interner.java

Standord Classifier实现了一个基于Java的最大熵分类器。用于模式识别

package edu.stanford.nlp.util;

import java.util.*;

/**
 *  Interner: Class for interning things. 
 *
 *  It maps any object given to an interned version.  If presented with a 
 *  new object which has no interned version, the presented object becomes
 *  the interned version.
 *
 *  Author: Dan Klein
 *  Date: 1/3/01
 *
 * @author Dan Klein
 */
public final class Interner {

  private Map entries = new HashMap();

  class InternerEntry {
    Internable i;
    public Internable entry() {
      return i;
    }
    public void setEntry(Internable i) {
      this.i = i;
    }
    public int hashCode() {
      return i.weakHashCode();
    }
    public boolean equals(Object o) {
      //if (o instanceof InternerEntry)
      return i.weakEquals(((InternerEntry)o).i);
      //else
      //return i.weakEquals(o);
    }
    InternerEntry(Internable i) {
      this.i = i;
    }
    InternerEntry() {
      i = null;
    }
  }


  private transient InternerEntry tempEntry = new InternerEntry();

  public Object intern(Internable o) {
    //if (o instanceof Internable)
    //InternerEntry e = new InternerEntry(o);
    tempEntry.setEntry(o);
    Object internedVersion = entries.get(tempEntry);
    if (internedVersion == null) {
      entries.put(tempEntry, tempEntry);
      internedVersion = tempEntry;
      tempEntry = new InternerEntry();
    }
    //if (internedVersion instanceof InternerEntry)
    return ((InternerEntry)internedVersion).entry();
    //return o;
  }

  /*
  public boolean contains(Object o) {
    if (o instanceof Internable)
      o = new InternerEntry((Internable)o);
    Object internedVersion = entries.get(o);
    if (internedVersion == null)
      return false;
    return true;
  }
  */

}