/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * Null.java
 * Copyright (C) 2009-2012 University of Waikato, Hamilton, New Zealand
 */

package weka.classifiers.evaluation.output.prediction;

import weka.classifiers.Classifier;
import weka.core.Instance;

/**
 <!-- globalinfo-start -->
 * Suppresses all output.
 * <p/>
 <!-- globalinfo-end -->
 *
 <!-- options-start -->
 * Valid options are: <p/>
 * 
 * <pre> -p <range>
 *  The range of attributes to print in addition to the classification.
 *  (default: none)</pre>
 * 
 * <pre> -distribution
 *  Whether to turn on the output of the class distribution.
 *  Only for nominal class attributes.
 *  (default: off)</pre>
 * 
 * <pre> -decimals <num>
 *  The number of digits after the decimal point.
 *  (default: 3)</pre>
 * 
 * <pre> -file <path>
 *  The file to store the output in, instead of outputting it on stdout.
 *  Gets ignored if the supplied path is a directory.
 *  (default: .)</pre>
 * 
 * <pre> -suppress
 *  In case the data gets stored in a file, then this flag can be used
 *  to suppress the regular output.
 *  (default: not suppressed)</pre>
 * 
 <!-- options-end -->
 *
 * @author  fracpete (fracpete at waikato dot ac dot nz)
 * @version $Revision: 8937 $
 */
public class Null
  extends AbstractOutput {
  
  /** for serialization. */
  private static final long serialVersionUID = 4988413155999044966L;

  /**
   * Returns a string describing the output generator.
   * 
   * @return 		a description suitable for
   * 			displaying in the GUI
   */
  public String globalInfo() {
    return "Suppresses all output.";
  }
  
  /**
   * Returns a short display text, to be used in comboboxes.
   * 
   * @return 		a short display text
   */
  public String getDisplay() {
    return "No output";
  }

  /**
   * Returns always false.
   * 
   * @return		always false
   */
  public boolean generatesOutput() {
    return false;
  }

  /**
   * Does nothing.
   */
  protected void doPrintHeader() {
  }

  /**
   * Does nothing.
   * 
   * @param classifier	the classifier to use
   * @param inst	the instance to generate text from
   * @param index	the index in the dataset
   * @throws Exception	if something goes wrong
   */
  protected void doPrintClassification(Classifier classifier, Instance inst, int index) throws Exception {
  }
  
  /**
   * Does nothing.
   * 
   * @param dist        the distribution to use
   * @param inst        the instance to generate text from
   * @param index       the index in the dataset
   * @throws Exception  if something goes wrong
   */
  protected void doPrintClassification(double[] dist, Instance inst, int index) throws Exception {    
  }
  
  /**
   * Does nothing.
   */
  protected void doPrintFooter() {
  }
}