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ObjSharing.hh

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#ifndef MANGO_OBJECT_SHARING_H
#define MANGO_OBJECT_SHARING_H

#include "PtrUsageSharing.hh" // inherit
#include "OwnershipTypes.hh"  // template param

namespace MangoPtr
{
template <OwnershipType oshiptype> // strict
class ObjSharing: public MangoPtrPrivateNamespace::PtrUsageSharing
{
    public:
        ObjSharing(): MangoPtrPrivateNamespace::PtrUsageSharing() {}
        void swap(ObjSharing& rhs)  { usageVal.swap(rhs.usageVal); }
        ObjSharing& operator()(void* optr) {
            MangoPtrPrivateNamespace::PtrUsageSharing::setFrom(optr);
            return *this;}
            
        bool isValid(void* optr) const { return isNotNull(optr); }
        bool destructNeedsDelete(void* optr) const {return isValid(optr);}
        size_t getCountOwned() const {return 1;}
        size_t getCountUser() const {
            return usageVal.getRefCount() - getCountOwned();}

    private:
        ObjSharing(const ObjSharing&);
        void operator=(const ObjSharing&);
};

template <> // shared
class ObjSharing<OShared>
    : public MangoPtrPrivateNamespace::PtrUsageSharing
{
    private:
        typedef MangoPtrPrivateNamespace::PtrUsageSharing US;

    public:
        ObjSharing(): US() {}
        ObjSharing(const ObjSharing& rhs)
            : US(rhs), ownership(rhs.ownership) 
        {
            if (! ownershipHasBeenShared()) 
                ownership.setValid(true);
        }
        void operator=(const ObjSharing& rhs) 
        {
            usageVal = rhs.usageVal;
            ownership = rhs.ownership;
            if (!ownershipHasBeenShared()) ownership.setValid(true);
        }

        void swap(ObjSharing& rhs) 
        {
            US::swap(rhs);
            ownership.swap(rhs.ownership);
        }

    public:
        ObjSharing& operator()(void* optr) 
        {
            MangoPtrPrivateNamespace::PtrUsageSharing::setFrom(optr);
            return *this;
        }

        void unlinkNew() 
        {
            US::unlinkNew();
            ownership.reset(false);
        }

    public:
        bool isValid(void* optr) const
        {
            // if ownership has been shared, make sure 
            // usage validator was initialized
            assert((! ownershipHasBeenShared()) || wasUsageInitialized());
            
            return ownershipHasBeenShared() ? 
                   usageVal.isValid() : isNotNull(optr);
        }

        bool destructNeedsDelete(void* optr) const 
        {
            return isValid(optr) && !ownership.isShared();
        }

        size_t getCountOwned() const {return ownership.getRefCount();}
        size_t getCountUser() const 
        {
            // Everytime an owner gets shared, its usage count increases
            // at the same time as owner count, hence this must be true:
            assert(usageVal.getRefCount() >= getCountOwned());
            
            return usageVal.getRefCount() - getCountOwned();
        }

    private:
        bool ownershipHasBeenShared() const {return ownership.isValid();}

    private:
        ValidityOwner ownership;  
};
        
}   // end namespace MangoPtr
 
#endif // MANGO_OBJECT_SHARING_H

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