optional.hpp

/*
 * Container for optional data.
 * Copyright (C) 2014  Michał Walenciak <MichalWalenciak@gmail.com>
 *
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef OPENLIBRARY_UTILS_OPTIONAL_HPP
#define OPENLIBRARY_UTILS_OPTIONAL_HPP

namespace ol
{

    template<typename T>
    class Optional
    {
        public:
            Optional(): m_data(), m_present(false) {}
            Optional(const Optional<T>& other): m_data(other.m_data), m_present(other.m_present) {}
            Optional(const T& data): m_data(data), m_present(true) {}
            Optional(Optional<T>&& other): m_data(std::move(other.m_data)), m_present(other.m_present) {}

            Optional<T>& operator=(const Optional<T>& other)
            {
                m_data = other.m_data;
                m_present = other.m_present;

                return *this;
            }

            Optional<T>& operator=(const T& data)
            {
                m_data = data;
                m_present = true;

                return *this;
            }

            Optional<T>& operator=(T&& data)
            {
                m_data = std::move(data);
                m_present = true;

                return *this;
            }

            const T* operator->() const
            {
                return &m_data;
            }

            T* operator->()
            {
                return &m_data;
            }

            const T& operator*() const
            {
                return m_data;
            }

            T& operator*()
            {
                return m_data;
            }

            bool operator!() const
            {
                return !m_present;
            }

            operator bool() const
            {
                return m_present;
            }

            bool is_initialized() const
            {
                return m_present;
            }

        private:
            T m_data;
            bool m_present;
    };

}

#endif // OPENLIBRARY_UTILS_OPTIONAL_HPP