Re: [Boost-users] [regex] validating expressions

Subject: Re: [Boost-users] [regex] validating expressions
From: John Maddock (boost.regex_at_[hidden])
Date: 2010-05-20 08:32:41

> Is this the correct way to validate a regex expression?
>
> bool validateExpression(std::string e)
> {
>   using namespace boost;
>   return !expression.empty()
>       && !regex(e, regex_constants::no_except).empty(); }
>
> This passes all of my existing unit tests except for the following strings 
> which boost::regex reports as valid.
>
> "[[[A-Z]]"
> "[A-Z]??"
>
> Both Qt's QRegExp and http://www.regexplanet.com/simple/index.html report 
> the first is invalid. Qt's QRegExp reports the second as invalid, while 
> http://www.regexplanet.com/simple/index.html report it as valid.
>
> Is boost::regex right or remiss? Is there a better on line regex 
> validator?

They're both accepted by Perl-5.10 and hence by Boost.Regex.

HTH, John.