Re: [Boost-bugs] [Boost C++ Libraries] #6095: boost::icl::is_empty fails for certain open intervals

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #6095: boost::icl::is_empty fails for certain open intervals
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2011-11-08 08:12:12

#6095: boost::icl::is_empty fails for certain open intervals
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  Reporter:  Marvin Sielenkemper <m.sielenkemper@…>             |       Owner:  jofaber                             
      Type:  Bugs                                               |      Status:  assigned                            
 Milestone:  Boost 1.48.0                                       |   Component:  ICL                                 
   Version:  Boost 1.47.0                                       |    Severity:  Problem                             
Resolution:                                                     |    Keywords:  icl, open interval, integer overflow
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Comment (by Marvin Sielenkemper <m.sielenkemper@…>):

 Hi Joachim,

 no problem :)

 But I would like to propose a maybe even more nifty fix:[[br]]
 An open interval {{{]a, b[}}} is empty if {{{b <= a || b <= a + 1}}}.

 This does not only avoid the second increment, it even avoids the first
 one in many cases due to the short circuit {{{||}}}-operator and does
 ''never'' run into the overflow case:[[br]]
 If the first check fails, we know that {{{a < b}}} and hence that there is
 at least one element to increment to without overflowing.

 So this should even work for bound types that are less forgiving than
 {{{int}}} when hitting their bounds, (e.g. throw exceptions).

 Best regards,[[br]]
 Marvin

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6095#comment:4>
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