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#pragma once
#include <AK/Assertions.h>
#include <LibC/errno_numbers.h>
enum KSuccessTag {
KSuccess
};
class KResult {
public:
explicit KResult(int negative_e)
: m_error(negative_e)
{
ASSERT(negative_e <= 0);
}
KResult(KSuccessTag)
: m_error(0)
{
}
operator int() const { return m_error; }
bool is_success() const { return m_error == ESUCCESS; }
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)
{
}
KResultOr(T&& value)
{
new (&m_storage) T(move(value));
}
template<typename U>
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.m_is_error = true;
other.m_error = KSuccess;
}
~KResultOr()
{
if (!m_is_error)
value().~T();
}
bool is_error() const { return m_is_error; }
KResult error() const
{
ASSERT(m_is_error);
return m_error;
}
T& value()
{
ASSERT(!m_is_error);
return *reinterpret_cast<T*>(&m_storage);
}
const T& value() const
{
ASSERT(!m_is_error);
return *reinterpret_cast<T*>(&m_storage);
}
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 };
};
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