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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;

import java.io.Serializable;

import edu.stanford.nlp.ling.CoreLabel;
import edu.stanford.nlp.ling.IndexedWord;

/**
 * A TypedDependency is a relation between two words in a
 * GrammaticalStructure.  Each TypedDependency
 * consists of a governor word, a dependent word, and a relation, which is
 * normally an instance of {@link GrammaticalRelation
 * GrammaticalRelation}.
 *
 * @author Bill MacCartney
 */
public class TypedDependency implements Comparable, Serializable {

  private static final long serialVersionUID = -7690294213151279779L;

  // TODO FIXME: these should all be final.  That they are mutable is
  // awful design.  Awful.  It means that underlying data structures
  // can be mutated in ways you don't intend.  For example, there was
  // a time when you could call typedDependenciesCollapsed() and it
  // would change the GrammaticalStructure because of the way that
  // object mutated its TypedDependency objects.
  private GrammaticalRelation reln;
  private IndexedWord gov;
  private IndexedWord dep;
  private boolean extra; // = false; // to code whether the dependency preserves the tree structure or not
  // cdm: todo: remove this field and use typing on reln?  Expand implementation of SEMANTIC_DEPENDENT

  public TypedDependency(GrammaticalRelation reln, IndexedWord gov, IndexedWord dep) {
    this.reln = reln;
    this.gov = gov;
    this.dep = dep;
  }

  public TypedDependency(TypedDependency other) {
    this.reln = other.reln;
    this.gov = other.gov;
    this.dep = other.dep;
    this.extra = other.extra;
  }

  public GrammaticalRelation reln() {
    return reln;
  }

  public void setGov(IndexedWord gov) {
    this.gov = gov;
  }

  public void setDep(IndexedWord dep) {
    this.dep = dep;
  }


  public IndexedWord gov() {
    return gov;
  }

  public IndexedWord dep() {
    return dep;
  }

  public boolean extra() {
    return extra;
  }

  public void setReln(GrammaticalRelation reln) {
    this.reln = reln;
  }

  public void setExtra() {
    this.extra = true;
  }

  @SuppressWarnings({"RedundantIfStatement"})
  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (!(o instanceof TypedDependency)) {
      return false;
    }
    final TypedDependency typedDep = (TypedDependency) o;

    if (reln != null ? !reln.equals(typedDep.reln) : typedDep.reln != null) {
      return false;
    }
    if (gov != null ? !gov.equals(typedDep.gov) : typedDep.gov != null) {
      return false;
    }
    if (dep != null ? !dep.equals(typedDep.dep) : typedDep.dep != null) {
      return false;
    }

    return true;
  }

  @Override
  public int hashCode() {
    int result = (reln != null ? reln.hashCode() : 17);
    result = 29 * result + (gov != null ? gov.hashCode() : 0);
    result = 29 * result + (dep != null ? dep.hashCode() : 0);
    return result;
  }

  @Override
  public String toString() {
    return toString(CoreLabel.OutputFormat.VALUE_INDEX);
  }

  public String toString(CoreLabel.OutputFormat format) {
    return reln + "(" + gov.toString(format) + ", " + dep.toString(format) + ")";
  }

  public int compareTo(TypedDependency tdArg) {
    IndexedWord depArg = tdArg.dep();
    IndexedWord depThis = this.dep();
    int indexArg = depArg.index();
    int indexThis = depThis.index();

    if (indexThis > indexArg) {
      return 1;
    } else if (indexThis < indexArg) {
      return -1;
    }

    // dependent indices are equal, check governor
    int govIndexArg  = tdArg.gov().index();
    int govIndexThis = this.gov().index();
    if (govIndexThis > govIndexArg) {
      return 1;
    } else if (govIndexThis < govIndexArg) {
      return -1;
    }

    // dependent and governor indices equal, the relation decides
    return this.reln().compareTo(tdArg.reln());
  }

}