Wrapper <img> to <figure> and <figcaption> for Wordpress

functions.php

<?php
/*
* @author Raylin Aquino <raylinaquino.com>
* @since 25-05-2015 (d m Y)
* Short script that wrapper all images (<img>) tags in a <figure> tag, with its alt attr. in a <figcaption> tag. 
* The goal this... is provide the way correct of to show the images in a blog post.
*/

function figure_wrap_img($content) {

   return preg_replace_callback(
    '/(<figure.*?>.*?)?(\<img.*?(alt(\s+)?=(\s+)?[\"|\']([\w\-.*\s_\p{Han}\X\p{L}]*)[\"|\']).*?\/?>)/isum',
    function ($match){
        if(stripos($match[0],"<figure") === false){
            $ptr = "\n<figure class='figure-wrap'>\n\t%s\n\t%s\r\n</figure>\n"; $figcap = "";

            if(!empty($match[6])) $figcap = "<figcaption>$match[6]</figcaption>";
            return sprintf($ptr,$match[0],$figcap);
        }
        return $match[0];
        
    }
    ,$content);
}
add_filter( 'the_content', 'figure_wrap_img' );
?>