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: 2011-11-07 08:21:30

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

 Hi Joachim,

 as a mathematician I have to disagree: what distinguishes the interval
 {{{Interval::open(max, max)}}} from {{{Interval::open(0, 0)}}}? For both
 there exist no elements, that is the point of being empty. Even intervals
 like {{{Interval::closed(17, 4)}}} are allowed and deemed empty!

 As a programmer I might be able to accept the responsibility to avoid such
 cases, but only if I were able to do so. I encountered the problem not
 while putting open intervals into the container but closed ones. And for
 those borders like {{{min}}} and {{{max}}} certainly make sense.

 What I was trying to do was
 {{{
     BOOST_AUTO_TEST_CASE(totalRangeTest)
     {
         typedef int
 Value;
         typedef boost::icl::interval<Value>
 Interval;
         typedef std::numeric_limits<Value>
 Limits;
         typedef boost::icl::interval_map<Value, int,
 boost::icl::total_enricher> Container;

         Value const min(Limits::min());
         Value const max(Limits::max());

         boost::icl::interval_map<Value, int, boost::icl::total_enricher>
 intervals;

         intervals += std::make_pair(Interval::closed(min, max), 0);
         intervals += std::make_pair(Interval::right_open(0, 10),  3);

         BOOST_CHECK_EQUAL(intervals.iterative_size(), 3);
    }
 }}}
 and this fails {{{BOOST_ASSERT(this->_map.find(inter_val) ==
 this->_map.end());}}} in {{{interval_base_map.hpp}}}, line 530 while
 trying to calculate the new third element of the container
 ({{{Interval::closed(10, max)}}}) when inserting the second interval.

 Drilling down on that, I found {{{is_empty}}} and its problematic
 behaviour.

 Thank you for your response!

 Best regards,[[br]]
 Marvin

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6095#comment:2>
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