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1a4dd47d5f
While the code did already VERIFY that the ErrorOr holds a value, this was done by Variant, so the error message was just that `has<T>()` is false. This is less helpful than I would like, especially if backtraces are not working and this is all you have to go on. Adding this extra VERIFY means the assertion message (`!is_error()`) is easier to understand.
137 lines
3.2 KiB
C++
137 lines
3.2 KiB
C++
/*
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* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Optional.h>
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#include <AK/StringView.h>
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#include <AK/Try.h>
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#include <AK/Variant.h>
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#if defined(__serenity__) && defined(KERNEL)
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# include <LibC/errno_codes.h>
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#else
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# include <errno.h>
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# include <string.h>
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#endif
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namespace AK {
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class Error {
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public:
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static Error from_errno(int code) { return Error(code); }
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static Error from_syscall(StringView syscall_name, int rc) { return Error(syscall_name, rc); }
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static Error from_string_literal(StringView string_literal) { return Error(string_literal); }
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bool is_errno() const { return m_code != 0; }
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bool is_syscall() const { return m_syscall; }
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int code() const { return m_code; }
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StringView string_literal() const { return m_string_literal; }
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protected:
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Error(int code)
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: m_code(code)
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{
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}
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private:
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Error(StringView string_literal)
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: m_string_literal(string_literal)
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{
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}
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Error(StringView syscall_name, int rc)
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: m_code(-rc)
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, m_string_literal(syscall_name)
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, m_syscall(true)
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{
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}
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int m_code { 0 };
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StringView m_string_literal;
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bool m_syscall { false };
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};
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template<typename T, typename ErrorType>
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class [[nodiscard]] ErrorOr final : public Variant<T, ErrorType> {
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public:
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using Variant<T, ErrorType>::Variant;
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template<typename U>
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ALWAYS_INLINE ErrorOr(U&& value) requires(!IsSame<RemoveCVReference<U>, ErrorOr<T>>)
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: Variant<T, ErrorType>(forward<U>(value))
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{
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}
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#ifdef __serenity__
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ErrorOr(ErrnoCode code)
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: Variant<T, ErrorType>(Error::from_errno(code))
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{
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}
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#endif
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T& value()
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{
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return this->template get<T>();
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}
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T const& value() const { return this->template get<T>(); }
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ErrorType& error() { return this->template get<ErrorType>(); }
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ErrorType const& error() const { return this->template get<ErrorType>(); }
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bool is_error() const { return this->template has<ErrorType>(); }
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T release_value() { return move(value()); }
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ErrorType release_error() { return move(error()); }
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T release_value_but_fixme_should_propagate_errors()
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{
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VERIFY(!is_error());
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return release_value();
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}
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private:
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// 'downcast' is fishy in this context. Let's hide it by making it private.
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using Variant<T, ErrorType>::downcast;
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};
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// Partial specialization for void value type
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template<typename ErrorType>
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class [[nodiscard]] ErrorOr<void, ErrorType> {
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public:
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ErrorOr(ErrorType error)
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: m_error(move(error))
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{
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}
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#ifdef __serenity__
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ErrorOr(ErrnoCode code)
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: m_error(Error::from_errno(code))
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{
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}
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#endif
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ErrorOr() = default;
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ErrorOr(ErrorOr&& other) = default;
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ErrorOr(ErrorOr const& other) = default;
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~ErrorOr() = default;
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ErrorOr& operator=(ErrorOr&& other) = default;
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ErrorOr& operator=(ErrorOr const& other) = default;
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ErrorType& error() { return m_error.value(); }
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bool is_error() const { return m_error.has_value(); }
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ErrorType release_error() { return m_error.release_value(); }
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void release_value() { }
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private:
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Optional<ErrorType> m_error;
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};
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}
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using AK::Error;
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using AK::ErrorOr;
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