Code cleanup in QVariant and QMetaType.

QMetaTypeGuiHelper was generalized and renamed to QMetaTypeInterface.
From now all types will have common interface which can be used for
basic operations.

Change-Id: I50d67f4a8081fa0f75c9d530a8211593ec37bc55
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

4 files changed, 84 insertions, 251 deletions

diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp
index ebb4548934..e3a8293ee6 100644
--- a/src/corelib/kernel/qmetatype.cpp
+++ b/src/corelib/kernel/qmetatype.cpp
@@ -287,42 +287,14 @@ static const struct { const char * typeName; int typeNameLength; int type; } typ
     {0, 0, QMetaType::Void}
 };
 
-struct QMetaTypeGuiHelper
-{
-    QMetaType::Creator creator;
-    QMetaType::Deleter deleter;
-#ifndef QT_NO_DATASTREAM
-    QMetaType::SaveOperator saveOp;
-    QMetaType::LoadOperator loadOp;
-#endif
-    QMetaType::Constructor constructor;
-    QMetaType::Destructor destructor;
-    int size;
-};
-Q_CORE_EXPORT const QMetaTypeGuiHelper *qMetaTypeGuiHelper = 0;
-Q_CORE_EXPORT const QMetaTypeGuiHelper *qMetaTypeWidgetsHelper = 0;
+Q_CORE_EXPORT const QMetaTypeInterface *qMetaTypeGuiHelper = 0;
+Q_CORE_EXPORT const QMetaTypeInterface *qMetaTypeWidgetsHelper = 0;
 
-class QCustomTypeInfo
+class QCustomTypeInfo : public QMetaTypeInterface
 {
 public:
-    QCustomTypeInfo() : typeName(), creator(0), deleter(0)
-#ifndef QT_NO_DATASTREAM
-    , saveOp(0), loadOp(0)
-#endif
-    , constructor(0), destructor(0), size(0)
-    {}
-
     QByteArray typeName;
-    QMetaType::Creator creator;
-    QMetaType::Deleter deleter;
-#ifndef QT_NO_DATASTREAM
-    QMetaType::SaveOperator saveOp;
-    QMetaType::LoadOperator loadOp;
-#endif
     int alias;
-    QMetaType::Constructor constructor;
-    QMetaType::Destructor destructor;
-    int size;
 };
 
 Q_DECLARE_TYPEINFO(QCustomTypeInfo, Q_MOVABLE_TYPE);
diff --git a/src/corelib/kernel/qmetatype_p.h b/src/corelib/kernel/qmetatype_p.h
index 521e8ff1ac..205516d862 100644
--- a/src/corelib/kernel/qmetatype_p.h
+++ b/src/corelib/kernel/qmetatype_p.h
@@ -111,6 +111,72 @@ QT_FOR_EACH_STATIC_WIDGETS_CLASS(QT_DECLARE_WIDGETS_MODULE_TYPES_ITER)
 #undef QT_DECLARE_GUI_MODULE_TYPES_ITER
 #undef QT_DECLARE_WIDGETS_MODULE_TYPES_ITER
 
