const std::tr1::shared_ptr<T>
next()
{
if (curr_ != end_)
{
std::tr1::shared_ptr<T> val = curr_.load();
++curr_;
return val;
}
throw stop_iteration();
}
void next() {
if(_end)
throw stop_iteration();
if(swapcontext(&_context_parent, &_context_child) == -1)
throw std::runtime_error("next: fail @ swapcontext");
}