Re: [Boost-users] [Regex]Converting from old style to new style

From: Bill Lear (rael_at_[hidden])
Date: 2006-07-29 07:38:47

On Saturday, July 29, 2006 at 22:40:31 (+1200) John Grabner writes:
>I used to be able to write this :
>
>void LineTracker::Analyse(const std::string &Buffer)
>{
>    std::string::const_iterator start, end;
>    start = Buffer.begin();
>    end = Buffer.end();
>    	 
>boost::regex_grep(std::bind1st(std::mem_fun(&LineTracker::grep_callback), 
>							this),
>                      start,
>                      end,
>                      expression);
>}
>
>to get the regex to call back into my class. With the change to the new 
>style using iterator I can do this.
>
>void LineTracker::Analyse(const std::string &Buffer)
>{
>    boost::sregex_iterator m1(Buffer.begin(), Buffer.end(), expression);
>    boost::sregex_iterator m2;
>    std::for_each(m1, m2, *this);	   		
>}
>
>However for_each makes a copy of my class, so at the end it does not 
>update the current instance with the results.
>
>What do I need to do to have the the current instance receive the call 
>back from regex?

Use an inner class functor, pass the functor constructor an instance
of your outer class when you call for_each:

    std::for_each(m1, m2, inner_functor(this));

Have inner_functor update your class as appropriate.

Bill