reference_counted_object.h

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#ifndef A_UTIL_UTIL_RESULT_IMPL_REFERENCE_COUNTED_OBJECT_HEADER_INCLUDED
#define A_UTIL_UTIL_RESULT_IMPL_REFERENCE_COUNTED_OBJECT_HEADER_INCLUDED
 
#include <a_util/result/detail/reference_counted_object_intf.h>
 
#include <atomic>  //std::atomic
#include <cstdint> //std::int32_t
#include <utility> //std::forward
 
namespace a_util {
namespace result {
namespace detail {
template <typename Interface, typename Implementation>
class ReferenceCountedObject : public ReferenceCountedObjectInterface<Interface> {
private:
    ReferenceCountedObject(const ReferenceCountedObject&);            //=delete;
    ReferenceCountedObject& operator=(const ReferenceCountedObject&); //=delete;
 
public:
    template <typename... Args>
    ReferenceCountedObject(Args&&... args)
        : ReferenceCountedObjectInterface<Interface>(),
          _reference_count(0),
          _resource(std::forward<Args>(args)...)
    {
    }

    virtual void addReference() const
    {
        ++_reference_count;
    }

    virtual void removeReference() const
    {
        if (0 == (--_reference_count)) {
            delete this;
        }
    }

    virtual const Interface& getObject() const
    {
        return _resource;
    }

    virtual Interface& getObject()
    {
        return _resource;
    }
 
private:
    virtual ~ReferenceCountedObject()
    {
    }
 
private:
#ifndef __QNX__
    mutable std::atomic<std::int32_t> _reference_count; 
#else
    mutable std::atomic_int_fast32_t _reference_count;
#endif
    Implementation _resource; 
};

template <typename Interface, typename Implementation>
class UncountedObject : public ReferenceCountedObjectInterface<Interface> {
private:
    UncountedObject(const UncountedObject&) = delete;
    UncountedObject& operator=(UncountedObject&) = delete;
    UncountedObject(UncountedObject&&) = delete;
    UncountedObject& operator=(UncountedObject&&) = delete;
 
public:
    UncountedObject() = default;

    template <typename... Args>
    UncountedObject(Args&&... args)
        : ReferenceCountedObjectInterface<Interface>(), _resource(std::forward<Args>(args)...)
    {
    }

    virtual ~UncountedObject() = default;

    void addReference() const override
    {
        // noop
    }

    void removeReference() const override
    {
        // noop
    }

    const Interface& getObject() const override
    {
        return _resource;
    }

    Interface& getObject() override
    {
        return _resource;
    }
 
private:
    Implementation _resource; 
};
 
} // namespace detail
} // namespace result
} // namespace a_util
 
#endif // A_UTIL_UTIL_RESULT_IMPL_REFERENCE_COUNTED_OBJECT_HEADER_INCLUDED