Kata

Given a MAC Address the purpose of this kata is to verify it's valid using regular expression.

General rule of a MAC Address is

1. It is a string of hexadecimal digits joined together by any of :, - or .
2. It can be strings of 2 hexadecimal digits in eight groups joined by - (e.g. 01-23-45-67-89-ab-cd-ef)
3. It can be strings of 2 hexadecimal digits in six groups joined by - or : (e.g. 01-23-45-67-89-ab or 01:23:45:67:8f:AB)
4. It can be strings of 4 hexadecimal digits in three groups joined by . (e.g. 0123.4567.89AB)

NOTE:

The variables $pattern and $flags will be turned into a regexp pattern using preg_match($pattern.$flags, $mac) so the beginning and ending slash "/~pattern~/" in the pattern are necessary.