+class QMetaTypeInterface
+{
+private:
+    template<typename T>
+    struct Impl {
+        static void *creator(const T *t)
+        {
+            if (t)
+                return new T(*t);
+            return new T();
+        }
+
+        static void deleter(T *t) { delete t; }
+    #ifndef QT_NO_DATASTREAM
+        static void saver(QDataStream &stream, const T *t) { stream << *t; }
+        static void loader(QDataStream &stream, T *t) { stream >> *t; }
+    #endif // QT_NO_DATASTREAM
+        static void destructor(T *t)
+        {
+            Q_UNUSED(t) // Silence MSVC that warns for POD types.
+            t->~T();
+        }
+        static void *constructor(void *where, const T *t)
+        {
+            if (t)
+                return new (where) T(*static_cast<const T*>(t));
+            return new (where) T;
+        }
+    };
+public:
+    template<typename T>
+    QMetaTypeInterface(T * = 0)
+        : creator(reinterpret_cast<QMetaType::Creator>(Impl<T>::creator))
+              , deleter(reinterpret_cast<QMetaType::Deleter>(Impl<T>::deleter))
+          #ifndef QT_NO_DATASTREAM
+              , saveOp(reinterpret_cast<QMetaType::SaveOperator>(Impl<T>::saver))
+              , loadOp(reinterpret_cast<QMetaType::LoadOperator>(Impl<T>::loader))
+          #endif
+              , constructor(reinterpret_cast<QMetaType::Constructor>(Impl<T>::constructor))
+              , destructor(reinterpret_cast<QMetaType::Destructor>(Impl<T>::destructor))
+              , size(sizeof(T))
+    {}
+
+    QMetaTypeInterface()
+        : creator(0)
+        , deleter(0)
+    #ifndef QT_NO_DATASTREAM
+        , saveOp(0)
+        , loadOp(0)
+    #endif
+        , constructor(0)
+        , destructor(0)
+        , size(0)
+    {}
+
+    QMetaType::Creator creator;
+    QMetaType::Deleter deleter;
+#ifndef QT_NO_DATASTREAM
+    QMetaType::SaveOperator saveOp;
+    QMetaType::LoadOperator loadOp;
+#endif
+    QMetaType::Constructor constructor;
+    QMetaType::Destructor destructor;
+    int size;
+};
+
 QT_END_NAMESPACE
 
 #endif // QMETATYPE_P_H
diff --git a/src/gui/kernel/qguivariant.cpp b/src/gui/kernel/qguivariant.cpp
index f0baf7064c..9198e7f119 100644
--- a/src/gui/kernel/qguivariant.cpp
+++ b/src/gui/kernel/qguivariant.cpp
@@ -474,158 +474,17 @@ const QVariant::Handler qt_gui_variant_handler = {
 #endif
 };
 
-struct QMetaTypeGuiHelper
-{
-    QMetaType::Creator creator;
-    QMetaType::Deleter deleter;
-#ifndef QT_NO_DATASTREAM
-    QMetaType::SaveOperator saveOp;
-    QMetaType::LoadOperator loadOp;
-#endif
-    QMetaType::Constructor constructor;
-    QMetaType::Destructor destructor;
-    int size;
-};
-
-extern Q_CORE_EXPORT const QMetaTypeGuiHelper *qMetaTypeGuiHelper;
-
-
-#ifdef QT_NO_DATASTREAM
-#  define Q_DECL_METATYPE_HELPER(TYPE) \
-     typedef void *(*QCreate##TYPE)(const TYPE *); \
-     static const QCreate##TYPE qCreate##TYPE = qMetaTypeCreateHelper<TYPE>; \
-     typedef void (*QDelete##TYPE)(TYPE *); \
-     static const QDelete##TYPE qDelete##TYPE = qMetaTypeDeleteHelper<TYPE>; \
-     typedef void *(*QConstruct##TYPE)(void *, const TYPE *); \
-     static const QConstruct##TYPE qConstruct##TYPE = qMetaTypeConstructHelper<TYPE>; \
-     typedef void (*QDestruct##TYPE)(TYPE *); \
-     static const QDestruct##TYPE qDestruct##TYPE = qMetaTypeDestructHelper<TYPE>;
-#else
-#  define Q_DECL_METATYPE_HELPER(TYPE) \
-     typedef void *(*QCreate##TYPE)(const TYPE *); \
-     static const QCreate##TYPE qCreate##TYPE = qMetaTypeCreateHelper<TYPE>; \
-     typedef void (*QDelete##TYPE)(TYPE *); \
-     static const QDelete##TYPE qDelete##TYPE = qMetaTypeDeleteHelper<TYPE>; \
-     typedef void *(*QConstruct##TYPE)(void *, const TYPE *); \
-     static const QConstruct##TYPE qConstruct##TYPE = qMetaTypeConstructHelper<TYPE>; \
-     typedef void (*QDestruct##TYPE)(TYPE *); \
-     static const QDestruct##TYPE qDestruct##TYPE = qMetaTypeDestructHelper<TYPE>; \
-     typedef void (*QSave##TYPE)(QDataStream &, const TYPE *); \
-     static const QSave##TYPE qSave##TYPE = qMetaTypeSaveHelper<TYPE>; \
-     typedef void (*QLoad##TYPE)(QDataStream &, TYPE *); \
-     static const QLoad##TYPE qLoad##TYPE = qMetaTypeLoadHelper<TYPE>;
-#endif
-
-Q_DECL_METATYPE_HELPER(QFont)
-Q_DECL_METATYPE_HELPER(QPixmap)
-Q_DECL_METATYPE_HELPER(QBrush)
-Q_DECL_METATYPE_HELPER(QColor)
-Q_DECL_METATYPE_HELPER(QPalette)
-Q_DECL_METATYPE_HELPER(QImage)
-Q_DECL_METATYPE_HELPER(QPolygon)
-Q_DECL_METATYPE_HELPER(QRegion)
-Q_DECL_METATYPE_HELPER(QBitmap)
-#ifndef QT_NO_CURSOR
-Q_DECL_METATYPE_HELPER(QCursor)
-#endif
-#ifndef QT_NO_SHORTCUT
-Q_DECL_METATYPE_HELPER(QKeySequence)
-#endif
-Q_DECL_METATYPE_HELPER(QPen)
-Q_DECL_METATYPE_HELPER(QTextLength)
-Q_DECL_METATYPE_HELPER(QTextFormat)
-Q_DECL_METATYPE_HELPER(QMatrix)
-Q_DECL_METATYPE_HELPER(QTransform)
-#ifndef QT_NO_MATRIX4X4
-Q_DECL_METATYPE_HELPER(QMatrix4x4)
-#endif
-#ifndef QT_NO_VECTOR2D
-Q_DECL_METATYPE_HELPER(QVector2D)
-#endif
-#ifndef QT_NO_VECTOR3D
-Q_DECL_METATYPE_HELPER(QVector3D)
-#endif
-#ifndef QT_NO_VECTOR4D
-Q_DECL_METATYPE_HELPER(QVector4D)
-#endif
-#ifndef QT_NO_QUATERNION
-Q_DECL_METATYPE_HELPER(QQuaternion)
-#endif
-Q_DECL_METATYPE_HELPER(QPolygonF)
+extern Q_CORE_EXPORT const QMetaTypeInterface *qMetaTypeGuiHelper;
 
