include/library/stateobject.hpp

   1 #ifndef _library__stateobject__hpp__included__
   2 #define _library__stateobject__hpp__included__
   3
   4 #include <stdexcept>
   5
   6 namespace stateobject
   7 {
   8 //Internal methods.
   9 void* _get(void* obj, void* (*create)());
  10 void* _get_soft(void* obj);
  11 void _clear(void* obj, void (*destroy)(void* obj));
  12
  13 template<typename T, typename U> class type
  14 {
  15 public:
  16 /**
  17  * Get state object, creating it if needed.
  18  *
  19  * Parameter obj: The object to get the state for.
  20  * Returns: The object state.
  21  */
  22         static U& get(T* obj)
  23         {
  24                 return *reinterpret_cast<U*>(_get(obj, []() -> void* { return new U; }));
  25         }
  26 /**
  27  * Get state object, but don't create if it does not already exist.
  28  *
  29  * Parameter obj: The object to get the state for.
  30  * Returns: The object state, or NULL if no existing state.
  31  */
  32         static U* get_soft(T* obj) throw() { return reinterpret_cast<U*>(_get_soft(obj)); }
  33 /**
  34  * Clear state object.
  35  */
  36         static void clear(T* obj) throw()
  37         {
  38                 return _clear(obj, [](void* obj) -> void { delete reinterpret_cast<U*>(obj); });
  39         }
  40 };
  41
  42 }
  43
  44 #endif