Chris@16: // Boost.Signals library
Chris@16: 
Chris@16: // Copyright Douglas Gregor 2001-2004. Use, modification and
Chris@16: // distribution is subject to the Boost Software License, Version
Chris@16: // 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: // For more information, see http://www.boost.org
Chris@16: 
Chris@16: #ifndef BOOST_SIGNALS_COMMON_HEADER
Chris@16: #define BOOST_SIGNALS_COMMON_HEADER
Chris@16: 
Chris@16: #ifndef BOOST_SIGNALS_NAMESPACE
Chris@16: #  define BOOST_SIGNALS_NAMESPACE signals
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/type_traits/conversion_traits.hpp>
Chris@16: #include <boost/ref.hpp>
Chris@16: #include <boost/signals/detail/config.hpp>
Chris@16: 
Chris@16: #ifdef BOOST_HAS_ABI_HEADERS
Chris@16: #  include BOOST_ABI_PREFIX
Chris@16: #endif
Chris@16: 
Chris@16: namespace boost {
Chris@16:   namespace BOOST_SIGNALS_NAMESPACE {
Chris@16:     namespace detail {
Chris@16:       // The unusable class is a placeholder for unused function arguments
Chris@16:       // It is also completely unusable except that it constructable from
Chris@16:       // anything. This helps compilers without partial specialization
Chris@16:       // handle slots returning void.
Chris@16:       struct unusable {
Chris@16:         unusable() {}
Chris@16:       };
Chris@16: 
Chris@16:       // Determine the result type of a slot call
Chris@16:       template<typename R>
Chris@16:       struct slot_result_type {
Chris@16:         typedef R type;
Chris@16:       };
Chris@16: 
Chris@16:       template<>
Chris@16:       struct slot_result_type<void> {
Chris@16:         typedef unusable type;
Chris@16:       };
Chris@16: 
Chris@16:       // Determine if the given type T is a signal
Chris@16:       class signal_base;
Chris@16: 
Chris@16:       template<typename T>
Chris@16:       struct is_signal {
Chris@16:         BOOST_STATIC_CONSTANT(bool,
Chris@16:           value = (is_convertible<T*, signal_base*>::value));
Chris@16:       };
Chris@16: 
Chris@16:       /*
Chris@16:        * The IF implementation is temporary code. When a Boost metaprogramming
Chris@16:        * library is introduced, Boost.Signals will use it instead.
Chris@16:        */
Chris@16:       namespace intimate {
Chris@16:         struct SelectThen
Chris@16:         {
Chris@16:           template<typename Then, typename Else>
Chris@16:           struct Result
Chris@16:           {
Chris@16:             typedef Then type;
Chris@16:           };
Chris@16:         };
Chris@16: 
Chris@16:         struct SelectElse
Chris@16:         {
Chris@16:           template<typename Then, typename Else>
Chris@16:           struct Result
Chris@16:           {
Chris@16:             typedef Else type;
Chris@16:           };
Chris@16:         };
Chris@16: 
Chris@16:         template<bool Condition>
Chris@16:         struct Selector
Chris@16:         {
Chris@16:           typedef SelectThen type;
Chris@16:         };
Chris@16: 
Chris@16:         template<>
Chris@16:         struct Selector<false>
Chris@16:         {
Chris@16:           typedef SelectElse type;
Chris@16:         };
Chris@16:       } // end namespace intimate
Chris@16: 
Chris@16:       template<bool Condition, typename Then, typename Else>
Chris@16:       struct IF
Chris@16:       {
Chris@16:         typedef typename intimate::Selector<Condition>::type select;
Chris@16:         typedef typename select::template Result<Then,Else>::type type;
Chris@16:       };
Chris@16: 
Chris@16:       // Determine if the incoming argument is a reference_wrapper
Chris@16:       template<typename T>
Chris@16:       struct is_ref
Chris@16:       {
Chris@16:         BOOST_STATIC_CONSTANT(bool, value = false);
Chris@16:       };
Chris@16: 
Chris@16:       template<typename T>
Chris@16:       struct is_ref<reference_wrapper<T> >
Chris@16:       {
Chris@16:         BOOST_STATIC_CONSTANT(bool, value = true);
Chris@16:       };
Chris@16: 
Chris@16:       // A slot can be a signal, a reference to a function object, or a
Chris@16:       // function object.
Chris@16:       struct signal_tag {};
Chris@16:       struct reference_tag {};
Chris@16:       struct value_tag {};
Chris@16: 
Chris@16:       // Classify the given slot as a signal, a reference-to-slot, or a
Chris@16:       // standard slot
Chris@16:       template<typename S>
Chris@16:       class get_slot_tag {
Chris@16:         typedef typename IF<(is_signal<S>::value),
Chris@16:                             signal_tag,
Chris@16:                             value_tag>::type signal_or_value;
Chris@16: 
Chris@16:       public:
Chris@16:         typedef typename IF<(is_ref<S>::value),
Chris@16:                             reference_tag,
Chris@16:                             signal_or_value>::type type;
Chris@16:       };
Chris@16: 
Chris@16:       // Forward declaration needed in lots of places
Chris@16:       class signal_base_impl;
Chris@16:       class bound_objects_visitor;
Chris@16:       class slot_base;
Chris@16:     } // end namespace detail
Chris@16:   } // end namespace BOOST_SIGNALS_NAMESPACE
Chris@16: } // end namespace boost
Chris@16: 
Chris@16: #ifdef BOOST_HAS_ABI_HEADERS
Chris@16: #  include BOOST_ABI_SUFFIX
Chris@16: #endif
Chris@16: 
Chris@16: #endif // BOOST_SIGNALS_COMMON_HEADER