-#ifdef QT_NO_DATASTREAM
-#  define Q_IMPL_METATYPE_HELPER(TYPE) \
-     { reinterpret_cast<QMetaType::Creator>(qCreate##TYPE), \
-       reinterpret_cast<QMetaType::Deleter>(qDelete##TYPE), \
-       reinterpret_cast<QMetaType::Constructor>(qConstruct##TYPE), \
-       reinterpret_cast<QMetaType::Destructor>(qDestruct##TYPE), \
-       sizeof(TYPE) \
-     }
-#else
-#  define Q_IMPL_METATYPE_HELPER(TYPE) \
-     { reinterpret_cast<QMetaType::Creator>(qCreate##TYPE), \
-       reinterpret_cast<QMetaType::Deleter>(qDelete##TYPE), \
-       reinterpret_cast<QMetaType::SaveOperator>(qSave##TYPE), \
-       reinterpret_cast<QMetaType::LoadOperator>(qLoad##TYPE), \
-       reinterpret_cast<QMetaType::Constructor>(qConstruct##TYPE), \
-       reinterpret_cast<QMetaType::Destructor>(qDestruct##TYPE), \
-       sizeof(TYPE) \
-     }
-#endif
+#define QT_IMPL_METATYPEINTERFACE_GUI_TYPES(MetaTypeName, MetaTypeId, RealName) \
+    QMetaTypeInterface(static_cast<RealName*>(0)),
 
