Introduce QMetaType::UnknownType.

QMetaType::Void was ambiguous, it was pointing to a valid type (void)
and in the same time it was signaling errors in QMetaType. There was
no clean way to check if returned type was valid void or some
unregistered type.

This feature will be used by new QMetaObject revision which will
store type ids instead of type names. So it will be easy to
distinguish between:
 void mySlot();
 MyUnregisteredType mySlot();

Change-Id: I73ff097f75585a95e12df74d50c6f3141153e771
Reviewed-by: Kent Hansen <kent.hansen@nokia.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

1 files changed, 35 insertions, 27 deletions

diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp
index 003ad1c32d..6d5973a7d0 100644
--- a/src/corelib/kernel/qmetatype.cpp
+++ b/src/corelib/kernel/qmetatype.cpp
@@ -242,6 +242,7 @@ template<> struct TypeDefinition<QRegExp> { static const bool IsAvailable = fals
     \value QEasingCurve QEasingCurve
 
     \value User  Base value for user types
+    \value UnknownType This is an invalid type id. It is returned from QMetaType for types that are not registered
 
     \omitvalue FirstGuiType
     \omitvalue FirstWidgetsType
@@ -311,7 +312,7 @@ static const struct { const char * typeName; int typeNameLength; int type; } typ
     QT_FOR_EACH_STATIC_TYPE(QT_ADD_STATIC_METATYPE)
     QT_FOR_EACH_STATIC_ALIAS_TYPE(QT_ADD_STATIC_METATYPE_ALIASES_ITER)
     QT_FOR_EACH_STATIC_HACKS_TYPE(QT_ADD_STATIC_METATYPE_HACKS_ITER)
-    {0, 0, QMetaType::Void}
+    {0, 0, QMetaType::UnknownType}
 };
 
 Q_CORE_EXPORT const QMetaTypeInterface *qMetaTypeGuiHelper = 0;
@@ -348,10 +349,7 @@ Q_GLOBAL_STATIC(QReadWriteLock, customTypesLock)
 void QMetaType::registerStreamOperators(const char *typeName, SaveOperator saveOp,
                                         LoadOperator loadOp)
 {
-    int idx = type(typeName);
-    if (!idx)
-        return;
-    registerStreamOperators(idx, saveOp, loadOp);
+    registerStreamOperators(type(typeName), saveOp, loadOp);
 }
 
 /*! \internal
@@ -434,7 +432,7 @@ static int qMetaTypeCustomType_unlocked(const char *typeName, int length)
 {
     const QVector<QCustomTypeInfo> * const ct = customTypes();
     if (!ct)
-        return 0;
+        return QMetaType::UnknownType;
 
     for (int v = 0; v < ct->count(); ++v) {
         const QCustomTypeInfo &customInfo = ct->at(v);
@@ -445,7 +443,7 @@ static int qMetaTypeCustomType_unlocked(const char *typeName, int length)
             return v + QMetaType::User;
         }
     }
-    return 0;
+    return QMetaType::UnknownType;
 }
 
 /*! \internal
@@ -488,11 +486,11 @@ int QMetaType::registerType(const char *typeName, Deleter deleter,
 
     int previousSize = 0;
     int previousFlags = 0;
-    if (!idx) {
+    if (idx == UnknownType) {
         QWriteLocker locker(customTypesLock());
         idx = qMetaTypeCustomType_unlocked(normalizedTypeName.constData(),
                                            normalizedTypeName.size());
-        if (!idx) {
+        if (idx == UnknownType) {
             QCustomTypeInfo inf;
             inf.typeName = normalizedTypeName;
             inf.creator = creator;
@@ -558,12 +556,12 @@ int QMetaType::registerTypedef(const char* typeName, int aliasId)
     int idx = qMetaTypeStaticType(normalizedTypeName.constData(),
                                   normalizedTypeName.size());
 
-    if (!idx) {
+    if (idx == UnknownType) {
         QWriteLocker locker(customTypesLock());
         idx = qMetaTypeCustomType_unlocked(normalizedTypeName.constData(),
                                                normalizedTypeName.size());
 
-        if (!idx) {
+        if (idx == UnknownType) {
             QCustomTypeInfo inf;
             inf.typeName = normalizedTypeName;
             inf.alias = aliasId;
@@ -592,17 +590,20 @@ int QMetaType::registerTypedef(const char* typeName, int aliasId)
 */
 bool QMetaType::isRegistered(int type)
 {
-    if (type >= 0 && type < User) {
-        // predefined type
+    // predefined type
+    if ((type >= FirstCoreType && type <= LastCoreType)
+        || (type >= FirstGuiType && type <= LastGuiType)
+        || (type >= FirstWidgetsType && type <= LastWidgetsType)) {
         return true;
     }
+
     QReadLocker locker(customTypesLock());
     const QVector<QCustomTypeInfo> * const ct = customTypes();
     return ((type >= User) && (ct && ct->count() > type - User) && !ct->at(type - User).typeName.isEmpty());
 }
 
 /*!
-    Returns a handle to the type called \a typeName, or 0 if there is
+    Returns a handle to the type called \a typeName, or QMetaType::UnknownType if there is
     no such type.
 
