ladybird/AK/RefCounted.h
2019-06-21 18:58:45 +02:00

79 lines
1.4 KiB
C++

#pragma once
#include "Assertions.h"
#include "StdLibExtras.h"
namespace AK {
template<class T>
constexpr auto call_will_be_destroyed_if_present(T* object) -> decltype(object->will_be_destroyed(), TrueType {})
{
object->will_be_destroyed();
return {};
}
constexpr auto call_will_be_destroyed_if_present(...) -> FalseType
{
return {};
}
template<class T>
constexpr auto call_one_ref_left_if_present(T* object) -> decltype(object->one_ref_left(), TrueType {})
{
object->one_ref_left();
return {};
}
constexpr auto call_one_ref_left_if_present(...) -> FalseType
{
return {};
}
class RefCountedBase {
public:
void ref()
{
ASSERT(m_ref_count);
++m_ref_count;
}
int ref_count() const
{
return m_ref_count;
}
protected:
RefCountedBase() {}
~RefCountedBase()
{
ASSERT(!m_ref_count);
}
void deref_base()
{
ASSERT(m_ref_count);
--m_ref_count;
}
int m_ref_count { 1 };
};
template<typename T>
class RefCounted : public RefCountedBase {
public:
void deref()
{
deref_base();
if (m_ref_count == 0) {
call_will_be_destroyed_if_present(static_cast<T*>(this));
delete static_cast<T*>(this);
} else if (m_ref_count == 1) {
call_one_ref_left_if_present(static_cast<T*>(this));
}
}
};
}
using AK::RefCounted;