edu.stanford.nlp.trees.UnnamedConcreteDependency Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of stanford-corenlp Show documentation

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.

There is a newer version: 4.5.7

Show newest version

package edu.stanford.nlp.trees;

import edu.stanford.nlp.ling.HasIndex;
import edu.stanford.nlp.ling.Label;
import edu.stanford.nlp.util.XMLUtils;

/**
 * An individual dependency between a head and a dependent. The dependency
 * is associated with the token indices of the lexical items.
 * 
 * A key difference between this class and UnnamedDependency is the equals()
 * method. Equality of two UnnamedConcreteDependency objects is defined solely
 * with respect to the indices. The surface forms are not considered. This permits 
 * a use case in which dependencies in two different parse trees have slightly different 
 * pre-processing, possibly due to pre-processing.
 * 
 * @author Spence Green
 * 
 */
public class UnnamedConcreteDependency extends UnnamedDependency {

  private static final long serialVersionUID = -8836949694741145222L;

  private final int headIndex;
  private final int depIndex;

  public UnnamedConcreteDependency(String regent, int regentIndex, String dependent, int dependentIndex) {
    super(regent, dependent);

    headIndex = regentIndex;
    depIndex = dependentIndex;
  }
  
  public UnnamedConcreteDependency(Label regent, int regentIndex, Label dependent, int dependentIndex) {
    super(regent, dependent);
    
    headIndex = regentIndex;
    depIndex = dependentIndex;
  }

  public UnnamedConcreteDependency(Label regent, Label dependent) {
    super(regent, dependent);

    if (governor() instanceof HasIndex) {
      headIndex = ((HasIndex) governor()).index();
    } else {
      throw new IllegalArgumentException("Label argument lacks IndexAnnotation.");
    }
    if (dependent() instanceof HasIndex) {
      depIndex = ((HasIndex) dependent()).index();
    } else {
      throw new IllegalArgumentException("Label argument lacks IndexAnnotation.");
    }
  }
  
  public int getGovernorIndex() { return headIndex; }
  
  public int getDependentIndex() { return depIndex; }
  
  @Override
  public int hashCode() {
    return headIndex * (depIndex << 16);
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    } else if( !(o instanceof UnnamedConcreteDependency)) {
      return false;
    }
    UnnamedConcreteDependency d = (UnnamedConcreteDependency) o;
    return headIndex == d.headIndex && depIndex == d.depIndex;
  }

  @Override
  public String toString() {
    String headWord = getText(governor());
    String depWord = getText(dependent());
    return String.format("%s [%d] --> %s [%d]", headWord, headIndex, depWord, depIndex);
  }

  /**
   * Provide different printing options via a String keyword.
   * The recognized options are currently "xml", and "predicate".
   * Otherwise the default toString() is used.
   */
  @Override
  public String toString(String format) {
    switch (format) {
      case "xml":
        String govIdxStr = " idx=\"" + headIndex + "\"";
        String depIdxStr = " idx=\"" + depIndex + "\"";
        return "  \n    " + XMLUtils.escapeXML(governor().value()) + "\n    " + XMLUtils.escapeXML(dependent().value()) + "\n  ";
      case "predicate":
        return "dep(" + governor() + "," + dependent() + ")";
      default:
        return toString();
    }
  }

  @Override
  public DependencyFactory dependencyFactory() {
    return DependencyFactoryHolder.df;
  }
  
  public static DependencyFactory factory() {
    return DependencyFactoryHolder.df;
  }

  // extra class guarantees correct lazy loading (Bloch p.194)
  private static class DependencyFactoryHolder {
    private static final DependencyFactory df = new UnnamedConcreteDependencyFactory();
  }

  /**
   * A DependencyFactory acts as a factory for creating objects
   * of class Dependency
   */
  private static class UnnamedConcreteDependencyFactory implements DependencyFactory {
    /**
     * Create a new Dependency.
     */
    public Dependency newDependency(Label regent, Label dependent) {
      return newDependency(regent, dependent, null);
    }

    /**
     * Create a new Dependency.
     */
    public Dependency newDependency(Label regent, Label dependent, Object name) {
      return new UnnamedConcreteDependency(regent, dependent);
    }
  }
}