ladybird/AK/NonnullOwnPtr.h
Sam Atkins 5013a6480d AK: Mark smart pointer classes as [[nodiscard]]
This makes it an error to not do something with a returned smart
pointer, which should help prevent mistakes. In cases where you do need
to ignore the value, casting to void will placate the compiler.

I did have to add comments to disable clang-format on a couple of lines,
where it wanted to format the code like this:

```c++
private : NonnullRefPtr() = delete;
```
2021-12-05 15:31:03 +01:00

206 lines
5.1 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Assertions.h>
#include <AK/Format.h>
#include <AK/RefCounted.h>
#include <AK/StdLibExtras.h>
#include <AK/Traits.h>
#include <AK/Types.h>
#define NONNULLOWNPTR_SCRUB_BYTE 0xf1
namespace AK {
template<typename T, typename PtrTraits>
class RefPtr;
template<typename T>
class NonnullRefPtr;
template<typename T>
class WeakPtr;
template<typename T>
class [[nodiscard]] NonnullOwnPtr {
public:
using ElementType = T;
enum AdoptTag { Adopt };
NonnullOwnPtr(AdoptTag, T& ptr)
: m_ptr(&ptr)
{
static_assert(
requires { requires typename T::AllowOwnPtr()(); } || !requires { requires !typename T::AllowOwnPtr()(); declval<T>().ref(); declval<T>().unref(); },
"Use NonnullRefPtr<> for RefCounted types");
}
NonnullOwnPtr(NonnullOwnPtr&& other)
: m_ptr(other.leak_ptr())
{
VERIFY(m_ptr);
}
template<typename U>
NonnullOwnPtr(NonnullOwnPtr<U>&& other)
: m_ptr(other.leak_ptr())
{
VERIFY(m_ptr);
}
~NonnullOwnPtr()
{
clear();
#ifdef SANITIZE_PTRS
m_ptr = (T*)(explode_byte(NONNULLOWNPTR_SCRUB_BYTE));
#endif
}
NonnullOwnPtr(const NonnullOwnPtr&) = delete;
template<typename U>
NonnullOwnPtr(const NonnullOwnPtr<U>&) = delete;
NonnullOwnPtr& operator=(const NonnullOwnPtr&) = delete;
template<typename U>
NonnullOwnPtr& operator=(const NonnullOwnPtr<U>&) = delete;
template<typename U, typename PtrTraits = RefPtrTraits<U>>
NonnullOwnPtr(const RefPtr<U, PtrTraits>&) = delete;
template<typename U>
NonnullOwnPtr(const NonnullRefPtr<U>&) = delete;
template<typename U>
NonnullOwnPtr(const WeakPtr<U>&) = delete;
template<typename U, typename PtrTraits = RefPtrTraits<U>>
NonnullOwnPtr& operator=(const RefPtr<U, PtrTraits>&) = delete;
template<typename U>
NonnullOwnPtr& operator=(const NonnullRefPtr<U>&) = delete;
template<typename U>
NonnullOwnPtr& operator=(const WeakPtr<U>&) = delete;
NonnullOwnPtr& operator=(NonnullOwnPtr&& other)
{
NonnullOwnPtr ptr(move(other));
swap(ptr);
return *this;
}
template<typename U>
NonnullOwnPtr& operator=(NonnullOwnPtr<U>&& other)
{
NonnullOwnPtr ptr(move(other));
swap(ptr);
return *this;
}
[[nodiscard]] T* leak_ptr()
{
return exchange(m_ptr, nullptr);
}
ALWAYS_INLINE RETURNS_NONNULL T* ptr()
{
VERIFY(m_ptr);
return m_ptr;
}
ALWAYS_INLINE RETURNS_NONNULL const T* ptr() const
{
VERIFY(m_ptr);
return m_ptr;
}
ALWAYS_INLINE RETURNS_NONNULL T* operator->() { return ptr(); }
ALWAYS_INLINE RETURNS_NONNULL const T* operator->() const { return ptr(); }
ALWAYS_INLINE T& operator*() { return *ptr(); }
ALWAYS_INLINE const T& operator*() const { return *ptr(); }
ALWAYS_INLINE RETURNS_NONNULL operator const T*() const { return ptr(); }
ALWAYS_INLINE RETURNS_NONNULL operator T*() { return ptr(); }
operator bool() const = delete;
bool operator!() const = delete;
void swap(NonnullOwnPtr& other)
{
::swap(m_ptr, other.m_ptr);
}
template<typename U>
void swap(NonnullOwnPtr<U>& other)
{
::swap(m_ptr, other.m_ptr);
}
template<typename U>
NonnullOwnPtr<U> release_nonnull()
{
VERIFY(m_ptr);
return NonnullOwnPtr<U>(NonnullOwnPtr<U>::Adopt, static_cast<U&>(*leak_ptr()));
}
private:
void clear()
{
if (!m_ptr)
return;
delete m_ptr;
m_ptr = nullptr;
}
T* m_ptr = nullptr;
};
#if !defined(KERNEL)
template<typename T>
inline NonnullOwnPtr<T> adopt_own(T& object)
{
return NonnullOwnPtr<T>(NonnullOwnPtr<T>::Adopt, object);
}
#endif
template<class T, class... Args>
requires(IsConstructible<T, Args...>) inline NonnullOwnPtr<T> make(Args&&... args)
{
return NonnullOwnPtr<T>(NonnullOwnPtr<T>::Adopt, *new T(forward<Args>(args)...));
}
// FIXME: Remove once P0960R3 is available in Clang.
template<class T, class... Args>
inline NonnullOwnPtr<T> make(Args&&... args)
{
return NonnullOwnPtr<T>(NonnullOwnPtr<T>::Adopt, *new T { forward<Args>(args)... });
}
template<typename T>
struct Traits<NonnullOwnPtr<T>> : public GenericTraits<NonnullOwnPtr<T>> {
using PeekType = T*;
using ConstPeekType = const T*;
static unsigned hash(const NonnullOwnPtr<T>& p) { return ptr_hash((FlatPtr)p.ptr()); }
static bool equals(const NonnullOwnPtr<T>& a, const NonnullOwnPtr<T>& b) { return a.ptr() == b.ptr(); }
};
template<typename T, typename U>
inline void swap(NonnullOwnPtr<T>& a, NonnullOwnPtr<U>& b)
{
a.swap(b);
}
template<typename T>
struct Formatter<NonnullOwnPtr<T>> : Formatter<const T*> {
ErrorOr<void> format(FormatBuilder& builder, NonnullOwnPtr<T> const& value)
{
return Formatter<const T*>::format(builder, value.ptr());
}
};
}
#if !defined(KERNEL)
using AK::adopt_own;
#endif
using AK::make;
using AK::NonnullOwnPtr;