serenity/AK/Error.h
Andreas Kling c4edb9f6c2 AK: Add Error and ErrorOr<T>
The goal with these is to eventually replace AK::Result, KResult and
KResultOr<T> with something that works (and makes sense) in both kernel
and userspace.

This first cut of Error can be made from an errno code, or from a string
literal (StringView)
2021-11-08 00:35:27 +01:00

121 lines
2.5 KiB
C++

/*
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Format.h>
#include <AK/Optional.h>
#include <AK/StringView.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_string_literal(StringView string_literal) { return Error(string_literal); }
bool is_errno() const { return m_code != 0; }
int code() const { return m_code; }
StringView string_literal() const { return m_string_literal; }
private:
Error(int code)
: m_code(code)
{
}
Error(StringView string_literal)
: m_string_literal(string_literal)
{
}
int m_code { 0 };
StringView m_string_literal;
};
template<typename T>
class [[nodiscard]] ErrorOr {
public:
ErrorOr(T const& value)
: m_value(value)
{
}
ErrorOr(T&& value)
: m_value(move(value))
{
}
ErrorOr(ErrnoCode errno)
: m_error(Error::from_errno(errno))
{
}
ErrorOr(Error&& error)
: m_error(move(error))
{
}
ErrorOr(ErrorOr&& other) = default;
ErrorOr(ErrorOr const& other) = default;
~ErrorOr() = default;
T& value() { return m_value.value(); }
Error& error() { return m_error.value(); }
bool is_error() const { return m_error.has_value(); }
T release_value() { return m_value.release_value(); }
Error release_error() { return m_error.release_value(); }
private:
Optional<T> m_value;
Optional<Error> m_error;
};
// Partial specialization for void value type
template<>
class [[nodiscard]] ErrorOr<void> {
public:
ErrorOr(Error error)
: m_error(move(error))
{
}
ErrorOr() = default;
ErrorOr(ErrorOr&& other) = default;
ErrorOr(const ErrorOr& other) = default;
~ErrorOr() = default;
Error& error() { return m_error.value(); }
bool is_error() const { return m_error.has_value(); }
Error release_error() { return m_error.release_value(); }
private:
Optional<Error> m_error;
};
template<>
struct Formatter<Error> : Formatter<FormatString> {
void format(FormatBuilder& builder, Error const& error)
{
if (error.is_errno())
return Formatter<FormatString>::format(builder, "Error(errno={})", error.code());
return Formatter<FormatString>::format(builder, "Error({})", error.string_literal());
}
};
}
using AK::ErrorOr;