tuple_matcher.hpp

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#pragma once
 
#include <boost/mp11/algorithm.hpp>
#include <boost/mp11/detail/mp_rename.hpp>
 
#include <concepts>
#include <cstring>
#include <functional>
#include <optional>
#include <string_view>
#include <tuple>
#include <type_traits>
#include <utility>
#include <variant>
 
namespace asmgrader {
 
namespace detail {
 
template <typename Ret, typename Func, typename T, typename... Ts>
constexpr Ret tuple_find_first_impl(Func&& pred, const T& val, const Ts&... rest) {
    if (std::invoke(std::forward<Func>(pred), val)) {
        return Ret{std::in_place, val};
    }
 
    if constexpr (sizeof...(Ts) > 0) {
        return tuple_find_first_impl<Ret>(std::forward<Func>(pred), rest...);
    }
 
    return std::nullopt;
}
 
} // namespace detail
 
template <typename Func, typename Tuple>
constexpr auto tuple_find_first(Func&& pred, const Tuple& val) {
    using VariantT = boost::mp11::mp_rename<boost::mp11::mp_unique<Tuple>, std::variant>;
    using Ret = std::optional<VariantT>;
 
    if constexpr (std::tuple_size_v<Tuple> == 0) {
        return Ret{std::nullopt};
    } else {
        return std::apply(
            [&pred](const auto&... elems) {
                return detail::tuple_find_first_impl<Ret>(std::forward<Func>(pred), elems...);
            },
            val);
    }
}
 
} // namespace asmgrader