public ASCII_CharStream(Reader dstream,
    int startline,
    int startcolumn) 
{
     this(dstream, startline, startcolumn, 4096);
}

 public ASCII_CharStream(InputStream dstream,
    int startline,
    int startcolumn) 
{
     this(dstream, startline, startcolumn, 4096);
}

 public ASCII_CharStream(Reader dstream,
    int startline,
    int startcolumn,
    int buffersize) 
{
    inputStream = dstream;
    line = startline;
    column = startcolumn - 1;
    available = bufsize = buffersize;
    buffer = new char[buffersize];
    bufline = new int[buffersize];
    bufcolumn = new int[buffersize];
}

 public ASCII_CharStream(InputStream dstream,
    int startline,
    int startcolumn,
    int buffersize) 
{
     this(new java.io.InputStreamReader(dstream), startline, startcolumn, 4096);
}

 public final char BeginToken() throws IOException 
{
     tokenBegin = -1;
     char c = readChar();
     tokenBegin = bufpos;
     return c;
}

 public  void Done() 
{
     buffer = null;
     bufline = null;
     bufcolumn = null;
}

 public final String GetImage() 
{
     if (bufpos  >= tokenBegin)
        return new String(buffer, tokenBegin, bufpos - tokenBegin + 1);
     else
        return new String(buffer, tokenBegin, bufsize - tokenBegin) +
                              new String(buffer, 0, bufpos + 1);
}

 public final char[] GetSuffix(int len) 
{
     char[] ret = new char[len];
     if ((bufpos + 1)  >= len)
        System.arraycopy(buffer, bufpos - len + 1, ret, 0, len);
     else
     {
        System.arraycopy(buffer, bufsize - (len - bufpos - 1), ret, 0,
                                                          len - bufpos - 1);
        System.arraycopy(buffer, 0, ret, len - bufpos - 1, bufpos + 1);
     }
     return ret;
}

 public  void ReInit(Reader dstream,
    int startline,
    int startcolumn) 
{
     ReInit(dstream, startline, startcolumn, 4096);
}

 public  void ReInit(InputStream dstream,
    int startline,
    int startcolumn) 
{
     ReInit(dstream, startline, startcolumn, 4096);
}

 public  void ReInit(Reader dstream,
    int startline,
    int startcolumn,
    int buffersize) 
{
    inputStream = dstream;
    line = startline;
    column = startcolumn - 1;
    if (buffer == null || buffersize != buffer.length)
    {
      available = bufsize = buffersize;
      buffer = new char[buffersize];
      bufline = new int[buffersize];
      bufcolumn = new int[buffersize];
    }
    prevCharIsLF = prevCharIsCR = false;
    tokenBegin = inBuf = maxNextCharInd = 0;
    bufpos = -1;
}

 public  void ReInit(InputStream dstream,
    int startline,
    int startcolumn,
    int buffersize) 
{
     ReInit(new java.io.InputStreamReader(dstream), startline, startcolumn, 4096);
}

 public  void adjustBeginLineColumn(int newLine,
    int newCol) 
{
     int start = tokenBegin;
     int len;
     if (bufpos  >= tokenBegin)
     {
        len = bufpos - tokenBegin + inBuf + 1;
     }
     else
     {
        len = bufsize - tokenBegin + bufpos + 1 + inBuf;
     }
     int i = 0, j = 0, k = 0;
     int nextColDiff = 0, columnDiff = 0;
     while (i <  len &&
            bufline[j = start % bufsize] == bufline[k = ++start % bufsize])
     {
        bufline[j] = newLine;
        nextColDiff = columnDiff + bufcolumn[k] - bufcolumn[j];
        bufcolumn[j] = newCol + columnDiff;
        columnDiff = nextColDiff;
        i++;
     } 
     if (i <  len)
     {
        bufline[j] = newLine++;
        bufcolumn[j] = newCol + columnDiff;
        while (i++ <  len)
        {
           if (bufline[j = start % bufsize] != bufline[++start % bufsize])
              bufline[j] = newLine++;
           else
              bufline[j] = newLine;
        }
     }
     line = bufline[j];
     column = bufcolumn[j];
}

Method to adjust line and column numbers for the start of a token.

 public final  void backup(int amount) 
{
    inBuf += amount;
    if ((bufpos -= amount) <  0)
       bufpos += bufsize;
}

 public final int getBeginColumn() 
{
     return bufcolumn[tokenBegin];
}

 public final int getBeginLine() 
{
     return bufline[tokenBegin];
}

 public final int getColumn() 
{
     return bufcolumn[bufpos];
}

 public final int getEndColumn() 
{
     return bufcolumn[bufpos];
}

 public final int getEndLine() 
{
     return bufline[bufpos];
}

 public final int getLine() 
{
     return bufline[bufpos];
}

 public final char readChar() throws IOException 
{
     if (inBuf  > 0)
     {
        --inBuf;
        return (char)((char)0xff & buffer[(bufpos == bufsize - 1) ? (bufpos = 0) : ++bufpos]);
     }
     if (++bufpos  >= maxNextCharInd)
        FillBuff();
     char c = (char)((char)0xff & buffer[bufpos]);
     UpdateLineColumn(c);
     return (c);
}