Remove wordpress's html p tags

/**
 * DOM Handler
*/
class Extended_DOMDocument extends DOMDocument {
	/**
	 * @var DOMElement $pluginStauts
	*/
	private $pluginStatus = false;

	const CONTAINER = "our_plugins_class_wrapper";
	const UTF8_META = '<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />';


	public function __construct($post){
		parent::__construct("1.0", "UTF-8");
		if (!@$this->loadHTML(self::UTF8_META.$post)){
			return ;
		}
		$this->isPluginInvolved();
	}

	private function isPluginInvolved(){
		$this->pluginStatus = $this->getElementByClassName(self::CONTAINER);
	}

	/**
 	 * Remove p tags
	 * @return string
	 */
	public function removeWpAutoP(){
		$content = $this->saveHTML();
		if (!$this->pluginStatus){
			return $content;
		}
		$html = self::DOMinnerHTML($this->pluginStatus);
		return str_replace($html,preg_replace('#<p>(.*?)<\/p>#','$1',$html),$content);
	}

	/**
	 * @see http://stackoverflow.com/questions/5404941/php-domdocument-outerhtml-for-element
	 */
	public static function DOMinnerHTML($n, $outer=true) {
	    $d = new DOMDocument('1.0');
	    $b = $d->importNode($n->cloneNode(true),true);
	    $d->appendChild($b); $h = $d->saveHTML();
	    // remove outter tags
	    if (!$outer) $h = substr($h,strpos($h,'>')+1,-(strlen($n->nodeName)+4));
	    return $h;
	}

	/**
	* Get all elements that have a tag of $tag and class of $className
	*
	* @param string $className The class name to search for
	* @param string $tag       Tag of the items to search
	* @return array            Array of DOMNode items that match
	*/
	public function getElementsByClassName($className, $tag="*") {
		$nodes = array();
		$domNodeList = $this->getElementsByTagName($tag);
		for ($i = 0; $i < $domNodeList->length; $i++) {
			$item = $domNodeList->item($i)->attributes->getNamedItem('class');
			if ($item) {
				$classes = explode(" ", $item->nodeValue);
				for ($j = 0; $j < count($classes); $j++) {
					if ($classes[$j] == $className) {
						$nodes[] = $domNodeList->item($i);
					}
				}
			}
		}
		return $nodes;
	}

	/**
	 * Convenience method to return a single element by class name when we know there's only going to be one
	 *
	 * @param string $className The class name to search for
	 * @param string $tag       Tag of the items to search
	 * @return array            Array of DOMNode items that match
	 */
	public function getElementByClassName($className, $tag="*") {
		$nodes = $this->getElementsByClassName($className, $tag);
		return count($nodes) == 1 ? $nodes[0] : $nodes;
	}
}


// setting this filter to priority 12
add_filter('the_content' , array('removeWpAutoP'), 12);
/**
 * remove auto wp p tags
 * @param string $content
 * @return string
 */
function rm_wpautop($content) {
	$dom = new Extended_DOMDocument($content);
	$content = $dom->removeWpAutoP();
	return $content;
}