countedptr.h

// Description: CountedPtr class
// Detail: A reference counted smart-pointer

#ifndef PASTELSYS_COUNTEDPTR_H
#define PASTELSYS_COUNTEDPTR_H

#include "pastel/sys/mytypes.h"
#include "pastel/sys/pointer/countedptr/referencecounted.h"
#include "pastel/sys/pointer/weakptr.h"

#include <compare>

namespace Pastel
{

    //! A reference counting smart-pointer
    /*!
   Any class wishing to use CountedPtr for reference counting
   must derive from ReferenceCounted. CountedPtr can't be
   used to reference count non-class types. See boost::shared_ptr
   for this capability. CountedPtr can't handle cyclic
   references: if A references B and B references A, then
   A and B will never be destructed. This is a common problem
   in reference counting which you must take care of.
   */
    template <typename Type>
    class CountedPtr
    {
    public:
        template <typename ThatType>
        friend class CountedPtr;

        //! Constructs an empty pointer.
        /*!
       Time complexity: constant
       Exception safety: nothrow
       */
        CountedPtr();

        //! Constructs a copy of the given pointer.
        /*!
       Time complexity: constant
       Exception safety: nothrow
       */
        CountedPtr(const CountedPtr<Type>& that);

        //! Constructs a copy of the given pointer.
        /*!
       Time complexity: constant
       Exception safety: nothrow

       Note implicit conversion is allowed.
       */
        template <typename ThatType>
        CountedPtr(const CountedPtr<ThatType>& that);

        template <typename ThatType>
        CountedPtr(const WeakPtr<ThatType>& that);

        //! Constructs a copy of the given pointer.
        /*!
       Time complexity: constant
       Exception safety: nothrow
       */
        explicit CountedPtr(Type* that);

        //! Destructs the pointer.
        /*!
       Time complexity: constant
       Exception safety: nothrow
       */
        ~CountedPtr();

        //! Copies the given pointer.
        /*!
       Time complexity: constant
       Exception safety: nothrow
       */
        CountedPtr<Type>& operator=(
            const CountedPtr<Type>& that);

        //! Copies the given pointer.
        /*!
       Time complexity: constant
       Exception safety: nothrow
       */
        template <typename ThatType>
        CountedPtr<Type>& operator=(
            const CountedPtr<ThatType>& that);

        //! Copies the given pointer.
        /*!
       Time complexity: constant
       Exception safety: nothrow
       */
        CountedPtr<Type>& operator=(Type* that);

        //! Compares two pointers.
        /*!
       Time complexity: constant
       Exception safety: nothrow
       */
        template <typename ThatType>
        bool operator<=>(const CountedPtr<ThatType>& that) const {
            return data_ <=> that.data_;
        }

        //! Returns the contained pointer.
        /*!
       Time complexity: constant
       Exception safety: nothrow
       */
        Type* get() const;

        //! Dereferences the object pointed to.
        /*!
       Preconditions:
       !empty()

       Time complexity: constant
       Exception safety: nothrow
       */
        Type* operator->() const;

        //! Dereferences the object pointed to.
        /*!
       Preconditions:
       !empty()

       Time complexity: constant
       Exception safety: nothrow
       */
        Type& operator*() const;

        //! Swaps two pointers.
        /*!
       Time complexity: constant
       Exception safety: nothrow
       */
        void swap(CountedPtr<Type>& that);

        //! Sets the current pointer to null pointer.
        /*!
       Time complexity: constant
       Exception safety: nothrow
       */
        void clear();

        //! Returns the number of active CountedPtr's to the current pointee.
        /*!
       Time complexity: constant
       Exception safety: nothrow
       */
        integer count() const;

        //! Returns true if this object points to a null pointer.
        /*!
       Time complexity: constant
       Exception safety: nothrow
       */
        bool empty() const;

    private:
        void increaseCount() const;
        void decreaseCount() const;

        Type* data_;
    };

    template <typename Type>
    void swap(CountedPtr<Type>& left,
        CountedPtr<Type>& right);

}

namespace std
{

    template <typename Type>
    struct hash<Pastel::CountedPtr<Type>>
    {
    public:
        Pastel::hash_integer operator()(
            const Pastel::CountedPtr<Type>& that) const
        {
            return Pastel::computeHash(that.get());
        }
    };

}

#include "pastel/sys/pointer/countedptr/countedptr.hpp"

#endif