{
        if ( n < 0L )
        {
            throw new IllegalArgumentException( "skip value is negative" );
        }

        for ( long i = 0; i < n; i++ )
        {
            if ( read() == -1 )
            {
                return i;
            }
        }
        return n;
    }

    /**
     * Reads characters into a portion of an array. This method will block until some input is available, an I/O error
     * occurs, or the end of the stream is reached.
     *
     * @param cbuf Destination buffer to write characters to. Must not be <code>null</code>.
     * @param off Offset at which to start storing characters.
     * @param len Maximum number of characters to read.
     * @return the number of characters read, or -1 if the end of the stream has been reached
     * @throws IOException If an I/O error occurs
     */
    @Override
    public int read( char cbuf[], int off, int len )
        throws IOException
    {
        for ( int i = 0; i < len; i++ )
        {
            int ch = read();
            if ( ch == -1 )
            {
                if ( i == 0 )
                {
                    return -1;
                }
                else
                {
                    return i;
                }
            }
            cbuf[off + i] = (char) ch;
        }
        return len;
    }

    /**
     * Returns the next character in the filtered stream, replacing tokens from the original stream.
     *
     * @return the next character in the resulting stream, or -1 if the end of the resulting stream has been reached
     * @throws IOException if the underlying stream throws an IOException during reading
     */
    @Override
    public int read()
        throws IOException
    {
        if ( replaceIndex > 0 )
        {
            return replaceData.charAt( replaceData.length() - ( replaceIndex-- ) );
        }
        if ( eof )
        {
            return -1;
        }

        if ( !foundToken )
        {

            in.reset();
            return in.read();

        }

        // we're committed, find the end token, EOL or EOF

        key.append( beginToken );
        in.reset();
        in.skip( beginToken.length() );
        ch = in.read();

        int endTokenSize = endToken.length();
        int end = endTokenSize;
        do
        {
            if ( ch == -1 )
            {
                break;
            }
            else if ( ch == '\n' && !supportMultiLineFiltering )
            {
                // EOL
                key.append( (char) ch );
                break;
            }

            key.append( (char) ch );

            if ( ch == this.endToken.charAt( endTokenSize - end ) )
            {
                end--;
                if ( end == 0 )
                {
                    break;
                }
            }
            else
            {
                end = endTokenSize;
            }

            ch = in.read();
        }
        while ( true );

        in.mark( markLength );

        int ch = in.read();
        if ( ch == -1 || ( ch == '\n' && !supportMultiLineFiltering ) )
        {
            return ch;
        }

        boolean inEscape = useEscape && ch == getEscapeString().charAt( 0 );

        StringBuilder key = new StringBuilder();

        // have we found an escape string?
        if ( inEscape )
        {
            for ( int i = 0; i < getEscapeString().length(); i++ )
            {
                key.append( (char) ch );

                if ( ch != getEscapeString().charAt( i ) || ch == -1 || ( ch == '\n' && !supportMultiLineFiltering ) )
                {
                    // mismatch, EOF or EOL, no escape string here
                    in.reset();
                    inEscape = false;
                    key.setLength( 0 );
                    break;
                }

                ch = in.read();
            }

        }