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/*==============================================================================

  Project: Simple JAVA Search Engine for Keyword Search
  
  JAVA Source file for the class SearchEngine
  
  COPYRIGHT (C), 1998, Thomas Baier

 *  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 2 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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
  $Source: /scratch/CVS-ARCHIVE/R/doc/html/search/SearchEngine.java,v $
  
  $Revision: 1.4 $

  $Date: 1999/11/18 12:30:58 $
  
  $Author: leisch $

==============================================================================*/


/* -------------------------------- Imports --------------------------------- */

import java.applet.*;
import java.awt.*;
import java.net.*;
import java.io.*;
import java.util.*;


/*==============================================================================
                          Interface of class SearchEngine
==============================================================================*/

/*------------------------------------------------------------------------------
  CLASS:    SearchEngine
  SUPER:    Applet
  CONF. TO: 
  PURPOSE:  
  NOTES:    

  HISTORY:  98-04-26: created 
            98-05-15: new member for search mode
------------------------------------------------------------------------------*/
public class SearchEngine extends Applet
{
  /*============================================================================
                                Public methods
  ============================================================================*/

  /*----------------------------------------------------------------------------
    INTERFACE: 
    PURPOSE:   default constructor
          
    NOTES:     
  
    PARAMS:    
    THROWS:    
    RETURNS:   void
  
    HISTORY:   98-04-26: created
               98-05-03: now reads the index file
           98-05-15: init new member
  ----------------------------------------------------------------------------*/
  public SearchEngine ()
  {
    iIndexTable = null;
    iSearchTerm = null;
    iSearchMode = 0;

    Tracer.write ("SearchEngine initializing\n");

    return;
  }


  /*----------------------------------------------------------------------------
    INTERFACE: 
    PURPOSE:   return general information about the applet
           
    NOTES:     
  
    PARAMS:    
    THROWS:    
    RETURNS:   String: the information
  
    HISTORY:   98-04-26: created
  ----------------------------------------------------------------------------*/
  public String getAppletInfo ()
  {
    return "Name: SearchEngine\r\n" +
      "Author: Thomas Baier\r\n" +
      "(C) 1998 Thomas Baier, ALL RIGHTS RESERVED";
  }


  /*----------------------------------------------------------------------------
    INTERFACE: 
    PURPOSE:   perform initialization
          
    NOTES:     creates the controls
  
    PARAMS:    
    THROWS:    
    RETURNS:   void
  
    HISTORY:   98-04-26: created
               98-05-03: now a do-nothing
  ----------------------------------------------------------------------------*/
  public void init ()
  {
    resize(640, 240);

    // get the name of the index file
    String indexName = getParameter (cIndexKeyword);
    String searchTerm = getParameter (cSearchKeyword);

    Tracer.write ("Index file is \"" + indexName + "\"\n");
    Tracer.write ("Search term is \"" + searchTerm + "\"\n");

    // use a default index file if none specified
    if (indexName == null) {
      indexName = cIndexFile;
    }

    iSearchTerm = searchTerm;

    /*
     * examine the URL to get the search term...
     *
     * if the URL ends with ?SEARCHTERM=xxxxx we know, xxxxx is the search term
     */
    {
      URL url = getDocumentBase ();
      String urlString = url.toString ();
      int index = urlString.indexOf ("?" + cSearchKeyword + "=");

      Tracer.write ("URL is \"" + urlString + "\"\n");

      // if found, take the rest as the search string
      if (index >= 0) {
    iSearchTerm =
      urlString.substring (index + 2 + cSearchKeyword.length ());
    Tracer.write ("found search term \"" + iSearchTerm + "\" in URL\n");
      }
    }

    readIndexFile (indexName);

    return;
  }


  /*----------------------------------------------------------------------------
    INTERFACE: 
    PURPOSE:   perform "destructor" code
          
    NOTES:     not required here
  
    PARAMS:    
    THROWS:    
    RETURNS:   void
  
    HISTORY:   98-04-26: created
  ----------------------------------------------------------------------------*/
  public void destroy ()
  {
    return;
  }


  /*----------------------------------------------------------------------------
    INTERFACE: 
    PURPOSE:   perform painting of the applet
          
    NOTES:     not required for our applet, controls do everything
  
    PARAMS:    Graphics g: the graphics context to draw on
    THROWS:    
    RETURNS:   void
  
    HISTORY:   98-04-26: created
  ----------------------------------------------------------------------------*/
  public void paint (Graphics g)
  {
  
    return;
  }


  /*----------------------------------------------------------------------------
    INTERFACE: 
    PURPOSE:   perform startup code everytime visiting the applet
          
