diff options
Diffstat (limited to 'src/corelib/global/qnativeinterface.h')
| -rw-r--r-- | src/corelib/global/qnativeinterface.h | 193 |
1 files changed, 100 insertions, 93 deletions
diff --git a/src/corelib/global/qnativeinterface.h b/src/corelib/global/qnativeinterface.h index d32e2cd982..89f33651c5 100644 --- a/src/corelib/global/qnativeinterface.h +++ b/src/corelib/global/qnativeinterface.h @@ -1,55 +1,10 @@ -/**************************************************************************** -** -** Copyright (C) 2021 The Qt Company Ltd. -** Contact: https://www.qt.io/licensing/ -** -** This file is part of the QtCore module of the Qt Toolkit. -** -** $QT_BEGIN_LICENSE:LGPL$ -** Commercial License Usage -** Licensees holding valid commercial Qt licenses may use this file in -** accordance with the commercial license agreement provided with the -** Software or, alternatively, in accordance with the terms contained in -** a written agreement between you and The Qt Company. For licensing terms -** and conditions see https://www.qt.io/terms-conditions. For further -** information use the contact form at https://www.qt.io/contact-us. -** -** GNU Lesser General Public License Usage -** Alternatively, this file may be used under the terms of the GNU Lesser -** General Public License version 3 as published by the Free Software -** Foundation and appearing in the file LICENSE.LGPL3 included in the -** packaging of this file. Please review the following information to -** ensure the GNU Lesser General Public License version 3 requirements -** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. -** -** GNU General Public License Usage -** Alternatively, this file may be used under the terms of the GNU -** General Public License version 2.0 or (at your option) the GNU General -** Public license version 3 or any later version approved by the KDE Free -** Qt Foundation. The licenses are as published by the Free Software -** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 -** included in the packaging of this file. Please review the following -** information to ensure the GNU General Public License requirements will -** be met: https://www.gnu.org/licenses/gpl-2.0.html and -** https://www.gnu.org/licenses/gpl-3.0.html. -** -** $QT_END_LICENSE$ -** -****************************************************************************/ +// Copyright (C) 2021 The Qt Company Ltd. +// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only #ifndef QNATIVEINTERFACE_H #define QNATIVEINTERFACE_H #include <QtCore/qglobal.h> -#include <QtCore/qloggingcategory.h> - -#ifndef QT_STATIC -# define Q_NATIVE_INTERFACE_EXPORT Q_DECL_EXPORT -# define Q_NATIVE_INTERFACE_IMPORT Q_DECL_IMPORT -#else -# define Q_NATIVE_INTERFACE_EXPORT -# define Q_NATIVE_INTERFACE_IMPORT -#endif QT_BEGIN_NAMESPACE @@ -61,12 +16,24 @@ QT_BEGIN_NAMESPACE #define QT_DECLARE_NATIVE_INTERFACE_3(NativeInterface, Revision, BaseType) \ protected: \ virtual ~NativeInterface(); \ + \ struct TypeInfo { \ using baseType = BaseType; \ static constexpr char const *name = QT_STRINGIFY(NativeInterface); \ static constexpr int revision = Revision; \ }; \ + \ + template <typename, typename> \ + friend struct QNativeInterface::Private::has_type_info; \ + \ + template <typename> \ + friend bool constexpr QNativeInterface::Private::hasTypeInfo(); \ + \ + template <typename> \ + friend struct QNativeInterface::Private::TypeInfo; \ public: \ + NativeInterface() = default; \ + Q_DISABLE_COPY_MOVE(NativeInterface) // Revisioned interfaces only make sense when exposed through a base // type via QT_DECLARE_NATIVE_INTERFACE_ACCESSOR, as the revision @@ -81,60 +48,100 @@ QT_BEGIN_NAMESPACE QT_OVERLOADED_MACRO(QT_DECLARE_NATIVE_INTERFACE, __VA_ARGS__) namespace QNativeInterface::Private { + + // Basic type-trait to verify that a given native interface has + // all the required type information for us to evaluate it. + template <typename NativeInterface, typename = void> + struct has_type_info : std::false_type {}; + + // The type-trait is friended by TypeInfo, so that we can + // evaluate TypeInfo in the template arguments. template <typename NativeInterface> - struct TypeInfo : private NativeInterface + struct has_type_info<NativeInterface, std::void_t< + typename NativeInterface::TypeInfo, + typename NativeInterface::TypeInfo::baseType, + decltype(&NativeInterface::TypeInfo::name), + decltype(&NativeInterface::TypeInfo::revision) + >> : std::true_type {}; + + // We need to wrap the instantiation of has_type_info in a + // function friended by TypeInfo, otherwise MSVC will not + // let us evaluate TypeInfo in the template arguments. + template <typename NativeInterface> + bool constexpr hasTypeInfo() { - static constexpr char const *name() { return NativeInterface::TypeInfo::name; } - static constexpr int revision() { return