memory.hpp

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#ifndef H_POTTU_MEMORY
#define H_POTTU_MEMORY
 
 
namespace pottu {
 
    class SharedResource {
    public:
    void _increaseRefCount() noexcept {
        ++_sharedCounter;
    }
    void _decreaseRefCount() noexcept {
        assert( _sharedCounter > 0 );
        --_sharedCounter;
    }
    size_t _getRefCount() const noexcept { return _sharedCounter; }
    private:
    size_t  _sharedCounter{0};
    };
 
 
 
    template <class R, class Deleter=std::default_delete<R> >
    class SharedResourceHandle {
    public:
    SharedResourceHandle() : _p(nullptr) {}
    
    SharedResourceHandle( R *p, Deleter deleter = Deleter{} )
        : _p(p), _deleter(deleter)
        {
        if( _p )
            _p->_increaseRefCount();
        }
    
    SharedResourceHandle( const SharedResourceHandle &o )
        : _p(o._p), _deleter(o._deleter)
        {
        if( _p )
            _p->_increaseRefCount();
        }
 
    SharedResourceHandle( SharedResourceHandle &&o )
        : _p(o._p), _deleter(o._deleter)
        {
        o._p = nullptr;
        }
 
    ~SharedResourceHandle() {
        if( _p ) {
        _p->_decreaseRefCount();
        if( !_p->_getRefCount() )
            _deleter( _p );
        }
    }
    
    SharedResourceHandle &operator=( SharedResourceHandle o ) noexcept
        {
        swap( o, *this );
        return *this;
        }
 
    SharedResourceHandle &operator=( SharedResourceHandle &&o ) noexcept
        {
        swap( std::move(o), *this );
        return *this;
        }
 
    friend void swap( SharedResourceHandle &h1, SharedResourceHandle &h2 ) noexcept
        {
        std::swap( h1._p, h2._p );
        std::swap( h1._deleter, h2._deleter );
        }
    
    explicit operator bool() const noexcept {
        return _p != nullptr;
    }
 
    
    R &operator*() const noexcept { return *_p; }
    R *operator->() const noexcept { return _p; }
 
    R *get() const noexcept { return _p; }
 
    
    R       *_p;
    Deleter  _deleter;
    };
 
 
}
 
 
#endif