gt: 	    if (fill() <= 0)
context: /* LineNumberReader.java -- A character input stream which counts line numbers
     Copyright (C) 1998, 1999, 2001, 2003 Free Software Foundation, Inc.
  
  This file is part of GNU Classpath.
  
  GNU Classpath 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, or (at your option)
  any later version.
  
  GNU Classpath 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 GNU Classpath; see the file COPYING.  If not, write to the
  Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  02111-1307 USA.
  
  Linking this library statically or dynamically with other modules is
  making a combined work based on this library.  Thus, the terms and
  conditions of the GNU General Public License cover the whole
  combination.
  
  As a special exception, the copyright holders of this library give you
  permission to link this library with independent modules to produce an
  executable, regardless of the license terms of these independent
  modules, and to copy and distribute the resulting executable under
  terms of your choice, provided that you also meet, for each linked
  independent module, the terms and conditions of the license of that
  module.  An independent module is a module which is not derived from
  or based on this library.  If you modify this library, you may extend
  this exception to your version of the library, but you are not
  obligated to do so.  If you do not wish to do so, delete this
  exception statement from your version. */
  
  package java.io;
  
  /**
   * This class functions like a standard <code>Reader</code> except that it
   * counts line numbers, and canonicalizes newline characters.  As data
   * is read, whenever the char sequences "\r", "\n", or "\r\n" are encountered,
   * the running line count is incremeted by one.  Additionally, the whatever
   * line termination sequence was encountered will be converted to a "\n"
   * char.  Note that this class numbers lines from 0.  When the first
   * line terminator is encountered, the line number is incremented to 1, and
   * so on.  Also note that actual "\r" and "\n" characters are looked for.
   * The system dependent line separator sequence is ignored.
   * <p>
   * This class counts only line termination characters.  If the last line
   * read from the stream does not end in a line termination sequence, it
   * will not be counted as a line.
   *
   * @author Per Bothner <bothner@cygnus.com>
   * @author Aaron M. Renn (arenn@urbanophile.com)
   * @author Guilhem Lavaux <guilhem@kaffe.org>
   * @date December 28, 2003.
   */
  /* Written using "Java Class Libraries", 2nd edition, plus online
   * API docs for JDK 1.2 beta from http://www.javasoft.com.
   * Status:  Believed complete and correct.
   *
   * This implementation has the feature that if '\r' is read, it
   * does not look for a '\n', but immediately returns '\n'.
   * On the next read(), if a '\n' is read, it is skipped.
   * This has the advantage that we do not read (and hang) unnecessarily.
   *
   * This implementation is also minimal in the number of fields it uses.
   */
  public class LineNumberReader extends BufferedReader
  {
    /** The current line number. */
    private int lineNumber;
    /** Whether we already found a new line in the former call. */
    private boolean matchedNewLine;
    /** The saved line number when calling mark() */
    private int savedLineNumber;
  
    /**
      * Create a new <code>LineNumberReader</code> that reads from the
      * specified subordinate <code>Reader</code>.  A default 8K char sized
      * buffer will be used for reads.
      *
      * @param in The subordinate <code>Reader</code> to read from
      */
    public LineNumberReader(Reader in)
    {
      super(in, DEFAULT_BUFFER_SIZE);
    }
  
    /**
      * This method initializes a new <code>LineNumberReader</code> to read
      * from the specified subordinate <code>Reader</code> using the specified
      * read buffer size.
      *
      * @param in The subordinate <code>Reader</code> to read from
      * @param size The buffer size to use for reading
      */
    public LineNumberReader(Reader in, int size)
    {
      super(in, size);
    }
  
    /**
      * This method returns the current line number
      *
      * @return The current line number
      */
    public int getLineNumber()
    {
      return lineNumber;
    }
  
    /**
      * This method sets the current line number to the specified value.
      *
      * @param line_number The new line number
      */
    public void setLineNumber(int lineNumber)
    {
      this.lineNumber = lineNumber;
    }
  
    /**
      * This method marks a position in the input to which the stream can be
      * "reset" char calling the <code>reset()</code> method.  The parameter
      * <code>readlimit</code> is the number of chars that can be read from the
      * stream after setting the mark before the mark becomes invalid.   For
      * example, if <code>mark()</code> is called with a read limit of 10,
      * then when
      * 11 chars of data are read from the stream before the <code>reset()</code>
      * method is called, then the mark is invalid and the stream object
      * instance is not required to remember the mark.
      * <p>
      * In this class, this method will remember the current line number as well
      * as the current position in the stream.  When the <code>reset()</code>
      * method
      * is called, the line number will be restored to the saved line number in
      * addition to the stream position.
      *
      * @param readlimit The number of chars that can be read before the
      * mark becomes invalid
      *
      * @exception IOException If an error occurs
      */
    public void mark(int readLimit) throws IOException
    {
      if (readLimit < 0)
        throw new IllegalArgumentException("Read-ahead limit is negative");
  
      synchronized (lock)
        {
  	// This is basically the same as BufferedReader.mark.
  	// However, if the previous character was a '\r', we need to
  	// save that 'r', in case the next character is a '\n'.
  	if (pos + readLimit > limit)
  	  {
  	    int saveCR = matchedNewLine ? 1 : 0;
  	    char[] old_buffer = buffer;
  	    if (readLimit > limit)
  	      buffer = new char[saveCR + readLimit];
  	    int copy_start = pos - saveCR;
  	    savedLineNumber = lineNumber;
  	    limit -= copy_start;
  	    System.arraycopy(old_buffer, copy_start, buffer, 0, limit);
  	    pos = saveCR;
  	  }
  	markPos = pos;
        }
    }
  