    NOTES:     
  
    PARAMS:    
    THROWS:    
    RETURNS:   void
  
    HISTORY:   98-04-26: created
               98-05-10: start the tracer
  ----------------------------------------------------------------------------*/
  public void start ()
  {
    Tracer.start ();
    return;
  }


  /*----------------------------------------------------------------------------
    INTERFACE: 
    PURPOSE:   perform cleanup evertime the applet "loses" the focus
          
    NOTES:     
  
    PARAMS:    
    THROWS:    
    RETURNS:   void
  
    HISTORY:   98-04-26: created
               98-05-10: stop the tracer
  ----------------------------------------------------------------------------*/
  public void stop ()
  {
    Tracer.stop ();
    return;
  }


  /*----------------------------------------------------------------------------
    INTERFACE: 
    PURPOSE:   perform the search and return the search results as a string
          
    NOTES:     
  
    PARAMS:    
    THROWS:    
    RETURNS:   void
  
    HISTORY:   98-05-03: created
               98-05-08: new format for output
           98-05-09: added trace
           98-05-10: now a front-end for search()
           98-05-15: new parameter for search-mode
  ----------------------------------------------------------------------------*/
  public String search (String key,boolean searchTitles)
  {
    iSearchTerm = key;

    if (searchTitles) {
      iSearchMode = IndexTable.cSearchDescription;
    } else {
      iSearchMode = 0;
    }

    return internalSearch ();
  }


  /*----------------------------------------------------------------------------
    INTERFACE: 
    PURPOSE:   perform the search (back-end)
          
    NOTES:     
  
    PARAMS:    
    THROWS:    
    RETURNS:   void
  
    HISTORY:   98-05-10: created
               98-05-15: forward search-mode
  ----------------------------------------------------------------------------*/
  public String internalSearch ()
  {
    Tracer.write ("Search for \"" + iSearchTerm + "\" started");

    Vector foundItems = null;

    if (iSearchTerm != null) {
      foundItems = iIndexTable.search (iSearchTerm,iSearchMode);
    } else {
      foundItems = null;
    }

    String result = null;

    // if nothing found, return a special string
    if (foundItems == null) {
      result = "No matches for <b>\"" + 
    iSearchTerm +
    "\"</b> have been found!<hr>";
    } else {
      Enumeration cursor = foundItems.elements ();

      result =
    "The search string was <b>\"" +
    iSearchTerm +
    "</b>\"" +
    "<hr>" +
    "<dl>";

      while (cursor.hasMoreElements ()) {
    IndexEntry entry = (IndexEntry) cursor.nextElement ();

    /*
     * the format for every entry is
     *
     * title
     *   description
     */

    result +=
      "<dt><a href=\"" +
      entry.getURL () +
      "\">" +
      entry.getTitle () +
      "</a></dt>\n";
    result += "<dd>" + entry.getDescription () + "</dd>\n";
      }

      result += "</dl>";
    }

    return result;
  }


  /*============================================================================
                              Protected methods
  ============================================================================*/

  /*============================================================================
                               Private methods
  ============================================================================*/

  /*----------------------------------------------------------------------------
    INTERFACE: 
    PURPOSE:   read the index file
          
    NOTES:     
  
    PARAMS:    
    THROWS:    
    RETURNS:   void
  
    HISTORY:   98-04-26: created
               98-05-08: now use an IndexStream
           98-05-10: also use prefix and suffix, build URL from first key
           98-05-19: add "Alias:" entry to keywords
           98-06-01: bugfix: don't null the variables
  ----------------------------------------------------------------------------*/
  private void readIndexFile (String idxFile)
  {
    // create the index table
    iIndexTable = new IndexTable ();

    URL baseURL = getCodeBase ();

    // get the index file and parse its contents
    try {
      URL idxFileURL = new URL (baseURL,idxFile);

      // get an IndexStream object for ease of parsing
      IndexStream idxStream = new IndexStream (idxFileURL);

      // now start parsing...
      
