content: /* ***** BEGIN LICENSE BLOCK *****
   * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   *
   * The contents of this file are subject to the Mozilla Public License Version
   * 1.1 (the "License"); you may not use this file except in compliance with
   * the License. You may obtain a copy of the License at
   * http://www.mozilla.org/MPL/
   *
   * Software distributed under the License is distributed on an "AS IS" basis,
   * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
   * for the specific language governing rights and limitations under the
   * License.
   *
   * The Original Code is Mozilla Communicator client code.
   *
   * The Initial Developer of the Original Code is
   * Netscape Communications Corporation.
   * Portions created by the Initial Developer are Copyright (C) 1998
   * the Initial Developer. All Rights Reserved.
   *
   * Contributor(s):
   *   Kohei TAKETA <k-tak@void.in> (Java port)
   *
   * Alternatively, the contents of this file may be used under the terms of
   * either the GNU General Public License Version 2 or later (the "GPL"), or
   * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
   * in which case the provisions of the GPL or the LGPL are applicable instead
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   *
   * ***** END LICENSE BLOCK ***** */
  
  package org.mozilla.universalchardet.prober.distributionanalysis;
  
  
  public abstract class CharDistributionAnalysis {
      ////////////////////////////////////////////////////////////////
      // constants
      ////////////////////////////////////////////////////////////////
      public static final float   SURE_NO = 0.01f;
      public static final float   SURE_YES = 0.99f;
      public static final int     ENOUGH_DATA_THRESHOLD = 1024;
      public static final int     MINIMUM_DATA_THRESHOLD = 4;
      
  
      ////////////////////////////////////////////////////////////////
      // fields
      ////////////////////////////////////////////////////////////////
      private int         freqChars;
      private int         totalChars;
      protected int[]     charToFreqOrder; // set by subclasses
      protected float     typicalDistributionRatio; // set by subclasses
      
  
      ////////////////////////////////////////////////////////////////
      // methods
      ////////////////////////////////////////////////////////////////
  	public CharDistributionAnalysis() {
          reset();
      }
      
  	public void handleData(final byte[] buf, int offset, int length) {
  	}
      
  	public void handleOneChar(final byte[] buf, int offset, int charLength) {
          int order = -1;
          
          if (charLength == 2) {
              order = getOrder(buf, offset);
          }
          
          if (order >= 0) {
              ++this.totalChars;
              if (order < this.charToFreqOrder.length) {
                  if (512 > this.charToFreqOrder[order]) {
                      ++this.freqChars;
                  }
              }
          }
      }
      
  	public float getConfidence() {
          if (this.totalChars <= 0 || this.freqChars <= MINIMUM_DATA_THRESHOLD) {
              return SURE_NO;
          }
          
          if (this.totalChars != this.freqChars) {
              float r = this.freqChars / ((this.totalChars - this.freqChars) * this.typicalDistributionRatio);
              
              if (r < SURE_YES) {
                  return r;
              }
          }
          
          return SURE_YES;
      }
      
  	public final void reset() {
          this.totalChars = 0;
          this.freqChars = 0;
      }
      
  	public void setOption() {
  	}
      
  	public boolean gotEnoughData() {
          return (this.totalChars > ENOUGH_DATA_THRESHOLD);
      }
      
      protected abstract int getOrder(final byte[] buf, int offset);
  }
  