ladybird/AK/Error.h

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/*
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Optional.h>
#include <AK/StringView.h>
#include <AK/Try.h>
#if defined(__serenity__) && defined(KERNEL)
# include <LibC/errno_numbers.h>
#else
# include <errno.h>
#endif
namespace AK {
class Error {
public:
static Error from_errno(int code) { return Error(code); }
static Error from_syscall(StringView syscall_name, int rc) { return Error(syscall_name, rc); }
static Error from_string_literal(StringView string_literal) { return Error(string_literal); }
bool is_errno() const { return m_code != 0; }
bool is_syscall() const { return m_syscall; }
int code() const { return m_code; }
StringView string_literal() const { return m_string_literal; }
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protected:
Error(int code)
: m_code(code)
{
}
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private:
Error(StringView string_literal)
: m_string_literal(string_literal)
{
}
Error(StringView syscall_name, int rc)
: m_code(-rc)
, m_string_literal(syscall_name)
, m_syscall(true)
{
}
int m_code { 0 };
StringView m_string_literal;
bool m_syscall { false };
};
template<typename T, typename ErrorType>
class [[nodiscard]] ErrorOr {
public:
ErrorOr(T const& value)
: m_value(value)
{
}
ErrorOr(T&& value)
: m_value(move(value))
{
}
template<typename U>
ALWAYS_INLINE ErrorOr(U&& value) requires(!IsSame<RemoveCVReference<U>, ErrorOr<T>>)
: m_value(forward<U>(value))
{
}
#ifdef __serenity__
ErrorOr(ErrnoCode code)
: m_error(Error::from_errno(code))
{
}
#endif
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ErrorOr(ErrorType&& error)
: m_error(move(error))
{
}
ErrorOr(ErrorOr&& other) = default;
ErrorOr(ErrorOr const& other) = default;
~ErrorOr() = default;
ErrorOr& operator=(ErrorOr&& other) = default;
ErrorOr& operator=(ErrorOr const& other) = default;
T& value() { return m_value.value(); }
T const& value() const { return m_value.value(); }
ErrorType& error() { return m_error.value(); }
ErrorType const& error() const { return m_error.value(); }
bool is_error() const { return m_error.has_value(); }
T release_value() { return m_value.release_value(); }
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ErrorType release_error() { return m_error.release_value(); }
T release_value_but_fixme_should_propagate_errors() { return release_value(); }
private:
Optional<T> m_value;
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Optional<ErrorType> m_error;
};
// Partial specialization for void value type
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template<typename ErrorType>
class [[nodiscard]] ErrorOr<void, ErrorType> {
public:
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ErrorOr(ErrorType error)
: m_error(move(error))
{
}
#ifdef __serenity__
ErrorOr(ErrnoCode code)
: m_error(Error::from_errno(code))
{
}
#endif
ErrorOr() = default;
ErrorOr(ErrorOr&& other) = default;
ErrorOr(ErrorOr const& other) = default;
~ErrorOr() = default;
ErrorOr& operator=(ErrorOr&& other) = default;
ErrorOr& operator=(ErrorOr const& other) = default;
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ErrorType& error() { return m_error.value(); }
bool is_error() const { return m_error.has_value(); }
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ErrorType release_error() { return m_error.release_value(); }
void release_value() { }
private:
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Optional<ErrorType> m_error;
};
}
using AK::Error;
using AK::ErrorOr;