Re: [Boost-bugs] [Boost C++ Libraries] #5561: error on calculating interval_map intersection

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #5561: error on calculating interval_map intersection
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2011-05-25 12:56:27

#5561: error on calculating interval_map intersection
------------------------------+---------------------------------------------
  Reporter:  denis@…          |       Owner:  jofaber
      Type:  Bugs             |      Status:  new    
 Milestone:  Boost 1.47.0     |   Component:  ICL    
   Version:  Boost 1.46.1     |    Severity:  Problem
Resolution:                   |    Keywords:         
------------------------------+---------------------------------------------

Comment (by jofaber):

 Hi Denis,

 as already mentioned in private mail, the behavior that you consider
 erroneous is correct and follows the specification (see docs). Since
 interval_maps perform aggregation on overlap, they pass a type's combine-
 operation to combine associated values for `+` and they pass a type's
 intersecting operation to intersect associated values on overlap, if an
 intersection is called on the interval_map.

 This is only possible if the type of the associated values (codomain_type)
 implements an intersection operation for operator &.

 so
 ||`Q = interval_map<T, Numeric>` ||is a Quantifier not having set
 semantics ||
 ||`interval_map<T, Q>`           ||is a Quantifier not having set
 semantics ||
 ||`C = interval_map<T, Set>`     ||is a Collector that has set semantics
 ||
 ||`interval_map<T, C>`           ||is a Collector that has set semantics
 ||

 For Quantifiers, the intersection operations & degenerates to +.

 See also
 http://www.joachim-

 faulhaber.de/boost_icl/doc/libs/icl/doc/html/boost_icl/semantics/collectors__maps_of_sets.html

 http://www.joachim-

 faulhaber.de/boost_icl/doc/libs/icl/doc/html/boost_icl/semantics/quantifiers__maps_of_numbers.html

 What you always can do is this

 {{{#!c++

 //Define a user defined type ...
 class MySettic
 {
     // Has some kind of intersection
     MySettic& operator &= (const MySettic& rhs){...};
     . . .
 };

 //... make it have set semantics by partial specialization
 //of template icl::is_set
 namespace boost{ namespace icl
 {
     struct is_set<MySettic>
     {
         typedef is_set<bits<NaturalT> > type;
         BOOST_STATIC_CONSTANT(bool, value = true);
     };
 } }

 //... and then use it in your interval maps.
 interval_map<int, MySettic> myIMap;

 }}}

 HTH, Best regards,

 Joachim

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/5561#comment:1>
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