"Eric Niebler" <eric@boost-consulting.com> wrote in message news:4924898A.4020101@boost-consulting.com...
Michael Goldshteyn wrote:
What is the best way to test for an empty boost::xpressive::regex object?
That is, if I have code like:
boost::xpressive::sregex re;
...
// Test if re is empty and should not be used to perform a regex_search if (?????)
There is, although it's not obvious from the documentation that it's possible. You can see from the postcondition on the default constructor of basic_regex that this->regex_id() == 0 for default-constructed regex objects and != 0 for non-default constructed regex objects. So your test above can be:
if( 0 != re.regex_id() )
HTH,
Thanks for the speedy reply. I did notice the postcondition on the constructor and the fact that the regex_id() will return 0 for a non-initialized regex, but was hoping that there was a more intuitive way to go about this test, since readers of the code may get confused without a comment. How hard would it be to add an empty() function with a signature that is similar to the one in boost::regex before Boost 1.38.0 comes out, since this functionality, at least in my humble opinion is very useful. The signature for the function in boost::regex is: bool empty() const; Thanks, Michael Goldshteyn