ladybird/Kernel/KResult.h

151 lines
3.9 KiB
C
Raw Normal View History

/*
* 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 <LibC/errno_numbers.h>
namespace Kernel {
enum KSuccessTag {
KSuccess
};
class KResult {
public:
ALWAYS_INLINE explicit KResult(int negative_e)
: m_error(negative_e)
{
ASSERT(negative_e <= 0);
}
KResult(KSuccessTag)
: m_error(0)
{
}
operator int() const { return m_error; }
int error() const { return m_error; }
bool is_success() const { return m_error == 0; }
bool is_error() const { return !is_success(); }
private:
template<typename T>
friend class KResultOr;
KResult() { }
int m_error { 0 };
};
template<typename T>
class alignas(T) KResultOr {
public:
KResultOr(KResult error)
: m_error(error)
, m_is_error(true)
{
}
ALWAYS_INLINE KResultOr(T&& value)
{
new (&m_storage) T(move(value));
}
template<typename U>
ALWAYS_INLINE KResultOr(U&& value)
{
new (&m_storage) T(move(value));
}
KResultOr(KResultOr&& other)
{
m_is_error = other.m_is_error;
if (m_is_error)
m_error = other.m_error;
else {
new (&m_storage) T(move(other.value()));
other.value().~T();
}
other.m_is_error = true;
other.m_error = KSuccess;
}
KResultOr& operator=(KResultOr&& other)
{
if (!m_is_error)
value().~T();
m_is_error = other.m_is_error;
if (m_is_error)
m_error = other.m_error;
else {
new (&m_storage) T(move(other.value()));
other.value().~T();
}
other.m_is_error = true;
other.m_error = KSuccess;
return *this;
}
~KResultOr()
{
if (!m_is_error)
value().~T();
}
bool is_error() const { return m_is_error; }
ALWAYS_INLINE KResult error() const
{
ASSERT(m_is_error);
return m_error;
}
KResult result() const { return m_is_error ? KSuccess : m_error; }
ALWAYS_INLINE T& value()
{
ASSERT(!m_is_error);
return *reinterpret_cast<T*>(&m_storage);
}
ALWAYS_INLINE const T& value() const
{
ASSERT(!m_is_error);
return *reinterpret_cast<T*>(&m_storage);
}
ALWAYS_INLINE T release_value()
{
ASSERT(!m_is_error);
T released_value = *reinterpret_cast<T*>(&m_storage);
value().~T();
return released_value;
}
private:
alignas(T) char m_storage[sizeof(T)];
KResult m_error;
bool m_is_error { false };
};
}