boost/signals/trackable.hpp

   1 // Boost.Signals library
   2
   3 // Copyright Douglas Gregor 2001-2004. Use, modification and
   4 // distribution is subject to the Boost Software License, Version
   5 // 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt)
   7
   8 // For more information, see http://www.boost.org
   9
  10 #ifndef BOOST_SIGNALS_TRACKABLE_HPP
  11 #define BOOST_SIGNALS_TRACKABLE_HPP
  12
  13 #include <boost/type_traits.hpp>
  14 #include <boost/signals/connection.hpp>
  15 #include <boost/ref.hpp>
  16 #include <boost/utility/addressof.hpp>
  17 #include <list>
  18 #include <vector>
  19
  20 #ifdef BOOST_HAS_ABI_HEADERS
  21 #  include BOOST_ABI_PREFIX
  22 #endif
  23
  24 namespace boost {
  25
  26 namespace BOOST_SIGNALS_NAMESPACE {
  27   // Base class for "trackable" objects that can be tracked when they are
  28   // bound in slot target functions. When a trackable object is destroyed,
  29   // the signal/slot connections are disconnected automatically.
  30   class BOOST_SIGNALS_DECL trackable {
  31   private:
  32     static void signal_disconnected(void* obj, void* data);
  33
  34     friend class detail::signal_base_impl;
  35     friend class detail::slot_base;
  36     void signal_connected(connection, BOOST_SIGNALS_NAMESPACE::detail::bound_object&) const;
  37
  38   protected:
  39     trackable() : connected_signals(), dying(false) {}
  40     trackable(const trackable&) : connected_signals(), dying(false) {}
  41     ~trackable();
  42
  43     trackable& operator=(const trackable&)
  44     {
  45       dying = true;
  46       connected_signals.clear();
  47       dying = false;
  48       return *this;
  49     }
  50
  51   private:
  52     typedef std::list<connection> connection_list;
  53     typedef connection_list::iterator connection_iterator;
  54
  55     // List of connections that this object is part of
  56     mutable connection_list connected_signals;
  57
  58     // True when the object is being destroyed
  59     mutable bool dying;
  60   };
  61
  62   namespace detail {
  63     template<bool Cond> struct truth {};
  64
  65     // A visitor that adds each trackable object to a vector
  66     class bound_objects_visitor {
  67     public:
  68       bound_objects_visitor(std::vector<const trackable*>& v) :
  69         bound_objects(v)
  70       {
  71       }
  72
  73       template<typename T>
  74       void operator()(const T& t) const
  75       {
  76         decode(t, 0);
  77       }
  78
  79     private:
  80       // decode() decides between a reference wrapper and anything else
  81       template<typename T>
  82       void decode(const reference_wrapper<T>& t, int) const
  83       {
  84         add_if_trackable(t.get_pointer());
  85       }
  86
  87       template<typename T>
  88       void decode(const T& t, long) const
  89       {
  90         typedef truth<(is_pointer<T>::value)> is_a_pointer;
  91         maybe_get_pointer(t, is_a_pointer());
  92       }
  93
  94       // maybe_get_pointer() decides between a pointer and a non-pointer
  95       template<typename T>
  96       void maybe_get_pointer(const T& t, truth<true>) const
  97       {
  98         add_if_trackable(t);
  99       }
 100
 101       template<typename T>
 102       void maybe_get_pointer(const T& t, truth<false>) const
 103       {
 104         // Take the address of this object, because the object itself may be
 105         // trackable
 106         add_if_trackable(boost::addressof(t));
 107       }
 108
 109       // add_if_trackable() adds trackable objects to the list of bound objects
 110       inline void add_if_trackable(const trackable* b) const
 111       {
 112         if (b) {
 113           bound_objects.push_back(b);
 114         }
 115       }
 116
 117       inline void add_if_trackable(const void*) const { }
 118
 119       template<typename R>
 120       inline void add_if_trackable(R (*)()) const { }
 121
 122       template<typename R, typename T1>
 123       inline void add_if_trackable(R (*)(T1)) const { }
 124
 125       template<typename R, typename T1, typename T2>
 126       inline void add_if_trackable(R (*)(T1, T2)) const { }
 127
 128       template<typename R, typename T1, typename T2, typename T3>
 129       inline void add_if_trackable(R (*)(T1, T2, T3)) const { }
 130
 131       template<typename R, typename T1, typename T2, typename T3, typename T4>
 132       inline void add_if_trackable(R (*)(T1, T2, T3, T4)) const { }
 133
 134       template<typename R, typename T1, typename T2, typename T3, typename T4,
 135                typename T5>
 136       inline void add_if_trackable(R (*)(T1, T2, T3, T4, T5)) const { }
 137
 138       template<typename R, typename T1, typename T2, typename T3, typename T4,
 139                typename T5, typename T6>
 140       inline void add_if_trackable(R (*)(T1, T2, T3, T4, T5, T6)) const { }
 141
 142       template<typename R, typename T1, typename T2, typename T3, typename T4,
 143                typename T5, typename T6, typename T7>
 144       inline void add_if_trackable(R (*)(T1, T2, T3, T4, T5, T6, T7)) const { }
 145
 146       template<typename R, typename T1, typename T2, typename T3, typename T4,
 147                typename T5, typename T6, typename T7, typename T8>
 148       inline void
 149       add_if_trackable(R (*)(T1, T2, T3, T4, T5, T6, T7, T8)) const { }
 150
 151       template<typename R, typename T1, typename T2, typename T3, typename T4,
 152                typename T5, typename T6, typename T7, typename T8, typename T9>
 153       inline void
 154       add_if_trackable(R (*)(T1, T2, T3, T4, T5, T6, T7, T8, T9)) const { }
 155
 156       template<typename R, typename T1, typename T2, typename T3, typename T4,
 157                typename T5, typename T6, typename T7, typename T8, typename T9,
 158                typename T10>
 159       inline void
 160       add_if_trackable(R (*)(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10)) const { }
 161
 162       std::vector<const trackable*>& bound_objects;
 163     };
 164   } // end namespace detail
 165 } // end namespace BOOST_SIGNALS_NAMESPACE
 166
 167 } // end namespace boost
 168
 169 #ifdef BOOST_HAS_ABI_HEADERS
 170 #  include BOOST_ABI_SUFFIX
 171 #endif
 172
 173 #endif // BOOST_SIGNALS_TRACKABLE_HPP