    /**
      * This method resets a stream to the point where the <code>mark()</code>
      * method
      * was called.  Any chars that were read after the mark point was set will
      * be re-read during subsequent reads.
      * <p>
      * In this class, this method will also restore the line number that was
      * current when the <code>mark()</code> method was called.
      *
      * @exception IOException If an error occurs
      */
    public void reset() throws IOException
    {
      synchronized (lock)
        {
  	if (markPos < 0)
  	  throw new IOException("mark never set or invalidated");
  	lineNumber = savedLineNumber;
  	pos = markPos;
  	matchedNewLine = (markPos > 0 && buffer[markPos-1] == '\r');
        }
    }
  
    /**
     * This private method fills the input buffer whatever pos is.
     * Consequently pos should be checked before calling this method.
     *
     * @return the number of bytes actually read from the input stream or
     * -1 if end of stream.
     * @exception IOException If an error occurs.
     */
    private int fill() throws IOException
    {
      if (markPos >= 0 && limit == buffer.length)
        markPos = -1;
      if (markPos < 0)
        pos = limit = 0;
      int count = in.read(buffer, limit, buffer.length - limit);
      if (count <= 0)
        return -1;
      limit += count;
  
      return count;
    }
  
    /**
      * This method reads an unsigned char from the input stream and returns it
      * as an int in the range of 0-65535.  This method will return -1 if the
      * end of the stream has been reached.
      * <p>
      * Note that if a line termination sequence is encountered (ie, "\r",
      * "\n", or "\r\n") then that line termination sequence is converted to
      * a single "\n" value which is returned from this method.  This means
      * that it is possible this method reads two chars from the subordinate
      * stream instead of just one.
      * <p>
      * Note that this method will block until a char of data is available
      * to be read.
      *
      * @return The char read or -1 if end of stream
      *
      * @exception IOException If an error occurs
      */
    public int read() throws IOException
    {
      synchronized (lock)
        {
  	skipRedundantLF();
  	if (pos >= limit && fill() < 0)
  	  return -1;
  	char ch = buffer[pos++];
  	
  	if ((matchedNewLine = (ch == '\r')) || ch == '\n')
  	  {
  	    lineNumber++;
  	    return '\n';
  	  }
  	matchedNewLine = false;
  	return (int) ch;
        }
    }
  
    /**
      * This method reads chars from a stream and stores them into a caller
      * supplied buffer.  It starts storing data at index <code>offset</code> into   
      * the buffer and attemps to read <code>len</code> chars.  This method can
      * return before reading the number of chars requested.  The actual number
      * of chars read is returned as an int.  A -1 is returned to indicated the
      * end of the stream.
      * <p>
      * This method will block until some data can be read.
      * <p>
      * Note that if a line termination sequence is encountered (ie, "\r",
      * "\n", or "\r\n") then that line termination sequence is converted to
      * a single "\n" value which is stored in the buffer.  Only a single
      * char is counted towards the number of chars read in this case.
      *
      * @param buf The array into which the chars read should be stored
      * @param offset The offset into the array to start storing chars
      * @param len The requested number of chars to read
      *
      * @return The actual number of chars read, or -1 if end of stream
      *
      * @exception IOException If an error occurs.
      * @exception NullPointerException If buf is null (in any case).
      * @exception IndexOutOfBoundsException If buffer parameters (offset and
      * count) lies outside of the buffer capacity.
      */
    public int read(char[] buf, int offset, int count) throws IOException
    {
      if (buf == null)
        throw new NullPointerException();
  
      if (offset + count > buf.length || offset < 0)
        throw new IndexOutOfBoundsException();
  
      if (count <= 0)
        {
  	if (count < 0)
  	  throw new IndexOutOfBoundsException();
  	return 0;
        }
  
      synchronized (lock)
        {
  	if (pos >= limit && fill() < 0)
  	  return -1;
  	
  	int start_offset = offset;
  	boolean matched = matchedNewLine;
  	
  	while (count-- > 0 && pos < limit)
  	  {
  	    char ch = buffer[pos++];
  	    if (ch == '\r')
  	      {
  		lineNumber++;
  		matched = true;
  	      }
  	    else if (ch == '\n' && !matched)
  	      lineNumber++;
  	    else
  	      matched = false;
  
  	    buf[offset++] = ch;
  	  }
  
  	matchedNewLine = matched;
  	return offset - start_offset;
        }
    }
  
    private void skipRedundantLF() throws IOException
    {
      if (pos > 0 && matchedNewLine)
        {
  	if (pos < limit)
  	  { // fast case
  	    if (buffer[pos] == '\n')
  	      pos++;
  	  }
  	else
  	  { // check whether the next buffer begins with '\n'.
  	    // in that case kill the '\n'.
  