ladybird/AK/MaybeOwned.h
2023-11-18 19:32:31 +01:00

68 lines
1.4 KiB
C++

/*
* Copyright (c) 2022, Tim Schumacher <timschumi@gmx.de>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/NonnullOwnPtr.h>
#include <AK/Variant.h>
namespace AK {
template<typename T>
class MaybeOwned {
AK_MAKE_NONCOPYABLE(MaybeOwned);
public:
template<DerivedFrom<T> U>
MaybeOwned(NonnullOwnPtr<U> handle)
: m_handle(static_cast<NonnullOwnPtr<T>&&>(move(handle)))
{
}
// This is made `explicit` to not accidentally create a non-owning MaybeOwned,
// which may not always be intended.
explicit MaybeOwned(T& handle)
: m_handle(&handle)
{
}
MaybeOwned(MaybeOwned&&) = default;
MaybeOwned& operator=(MaybeOwned&&) = default;
T* ptr()
{
if (m_handle.template has<T*>())
return m_handle.template get<T*>();
else
return m_handle.template get<NonnullOwnPtr<T>>();
}
T const* ptr() const
{
if (m_handle.template has<T*>())
return m_handle.template get<T*>();
else
return m_handle.template get<NonnullOwnPtr<T>>();
}
T* operator->() { return ptr(); }
T const* operator->() const { return ptr(); }
T& operator*() { return *ptr(); }
T const& operator*() const { return *ptr(); }
bool is_owned() const { return m_handle.template has<NonnullOwnPtr<T>>(); }
private:
Variant<NonnullOwnPtr<T>, T*> m_handle;
};
}
#if USING_AK_GLOBALLY
using AK::MaybeOwned;
#endif