Method pop

example/cpp14/executors/pipeline.cpp:139–151

  }

  bool pop(T& t)
  {
    std::unique_lock<std::mutex> lock(impl_->mutex_);
    while (impl_->queue_.empty() && !impl_->stop_)
      impl_->condition_.wait(lock);
    if (!impl_->queue_.empty())
    {
      t = impl_->queue_.front();
      impl_->queue_.pop();
      return true;
    }
    return false;
  }

private:
  std::shared_ptr<queue_impl<T>> impl_;