/**

  * Distribution License:

  * JSword is free software; you can redistribute it and/or modify it under

  * the terms of the GNU Lesser General Public License, version 2.1 or later

  * as published by the Free Software Foundation. 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 Lesser General Public License for more details.

  *

  * The License is available on the internet at:

  *      http://www.gnu.org/copyleft/lgpl.html

  * or by writing to:

  *      Free Software Foundation, Inc.

  *      59 Temple Place - Suite 330

  *      Boston, MA 02111-1307, USA

  *

  * © CrossWire Bible Society, 2005 - 2016

  *

  */

 package org.crosswire.common.util;

 import java.util.HashMap;

 import java.util.Map;

 /**

  * A simple implementation of a histogram. It would be nice to enhance it to

  * order on frequency.

  * 

  * @see gnu.lgpl.License The GNU Lesser General Public License for details.

  * @author DM Smith

  */

 public class Histogram {

     /**

      * Create an empty histogram

      */

     public Histogram() {

         hist = new HashMap<String, Counter>();

     }

     /**

      * Note that this key has been seen one time more than before.

      * 

      * @param key the key to increment

      */

     public void increment(String key) {

         Counter counter = hist.get(key);

         if (counter == null) {

             counter = new Counter();

             hist.put(key, counter);

         }

         counter.increment();

     }

     public void clear() {

         hist.clear();

     }

     /**

      * The format of the histogram is an unordered list of string and the counts

      * of the number of times it has been seen.

      * 

      * @return the resultant histogram

      * @see java.lang.Object#toString()

      */

     @Override

     public String toString() {

         StringBuilder buf = new StringBuilder();

         for (Map.Entry<String, Counter> entry : hist.entrySet()) {

             buf.append(entry.getKey());

             buf.append('\t');

             buf.append(entry.getValue().toString());

             buf.append('\n');

         }

         return buf.toString();

     }

     /**

      * Trivial mutable counting integer class.

      */

     private static class Counter {

         Counter() {

         }

         public void increment() {

             counter++;

         }

         @Override

         public String toString() {

             return Integer.toString(counter);

         }

         private int counter;

     }

     private Map<String, Counter> hist;

 }