wrappers.hxx

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/*
 * Copyright (C) 2024-2026 David C. Manuelda (StormBytePP)
 *
 * This file is part of StormByte.
 *
 * StormByte is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License version 3
 * or later, as published by the Free Software Foundation.
 *
 * StormByte 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with StormByte. If not, see
 * <https://www.gnu.org/licenses/lgpl-3.0.html>.
 */
 
#pragma once
 
#include <concepts>
#include <cstddef>
#include <optional>
#include <type_traits>
#include <utility>
#include <variant>
 
namespace StormByte {
    namespace Type {
        namespace Detail {
            template<typename T>
            constexpr bool is_variant_v = false;
 
            template<typename... Ts>
            constexpr bool is_variant_v<std::variant<Ts...>> = true;
 
            template<typename VariantT, typename U, std::size_t... I>
            constexpr bool variant_has_type_impl(std::index_sequence<I...> seq) noexcept {
                (void)seq;
                return ((std::is_same_v<
                    std::remove_cvref_t<U>,
                    std::remove_cvref_t<std::variant_alternative_t<I, VariantT>>
                >) || ...);
            }
 
            template<typename VariantT, typename U>
            constexpr bool variant_has_type_v =
                variant_has_type_impl<VariantT, U>(
                    std::make_index_sequence<std::variant_size_v<VariantT>>()
                );
        }
 
        template<typename T>
        concept Optional =
            requires { typename T::value_type; } &&
            std::same_as<T, std::optional<typename T::value_type>>;
 
        template<typename T>
        concept Pair = requires(T t) {
            t.first;
            t.second;
        };
 
        template<typename T>
        concept Variant = Detail::is_variant_v<std::remove_cvref_t<T>>;
 
        template<typename T, typename U>
        concept VariantHasType =
            Variant<T> &&
            Detail::variant_has_type_v<std::remove_cvref_t<T>, U>;
    }
}