ceph/src/boost/boost/signals2/detail/signals_common.hpp

   1 // Boost.Signals library
   2
   3 // Copyright Douglas Gregor 2001-2004.
   4 // Copyright Frank Mori Hess 2007. Use, modification and
   5 // distribution is subject to the Boost Software License, Version
   6 // 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   7 // http://www.boost.org/LICENSE_1_0.txt)
   8
   9 // For more information, see http://www.boost.org
  10
  11 #ifndef BOOST_SIGNALS2_SIGNALS_COMMON_HPP
  12 #define BOOST_SIGNALS2_SIGNALS_COMMON_HPP
  13
  14 #include <boost/mpl/bool.hpp>
  15 #include <boost/mpl/if.hpp>
  16 #include <boost/ref.hpp>
  17 #include <boost/signals2/signal_base.hpp>
  18 #include <boost/type_traits/is_base_of.hpp>
  19
  20 namespace boost {
  21   namespace signals2 {
  22     namespace detail {
  23       // Determine if the given type T is a signal
  24       template<typename T>
  25       class is_signal: public mpl::bool_<is_base_of<signal_base, T>::value>
  26       {};
  27
  28       // A slot can be a signal, a reference to a function object, or a
  29       // function object.
  30       struct signal_tag {};
  31       struct reference_tag {};
  32       struct value_tag {};
  33
  34       // Classify the given slot as a signal, a reference-to-slot, or a
  35       // standard slot
  36       template<typename S>
  37       class get_slot_tag {
  38         typedef typename mpl::if_<is_signal<S>,
  39           signal_tag, value_tag>::type signal_or_value;
  40       public:
  41         typedef typename mpl::if_<is_reference_wrapper<S>,
  42                             reference_tag,
  43                             signal_or_value>::type type;
  44       };
  45
  46       // Get the slot so that it can be copied
  47       template<typename F>
  48       typename F::weak_signal_type
  49       get_invocable_slot(const F &signal, signal_tag)
  50       { return typename F::weak_signal_type(signal); }
  51
  52       template<typename F>
  53       const F&
  54       get_invocable_slot(const F& f, reference_tag)
  55       { return f; }
  56
  57       template<typename F>
  58       const F&
  59       get_invocable_slot(const F& f, value_tag)
  60       { return f; }
  61
  62       // Determines the type of the slot - is it a signal, a reference to a
  63       // slot or just a normal slot.
  64       template<typename F>
  65       typename get_slot_tag<F>::type
  66       tag_type(const F&)
  67       {
  68         typedef typename get_slot_tag<F>::type
  69           the_tag_type;
  70         the_tag_type tag = the_tag_type();
  71         return tag;
  72       }
  73     } // end namespace detail
  74   } // end namespace signals2
  75 } // end namespace boost
  76
  77 #endif // BOOST_SIGNALS2_SIGNALS_COMMON_HPP