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 Universal charset detector code.
   *
   * The Initial Developer of the Original Code is
   *          Shy Shalom <shooshX@gmail.com>
   * Portions created by the Initial Developer are Copyright (C) 2005
   * 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
   * of those above. If you wish to allow use of your version of this file only
   * under the terms of either the GPL or the LGPL, and not to allow others to
   * use your version of this file under the terms of the MPL, indicate your
   * decision by deleting the provisions above and replace them with the notice
   * and other provisions required by the GPL or the LGPL. If you do not delete
   * the provisions above, a recipient may use your version of this file under
   * the terms of any one of the MPL, the GPL or the LGPL.
   *
   * ***** END LICENSE BLOCK ***** */
  
  package org.mozilla.universalchardet.prober;
  
  import org.mozilla.universalchardet.Constants;
  
  
  public class HebrewProber extends CharsetProber {
      ////////////////////////////////////////////////////////////////
      // fields
      ////////////////////////////////////////////////////////////////
      public static final int FINAL_KAF   = 0xEA;
      public static final int NORMAL_KAF  = 0xEB;
      public static final int FINAL_MEM   = 0xED;
      public static final int NORMAL_MEM  = 0xEE;
      public static final int FINAL_NUN   = 0xEF;
      public static final int NORMAL_NUN  = 0xF0;
      public static final int FINAL_PE    = 0xF3;
      public static final int NORMAL_PE   = 0xF4;
      public static final int FINAL_TSADI = 0xF5;
      public static final int NORMAL_TSADI= 0xF6;
      
      public static final byte SPACE      = 0x20;
      
      public static final int MIN_FINAL_CHAR_DISTANCE = 5;
      public static final float MIN_MODEL_DISTANCE = 0.01f;
      
  
      ////////////////////////////////////////////////////////////////
      // fields
      ////////////////////////////////////////////////////////////////
      private int     finalCharLogicalScore;
      private int     finalCharVisualScore;
      private byte    prev;
      private byte    beforePrev;
      
      private CharsetProber logicalProber;
      private CharsetProber visualProber;
  
  
      ////////////////////////////////////////////////////////////////
      // methods
      ////////////////////////////////////////////////////////////////
  	public HebrewProber() {
          super();
          this.logicalProber = null;
          this.visualProber = null;
          reset();
      }
      
  	public void setModalProbers(CharsetProber logicalProber, CharsetProber visualProber) {
          this.logicalProber = logicalProber;
          this.visualProber = visualProber;
      }
  
      @Override
  	public String getCharSetName() {
          // If the final letter score distance is dominant enough, rely on it.
          int finalsub = this.finalCharLogicalScore - this.finalCharVisualScore;
          if (finalsub >= MIN_FINAL_CHAR_DISTANCE) {
              return Constants.CHARSET_WINDOWS_1255;
          }
          if (finalsub <= -MIN_FINAL_CHAR_DISTANCE) {
              return Constants.CHARSET_ISO_8859_8;
          }
          
          // It's not dominant enough, try to rely on the model scores instead.
          float modelsub = this.logicalProber.getConfidence() - this.visualProber.getConfidence();
          if (modelsub > MIN_MODEL_DISTANCE) {
              return Constants.CHARSET_WINDOWS_1255;
          }
          if (modelsub < -MIN_MODEL_DISTANCE) {
              return Constants.CHARSET_ISO_8859_8;
          }
          
          // Still no good, back to final letter distance, maybe it'll save the day.
          if (finalsub < 0) {
              return Constants.CHARSET_ISO_8859_8;
          }
          
          // (finalsub > 0 - Logical) or (don't know what to do) default to Logical.
          return Constants.CHARSET_WINDOWS_1255;
      }
  
      @Override
  	public float getConfidence() {
          return 0.0f;
      }
  
      @Override
  	public ProbingState getState() {
          // Remain active as long as any of the model probers are active.
          if ((this.logicalProber.getState() == ProbingState.NOT_ME) &&
              (this.visualProber.getState() == ProbingState.NOT_ME)) {
              return ProbingState.NOT_ME;
          }
  
          return ProbingState.DETECTING;
      }
  
      @Override
  	public ProbingState handleData(byte[] buf, int offset, int length) {
          if (getState() == ProbingState.NOT_ME) {
              return ProbingState.NOT_ME;
          }
          
          byte c;
          int maxPos = offset + length;
          for (int i=offset; i<maxPos; ++i) {
              c = buf[i];
              if (c == SPACE) {
                  if (this.beforePrev != SPACE) {
                      if (isFinal(this.prev)) {
                          ++this.finalCharLogicalScore;
                      } else if (isNonFinal(this.prev)) {
                          ++this.finalCharVisualScore;
                      }
                  }
              } else {
                  if ((this.beforePrev == SPACE) &&
                       isFinal(this.prev) &&
                       c != SPACE) {
                      ++this.finalCharVisualScore;
                  }
              }
              this.beforePrev = this.prev;
              this.prev = c;
          }
          
          return ProbingState.DETECTING;
      }
  
      @Override
  	public final void reset() {
          this.finalCharLogicalScore = 0;
          this.finalCharVisualScore = 0;
          
          // mPrev and mBeforePrev are initialized to space in order to simulate a word 
          // delimiter at the beginning of the data
          this.prev = SPACE;
          this.beforePrev = SPACE;
      }
  
      @Override
  	public void setOption() {
  	}
  
  	protected static boolean isFinal(byte b) {
          int c = b & 0xFF;
          return (
                  c == FINAL_KAF ||
                  c == FINAL_MEM ||
                  c == FINAL_NUN ||
                  c == FINAL_PE ||
                  c == FINAL_TSADI
                  );
      }
      
  	protected static boolean isNonFinal(byte b) {
          int c = b & 0xFF;
          return (
                  c == NORMAL_KAF ||
                  c == NORMAL_MEM ||
                  c == NORMAL_NUN ||
                  c == NORMAL_PE
                  );
          // The normal Tsadi is not a good Non-Final letter due to words like 
          // 'lechotet' (to chat) containing an apostrophe after the tsadi. This 
          // apostrophe is converted to a space in FilterWithoutEnglishLetters causing 
          // the Non-Final tsadi to appear at an end of a word even though this is not 
          // the case in the original text.
          // The letters Pe and Kaf rarely display a related behavior of not being a 
          // good Non-Final letter. Words like 'Pop', 'Winamp' and 'Mubarak' for 
          // example legally end with a Non-Final Pe or Kaf. However, the benefit of 
          // these letters as Non-Final letters outweighs the damage since these words 
          // are quite rare.
      }
  }
  