Question

I’m making a reusable piece of code. One can specify the regular expression for capturing the api_key and signature groups, like in the following Authorization header:

AWS 44CF9590006BF252F707:jZNOcbfWmD/A/f3hSvVzXZjM2HU=

The regular expression would be:

^AWS (?<api_key>.+):(?<signature>.+)$

Of course AWS and the order of the key/signature pair may change (that’s why I’m using a regular expression). But there should be always an api_key capturing group and a signature capturing group.

How can I check if these groups are present, using another regular expression?

EDIT: based on the answers it seems that I was not good at all at explaining the problem.

The user (of this code) is going to provider the regex (like the one above). I need only to check that the given regex as (at least) two capturing grops (api_key and signature). I’ll then use the regex provided to test against Authorization header.

Answer 1

But how do you know that your new regex tests your regex properly? You might need 20-30 levels of regexes :). How about you just try something simple like:

if (strpos($yourRegEx, "(?<api_key>") !== false && strpos($yourRegEx, "(?<signature>") !== false) {

This is I guess more fool proof:

preg_match("\(\?<api_key>.+?\)", $yourRegEx) && preg_match("\(\?<signature>.+?\)", $yourRegEx)