Cách dùng Preg_match trong PHP

gistfile1.php

	if ( !function_exists( 'extract_gallery_images_ids' ) ) {
	    
	    function extract_gallery_images_ids() {
	        
	        global $post;
	        
	        $content = "[gallery ids="7,8,9,10"]";
	        $pattern = "\[(\[?)(embed|wp_caption|caption|playlist|audio|video|dot_recommends|dot_recommended_posts|gallery)(?![\w-])([^\]\/]*(?:\/(?!\])[^\]\/]*)*?)(?:(\/)\]|\](?:([^\[]*+(?:\[(?!\/\2\])[^\[]*+)*+)\[\/\2\])?)(\]?)"
	        
	        preg_match( "/$pattern/s", $content, $match );
	        
	        if( isset( $match[2] ) && ( "gallery" == $match[2] ) ) {
	            
	            $atts = $match[3];
	            $atts = shortcode_parse_atts( $match[3] );
	            
	            $gallery_images = isset( $atts['ids'] ) ? explode( ',', $atts['ids'] ) : get_children( 'post_type=attachment&post_mime_type=image&post_parent=' . $post->ID .'&order=ASC&orderby=menu_order ID' );

	            return $gallery_images;
	            
	        }         
	    
	    }

	}