The R Project SVN R

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

  Project: 

  JAVA Source file for the class IndexStream

  COPYRIGHT (C), 1998, Thomas Baier

  ALL RIGHTS RESERVED.

  $Source: /scratch/CVS-ARCHIVE/R/doc/html/search/IndexStream.java,v $

  $Revision: 1.1 $

  $Date: 1998/05/15 10:38:09 $

  $Author: leisch $

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

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

import java.util.*;

import java.applet.*;

import java.awt.*;

import java.net.*;

import java.io.*;

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

                          Interface of class IndexStream

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

/*------------------------------------------------------------------------------

  CLASS:    IndexStream

  SUPER:    Object

  CONF. TO: 

  PURPOSE:  reading and parsing a stream of multiple index entries, also handles

            some keywords, e.g. include of other streams, provides a context

            for environment space

  NOTES:    

  HISTORY:  98-05-08: created

------------------------------------------------------------------------------*/

public class IndexStream extends Object

{

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

                                Public methods

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

  /*----------------------------------------------------------------------------

    INTERFACE: 

    PURPOSE:   default constructor

    NOTES:    

    PARAMS:   

    THROWS:    

    RETURNS:   void

    HISTORY:   98-05-08: created

  ----------------------------------------------------------------------------*/

  public IndexStream (URL inputURL)

  {

    // init the instance data

    iInputURL = inputURL;

    iIndex = 0;

    iData = new Vector ();

    // read the index data from the stream

    readStream ();

  }

  /*----------------------------------------------------------------------------

    INTERFACE: 

    PURPOSE:   

    NOTES:     

    PARAMS:    

    THROWS:    

    RETURNS:   void

    HISTORY:   98-05-08: created

  ----------------------------------------------------------------------------*/

  public Value popEntry ()

  {

    if (iIndex < 0) {

      iIndex = 0;

    }

    if (iIndex >= iData.size ()) {

      return null;

    }

    iIndex++;

    return (Value) iData.elementAt (iIndex - 1);

  }

  /*----------------------------------------------------------------------------

    INTERFACE: 

    PURPOSE:   

    NOTES:     

    PARAMS:    

    THROWS:    

    RETURNS:   void

    HISTORY:   98-05-08: created

  ----------------------------------------------------------------------------*/

  public void pushEntry (Value anEntry)

  {

    if (iIndex < 0) {

      iIndex = 0;

    }

    if (iIndex >= iData.size ()) {

      iIndex = iData.size ();

    }

    iData.insertElementAt (anEntry,iIndex);

    return;

  }

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

                              Protected methods

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

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

                               Private methods

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

  /*----------------------------------------------------------------------------

    INTERFACE: 

    PURPOSE:   

    NOTES:     

    PARAMS:    

    THROWS:    

    RETURNS:   void

    HISTORY:   98-05-08: created

  ----------------------------------------------------------------------------*/

  public void readStream ()

  {

    try {

      InputStream stream = iInputURL.openStream ();

      DataInputStream is = new DataInputStream (stream);

      // now read and parse all lines of the file.

      String line = is.readLine ();

      while (line != null) {

	parseLine (line);

	line = is.readLine ();

      }

      is.close ();

      stream.close ();

    } catch (IOException exc) {

      // there's some error, ignore it!

    }

    return;

  }

  /*----------------------------------------------------------------------------

    INTERFACE: 

    PURPOSE:   

    NOTES:     

    PARAMS:    

    THROWS:    

    RETURNS:   void

    HISTORY:   98-05-08: created

  ----------------------------------------------------------------------------*/

  public void parseLine (String line)

  {

    // if the line is empty, we'll ignore it

    if (line.length () == 0) {

      return;

    }

    // if the line starts with #, its a comment

    if (line.startsWith ("#")) {

      return;

    }

    // if the line starts with whitespace, its a continuation

    if (line.startsWith ("\t")

	|| line.startsWith (" ")) {

      parseContinuation (line);

    }

    // else, it must be a key/value pair

    parseKeyValue (line);

    return;

  }

  /*----------------------------------------------------------------------------

    INTERFACE: 

    PURPOSE:   

    NOTES:     

    PARAMS:    

    THROWS:    

    RETURNS:   void

    HISTORY:   98-05-08: created

  ----------------------------------------------------------------------------*/

  public void parseContinuation (String line)

  {

    // if there's no key/value pair in the list, ignore it

    if (iData.size () < 1) {

      return;

    }

    // we'll trim whitespace

    String value = line.trim ();

    // get the last object

    Value lastObject = (Value) iData.lastElement ();

    // modify it

    lastObject.addToValue (value);

    return;

  }

  /*----------------------------------------------------------------------------

    INTERFACE: 

    PURPOSE:   

    NOTES:     for safety, we'll ignore everything not ok

    PARAMS:    

    THROWS:    

    RETURNS:   void

    HISTORY:   98-05-08: created

  ----------------------------------------------------------------------------*/

  public void parseKeyValue (String line)

  {

    int index = line.indexOf (":");

    // not found or : as first character

    if (index < 1) {

      return;

    }

    // everything from the start to the : is a key

    String key = line.substring (0,index);

    String value = null;

    // value starts after :, trim whitespace

    try {

      value = line.substring (index + 1).trim ();

    } catch (IndexOutOfBoundsException exc) {

      line = "";

    }

    // create the value and add it to the vector

    Value newValue = new Value (key,value);

    iData.addElement (newValue);

    return;

  }

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

                             Instance Variables

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

  private URL    iInputURL;

  private int    iIndex;

  private Vector iData;

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

                                Static Data

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

}

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

  HISTORY:

  $Log: IndexStream.java,v $

  Revision 1.1  1998/05/15 10:38:09  leisch

  New: Search Engine

  Revision 1.1  1998/05/10 02:43:37  baier

  Initial revision

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

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