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Stanford Parser processes raw text in English, Chinese, German, Arabic, and French, and extracts constituency parse trees.

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package edu.stanford.nlp.ling;


/**
 * A {@code Word} object acts as a Label by containing a String.
 * This class is in essence identical to a {@code StringLabel}, but
 * it also uses the value to implement the {@code HasWord} interface.
 *
 * @author Christopher Manning
 * @version 2000/12/20
 */
public class Word extends StringLabel implements HasWord {

  /**
   * String representation of an empty.
   */
  private static final String EMPTY_STRING = "*t*";

  /**
   * Word representation of an empty.
   */
  public static final Word EMPTY = new Word(EMPTY_STRING);

  /**
   * Construct a new word with a {@code null} value.
   */
  public Word() {
    super();
  }

  /**
   * Construct a new word, with the given value.
   *
   * @param word String value of the Word
   */
  public Word(String word) {
    super(word);
  }

  /**
   * Construct a new word, with the given value.
   *
   * @param word String value of the Word
   */
  public Word(String word, int beginPosition, int endPosition) {
    super(word, beginPosition, endPosition);
  }


  /**
   * Creates a new word whose word value is the value of any
   * class that supports the {@code Label} interface.
   *
   * @param lab The label to be used as the basis of the new Word
   */
  public Word(Label lab) {
    super(lab);
  }


  @Override
  public String word() {
    return value();
  }


  @Override
  public void setWord(String word) {
    setValue(word);
  }

  // extra class guarantees correct lazy loading (Bloch p.194)
  private static class WordFactoryHolder {

    private static final LabelFactory lf = new WordFactory();

    private WordFactoryHolder() { }

  }

  /**
   * Return a factory for this kind of label (i.e., {@code Word}).
   * The factory returned is always the same one (a singleton).
   *
   * @return The label factory
   */
  @Override
  public LabelFactory labelFactory() {
    return WordFactoryHolder.lf;
  }


  /**
   * Return a factory for this kind of label.
   *
   * @return The label factory
   */
  public static LabelFactory factory() {
    return WordFactoryHolder.lf;
  }

  private static final long serialVersionUID = -4817252915997034058L;

}