RegEx match parent items containing duplicates

Question

The title is probably confusing, but I have no idea how to properly phrase this.

So here's my goal. I have this string (or something like it):

[some_element]Random string chars [some_element]Ramdon[/some_element] some more random chars[/some_element]

(Some of you may recognize that these are WordPress shortcodes, but this methodology would still be useful elsewhere to me as well.)

What I need to do is match the parent "element". My usual approach might be something like this:

\[(\w+)].*?\[\/\1]

The problem is, this won't work in the above example, because it's "child element" has a the same closing "tag".

How could I get this regex to work, reglardless of how many nested children exist (literally, an infinite number of duplicate nested children)?

Answer 1

You can use this recursive regex in PHP:

$re = '~\s* ( \[some_element\] ( (?: .* | (?1) )* ) \[/some_element\] )~x';

RegEx Demo

This will give you this string in matched group #2:

Random string chars [some_element]Ramdon[/some_element] some more random chars

Answer 2

This looks like a job for recursive patterns (in php).
But I am sadly way too inexperienced to write the pattern here without trying :(
Maybe you can figure that out yourself. I am going to try it too, but that's gonna take a while...

would you look at that:

(The words between {[< and >]} are not part of the pattern, they describe what the subpattern should do.)

[ ( ( {[< some way to match any string except [word] >]} ) | (?R) )* ]