VuFilter class

Subclasses :VuKeyFilter; VuStandardFilter; VuAssociationFilter; VuTypeFilter; VuOpaqueFilter

#ifdef USE_SH_POOLS
public:
                // Overload new/delete to use a SmartHeap pool
                void *operator new(size_t size) { return MemAllocPtr(gVuFilterMemPool,size,FALSE);      };
                void operator delete(void *mem) { if (mem) MemFreePtr(mem); };
#endif
public:
virtual ~VuFilter();

virtual int Compare(VuEntity *ent1, VuEntity *ent2) = 0;
        // < 0 --> ent1 < ent2
        // == 0 --> ent1 == ent2
        // > 0 --> ent1 > ent2
virtual VU_BOOL Test(VuEntity *ent) = 0;
        // TRUE --> ent in sub-set
        // FALSE --> ent not in sub-set
virtual VU_BOOL RemoveTest(VuEntity *ent);
        // TRUE --> ent might be in sub-set
        // FALSE --> ent could never have been in sub-set
        //   -- default implementation returns True()
virtual VU_BOOL Notice(VuMessage *event);
        // TRUE --> event may cause a change to result of Test()
        // FALSE --> event will never cause a change to result of Test()
        //   -- default implementation returns FALSE

virtual VuFilter *Copy() = 0; // allocates and returns a copy

protected:
// base is empty
VuFilter() {}
// copy constructor
VuFilter(VuFilter *) {}

// DATA
// implementation (and members) empty
// --> must be provided by sub-classes