Common.hpp

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//          Copyright Dominic (DNKpp) Koepke 2024 - 2025.
// Distributed under the Boost Software License, Version 1.0.
//    (See accompanying file LICENSE_1_0.txt or copy at
//          https://www.boost.org/LICENSE_1_0.txt)
 
#ifndef MIMICPP_MATCHERS_COMMON_HPP
#define MIMICPP_MATCHERS_COMMON_HPP
 
#pragma once
 
#include "mimic++/Fwd.hpp"
#include "mimic++/config/Config.hpp"
#include "mimic++/utilities/Concepts.hpp"
#include "mimic++/utilities/PriorityTag.hpp"
 
#ifndef MIMICPP_DETAIL_IS_MODULE
    #include <concepts>
    #include <optional>
    #include <type_traits>
#endif
 
MIMICPP_DETAIL_MODULE_EXPORT namespace mimicpp::custom
{
    template <typename Matcher>
    struct matcher_traits;
}
 
namespace mimicpp::detail::matches_hook
{
    template <typename Matcher, typename T, typename... Others>
    [[nodiscard]]
    constexpr bool matches_impl(
        [[maybe_unused]] util::priority_tag<1> const,
        Matcher const& matcher,
        T& target,
        Others&... others)
        requires requires {
            { custom::matcher_traits<Matcher>{}.matches(matcher, target, others...) } -> util::boolean_testable;
        }
    {
        return custom::matcher_traits<Matcher>{}.matches(matcher, target, others...);
    }
 
    template <typename Matcher, typename T, typename... Others>
    [[nodiscard]]
    constexpr bool matches_impl(
        [[maybe_unused]] util::priority_tag<0> const,
        Matcher const& matcher,
        T& target,
        Others&... others)
        requires requires {
            { matcher.matches(target, others...) } -> util::boolean_testable;
        }
    {
        return matcher.matches(target, others...);
    }
 
    inline constexpr util::priority_tag<1> maxTag{};
 
    struct matches_fn
    {
        template <typename Matcher, typename T, typename... Others>
        [[nodiscard]]
        constexpr bool operator()(Matcher const& matcher, T& target, Others&... others) const
            requires requires {
                { matches_impl(maxTag, matcher, target, others...) } -> util::boolean_testable;
            }
        {
            return matches_impl(maxTag, matcher, target, others...);
        }
    };
 
    inline constexpr matches_fn matches{};
}
 
namespace mimicpp::detail::describe_hook
{
    // This section uses trailing return-types because this seems to help clangd in some cases.
    template <typename Matcher>
    [[nodiscard]]
    constexpr auto describe_impl([[maybe_unused]] util::priority_tag<1> const, Matcher const& matcher)
        -> decltype(custom::matcher_traits<Matcher>{}.describe(matcher))
        requires requires {
            {
                custom::matcher_traits<Matcher>{}.describe(matcher)
            } -> util::explicitly_convertible_to<std::optional<StringT>>;
        }
    {
        return custom::matcher_traits<Matcher>{}.describe(matcher);
    }
 
    template <typename Matcher>
    [[nodiscard]]
    constexpr auto describe_impl([[maybe_unused]] util::priority_tag<0> const, Matcher const& matcher)
        -> decltype(matcher.describe())
        requires requires {
            { matcher.describe() } -> util::explicitly_convertible_to<std::optional<StringT>>;
        }
    {
        return matcher.describe();
    }
 
    inline constexpr util::priority_tag<1> maxTag{};
 
    struct describe_fn
    {
        template <typename Matcher>
        [[nodiscard]]
        constexpr auto operator()(Matcher const& matcher) const
            -> decltype(describe_impl(maxTag, matcher))
            requires requires {
                { describe_impl(maxTag, matcher) } -> util::explicitly_convertible_to<std::optional<StringT>>;
            }
        {
            return describe_impl(maxTag, matcher);
        }
    };
 
    inline constexpr describe_fn describe{};
}
 
namespace mimicpp
{
    namespace detail
    {
        template <typename Matcher, typename... Args>
        struct is_matcher_accepting
            : public std::true_type
        {
        };
 
        template <template <typename...> typename is_accepting, typename... Args>
        struct is_matcher_accepting_helper
            : public is_accepting<Args...>
        {
        };

        template <typename Matcher, typename... Args>
            requires requires { typename is_matcher_accepting_helper<Matcher::template is_accepting, Args...>; }
        struct is_matcher_accepting<Matcher, Args...>
            : public is_matcher_accepting_helper<Matcher::template is_accepting, Args...>
        {
        };
    }

    template <typename Matcher, typename... Args>
    inline constexpr bool is_matcher_accepting_v{detail::is_matcher_accepting<Matcher, Args...>::value};
}
 
MIMICPP_DETAIL_MODULE_EXPORT namespace mimicpp
{
    template <typename T, typename First, typename... Others>
    concept matcher_for = std::same_as<T, std::remove_cvref_t<T>>
                       && std::is_move_constructible_v<T>
                       && std::destructible<T>
                       && is_matcher_accepting_v<T, First, Others...>
                       && requires(T const& matcher, First& first, Others&... others) {
                              { detail::matches_hook::matches(matcher, first, others...) } -> util::boolean_testable;
                              { detail::describe_hook::describe(matcher) } -> util::explicitly_convertible_to<std::optional<StringT>>;
                          };
}
 
#endif