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/*
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/StringView.h>
#include <AK/Try.h>
#include <AK/Variant.h>
#if defined(AK_OS_SERENITY) && defined(KERNEL)
# include <LibC/errno_codes.h>
#else
# include <errno.h>
# include <string.h>
#endif
namespace AK {
class Error {
public:
[[nodiscard]] static Error from_errno(int code) { return Error(code); }
[[nodiscard]] static Error from_syscall(StringView syscall_name, int rc) { return Error(syscall_name, rc); }
[[nodiscard]] static Error from_string_view(StringView string_literal) { return Error(string_literal); }
// NOTE: Prefer `from_string_literal` when directly typing out an error message:
//
// return Error::from_string_literal("Class: Some failure");
//
// If you need to return a static string based on a dynamic condition (like
// picking an error from an array), then prefer `from_string_view` instead.
template<size_t N>
[[nodiscard]] ALWAYS_INLINE static Error from_string_literal(char const (&string_literal)[N])
{
return from_string_view(StringView { string_literal, N - 1 });
}
// Note: Don't call this from C++; it's here for Jakt interop (as the name suggests).
template<SameAs<StringView> T>
ALWAYS_INLINE static Error __jakt_from_string_literal(T string)
{
return from_string_view(string);
}
bool operator==(Error const& other) const
{
return m_code == other.m_code && m_string_literal == other.m_string_literal && m_syscall == other.m_syscall;
}
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; }
protected:
Error(int code)
: m_code(code)
{
}
private:
Error(StringView string_literal)
: m_string_literal(string_literal)
{
}
Error(StringView syscall_name, int rc)
: m_string_literal(syscall_name)
, m_code(-rc)
, m_syscall(true)
{
}
StringView m_string_literal;
int m_code { 0 };
bool m_syscall { false };
};
template<typename T, typename E>
class [[nodiscard]] ErrorOr {
template<typename U, typename F>
friend class ErrorOr;
public:
using ResultType = T;
using ErrorType = E;
ErrorOr()
requires(IsSame<T, Empty>)
: m_value_or_error(Empty {})
{
}
ALWAYS_INLINE ErrorOr(ErrorOr&&) = default;
ALWAYS_INLINE ErrorOr(ErrorOr const&) = default;
ALWAYS_INLINE ErrorOr& operator=(ErrorOr&&) = default;
ALWAYS_INLINE ErrorOr& operator=(ErrorOr const&) = default;
template<typename U>
ALWAYS_INLINE ErrorOr(ErrorOr<U, ErrorType> const& value)
requires(IsConvertible<U, T>)
: m_value_or_error(value.m_value_or_error.visit([](U const& v) -> Variant<T, ErrorType> { return v; }, [](ErrorType const& error) -> Variant<T, ErrorType> { return error; }))
{
}
template<typename U>
ALWAYS_INLINE ErrorOr(ErrorOr<U, ErrorType>& value)
requires(IsConvertible<U, T>)
: m_value_or_error(value.m_value_or_error.visit([](U& v) { return Variant<T, ErrorType>(move(v)); }, [](ErrorType& error) { return Variant<T, ErrorType>(move(error)); }))
{
}
template<typename U>
ALWAYS_INLINE ErrorOr(ErrorOr<U, ErrorType>&& value)
requires(IsConvertible<U, T>)
: m_value_or_error(value.m_value_or_error.visit([](U& v) { return Variant<T, ErrorType>(move(v)); }, [](ErrorType& error) { return Variant<T, ErrorType>(move(error)); }))
{
}
template<typename U>
ALWAYS_INLINE ErrorOr(U&& value)
requires(
requires { T(declval<U>()); } || requires { ErrorType(declval<RemoveCVReference<U>>()); })
: m_value_or_error(forward<U>(value))
{
}
#ifdef AK_OS_SERENITY
ErrorOr(ErrnoCode code)
: m_value_or_error(Error::from_errno(code))
{
}
#endif
T& value()
{
return m_value_or_error.template get<T>();
}
T const& value() const { return m_value_or_error.template get<T>(); }
ErrorType& error() { return m_value_or_error.template get<ErrorType>(); }
ErrorType const& error() const { return m_value_or_error.template get<ErrorType>(); }
bool is_error() const { return m_value_or_error.template has<ErrorType>(); }
T release_value() { return move(value()); }
ErrorType release_error() { return move(error()); }
T release_value_but_fixme_should_propagate_errors()
{
VERIFY(!is_error());
return release_value();
}
private:
Variant<T, ErrorType> m_value_or_error;
};
template<typename ErrorType>
class [[nodiscard]] ErrorOr<void, ErrorType> : public ErrorOr<Empty, ErrorType> {
public:
using ResultType = void;
using ErrorOr<Empty, ErrorType>::ErrorOr;
};
}
#if USING_AK_GLOBALLY
using AK::Error;
using AK::ErrorOr;
#endif
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