How to match text inside starting and closing curly brace, the tags and the specified attributes

Question

I am implementing a plugin code for my CMS system. Something like a shortcode but will be applicable in many scenarios. I want a case where an admin writes his code like thi

Answer 1

This regex will work as you specified:

$regex = '~

#opening tag
\{(RAW|ACCESS|DWNLINK|MODL|\w+)
 #optional attributes
 (?>
     \{   ([^}]*)   }
 )?

}


#optional text and closing tag
(?:
    (   #text:= any char except "{", or a "{" not followed by /commandname
        [^{]*+
        (?>\{(?!/?\1[{}])[^{]*)*+
    )

    #closing tag
    (   \{/\1}   )
)?

~ix';

regex101 demo

---

Compared to what you had:

First of all, I used the /x modifier (at the end), which ignores whitespace and #comments.

In the opening tag, I used your options, but you may as well use \w+ to match any command name:

\{(RAW|ACCESS|DWNLINK|MODL|\w+)

For the optional attributes, you had [\{]{0,1}([\w\W\s]*?)\}{0}, which was avalid attempt to make every part optional. Instead, I'm using a (?> group )? (See non-capturing groups and atomic groups) to make the whole subpattern optional (with the ? quantifier).

 (?>
     \{   ([^}]*)   }
 )?

The same logic is applied to the text and closing tag, to make it optional.

You were using [\w\s]+ to match the text, which matches word characters and whitespace, but fails to match punctuation and other characters. I could have used .*? and it would work just as fine. However, I used the following construct, which matches the same, but performs better:

    (   #text:= any char except "{", or a "{" not followed by /commandname
        [^{]*+
        (?>\{(?!/?\1[{}])[^{]*)*?
    )

And finally, I'm matching the closing tag using \1, which is a backreference to the text matched in group 1 (the opening tag name):

\{/\1}

---

Assumptions:

• An attribute does not have a closing brace in quotes such as "te}xt" that could make it break.