-static const QMetaTypeGuiHelper qVariantGuiHelper[] = {
-    Q_IMPL_METATYPE_HELPER(QFont),
-    Q_IMPL_METATYPE_HELPER(QPixmap),
-    Q_IMPL_METATYPE_HELPER(QBrush),
-    Q_IMPL_METATYPE_HELPER(QColor),
-    Q_IMPL_METATYPE_HELPER(QPalette),
-    Q_IMPL_METATYPE_HELPER(QImage),
-    Q_IMPL_METATYPE_HELPER(QPolygon),
-    Q_IMPL_METATYPE_HELPER(QRegion),
-    Q_IMPL_METATYPE_HELPER(QBitmap),
-#ifdef QT_NO_CURSOR
-    {0, 0, 0, 0, 0, 0, 0},
-#else
-    Q_IMPL_METATYPE_HELPER(QCursor),
-#endif
-#ifdef QT_NO_SHORTCUT
-    {0, 0, 0, 0, 0, 0, 0},
-#else
-    Q_IMPL_METATYPE_HELPER(QKeySequence),
-#endif
-    Q_IMPL_METATYPE_HELPER(QPen),
-    Q_IMPL_METATYPE_HELPER(QTextLength),
-    Q_IMPL_METATYPE_HELPER(QTextFormat),
-    Q_IMPL_METATYPE_HELPER(QMatrix),
-    Q_IMPL_METATYPE_HELPER(QTransform),
-#ifndef QT_NO_MATRIX4X4
-    Q_IMPL_METATYPE_HELPER(QMatrix4x4),
-#else
-    {0, 0, 0, 0, 0, 0, 0},
-#endif
-#ifndef QT_NO_VECTOR2D
-    Q_IMPL_METATYPE_HELPER(QVector2D),
-#else
-    {0, 0, 0, 0, 0, 0, 0},
-#endif
-#ifndef QT_NO_VECTOR3D
-    Q_IMPL_METATYPE_HELPER(QVector3D),
-#else
-    {0, 0, 0, 0, 0, 0, 0},
-#endif
-#ifndef QT_NO_VECTOR4D
-    Q_IMPL_METATYPE_HELPER(QVector4D),
-#else
-    {0, 0, 0, 0, 0, 0, 0},
-#endif
-#ifndef QT_NO_QUATERNION
-    Q_IMPL_METATYPE_HELPER(QQuaternion),
-#else
-    {0, 0, 0, 0, 0, 0, 0},
-#endif
-    Q_IMPL_METATYPE_HELPER(QPolygonF)
+static const QMetaTypeInterface qVariantGuiHelper[] = {
+    QT_FOR_EACH_STATIC_GUI_CLASS(QT_IMPL_METATYPEINTERFACE_GUI_TYPES)
 };
 
+#undef QT_IMPL_METATYPEINTERFACE_GUI_TYPES
+
 static const QVariant::Handler *qt_guivariant_last_handler = 0;
 int qRegisterGuiVariant()
 {
diff --git a/src/widgets/kernel/qwidgetsvariant.cpp b/src/widgets/kernel/qwidgetsvariant.cpp
index dcffa0e87e..2e945d28e1 100644
--- a/src/widgets/kernel/qwidgetsvariant.cpp
+++ b/src/widgets/kernel/qwidgetsvariant.cpp
@@ -45,6 +45,7 @@
 #include "qsizepolicy.h"
 
 #include "private/qvariant_p.h"
+#include <private/qmetatype_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -137,82 +138,17 @@ static const QVariant::Handler widgets_handler = {
 #endif
 };
 
