BBCODE Problem

class BBCode {


    // Plugin initialization
    function BBCode() {
        // This version only supports WP 2.5+ (learn to upgrade please!)
        if ( !function_exists('add_shortcode') ) return;


        // Register the shortcodes
        add_shortcode( 'b' , array(&$this, 'shortcode_bold') );
        add_shortcode( 'B' , array(&$this, 'shortcode_bold') );
        add_shortcode( 'i' , array(&$this, 'shortcode_italics') );
        add_shortcode( 'I' , array(&$this, 'shortcode_italics') );
        add_shortcode( 'u' , array(&$this, 'shortcode_underline') );
        add_shortcode( 'U' , array(&$this, 'shortcode_underline') );
        add_shortcode( 'url' , array(&$this, 'shortcode_url') );
        add_shortcode( 'URL' , array(&$this, 'shortcode_url') );
        add_shortcode( 'img' , array(&$this, 'shortcode_image') );
        add_shortcode( 'IMG' , array(&$this, 'shortcode_image') );
        add_shortcode( 'quote' , array(&$this, 'shortcode_quote') );
        add_shortcode( 'QUOTE' , array(&$this, 'shortcode_quote') );
    }




    // No-name attribute fixing
    function attributefix( $atts = array() ) {
        if ( empty($atts[0]) ) return $atts;


        if ( 0 !== preg_match( '#=("|\')(.*?)("|\')#', $atts[0], $match ) )
            $atts[0] = $match[2];


        return $atts;
    }




    // Bold shortcode
    function shortcode_bold( $atts = array(), $content = NULL ) {
        if ( NULL === $content ) return '';


        return '<strong>' . do_shortcode( $content ) . '</strong>';
    }




    // Italics shortcode
    function shortcode_italics( $atts = array(), $content = NULL ) {
        if ( NULL === $content ) return '';


        return '<em>' . do_shortcode( $content ) . '</em>';
    }




    // Italics shortcode
    function shortcode_underline( $atts = array(), $content = NULL ) {
        if ( NULL === $content ) return '';


        return '<span style="text-decoration:underline">' . do_shortcode( $content ) . '</span>';
    }




    // Italics shortcode
    function shortcode_url( $atts = array(), $content = NULL ) {
        $atts = $this->attributefix( $atts );


        // [URL="http://www.google.com/"]Google[/URL]
        if ( isset($atts[0]) ) {
            $url = $atts[0];
            $text = $content;
        }
        // [URL]http://www.google.com/[/URL]
        else {
            $url = $text = $content;
        }


        if ( empty($url) ) return '';
        if ( empty($text) ) $text = $url;


        return '<a href="' . $url . '">' . do_shortcode( $text ) . '</a>';
    }




    // Italics shortcode
    function shortcode_image( $atts = array(), $content = NULL ) {
        if ( NULL === $content ) return '';


        return '<img src="' . $content . '" alt="" />';
    }




    // Italics shortcode
    function shortcode_quote( $atts = array(), $content = NULL ) {
        if ( NULL === $content ) return '';


        return '<blockquote>' . do_shortcode( $content ) . '</blockquote>';
    }
}


// Start this plugin once all other plugins are fully loaded
add_action( 'plugins_loaded', create_function( '', 'global $BBCode; $BBCode = new BBCode();' ) );