Shortcode to restrict a piece of content

shortcode.php

<?php
Class Shortcode {

	public function __construct(){
		add_shortcode( 'restricted:content', array( &$this, 'restricted_content' ) );
	}

	private function explode_params( $params = null, $flag = ',' ){
		if ( is_null( $params ) || empty( $params ) ) {
			return null;
		}
		if ( stripos( $params, $flag ) !== false ) {
			$params = explode( $flag, $params );
		}
		return array_map( 'trim', (array) $params );
	}

	private function filter_params( $params = null, $flag = '-' ){
		$results = array(
			array(),
			array(),
		);

		if ( is_null( $params ) || empty( $params ) ) {
			return $results;
		}

		foreach( (array) $params as $param ) {
			if ( empty( $param ) || !is_string( $param ) ) {
				continue;
			}
			if ( stripos( $param, $flag ) === false ) {
				$results[0][] = $param;
			} else {
				$results[1][] = str_replace($flag, '', $param );
			}
		}
		return $results;
	}

	public function restricted_content( $data, $content = null ){
		$data = (object) shortcode_atts( array(
		    'role' => '',
		    'user' => '',
		    'tax' => '',
		    'post_type' => '',
	 	), $data );

		if ( !empty( $data->role ) ) {
	 		list( $data->role__in, $data->role__not_in ) = $this->filter_params( $this->explode_params( $data->role ) );
		}

		if ( !empty( $data->user ) ) {
	 		list( $data->user__in, $data->user__not_in ) = $this->filter_params( $this->explode_params( $data->user ) );
		}

		if ( !empty( $data->tax ) ) {
	 		list( $data->tax__in, $data->tax__not_in ) = $this->filter_params( $this->explode_params( $data->tax ) );
		}

		if ( !empty( $data->post_type ) ) {
	 		list( $data->post_type__in, $data->post_type__not_in ) = $this->filter_params( $this->explode_params( $data->post_type ) );
		}

		return '<pre>' . print_r( $data, true ) . '</pre>';
	}
}

$s = new Shortcode();