php写的设置过滤及保留属性的类

<?php
/**
  @ 设置及保留属性的类
  @ class cleanHtml
  @ link：www.jb200.com
  @ 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; 
        }     
    } 
?>

<?php
$str = 'Here is some sample html that is <span id="good" class="aClass" style="abc" font="3"> <font color="red"> getting broken </font> </span> <iframe width="540" height="304" src="http://www.youtube.com/embed/YacZqlFz2bI?fs=1&#038;feature=oembed" frameborder="0" allowfullscreen></iframe> <img id="featuredon" src="http://www.goodfinancialcents.com/wp-content/themes/thesis_182/custom/images/featuredon.jpg" height="23" width="265" />'; 
     
$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 );
?>