php - URL-BBCode Regex -

i'm trying url bbcode. there 4 possibilities it, , that's current problem:

[url]http://stackoverflow.com/[/url] [url='http://stackoverflow.com/']http://stackoverflow.com/[/url] [url="http://stackoverflow.com/"]http://stackoverflow.com/[/url] [url=http://stackoverflow.com/]http://stackoverflow.com/[/url] 

i need both. is, have far:

/\[url(?:\=\'([^\'"]+)\')?](.+?)\[\/url]/i 

but work case 1 & 2.

edit:

this works better:

/\[url(?:\=(?:[\"|'])?(.*)(?:[^[]+)?)?\](.*)\[\/url\]/i 

but still not perfect.

edit:

i guess, got it. may need optimization, seems work:

/\[url(?:\=("|\'|)?(.*)?\1)?\](.*)\[\/url\]/i 

see regexp-tester

you can use pattern:

$pattern = '~\[url(?|=[\'"]?([^]"\']+)[\'"]?]([^[]+)|](([^[]+)))\[/url]~'; $replacement = '<a href="$1">$2</a>';  $result = preg_replace($pattern, $replacement, $subject); 

the idea preserve groups numbers each branch of alternation using branch reset feature. in way, group 1 contains url , group 2 link description. when there no description, url used in place, that's why url twice enclosed in capture group second branch.