      /*
       * An entry consists of a title, keywords, an URL and a description.
       * everything else is ignored. Every entry starts with the keyword
       * "Entry" (case is ignored)
       *
       * must-have entries are "Entry" and "Keywords"
       *
       * 98-06-01: bugfix: don't null the variables
       */
      String entry = "";
      String keywords = "";
      String url = "";
      String description = "";
      String prefix = "";
      String suffix = "";

      Value value = idxStream.popEntry ();

      while (value != null) {
    // parse the value now
    if (value.getKey ().equalsIgnoreCase ("entry")) {
      // if a new entry is about to start, add the current one
      addEntry (entry,keywords,description,url,prefix,suffix);

      entry = value.getValue ();
      keywords = "";
      url = "";
      description = "";
    } else if (value.getKey ().equalsIgnoreCase ("keywords")) {
      keywords += value.getValue ();
    } else if (value.getKey ().equalsIgnoreCase ("url")) {
      // use prefix and suffix
      url = prefix + value.getValue () + suffix;
    } else if (value.getKey ().equalsIgnoreCase ("description")) {
      description = value.getValue ();
    } else if (value.getKey ().equalsIgnoreCase ("prefix")) {
      prefix = value.getValue ();
      Tracer.write ("using new URL prefix \"" + prefix + "\"\n");
    } else if (value.getKey ().equalsIgnoreCase ("suffix")) {
      suffix = value.getValue ();
      Tracer.write ("using new URL suffix \"" + suffix + "\"\n");
    } else if (value.getKey ().equalsIgnoreCase ("aliases")) {
      keywords += value.getValue ();
    }
    value = idxStream.popEntry ();
      }

      // the final entry just read
      addEntry (entry,keywords,description,url,prefix,suffix);
    } catch (MalformedURLException exc) {
      // an error occured while reading...
    }

    return;
  }

  
  /*----------------------------------------------------------------------------
    INTERFACE: 
    PURPOSE:   
          
    NOTES:     
  
    PARAMS:    
    THROWS:    
    RETURNS:   void
  
    HISTORY:   98-05-10: created
               98-06-01: value is "", not null if empty
  ----------------------------------------------------------------------------*/
  private void addEntry (String entry,String keywords,
             String description,String url,
             String prefix,String suffix)
  {
    // the entry must be set
    if (entry.length () == 0) {
      return;
    }

    // the keywords must be set, else ignore it
    if (keywords.length () != 0) {
      if (url.length () == 0) {
    // if the URL is empty, construct one following the rule:
    // URL = prefix + first keyword + suffix
    int endOfFirstKeyword = keywords.indexOf (" ");
    
    // because we have trimmed the string, the first character must
    // not be a blank
    if (endOfFirstKeyword >= 0) {
      url = keywords.substring (0,endOfFirstKeyword);
      Tracer.write ("constructing URL, keywords=\"" +
            keywords + "\"" +
            "using \"" + 
            url +
            "\" (results in \"" +
            prefix + url + suffix + "\")\n");
    } else {
      // just a single keyword
      url = keywords;
      Tracer.write ("constructing URL, using keyword \"" + 
            url +
            "\" (results in \"" +
            prefix + url + suffix + "\")\n");
    }
    // add prefix and suffix
    url = prefix + url + suffix;
      }
      IndexEntry idxEntry =
    new IndexEntry (entry,keywords,description,url);
      iIndexTable.addElement (idxEntry);
    }

    return;
  }


  /*============================================================================
                             Instance Variables
  ============================================================================*/
  private IndexTable iIndexTable;
  private String     iSearchTerm;
  private int        iSearchMode;


  /*============================================================================
                                Static Data
  ============================================================================*/

  private static final String cIndexFile = "index.txt";
  private static final String cIndexKeyword = "INDEXFILE";
  private static final String cSearchKeyword = "SEARCHTERM";
}

/*==============================================================================

  HISTORY:
  
  $Log: SearchEngine.java,v $
  Revision 1.4  1999/11/18 12:30:58  leisch
  use seperate aliases field

  Revision 1.3  1999/08/10 09:56:03  ripley
  change FSF address in copyrights
  add some copyrights in src/gnome and elsewhere

  Revision 1.2  1999/03/04 17:15:18  leisch
  various bugfixes

  Revision 1.1.4.1  1999/03/02 15:19:57  leisch
  search used only kewords, no titles

  Revision 1.6  1998/05/19 20:23:13  baier
  added alias support

  Revision 1.5  1998/05/15 22:10:05  baier
  allow searching in description, fix bug in results list

  Revision 1.4  1998/05/10 22:56:53  baier
  internal search function, parameter expansion

  Revision 1.3  1998/05/10 02:44:32  baier
  traces, output in HTML via JavaScript, new index generation

  Revision 1.2  1998/04/26 22:36:34  baier
  documentation changes



  Revision 1.1  1998/04/26 21:32:54  baier
  Initial revision


==============================================================================*/


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