result.h

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/*
    Gemini Power Box Hub Advanced v3 INDI Driver
 
    Copyright (C) 2026 Dieter R Kedrowitsch <[email protected]>
 
    This program is free software; you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by the Free
    Software Foundation; either version 2 of the License, or (at your option)
    any later version.
 
    This program is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
    more details.
 
    You should have received a copy of the GNU General Public License along with
    this program; if not, write to the Free Software Foundation, Inc., 59 Temple
    Place - Suite 330, Boston, MA  02111-1307, USA.
 
    The full GNU General Public License is included in this distribution in the
    file called LICENSE.
*/
 
#pragma once
 
#include <optional>
#include <utility>
 
namespace geminipbh
{
 
enum class Error
{
    None,
    InvalidChannel,
    InvalidValue,
    NotConnected,
    CommunicationFailure,
    QueueRejected,
    ProtocolRejected,
    ValueUnavailable,
    InvalidState,
    Busy,
    Cancelled
};
 
class Result
{
    public:
        constexpr Result() = default;
 
        static constexpr Result success()
        {
            return Result(Error::None);
        }
        static constexpr Result failure(Error error)
        {
            return Result(error == Error::None ? Error::ProtocolRejected : error);
        }
 
        constexpr bool ok() const
        {
            return error_ == Error::None;
        }
        constexpr explicit operator bool() const
        {
            return ok();
        }
        constexpr Error error() const
        {
            return error_;
        }
 
    private:
        constexpr explicit Result(Error error) : error_(error) {}
 
        Error error_ = Error::None;
};
 
template <typename T>
class ValueResult
{
    public:
        explicit ValueResult(T value) : error_(Error::None), value_(std::move(value)) {}
 
        static ValueResult failure(Error error)
        {
            return ValueResult(error == Error::None ? Error::ValueUnavailable : error);
        }
 
        bool ok() const
        {
            return error_ == Error::None;
        }
        explicit operator bool() const
        {
            return ok();
        }
        Error error() const
        {
            return error_;
        }
        const T &value() const
        {
            return *value_;
        }
 
    private:
        explicit ValueResult(Error error) : error_(error) {}
 
        Error error_ = Error::None;
        std::optional<T> value_;
};
 
} // namespace geminipbh