Classes written in PHP to set filtering and retain attributes

/**
 @ Class for setting and retaining attributes
 @ class cleanHtml
 @ link: bbs.it-home.org
 @ date: 2013/2/28
*/
    function reg_escape( $str )
    {
        $conversions = array( "^" => "^", "[" => "[", "." => ".", "$" => "$", "{" => "{", "*" => "*", "(" => "(", "\" => "\\", "/" => "/", "+" => "+", ")" => ")", "|" => "|", "?" => "?", "<" => "<", ">" => ">" );
        return strtr( $str, $conversions );
    }

    /**
    * Strip attribute Class
    * Remove attributes from XML elements
    * @author David (semlabs.co.uk)
    * @version 0.2.1
*/

    class cleanHtml{
        public $str         = '';
        public $allow       = array();
        public $exceptions  = array();
        public $ignore      = array();

        public function strip( $str )
        {
            $this->str = $str;

            if( is_string( $str ) && strlen( $str ) > 0 )
            {
                $res = $this->findElements();
                if( is_string( $res ) )
                    return $res;
                $nodes = $this->findAttributes( $res );
                $this->removeAttributes( $nodes );
            }

            return $this->str;
        }

        private function findElements()
        {

            # Create an array of elements with attributes
            $nodes = array();
            preg_match_all( "/<([^ !/>n]+)([^>]*)>/i", $this->str, $elements );
            foreach( $elements[1] as $el_key => $element )
            {
                if( $elements[2][$el_key] )
                {
                    $literal = $elements[0][$el_key];
                    $element_name = $elements[1][$el_key];
                    $attributes = $elements[2][$el_key];
                    if( is_array( $this->ignore ) && !in_array( $element_name, $this->ignore ) )
                        $nodes[] = array( 'literal' => $literal, 'name' => $element_name, 'attributes' => $attributes );
                }
            }

            # Return the XML if there were no attributes to remove
            if( !$nodes[0] )
                return $this->str;
            else
                return $nodes;
        }

        private function findAttributes( $nodes )
        {

            # Extract attributes
            foreach( $nodes as &$node )
            {
                preg_match_all( "/([^ =]+)s*=s*["|']{0,1}([^"']*)["|']{0,1}/i", $node['attributes'], $attributes );
                if( $attributes[1] )
                {
                    foreach( $attributes[1] as $att_key => $att )
                    {
                        $literal = $attributes[0][$att_key];
                        $attribute_name = $attributes[1][$att_key];
                        $value = $attributes[2][$att_key];
                        $atts[] = array( 'literal' => $literal, 'name' => $attribute_name, 'value' => $value );
                    }
                }
                else
                    $node['attributes'] = null;

                $node['attributes'] = $atts;
                unset( $atts );
            }

            return $nodes;
        }

        private function removeAttributes( $nodes )
        {

            # Remove unwanted attributes
            foreach( $nodes as $node )
            {

                # Check if node has any attributes to be kept
                $node_name = $node['name'];
                $new_attributes = '';
                if( is_array( $node['attributes'] ) )
                {
                    foreach( $node['attributes'] as $attribute )
                    {
                        if( ( is_array( $this->allow ) && in_array( $attribute['name'], $this->allow ) ) || $this->isException( $node_name, $attribute['name'], $this->exceptions ) )
                            $new_attributes = $this->createAttributes( $new_attributes, $attribute['name'], $attribute['value'] );
                    }
                }
                $replacement = ( $new_attributes ) ? "<$node_name $new_attributes>" : "<$node_name>";
                $this->str = preg_replace( '/'. reg_escape( $node['literal'] ) .'/', $replacement, $this->str );
            }
        }

        private function isException( $element_name, $attribute_name, $exceptions )
        {
            if( array_key_exists($element_name, $this->exceptions) )
            {
                if( in_array( $attribute_name, $this->exceptions[$element_name] ) )
                    return true;
            }

            return false;
        }

        private function createAttributes( $new_attributes, $name, $value )
        {
            if( $new_attributes )
                $new_attributes .= " ";
            $new_attributes .= "$name="$value"";

            return $new_attributes;
        }
    }
?>

调用实例：

$str = 'Here is some sample html that is   getting broken    ';

$sa = new cleanHtml;
$sa->allow = array( 'id' );

$sa->exceptions = array(
    'img' => array( 'src', 'alt' ),
    'a' => array( 'href', 'title' ),
    'iframe'=>array('src','frameborder'),
);

echo $str = $sa->strip( $str );
?>