[Cppunit-devel] regular expression match

[Volker B. <vbo...@te...>]

Hi,

for quite a while now it has been a plan of mine to add some sort of
regular expression support to cppunit. Whenever it gets to comparing
strings it would often help to use regular expressions instead of
exact string match.

Often dynamic information is the problem. An example: I want to check
the output of a logging server. Every message should have this format:

  <msg. sequence no.> <process id> <date> <time> <message>

e.g.

  2 15337 2002-04-05 09:44 server started

With current cppunit I use shell scripts to check the output. With regular
expressions it would be much easier, e.g.

  CPPUNIT_ASSERT_REGEX_MATCH("^\d+ \d+ 20\d{2}-\d{2}-\d{2}"
    "\d{2}:\d{2} server started", logline);

(with perl style \d :=3D [0-9]).

But there might be some issues with using regular expressions in C++:

 - Although regular expression handling is part of the POSIX standard
   I don't know how portable it is.
 - The regex interface is somewhat more complicated than a simple
   string equality. There are a lot of switches and options
   controlling the type of match. But it should be *really simple* to
   use in cppunit.
 - There are some concurring regex implementation. On Debian Linux
   e.g. there are at least 5: glibc (libc/POSIX), libregex (GNU),
   libregexx (C++ wrapper for libregex), libboost (C++, maintained by
   well known Steve M. Robbins...), libpcre (perl style regex)

I think, we should have at least one simple regex-assert, at least on
some platforms that supports regexps.

Perhaps we could have a requirement like this 'if you want to use
regexps with cppunit you have to install libXXX otherwise they will be
disabled' (the way cppunit deals with doxygen). I think this has some
advantages:

  - One could use the 'best suited' library, e.g. a C++-library.
  - There might be less portability issues.

Comments?
Are there even any existing implementations of regex-asserts already?

Best regards,
Volker

(BTW. regexps are still less than one could think of: In the example
above there is no way to ensure that the timestamp is a valid
date...)
--=20
Volker Boerchers <vbo...@te...>
System Engineer
TECON Systems AG, Perlengraben 2, 50676 K=F6ln, http://www.tecon.de
Tel: +49-221-92007-55, Fax: +49-221-92007-77