edu.stanford.nlp.parser.lexparser.Hook 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.parser.lexparser;

/** Class for parse table hooks.  A "hook" is the parse item that Eisner and
 *  Satta introduced to reduce the complexity of lexicalized parsing to 
 *  O(n^4).
 *
 *  @author Dan Klein
 */
public class Hook extends Item {

  public int subState;

  public Hook(boolean exhaustiveTest) {
  	super(exhaustiveTest);
  }
  
  public Hook(Hook h) {
  	super(h);
  	subState = h.subState;
  }
  
  @Override
  public boolean isPreHook() {
    return head < start;
  }

  @Override
  public boolean isPostHook() {
    return head >= end;
  }

  @Override
  public String toString() {
    // TODO: used to have more useful information
    //return (isPreHook() ? "Pre" : "Post") + "Hook(" + Numberer.getGlobalNumberer("states").object(state) + "|" + Numberer.getGlobalNumberer("states").object(subState) + ":" + start + "-" + end + "," + head + "/" + Numberer.getGlobalNumberer("tags").object(tag) + ")";
    return (isPreHook() ? "Pre" : "Post") + "Hook(" + state + "|" + subState + ":" + start + "-" + end + "," + head + "/" + tag + ")";
  }

  @Override
  public int hashCode() {
    return 1 + (state << 14) ^ (subState << 16) ^ (head << 22) ^ (tag << 27) ^ (start << 1) ^ (end << 7);
  }

  /** Hooks are equal if they have same state, substate, head, tag, start, 
   *  and end.
   */
  @Override
  public boolean equals(Object o) {
    // System.out.println("\nCHECKING HOOKS: " + this + " vs. " + o);
    if (this == o) {
      return true;
    }
    if (o instanceof Hook) {
      Hook e = (Hook) o;
      if (state == e.state && subState == e.subState && head == e.head &&
          tag == e.tag && start == e.start && end == e.end) {
        return true;
      }
    }
    return false;
  }

}