Program Listing for File error.hpp

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/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2022 Maarten L. Hekkelman
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

#include <cassert>
#include <string>
#include <system_error>

namespace mcfp
{

// we use the new system_error stuff.

enum class config_error
{
    unknown_option = 1,
    option_does_not_accept_argument,
    missing_argument_for_option,
    option_not_specified,
    invalid_config_file,
    wrong_type_cast,
    config_file_not_found
};
class config_category_impl : public std::error_category
{
  public:
    const char *name() const noexcept override
    {
        return "configuration";
    }

    std::string message(int ev) const override
    {
        switch (static_cast<config_error>(ev))
        {
            case config_error::unknown_option:
                return "unknown option";
            case config_error::option_does_not_accept_argument:
                return "option does not accept argument";
            case config_error::missing_argument_for_option:
                return "missing argument for option";
            case config_error::option_not_specified:
                return "option was not specified";
            case config_error::invalid_config_file:
                return "config file contains a syntax error";
            case config_error::wrong_type_cast:
                return "the implementation contains a type cast error";
            case config_error::config_file_not_found:
                return "the specified config file was not found";
            default:
                assert(false);
                return "unknown error code";
        }
    }

    bool equivalent(const std::error_code & /*code*/, int /*condition*/) const noexcept override
    {
        return false;
    }
};

inline std::error_category &config_category()
{
    static config_category_impl instance;
    return instance;
}

inline std::error_code make_error_code(config_error e)
{
    return std::error_code(static_cast<int>(e), config_category());
}

inline std::error_condition make_error_condition(config_error e)
{
    return std::error_condition(static_cast<int>(e), config_category());
}

} // namespace mcfp