cow_ptr.hpp

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#ifndef GLI_COW_PTR_INCLUDED
#define GLI_COW_PTR_INCLUDED

#include "shared_ptr.hpp"

namespace gli
{
        template <typename T>
        class cow_ptr
        {
        public:
                cow_ptr(T* Pointer) :
                        SharedPtr(Pointer)
                {}

                cow_ptr(shared_ptr<T> const & SharedPtr) :
                        SharedPtr(SharedPtr)
                {}

                cow_ptr(cow_ptr<T> const & CowPtr) :
                        SharedPtr(CowPtr.Pointer)
                {}

                cow_ptr & operator=(cow_ptr<T> const & CowPtr)
                {
                        // no need to check for self-assignment with shared_ptr

                        this->SharedPtr = CowPtr.SharedPtr; 
                        return *this;
                }

                T const & operator*() const
                {
                        return *this->SharedPtr;
                }

                T & operator*()
                {
                        this->detach();
                        return *this->SharedPtr;
                }

                T const * operator->() const
                {
                        return this->SharedPtr.operator->();
                }

                T * operator->()
                {
                        this->detach();
                        return this->SharedPtr.operator->();
                }

        private:
                void detach()
                {
                        T* Tmp = this->SharedPtr.get();
                        if(!(Tmp == 0 || this->SharedPtr.unique()))
                                this->SharedPtr = cow_ptr<T>(new T(*Tmp));
                }

                shared_ptr<T> SharedPtr;
        };
}//namespace gli

#endif//GLI_COW_PTR_INCLUDED