. Fixes trees with non-unary roots, does nothing else.
   */
  @Override
  public Tree normalizeWholeTree(Tree tree, TreeFactory tf) {
    if (tree.label().value().equals(root) && tree.children().length > 1) {
      Tree underRoot = tree.treeFactory().newTreeNode(root, tree.getChildrenAsList());
      tree.setChildren(new Tree[1]);
      tree.setChild(0, underRoot);

    }
    // we just want the non-unary root fixed.
    return tree;
  }

  private static final long serialVersionUID = 8009544230321390490L;

}