Question

Trying to come up with a Regex that matches a uri path that doesn’t start with a country prefix. Following use cases are an example:

'^/$'          == true
'^/es$'        == false
'^/es/$'       == false
'^/es/.*$'     == false
'^/escro.*$'   == true
'^/lies$'      == true # newish
'^/lies/$'     == true # newish
'^/fr$'        == false
'^/fr/$'       == false
'^/fr/.*$'     == false
'^/freedom/$'  == true
'^/it$'        == false
'^/it/$'       == false
'^/it/.*$'     == false
'^/item/.*$'   == true
'^/foo/bar/$'  == true

Summary: Should match any URL that doesn’t pass “^/(fr|it|es)$” or “^/(fr|it|es)/.*$”

Answer 1

Here is a much more compact version that worked for me:

^/[^/]*(?<!/(?:es|fr|it))(?:/.*?)?$

I used a PHP bootstrap to test it, and you can see from the demo that it passes all of the test cases.

Regex:

^               - Start of string
/               - Match a forward slash
[^/]*           - Match anything that's not a forward slash, 0 or more times
(?<!            - Negative lookbehind making sure
  /(?:es|fr|it) -      We didn't match a forward slash followed by (es|fr|it)
)   
(?:/.*?)?       - Match a forward slash followed by any number of characters, optionally
$               - End of string