[Boost-bugs] [Boost C++ Libraries] #6373: transform_iterator not preserving bidirectionality of std::map iterator

Subject: [Boost-bugs] [Boost C++ Libraries] #6373: transform_iterator not preserving bidirectionality of std::map iterator
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-01-10 02:15:30

#6373: transform_iterator not preserving bidirectionality of std::map iterator
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 Reporter:  JonT <jon@…>                               |       Owner:  dave    
     Type:  Bugs                                       |      Status:  new     
Milestone:  To Be Determined                           |   Component:  iterator
  Version:  Boost 1.49.0                               |    Severity:  Problem 
 Keywords:  transform_iterator bidirectional std::map  |  
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 Using transform_iterator on std::map iterator does not seem to preserve
 bidirectionality.

 {{{
 #!cpp
 map::iterator itend = data.end();
 XIt xend = boost::make_transform_iterator(itend,xfunc());
 XIt xlast = xend;
 --xlast;
 assert(xend != xlast); // succeeds !
 xlast = xend;
 std::advance(xlast,-1);
 assert(xend != xlast); // fails !
 }}}

 See also [http://stackoverflow.com/questions/8783048/bidirectional-boost-

 transform-iterator-as-with-stdmap StackOverflow Issue 8783048] for longer
 (compilable) example.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6373>
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