我的正则表达有多糟糕？

Question

Ok so I managed to solve a problem at work with regex, but the solution is a bit of a monster.

The string to be validated must be:

zero or more: A-Z a-z 0-9, spaces, or these symbols: . - = + ' , : ( ) /

But, the first and/or last characters must not be a forward slash /

This was my solution (used preg_match php function):

"/^[a-z\d\s\.\-=\+\',:\(\)][a-z\d\s\.\-=\+\',\/:\(\)]*[a-z\d\s\.\-=\+\',:\(\)]$|^[a-z\d\s\.\-=\+\',:\(\)]$/i"

A colleague thinks this is too big and complicated. Well it works, so is it really that bad? Anyone in the mood for some regex-golf?

Answer 1

You can simplify your expression to this:

/^(?:[a-z\d\s.\-=+',:()]+(?:/+[a-z\d\s.\-=+',:()]+)*)?$/i

The outer (?:…)? is to allow an empty string. The [a-z\d\s.\-=+',:()]+ allows to start with one or more of the specified characters except the /. If a / follows, it also must be followed by one or more of the other specified characters ((?:/[a-z\d\s.\-=+',:()]+)*).

Furthermore, inside a character set, you only need to escape the characters \, ], and depending on the position also ^ and -.