ResourcePtr.h

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#pragma once

#include <type_traits>


class ResourceObject;


template< typename ResourceType >
class ResourcePtr
{
private:
    ResourceType*       m_resource;

public:
    ResourcePtr()
    {
        static_assert( std::is_base_of< ResourceObject, ResourceType >::value, "Template parameter type must inherit from ResourceObject" );
        m_resource = nullptr;
    }

    ResourcePtr( ResourceType* ptr )
    {
        static_assert( std::is_base_of< ResourceObject, ResourceType >::value, "Template parameter type must inherit from ResourceObject" );
        m_resource = ptr;
    }

    ~ResourcePtr()
    {
        ReleaseResource();
    }

    ResourcePtr( const ResourcePtr& other )
    {
        m_resource = nullptr;
        AssignPointer( other.m_resource );
    }

    ResourcePtr( ResourcePtr&& other )
    {
        if( this != &other)
        {
            m_resource = other.m_resource;
            other.m_resource = nullptr;
        }
    }

    void operator=( ResourceType* ptr )
    {
        ReleaseResource();
        AssignPointer( ptr );
    }

    void operator=( const ResourcePtr< ResourceType >& ptr )
    {
        ReleaseResource();
        AssignPointer( ptr.m_resource );
    }

    operator void*() const
    {
        return m_resource;
    }

    ResourceType* operator*()
    {
        return m_resource;
    }

    ResourceType* operator->()
    {
        return m_resource;
    }

    const ResourceType* operator*() const
    {
        return m_resource;
    }

    const ResourceType* operator->() const
    {
        return m_resource;
    }

    void ReleaseResource()
    {
        if( m_resource )
            m_resource->DeleteObjectReference();
        m_resource = nullptr;
    }

    void AssignPointer( ResourceType* ptr )
    {
        if( ptr )
        {
            m_resource = ptr;
            m_resource->AddObjectReference();
        }
    }

    ResourceType*   Ptr () const
    { return m_resource; }

};



namespace rttr
{

// This part of code enables ResourcePtr as wrapper for rttr system.


template< typename T >
struct wrapper_mapper< ResourcePtr< T > >
{
    using wrapped_type  = decltype( std::declval< ResourcePtr< T > >().Ptr() );
    using type          = ResourcePtr< T >;

    inline static wrapped_type  get     ( const type& obj )
    {
       return obj.Ptr();
    }

    inline static type          create  ( const wrapped_type& value )
    {
       return ResourcePtr< T >( value );
    } 
};


} // end namespace rttr