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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#ifdef KERNEL
# include <Kernel/Library/ThreadSafeRefCounted.h>
#else
# include <AK/Assertions.h>
# include <AK/Checked.h>
# include <AK/Noncopyable.h>
# include <AK/Platform.h>
# include <AK/StdLibExtras.h>
namespace AK {
template<class T>
constexpr auto call_will_be_destroyed_if_present(const T* object) -> decltype(const_cast<T*>(object)->will_be_destroyed(), TrueType {})
{
const_cast<T*>(object)->will_be_destroyed();
return {};
}
// NOLINTNEXTLINE(cert-dcl50-cpp) variadic argument used to implement "is detected" pattern
constexpr auto call_will_be_destroyed_if_present(...) -> FalseType
{
return {};
}
template<class T>
constexpr auto call_one_ref_left_if_present(const T* object) -> decltype(const_cast<T*>(object)->one_ref_left(), TrueType {})
{
const_cast<T*>(object)->one_ref_left();
return {};
}
// NOLINTNEXTLINE(cert-dcl50-cpp) variadic argument used to implement "is detected" pattern
constexpr auto call_one_ref_left_if_present(...) -> FalseType
{
return {};
}
class RefCountedBase {
AK_MAKE_NONCOPYABLE(RefCountedBase);
AK_MAKE_NONMOVABLE(RefCountedBase);
public:
using RefCountType = unsigned int;
using AllowOwnPtr = FalseType;
ALWAYS_INLINE void ref() const
{
VERIFY(m_ref_count > 0);
VERIFY(!Checked<RefCountType>::addition_would_overflow(m_ref_count, 1));
++m_ref_count;
}
[[nodiscard]] bool try_ref() const
{
if (m_ref_count == 0)
return false;
ref();
return true;
}
[[nodiscard]] RefCountType ref_count() const { return m_ref_count; }
protected:
RefCountedBase() = default;
~RefCountedBase() { VERIFY(!m_ref_count); }
ALWAYS_INLINE RefCountType deref_base() const
{
VERIFY(m_ref_count);
return --m_ref_count;
}
RefCountType mutable m_ref_count { 1 };
};
template<typename T>
class RefCounted : public RefCountedBase {
public:
bool unref() const
{
auto new_ref_count = deref_base();
if (new_ref_count == 0) {
call_will_be_destroyed_if_present(static_cast<const T*>(this));
delete static_cast<const T*>(this);
return true;
} else if (new_ref_count == 1) {
call_one_ref_left_if_present(static_cast<const T*>(this));
}
return false;
}
};
}
using AK::RefCounted;
using AK::RefCountedBase;
#endif
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