knx/examples/knxPython/pybind11/tests/object.h

#if !defined(__OBJECT_H)
#    define __OBJECT_H

#    include "constructor_stats.h"

#    include <atomic>

/// Reference counted object base class
class Object
{
    public:
        /// Default constructor
        Object()
        {
            print_default_created(this);
        }

        /// Copy constructor
        Object(const Object&) : m_refCount(0)
        {
            print_copy_created(this);
        }

        /// Return the current reference count
        int getRefCount() const
        {
            return m_refCount;
        };

        /// Increase the object's reference count by one
        void incRef() const
        {
            ++m_refCount;
        }

        /** \brief Decrease the reference count of
         * the object and possibly deallocate it.
         *
         * The object will automatically be deallocated once
         * the reference count reaches zero.
         */
        void decRef(bool dealloc = true) const
        {
            --m_refCount;

            if (m_refCount == 0 && dealloc)
            {
                delete this;
            }
            else if (m_refCount < 0)
            {
                throw std::runtime_error("Internal error: reference count < 0!");
            }
        }

        virtual std::string toString() const = 0;

    protected:
        /** \brief Virtual protected deconstructor.
         * (Will only be called by \ref ref)
         */
        virtual ~Object()
        {
            print_destroyed(this);
        }

    private:
        mutable std::atomic<int> m_refCount{0};
};

// Tag class used to track constructions of ref objects.  When we track constructors, below, we
// track and print out the actual class (e.g. ref<MyObject>), and *also* add a fake tracker for
// ref_tag.  This lets us check that the total number of ref<Anything> constructors/destructors is
// correct without having to check each individual ref<Whatever> type individually.
class ref_tag {};

/**
 * \brief Reference counting helper
 *
 * The \a ref refeference template is a simple wrapper to store a
 * pointer to an object. It takes care of increasing and decreasing
 * the reference count of the object. When the last reference goes
 * out of scope, the associated object will be deallocated.
 *
 * \ingroup libcore
 */
template <typename T>
class ref
{
    public:
        /// Create a nullptr reference
        ref() : m_ptr(nullptr)
        {
            print_default_created(this);
            track_default_created((ref_tag*) this);
        }

        /// Construct a reference from a pointer
        explicit ref(T* ptr) : m_ptr(ptr)
        {
            if (m_ptr)
            {
                ((Object*) m_ptr)->incRef();
            }

            print_created(this, "from pointer", m_ptr);
            track_created((ref_tag*) this, "from pointer");
        }

        /// Copy constructor
        ref(const ref& r) : m_ptr(r.m_ptr)
        {
            if (m_ptr)
            {
                ((Object*) m_ptr)->incRef();
            }

            print_copy_created(this, "with pointer", m_ptr);
            track_copy_created((ref_tag*) this);
        }

        /// Move constructor
        ref(ref&& r) noexcept : m_ptr(r.m_ptr)
        {
            r.m_ptr = nullptr;

            print_move_created(this, "with pointer", m_ptr);
            track_move_created((ref_tag*) this);
        }

        /// Destroy this reference
        ~ref()
        {
            if (m_ptr)
            {
                ((Object*) m_ptr)->decRef();
            }

            print_destroyed(this);
            track_destroyed((ref_tag*) this);
        }

        /// Move another reference into the current one
        ref& operator=(ref&& r) noexcept
        {
            print_move_assigned(this, "pointer", r.m_ptr);
            track_move_assigned((ref_tag*) this);

            if (*this == r)
            {
                return *this;
            }

            if (m_ptr)
            {
                ((Object*) m_ptr)->decRef();
            }

            m_ptr = r.m_ptr;
            r.m_ptr = nullptr;
            return *this;
        }

        /// Overwrite this reference with another reference
        ref& operator=(const ref& r)
        {
            if (this == &r)
            {
                return *this;
            }

            print_copy_assigned(this, "pointer", r.m_ptr);
            track_copy_assigned((ref_tag*) this);

            if (m_ptr == r.m_ptr)
            {
                return *this;
            }

            if (m_ptr)
            {
                ((Object*) m_ptr)->decRef();
            }

            m_ptr = r.m_ptr;

            if (m_ptr)
            {
                ((Object*) m_ptr)->incRef();
            }

            return *this;
        }

        /// Overwrite this reference with a pointer to another object
        ref& operator=(T* ptr)
        {
            print_values(this, "assigned pointer");
            track_values((ref_tag*) this, "assigned pointer");

            if (m_ptr == ptr)
            {
                return *this;
            }

            if (m_ptr)
            {
                ((Object*) m_ptr)->decRef();
            }

            m_ptr = ptr;

            if (m_ptr)
            {
                ((Object*) m_ptr)->incRef();
            }

            return *this;
        }

        /// Compare this reference with another reference
        bool operator==(const ref& r) const
        {
            return m_ptr == r.m_ptr;
        }

        /// Compare this reference with another reference
        bool operator!=(const ref& r) const
        {
            return m_ptr != r.m_ptr;
        }

        /// Compare this reference with a pointer
        bool operator==(const T* ptr) const
        {
            return m_ptr == ptr;
        }

        /// Compare this reference with a pointer
        bool operator!=(const T* ptr) const
        {
            return m_ptr != ptr;
        }

        /// Access the object referenced by this reference
        T* operator->()
        {
            return m_ptr;
        }

        /// Access the object referenced by this reference
        const T* operator->() const
        {
            return m_ptr;
        }

        /// Return a C++ reference to the referenced object
        T& operator*()
        {
            return *m_ptr;
        }

        /// Return a const C++ reference to the referenced object
        const T& operator*() const
        {
            return *m_ptr;
        }

        /// Return a pointer to the referenced object
        explicit operator T* ()
        {
            return m_ptr;
        }

        /// Return a const pointer to the referenced object
        T* get_ptr()
        {
            return m_ptr;
        }

        /// Return a pointer to the referenced object
        const T* get_ptr() const
        {
            return m_ptr;
        }

    private:
        T* m_ptr;
};

#endif /* __OBJECT_H */