Result.h

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// Copyright 2024 libsese
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
 
#pragma once
 
#include "sese/net/Socket.h"
#include "Util.h"
#include "ErrorCode.h"
 
#include <variant>
 
namespace sese {
 
template<class T>
class Result final {
    std::variant<ErrorCode, T> err_result;
 
public:
    Result(ErrorCode err) : err_result(err) {} // NOLINT
 
    Result(int32_t code, const std::string &msg) : err_result(ErrorCode{code, msg}) {}
 
    Result(T result) : err_result(std::forward<T>(result)) {} // NOLINT
 
    static Result fromLastError();
 
    static Result fromLastNetworkError();
 
    explicit operator bool() const noexcept {
        return std::holds_alternative<ErrorCode>(err_result);
    }
 
    [[nodiscard]] ErrorCode err() const noexcept {
        assert(std::holds_alternative<ErrorCode>(err_result));
        return std::get<ErrorCode>(err_result);
    }
 
    T &get() noexcept {
        assert(std::holds_alternative<T>(err_result));
        return std::get<T>(err_result);
    }
 
    const T &get() const noexcept {
        assert(std::holds_alternative<T>(err_result));
        return std::get<T>(err_result);
    }
};
 
template<class T>
Result<T> Result<T>::fromLastError() {
    return {getErrorCode(), getErrorString()};
}
 
template<class T>
Result<T> Result<T>::fromLastNetworkError() {
    return {net::getNetworkError(), net::getNetworkErrorString()};
}
 
} // namespace sese