-struct QMetaTypeGuiHelper
-{
-    QMetaType::Creator creator;
-    QMetaType::Deleter deleter;
-#ifndef QT_NO_DATASTREAM
-    QMetaType::SaveOperator saveOp;
-    QMetaType::LoadOperator loadOp;
-#endif
-    QMetaType::Constructor constructor;
-    QMetaType::Destructor destructor;
-    int size;
-};
-
-extern Q_CORE_EXPORT const QMetaTypeGuiHelper *qMetaTypeWidgetsHelper;
-
-
-#ifdef QT_NO_DATASTREAM
-#  define Q_DECL_METATYPE_HELPER(TYPE) \
-     typedef void *(*QCreate##TYPE)(const TYPE *); \
-     static const QCreate##TYPE qCreate##TYPE = qMetaTypeCreateHelper<TYPE>; \
-     typedef void (*QDelete##TYPE)(TYPE *); \
-     static const QDelete##TYPE qDelete##TYPE = qMetaTypeDeleteHelper<TYPE>; \
-     typedef void *(*QConstruct##TYPE)(void *, const TYPE *); \
-     static const QConstruct##TYPE qConstruct##TYPE = qMetaTypeConstructHelper<TYPE>; \
-     typedef void (*QDestruct##TYPE)(TYPE *); \
-     static const QDestruct##TYPE qDestruct##TYPE = qMetaTypeDestructHelper<TYPE>;
-#else
-#  define Q_DECL_METATYPE_HELPER(TYPE) \
-     typedef void *(*QCreate##TYPE)(const TYPE *); \
-     static const QCreate##TYPE qCreate##TYPE = qMetaTypeCreateHelper<TYPE>; \
-     typedef void (*QDelete##TYPE)(TYPE *); \
-     static const QDelete##TYPE qDelete##TYPE = qMetaTypeDeleteHelper<TYPE>; \
-     typedef void *(*QConstruct##TYPE)(void *, const TYPE *); \
-     static const QConstruct##TYPE qConstruct##TYPE = qMetaTypeConstructHelper<TYPE>; \
-     typedef void (*QDestruct##TYPE)(TYPE *); \
-     static const QDestruct##TYPE qDestruct##TYPE = qMetaTypeDestructHelper<TYPE>; \
-     typedef void (*QSave##TYPE)(QDataStream &, const TYPE *); \
-     static const QSave##TYPE qSave##TYPE = qMetaTypeSaveHelper<TYPE>; \
-     typedef void (*QLoad##TYPE)(QDataStream &, TYPE *); \
-     static const QLoad##TYPE qLoad##TYPE = qMetaTypeLoadHelper<TYPE>;
-#endif
+extern Q_CORE_EXPORT const QMetaTypeInterface *qMetaTypeWidgetsHelper;
 
-#ifndef QT_NO_ICON
-Q_DECL_METATYPE_HELPER(QIcon)
-#endif
-Q_DECL_METATYPE_HELPER(QSizePolicy)
-
-#ifdef QT_NO_DATASTREAM
-#  define Q_IMPL_METATYPE_HELPER(TYPE) \
-     { reinterpret_cast<QMetaType::Creator>(qCreate##TYPE), \
-       reinterpret_cast<QMetaType::Deleter>(qDelete##TYPE), \
-       reinterpret_cast<QMetaType::Constructor>(qConstruct##TYPE), \
-       reinterpret_cast<QMetaType::Destructor>(qDestruct##TYPE), \
-       sizeof(TYPE) \
-     }
-#else
-#  define Q_IMPL_METATYPE_HELPER(TYPE) \
-     { reinterpret_cast<QMetaType::Creator>(qCreate##TYPE), \
-       reinterpret_cast<QMetaType::Deleter>(qDelete##TYPE), \
-       reinterpret_cast<QMetaType::SaveOperator>(qSave##TYPE), \
-       reinterpret_cast<QMetaType::LoadOperator>(qLoad##TYPE), \
-       reinterpret_cast<QMetaType::Constructor>(qConstruct##TYPE), \
-       reinterpret_cast<QMetaType::Destructor>(qDestruct##TYPE), \
-       sizeof(TYPE) \
-     }
-#endif
+#define QT_IMPL_METATYPEINTERFACE_WIDGETS_TYPES(MetaTypeName, MetaTypeId, RealName) \
+    QMetaTypeInterface(static_cast<RealName*>(0)),
 
-static const QMetaTypeGuiHelper qVariantWidgetsHelper[] = {
-#ifdef QT_NO_ICON
-    {0, 0, 0, 0},
-#else
-    Q_IMPL_METATYPE_HELPER(QIcon),
-#endif
-    Q_IMPL_METATYPE_HELPER(QSizePolicy),
+static const QMetaTypeInterface qVariantWidgetsHelper[] = {
+    QT_FOR_EACH_STATIC_WIDGETS_CLASS(QT_IMPL_METATYPEINTERFACE_WIDGETS_TYPES)
 };
 
+#undef QT_IMPL_METATYPEINTERFACE_WIDGETS_TYPES
+
 extern Q_GUI_EXPORT const QVariant::Handler *qt_widgets_variant_handler;
 
 int qRegisterWidgetsVariant()