Removing stray brackets from in between shortcodes

Question

I was wondering if someone could point me in the right direction for cleaning up this code.

WordPress uses shortcodes in the form [shortcode] to add extended functionality to posts and pages.

What I am trying to do is to return a string with all of the 'stray' brackets, ones not being used by any of shortcodes, as html entities.

What I have to work with are these variables via WordPress:

• $shortcode_tags: an array of all shortcodes as strings (without brackets)
• get_shortcode_regex(): combines all registered shortcode tags into a single regular expression. (I am not using this in the code below)

function find_stray_brackets ($content) {
// this code repalces all occurences of every shortcode with special brackets.
// It then replaces remaining 'stray' brackets with the HTML character entitiy.

        global shortcode_tags;
        foreach($shortcode_tags as $k=>$item)
        {

            $pattern='/\[('.$k.'.*?(?=\]))\]/';
            $content=preg_replace($pattern,'*{*$1*}*',$content);
            $pattern='/\[\/('.$k.'.*?(?=\]))\]/';
            $content=preg_replace($pattern,'*{*/$1*}*',$content);

        }

        $content=str_replace('[','[',$content);
        $content=str_replace(']',']',$content);
        $content=str_replace('*{*','[',$content);
        $content=str_replace('*}*',']',$content);

    return($content);
}

The approach is to replace all of the brackets that surround shortcodes with special characters-> replace stray brackets with html entities -> re-insert original brackets

My end goal is to put all of the text between short codes (including before the first and after the last shortcode) into an array. I couldn't get the regex that Wordpress produces to do what I wanted, so wrote my own regex that relies on brackets - this is why I need to deal with the strays.

Here is the regex that WordPress outputs and some sample text with nested shortcodes.

Answer 1

You can simplify and improve this part:

$pattern = '/\[('.$k.'.*?(?=\]))\]/';
$content = preg_replace($pattern,'*{*$1*}*',$content);
$pattern = '/\[\/('.$k.'.*?(?=\]))\]/';
$content = preg_replace($pattern,'*{*/$1*}*',$content);

Instead of using two replacements for [k] and [/k], you can add the /? inside the capture group and use a single replacement:

$pattern = '/\[(\/?'.$k.'.*?(?=\]))\]/';
$content = preg_replace($pattern,'*{*$1*}*',$content);

This regex can be still improved. Is the positive look-ahead really necessary? It seems to me that this should do the job just as well:

$pattern = '/\[(\/?'.$k.'.*?)\]/';

On the other hand, this is not very strict. For example, if you have shortcode gallery, then [galleryzzz] will also match and not be treated as "stray brackets". Maybe that's fine with you, but in any case, it's easy to prevent that by adding a zero-width word boundary check:

$pattern = '/\[(\/?'.$k.'\b.*?)\]/';