NativeInterface::TypeInfo::revision; } + return has_type_info<NativeInterface>::value; + } - template<typename BaseType> - static constexpr bool isCompatibleWith = - std::is_base_of<typename NativeInterface::TypeInfo::baseType, BaseType>::value; + template <typename NativeInterface> + struct TypeInfo + { + // To ensure SFINAE works for hasTypeInfo we can't use it in a constexpr + // variable that also includes an expression that relies on the type + // info. This helper variable is okey, as it it self contained. + static constexpr bool haveTypeInfo = hasTypeInfo<NativeInterface>(); + + // We can then use the helper variable in a constexpr condition in a + // function, which does not break SFINAE if haveTypeInfo is false. + template <typename BaseType> + static constexpr bool isCompatibleHelper() + { + if constexpr (haveTypeInfo) + return std::is_base_of<typename NativeInterface::TypeInfo::baseType, BaseType>::value; + else + return false; + } + + // MSVC however doesn't like constexpr functions in enable_if_t conditions, + // so we need to wrap it yet again in a constexpr variable. This is fine, + // as all the SFINAE magic has been resolved at this point. + template <typename BaseType> + static constexpr bool isCompatibleWith = isCompatibleHelper<BaseType>(); + + // The revision and name accessors are not used in enable_if_t conditions, + // so we can leave them as constexpr functions. As this class template is + // friended by TypeInfo we can access the protected members of TypeInfo. + static constexpr int revision() + { + if constexpr (haveTypeInfo) + return NativeInterface::TypeInfo::revision; + else + return 0; + } + + static constexpr char const *name() + { + if constexpr (haveTypeInfo) + return NativeInterface::TypeInfo::name; + else + return nullptr; + } }; - template <typename T> - Q_NATIVE_INTERFACE_IMPORT void *resolveInterface(const T *that, const char *name, int revision); - - Q_CORE_EXPORT Q_DECLARE_LOGGING_CATEGORY(lcNativeInterface) -} + // Wrapper type to make the error message in case + // of incompatible interface types read better. + template <typename I> + struct NativeInterface : TypeInfo<I> {}; +} // QNativeInterface::Private // Declares an accessor for the native interface -#define QT_DECLARE_NATIVE_INTERFACE_ACCESSOR \ - template <typename I> \ - I *nativeInterface() const \ +#ifdef Q_QDOC +#define QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(T) \ + template <typename QNativeInterface> \ + QNativeInterface *nativeInterface() const; +#else +#define QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(T) \ + template <typename NativeInterface, typename TypeInfo = QNativeInterface::Private::NativeInterface<NativeInterface>, \ + typename BaseType = T, std::enable_if_t<TypeInfo::template isCompatibleWith<T>, bool> = true> \ + NativeInterface *nativeInterface() const \ { \ - using T = std::decay_t<decltype(*this)>; \ - using NativeInterface = QNativeInterface::Private::TypeInfo<I>; \ - static_assert(NativeInterface::template isCompatibleWith<T>, \ - "T::nativeInterface<I>() requires that native interface I is compatible with T"); \ - \ - return static_cast<I*>(QNativeInterface::Private::resolveInterface(this, \ - NativeInterface::name(), NativeInterface::revision())); \ - } - -// Provides a definition for the interface destructor -#define QT_DEFINE_NATIVE_INTERFACE_2(Namespace, InterfaceClass) \ - QT_PREPEND_NAMESPACE(Namespace)::InterfaceClass::~InterfaceClass() = default - -#define QT_DEFINE_NATIVE_INTERFACE(...) QT_OVERLOADED_MACRO(QT_DEFINE_NATIVE_INTERFACE, QNativeInterface, __VA_ARGS__) -#define QT_DEFINE_PRIVATE_NATIVE_INTERFACE(...) QT_OVERLOADED_MACRO(QT_DEFINE_NATIVE_INTERFACE, QNativeInterface::Private, __VA_ARGS__) - -#define QT_NATIVE_INTERFACE_RETURN_IF(NativeInterface, baseType) \ - using QNativeInterface::Private::lcNativeInterface; \ - qCDebug(lcNativeInterface, "Comparing requested interface name %s with available %s", \ - name, TypeInfo<NativeInterface>::name()); \ - if (qstrcmp(name, TypeInfo<NativeInterface>::name()) == 0) { \ - qCDebug(lcNativeInterface, "Match for interface %s. Comparing revisions (requested %d / available %d)", \ - name, revision, TypeInfo<NativeInterface>::revision()); \ - if (revision == TypeInfo<NativeInterface>::revision()) { \ - qCDebug(lcNativeInterface) << "Full match. Returning dynamic cast of" << baseType; \ - return dynamic_cast<NativeInterface*>(baseType); \ - } else { \ - qCWarning(lcNativeInterface, "Native interface revision mismatch (requested %d / available %d) for interface %s", \ - revision, TypeInfo<NativeInterface>::revision(), name); \ - return nullptr; \ - } \ - } + return static_cast<NativeInterface*>(resolveInterface( \ + TypeInfo::name(), TypeInfo::revision())); \ + } \ + protected: \ + void *resolveInterface(const char *name, int revision) const; \ + public: +#endif QT_END_NAMESPACE |