Question

I’ve got a working regular expression, but I’d like to make it a tad more readable, and I’m far from a regex guru, so I was humbly hoping for some tips.

This is designed to scrape the output of several different compilers, linkers, and other build tools, and is used to build a nice little summery report. It does it’s job great, but I’m left feeling like I wrote it in a clunky fashion, and I’d sooner learn than keep it the wrong way.

(.*?)\s?:?\s?(informational|warning|error|fatal error)?\s([A-Z]+[0-9][0-9][0-9][0-9]):\s(.*)$

Which, broken down simply, is as follows:

(.*?)                                       # non-greedily match up until...
\s?:?\s?                                    # we come across a possible " : "
(informational|warning|error|fatal error)?  # possibly followed by one of these
\s([A-Z]+[0-9][0-9][0-9][0-9]):\s           # but 100% followed by this alphanum
(.*)$                                       # and then capture the rest

I’m mostly interested in making the 2nd and 4th entry above more… beautiful. For some reason, the regex tester I was using (The Regulator) didn’t match plain spaces, so I had to use the \s… but it is not meant to match any other whitespace.

Any schooling will be greatly appreciated.

Answer 1

Line 2

I think your regular expression doesn’t match with the comment. You probably want this instead:

(\s:\s)?

To make it non-capturing:

(?:\s:\s)?

You should be able to use a literal space instead of \s. This must be a restriction in the tool you are using.

Line 4

[0-9][0-9][0-9][0-9] can be replaced with [0-9]{4}.

In some languages [0-9] is equivalent to \d.