qhttpserverrouterviewtraits.h

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// Copyright (C) 2020 Mikhail Svetkin <mikhail.svetkin@gmail.com>

// Copyright (C) 2019 The Qt Company Ltd.

// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only

// Qt-Security score:significant reason:default

#ifndef QHTTPSERVERROUTERVIEWTRAITS_H

#define QHTTPSERVERROUTERVIEWTRAITS_H

#include <QtHttpServer/qhttpserverviewtraits_impl.h>

QT_BEGIN_NAMESPACE

class QHttpServerRequest;

class QHttpServerResponder;

namespace QtPrivate {

template<typename ViewHandler, bool DisableStaticAssert>

struct RouterViewTraitsHelper : ViewTraits<ViewHandler, DisableStaticAssert> {

    using VTraits = ViewTraits<ViewHandler, DisableStaticAssert>;

    using FunctionTraits = typename VTraits::FTraits;

    template<int I>

    struct ArgumentChecker : FunctionTraits::template Arg<I> {

        using IsRequestCLvalue = typename VTraits::template Special<I, const QHttpServerRequest &>;

        using IsRequestValue = typename VTraits::template Special<I, QHttpServerRequest>;

        using IsRequest = CheckAny<IsRequestCLvalue, IsRequestValue>;

        static_assert(IsRequest::StaticAssert,

                      "ViewHandler arguments error: "

                      "QHttpServerRequest can only be passed by value or as a const Lvalue");

        using IsResponderLvalue = typename VTraits::template Special<I, QHttpServerResponder &>;

        using IsResponderRvalue = typename VTraits::template Special<I, QHttpServerResponder &&>;

        using IsResponder = CheckAny<IsResponderLvalue, IsResponderRvalue>;

        static_assert(IsResponder::StaticAssert,

                      "ViewHandler arguments error: "

                      "QHttpServerResponder can only be passed as a reference or Rvalue "

                      "reference");

        using IsSpecial = CheckAny<IsRequest, IsResponder>;

        struct IsSimple {

            static constexpr bool TypeMatched = !IsSpecial::TypeMatched &&

                                           I < FunctionTraits::ArgumentCount &&

                                           FunctionTraits::ArgumentIndexMax != -1;

            static constexpr bool Value =

                    !IsSpecial::Value && FunctionTraits::template Arg<I>::CopyConstructible;

            static constexpr bool StaticAssert =

                DisableStaticAssert || Value || !TypeMatched;

            static_assert(StaticAssert,

                          "ViewHandler arguments error: "

                          "Type is not copy constructible");

};

        using CheckOk = CheckAny<IsSimple, IsSpecial>;

        static constexpr bool Value = CheckOk::Value;

        static constexpr bool StaticAssert = CheckOk::StaticAssert;

};

    struct Arguments {

        template<size_t ... I>

        struct ArgumentsReturn {

            template<int Idx>

            using Arg = ArgumentChecker<Idx>;

            template<int Idx>

            static constexpr QMetaType metaType() noexcept

                using Type = typename FunctionTraits::template Arg<Idx>::CleanType;

                constexpr bool Simple = Arg<Idx>::IsSimple::Value;

                if constexpr (Simple && std::is_copy_assignable_v<Type>)

                    return QMetaType::fromType<Type>();

                else

                    return QMetaType::fromType<void>();

            static constexpr std::size_t Count = FunctionTraits::ArgumentCount;

            static constexpr std::size_t CapturableCount =

                    (0 + ... + static_cast<std::size_t>(Arg<I>::IsSimple::Value));

            static constexpr std::size_t SpecialsCount = Count - CapturableCount;

            static constexpr bool Value = (Arg<I>::Value && ...);

            static constexpr bool StaticAssert = (Arg<I>::StaticAssert && ...);

            using Indexes = std::index_sequence<I...>;

            using CapturableIndexes = std::make_index_sequence<CapturableCount>;

            using SpecialIndexes = std::make_index_sequence<SpecialsCount>;

            using Last = Arg<FunctionTraits::ArgumentIndexMax>;

            using SecondLast = Arg<FunctionTraits::ArgumentIndexMax - 1>;

};

        template<size_t ... I>

        static constexpr ArgumentsReturn<I...> eval(std::index_sequence<I...>) noexcept;

};

    template<int CaptureOffset>

    struct BindType {

        template<typename ... Args>

        struct FunctionWrapper {

            using Type = std::function<typename FunctionTraits::ReturnType (Args...)>;

};

        template<int Id>

        using OffsetArg = typename FunctionTraits::template Arg<CaptureOffset + Id>::Type;

        template<size_t ... Idx>

        static constexpr typename FunctionWrapper<OffsetArg<Idx>...>::Type

                eval(std::index_sequence<Idx...>) noexcept;

};

};

} // namespace QtPrivate

template <typename ViewHandler, bool DisableStaticAssert = false>

struct QHttpServerRouterViewTraits

    using Helpers = typename QtPrivate::RouterViewTraitsHelper<ViewHandler, DisableStaticAssert>;

    using ReturnType = typename Helpers::FunctionTraits::ReturnType;

    using Arguments = decltype(Helpers::Arguments::eval(typename Helpers::ArgumentIndexes{}));

    using BindableType = decltype(Helpers::template BindType<Arguments::CapturableCount>::eval(

            typename Arguments::SpecialIndexes{}));

};

QT_END_NAMESPACE

#endif  // QHTTPSERVERROUTERVIEWTRAITS_H