105 lines
2.3 KiB
C++
105 lines
2.3 KiB
C++
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// Copyright 2024 The DMBMX2Tools Authors
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// SPDX-License-Identifier: MIT
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#pragma once
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#include <optional>
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#include <system_error>
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#include <variant>
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namespace dmtools {
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template <class T>
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struct ErrorOr {
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private:
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using Variant = std::variant<T, std::error_code>;
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public:
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constexpr static auto IsVoid = false;
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ErrorOr() = default;
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ErrorOr(const ErrorOr&) = default;
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ErrorOr(ErrorOr&&) = default;
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ErrorOr(const T& v)
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: maybeVariant(v) {}
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ErrorOr(const std::error_code& v)
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: maybeVariant(v) {}
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ErrorOr& operator=(const T& value) {
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maybeVariant = value;
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return *this;
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}
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ErrorOr& operator=(const std::error_code& ec) {
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maybeVariant = ec;
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return *this;
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}
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bool HasValue() const {
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if(maybeVariant)
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return std::holds_alternative<T>(*maybeVariant);
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// No value.
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return false;
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}
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bool HasError() const {
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if(maybeVariant)
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return std::holds_alternative<std::error_code>(*maybeVariant);
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// No error. Possibly in the default constructed state
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return false;
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}
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// ASSERT TODO
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T& Value() { return std::get<T>(maybeVariant.value()); }
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const T& Value() const { return std::get<T>(maybeVariant.value()); }
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operator T&() { return Value(); }
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operator const T&() { return Value(); }
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std::error_code& Error() { return std::get<std::error_code>(maybeVariant.value()); }
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const std::error_code& Error() const { return std::get<std::error_code>(maybeVariant.value()); }
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operator std::error_code&() { return Error(); }
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operator const std::error_code&() const { return Error(); }
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private:
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std::optional<Variant> maybeVariant;
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};
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template <>
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struct ErrorOr<void> {
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constexpr static auto IsVoid = true;
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ErrorOr() = default;
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ErrorOr(const ErrorOr&) = default;
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ErrorOr(ErrorOr&&) = default;
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ErrorOr(const std::error_code& v)
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: maybeEc(v) {}
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ErrorOr& operator=(const std::error_code& ec) {
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maybeEc = ec;
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return *this;
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}
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bool HasError() const { return maybeEc.has_value(); }
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std::error_code& Error() { return maybeEc.value(); }
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const std::error_code& Error() const { return maybeEc.value(); }
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operator std::error_code&() { return Error(); }
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operator const std::error_code&() const { return Error(); }
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private:
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std::optional<std::error_code> maybeEc;
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};
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inline std::error_code ThrowErrno() {
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return { errno, std::system_category() };
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}
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} // namespace dmtools
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