ladybird/AK/Retained.h

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#pragma once
#include <AK/Assertions.h>
#include <AK/Types.h>
#ifdef __clang__
#define CONSUMABLE(initial_state) __attribute__((consumable(initial_state)))
#define CALLABLE_WHEN(...) __attribute__((callable_when(__VA_ARGS__)))
#define SET_TYPESTATE(state) __attribute__((set_typestate(state)))
#define RETURN_TYPESTATE(state) __attribute__((return_typestate(state)))
#else
#define CONSUMABLE(initial_state)
#define CALLABLE_WHEN(state)
#define SET_TYPESTATE(state)
#define RETURN_TYPESTATE(state)
#endif
namespace AK {
template<typename T>
inline void retain_if_not_null(T* ptr)
{
if (ptr)
ptr->retain();
}
template<typename T>
inline void release_if_not_null(T* ptr)
{
if (ptr)
ptr->release();
}
template<typename T>
class CONSUMABLE(unconsumed) Retained {
public:
enum AdoptTag { Adopt };
RETURN_TYPESTATE(unconsumed) Retained(const T& object) : m_ptr(const_cast<T*>(&object)) { m_ptr->retain(); }
RETURN_TYPESTATE(unconsumed) Retained(T& object) : m_ptr(&object) { m_ptr->retain(); }
template<typename U> RETURN_TYPESTATE(unconsumed) Retained(U& object) : m_ptr(&static_cast<T&>(object)) { m_ptr->retain(); }
RETURN_TYPESTATE(unconsumed) Retained(AdoptTag, T& object) : m_ptr(&object) { }
RETURN_TYPESTATE(unconsumed) Retained(Retained& other) : m_ptr(&other.copy_ref().leak_ref()) { }
RETURN_TYPESTATE(unconsumed) Retained(Retained&& other) : m_ptr(&other.leak_ref()) { }
template<typename U> RETURN_TYPESTATE(unconsumed) Retained(Retained<U>&& other) : m_ptr(static_cast<T*>(&other.leak_ref())) { }
RETURN_TYPESTATE(unconsumed) Retained(const Retained& other) : m_ptr(&const_cast<Retained&>(other).copy_ref().leak_ref()) { }
template<typename U> RETURN_TYPESTATE(unconsumed) Retained(const Retained<U>& other) : m_ptr(&const_cast<Retained<U>&>(other).copy_ref().leak_ref()) { }
~Retained()
{
release_if_not_null(m_ptr);
m_ptr = nullptr;
#ifdef SANITIZE_PTRS
if constexpr(sizeof(T*) == 8)
m_ptr = (T*)(0xb0b0b0b0b0b0b0b0);
else
m_ptr = (T*)(0xb0b0b0b0);
#endif
}
CALLABLE_WHEN(unconsumed) Retained& operator=(Retained&& other)
{
if (this != &other) {
release_if_not_null(m_ptr);
m_ptr = &other.leak_ref();
}
return *this;
}
template<typename U>
CALLABLE_WHEN(unconsumed) Retained& operator=(Retained<U>&& other)
{
if (this != static_cast<void*>(&other)) {
release_if_not_null(m_ptr);
m_ptr = &other.leak_ref();
}
return *this;
}
CALLABLE_WHEN(unconsumed) Retained& operator=(T& object)
{
if (m_ptr != &object)
release_if_not_null(m_ptr);
m_ptr = &object;
m_ptr->retain();
return *this;
}
CALLABLE_WHEN(unconsumed) Retained copy_ref() const
{
return Retained(*m_ptr);
}
CALLABLE_WHEN(unconsumed) SET_TYPESTATE(consumed)
T& leak_ref()
{
ASSERT(m_ptr);
T* leakedPtr = m_ptr;
m_ptr = nullptr;
return *leakedPtr;
}
CALLABLE_WHEN(unconsumed) T* ptr() { ASSERT(m_ptr); return m_ptr; }
CALLABLE_WHEN(unconsumed) const T* ptr() const { ASSERT(m_ptr); return m_ptr; }
CALLABLE_WHEN(unconsumed) T* operator->() { ASSERT(m_ptr); return m_ptr; }
CALLABLE_WHEN(unconsumed) const T* operator->() const { ASSERT(m_ptr); return m_ptr; }
CALLABLE_WHEN(unconsumed) T& operator*() { ASSERT(m_ptr); return *m_ptr; }
CALLABLE_WHEN(unconsumed) const T& operator*() const { ASSERT(m_ptr); return *m_ptr; }
CALLABLE_WHEN(unconsumed) operator T*() { ASSERT(m_ptr); return m_ptr; }
CALLABLE_WHEN(unconsumed) operator const T*() const { ASSERT(m_ptr); return m_ptr; }
private:
Retained() { }
T* m_ptr { nullptr };
};
template<typename T>
inline Retained<T> adopt(T& object)
{
return Retained<T>(Retained<T>::Adopt, object);
}
}
using AK::Retained;
using AK::adopt;