Hi, I asking for help in my PHP code optimization. I try to rewrite my old/slow BBCode conversion function to use regex. The allowed BBCodes are

[ b]text[ /b]
[ i]text[ /i]
[ url]domain.com[ /url] or [ url]domain.com|domainname[ /url]
[ img]filename.ext[ /img] or [ img]filename.ext|description[ /img]

It is possible to construct regex with the following conditions?

[ b] - inside only [ i] and [ url] BBCode allowed, newline NOT allowed
[ i] - as [ b]
[ url] - inside NO BBCode allowed, newline NOT allowed
[ img] - as [ url]

(I try to make difference between two [ url] (or [ img]) syntax with '/\[url\](.+?)\[\/url\]/is' and '/\[url\](.+?)\|(.+?)\[\/url\]/is' patterns, but it generates malfunction.)

Thanks for help in advance