ladybird/AK/Userspace.h
Lenny Maiorani e6f907a155 AK: Simplify constructors and conversions from nullptr_t
Problem:
- Many constructors are defined as `{}` rather than using the ` =
  default` compiler-provided constructor.
- Some types provide an implicit conversion operator from `nullptr_t`
  instead of requiring the caller to default construct. This violates
  the C++ Core Guidelines suggestion to declare single-argument
  constructors explicit
  (https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#c46-by-default-declare-single-argument-constructors-explicit).

Solution:
- Change default constructors to use the compiler-provided default
  constructor.
- Remove implicit conversion operators from `nullptr_t` and change
  usage to enforce type consistency without conversion.
2021-01-12 09:11:45 +01:00

99 lines
3.0 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <AK/Assertions.h>
#include <AK/StdLibExtras.h>
#include <AK/Types.h>
namespace AK {
// HACK: This is just here to make syntax highlighting work in Qt Creator.
// Once it supports C++20 concepts, we can remove this.
#if defined(__cpp_concepts) && !defined(__COVERITY__)
template<typename T>
concept PointerTypeName = IsPointer<T>::value;
template<PointerTypeName T>
#else
template<typename T, typename EnableIf<IsPointer<T>::value, int>::Type = 0>
#endif
class Userspace {
public:
Userspace() = default;
operator bool() const { return m_ptr; }
operator FlatPtr() const { return (FlatPtr)m_ptr; }
// Disable default implementations that would use surprising integer promotion.
bool operator==(const Userspace&) const = delete;
bool operator<=(const Userspace&) const = delete;
bool operator>=(const Userspace&) const = delete;
bool operator<(const Userspace&) const = delete;
bool operator>(const Userspace&) const = delete;
#ifdef KERNEL
Userspace(FlatPtr ptr)
: m_ptr(ptr)
{
}
FlatPtr ptr() const { return m_ptr; }
T unsafe_userspace_ptr() const { return (T)m_ptr; }
#else
Userspace(T ptr)
: m_ptr(ptr)
{
}
T ptr() const { return m_ptr; }
#endif
private:
#ifdef KERNEL
FlatPtr m_ptr { 0 };
#else
T m_ptr { nullptr };
#endif
};
template<typename T, typename U>
inline Userspace<T> static_ptr_cast(const Userspace<U>& ptr)
{
#ifdef KERNEL
auto casted_ptr = static_cast<T>(ptr.unsafe_userspace_ptr());
#else
auto casted_ptr = static_cast<T>(ptr.ptr());
#endif
return Userspace<T>((FlatPtr)casted_ptr);
}
}
using AK::static_ptr_cast;
using AK::Userspace;