I’m currently on Boost 1.56 so this might have been fixed by now, but in a simple test Boost.Coroutine fails to properly model the InputIterator concept, because *it++ does not conform to the operational semantics { T tmp = *it; ++it; return tmp; } required by the standard.

The failing program:

#include <boost/coroutine/asymmetric_coroutine.hpp>

#include <iostream>

template<typename Continuation>

auto foo(Continuation && yield) -> void

{

      yield("Hello");

      yield(", ");

      yield("World");

      yield("!\n");

}

//using T = char const *;

using T = std::string;

auto foo() -> boost::coroutines::asymmetric_coroutine<T>::pull_type

{

      using namespace boost::coroutines;

      return asymmetric_coroutine<T>::pull_type{

            [](asymmetric_coroutine<T>::push_type& yield) { foo(yield); }

      };

}

auto main(int, char **) -> int

{

      auto f = foo();

      for(auto it = boost::begin(f); it != boost::end(f);)

            std::cout << *it++;

}

Which (on my machine) outputs:

, World!

X☺à      r2     ` ,     ` ,      Ç2      Ç

Failing to model the InputIterator concept is bad, because then it isn’t any kind of standards-conforming iterator at all. Interestingly, if T is char const * and not std::string the program works as expected. Is there some other subtle bug at work here?

--

Johannes S. Mueller-Roemer, MSc

Wiss. Mitarbeiter - Interactive Engineering Technologies (IET)

Fraunhofer-Institut für Graphische Datenverarbeitung IGD

Fraunhoferstr. 5  |  64283 Darmstadt  |  Germany

Tel +49 6151 155-606  |  Fax +49 6151 155-139

johannes.mueller-roemer@igd.fraunhofer.de  |  www.igd.fraunhofer.de