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Jazzy example source code file (SpellDictionaryDichoDisk.java)

This example Jazzy source code file (SpellDictionaryDichoDisk.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Jazzy tags/keywords

eofexception, file, filenotfoundexception, io, ioexception, ioexception, linkedlist, linkedlist, list, randomaccessfile, randomaccessfile, spelldictionaryaspell, spelldictionarydichodisk, string, string, util

The Jazzy SpellDictionaryDichoDisk.java source code

/*
Jazzy - a Java library for Spell Checking
Copyright (C) 2001 Mindaugas Idzelis
Full text of license can be found in LICENSE.txt

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library 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.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/
package com.swabunga.spell.engine;

import java.io.*;
import java.util.*;

/**
 * Another implementation of <code>SpellDictionary that doesn't cache any words in memory. Avoids the huge
 * footprint of <code>SpellDictionaryHashMap at the cost of relatively minor latency. A future version
 * of this class that implements some caching strategies might be a good idea in the future, if there's any
 * demand for it.
 *
 * This implementation requires a special dictionary file, with "code*word" lines sorted by code.
 * It's using a dichotomy algorithm to search for words in the dictionary
 *
 * @author Damien Guillaume
 * @version 0.1
 */
public class SpellDictionaryDichoDisk extends SpellDictionaryASpell {

  /** Holds the dictionary file for reading*/
  private RandomAccessFile dictFile = null;
  
  /** dictionary and phonetic file encoding */
  private String encoding = null;

  /**
   * Dictionary Convienence Constructor.
   */
  public SpellDictionaryDichoDisk(File wordList)
    throws FileNotFoundException, IOException {
    super((File) null);
    dictFile = new RandomAccessFile(wordList, "r");
  }

  /**
   * Dictionary Convienence Constructor.
   */
  public SpellDictionaryDichoDisk(File wordList, String encoding)
    throws FileNotFoundException, IOException {
    super((File) null);
    this.encoding = encoding;
    dictFile = new RandomAccessFile(wordList, "r");
  }

  /**
  * Dictionary constructor that uses an aspell phonetic file to
  * build the transformation table.
  */
  public SpellDictionaryDichoDisk(File wordList, File phonetic)
    throws FileNotFoundException, IOException {
    super(phonetic);
    dictFile = new RandomAccessFile(wordList, "r");
  }
  
  /**
  * Dictionary constructor that uses an aspell phonetic file to
  * build the transformation table.
  */
  public SpellDictionaryDichoDisk(File wordList, File phonetic, String encoding)
    throws FileNotFoundException, IOException {
    super(phonetic, encoding);
    this.encoding = encoding;
    dictFile = new RandomAccessFile(wordList, "r");
  }
  
  /**
   * Add a word permanantly to the dictionary (and the dictionary file).
   * <i>not implemented !
   */
  public void addWord(String word) {
    System.err.println("error: addWord is not implemented for SpellDictionaryDichoDisk");
  }

  /**
    * Search the dictionary file for the words corresponding to the code
    * within positions p1 - p2
    */
   private LinkedList dichoFind(String code, long p1, long p2) throws IOException {
     //System.out.println("dichoFind("+code+","+p1+","+p2+")");
     long pm = (p1 + p2) / 2;
    dictFile.seek(pm);
    String l;
    if (encoding == null)
      l = dictFile.readLine();
    else
      l = dictReadLine();
    pm = dictFile.getFilePointer();
    if (encoding == null)
      l = dictFile.readLine();
    else
      l = dictReadLine();
    long pm2 = dictFile.getFilePointer();
    if (pm2 >= p2)
      return(seqFind(code, p1, p2));
    int istar = l.indexOf('*');
    if (istar == -1)
      throw new IOException("bad format: no * !");
    String testcode = l.substring(0, istar);
    int comp = code.compareTo(testcode);
    if (comp < 0)
      return(dichoFind(code, p1, pm-1));
    else if (comp > 0)
      return(dichoFind(code, pm2, p2));
    else {
      LinkedList l1 = dichoFind(code, p1, pm-1);
      LinkedList l2 = dichoFind(code, pm2, p2);
      String word = l.substring(istar+1);
      l1.add(word);
      l1.addAll(l2);
      return(l1);
    }
   }
   
   private LinkedList seqFind(String code, long p1, long p2) throws IOException {
     //System.out.println("seqFind("+code+","+p1+","+p2+")");
     LinkedList list = new LinkedList();
    dictFile.seek(p1);
    while (dictFile.getFilePointer() < p2) {
      String l;
      if (encoding == null)
        l = dictFile.readLine();
      else
        l = dictReadLine();
      int istar = l.indexOf('*');
      if (istar == -1)
        throw new IOException("bad format: no * !");
      String testcode = l.substring(0, istar);
      if (testcode.equals(code)) {
        String word = l.substring(istar+1);
        list.add(word);
      }
    }
    return(list);
   }
   
   /**
     * Read a line of dictFile with a specific encoding
     */
   private String dictReadLine() throws IOException {
     int max = 255;
     byte b=0;
    byte[] buf = new byte[max];
    int i=0;
     try {
       for (; b != '\n' && b != '\r' && i<max-1; i++) {
        b = dictFile.readByte();
         buf[i] = b;
      }
    } catch (EOFException ex) {
    }
    if (i == 0)
      return("");
    String s = new String(buf, 0, i-1, encoding);
    return(s);
   }
   
  /**
   * Returns a list of strings (words) for the code.
   */
  public List getWords(String code) {
     //System.out.println("getWords("+code+")");
    LinkedList list;
    try {
      list = dichoFind(code, 0, dictFile.length()-1);
      //System.out.println(list);
    } catch (IOException ex) {
      System.err.println("IOException: " + ex.getMessage());
      list = new LinkedList();
    }
    return list;
  }

}

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