     \sa isRegistered(), typeName(), Type
@@ -611,17 +612,17 @@ int QMetaType::type(const char *typeName)
 {
     int length = qstrlen(typeName);
     if (!length)
-        return 0;
+        return UnknownType;
     int type = qMetaTypeStaticType(typeName, length);
-    if (!type) {
+    if (type == UnknownType) {
         QReadLocker locker(customTypesLock());
         type = qMetaTypeCustomType_unlocked(typeName, length);
 #ifndef QT_NO_QOBJECT
-        if (!type) {
+        if (type == UnknownType) {
             const NS(QByteArray) normalizedTypeName = QMetaObject::normalizedType(typeName);
             type = qMetaTypeStaticType(normalizedTypeName.constData(),
                                        normalizedTypeName.size());
-            if (!type) {
+            if (type == UnknownType) {
                 type = qMetaTypeCustomType_unlocked(normalizedTypeName.constData(),
                                                     normalizedTypeName.size());
             }
@@ -652,6 +653,7 @@ bool QMetaType::save(QDataStream &stream, int type, const void *data)
         return false;
 
     switch(type) {
+    case QMetaType::UnknownType:
     case QMetaType::Void:
     case QMetaType::VoidStar:
     case QMetaType::QObjectStar:
@@ -857,6 +859,7 @@ bool QMetaType::load(QDataStream &stream, int type, void *data)
         return false;
 
     switch(type) {
+    case QMetaType::UnknownType:
     case QMetaType::Void:
     case QMetaType::VoidStar:
     case QMetaType::QObjectStar:
@@ -1154,6 +1157,7 @@ void *QMetaType::create(int type, const void *copy)
         case QMetaType::QModelIndex:
             return new NS(QModelIndex)(*static_cast<const NS(QModelIndex)*>(copy));
 #endif
+        case QMetaType::UnknownType:
         case QMetaType::Void:
             return 0;
         default:
@@ -1257,6 +1261,7 @@ void *QMetaType::create(int type, const void *copy)
         case QMetaType::QModelIndex:
             return new NS(QModelIndex);
 #endif
+        case QMetaType::UnknownType:
         case QMetaType::Void:
             return 0;
         default:
@@ -1318,6 +1323,7 @@ public:
     template<typename T>
     void delegate(const T *where) { DestroyerImpl<T>::Destroy(m_type, const_cast<T*>(where)); }
     void delegate(const void *) {}
+    void delegate(const QMetaTypeSwitcher::UnknownType*) {}
     void delegate(const QMetaTypeSwitcher::NotBuiltinType *where) { customTypeDestroyer(m_type, (void*)where); }
 
 private:
@@ -1380,6 +1386,7 @@ public:
     template<typename T>
     void *delegate(const T *copy) { return ConstructorImpl<T>::Construct(m_type, m_where, copy); }
     void *delegate(const void *) { return m_where; }
+    void *delegate(const QMetaTypeSwitcher::UnknownType*) { return m_where; }
     void *delegate(const QMetaTypeSwitcher::NotBuiltinType *copy) { return customTypeConstructor(m_type, m_where, copy); }
 
 private:
@@ -1468,6 +1475,7 @@ public:
     template<typename T>
     void delegate(const T *where) { DestructorImpl<T>::Destruct(m_type, const_cast<T*>(where)); }
     void delegate(const void *) {}
+    void delegate(const QMetaTypeSwitcher::UnknownType*) {}
     void delegate(const QMetaTypeSwitcher::NotBuiltinType *where) { customTypeDestructor(m_type, (void*)where); }
 
 private:
@@ -1536,6 +1544,7 @@ public:
 
     template<typename T>
     int delegate(const T*) { return SizeOfImpl<T>::Size(m_type); }
+    int delegate(const QMetaTypeSwitcher::UnknownType*) { return 0; }
     int delegate(const QMetaTypeSwitcher::NotBuiltinType*) { return customTypeSizeOf(m_type); }
 private:
     static int customTypeSizeOf(const int type)
@@ -1606,13 +1615,14 @@ public:
     template<typename T>
     quint32 delegate(const T*) { return FlagsImpl<T>::Flags(m_type); }
     quint32 delegate(const void*) { return 0; }
+    quint32 delegate(const QMetaTypeSwitcher::UnknownType*) { return 0; }
     quint32 delegate(const QMetaTypeSwitcher::NotBuiltinType*) { return customTypeFlags(m_type); }
 private:
     const int m_type;
     static quint32 customTypeFlags(const int type)
     {
         const QVector<QCustomTypeInfo> * const ct = customTypes();
-        if (Q_UNLIKELY(!ct))
+        if (Q_UNLIKELY(!ct || type < QMetaType::User))
             return 0;
         QReadLocker locker(customTypesLock());
         if (Q_UNLIKELY(ct->count() <= type - QMetaType::User))
@@ -1793,6 +1803,7 @@ public:
     template<typename T>
     void delegate(const T*) { TypeInfoImpl<T>(m_type, info); }
     void delegate(const void*) {}
+    void delegate(const QMetaTypeSwitcher::UnknownType*) {}
     void delegate(const QMetaTypeSwitcher::NotBuiltinType*) { customTypeInfo(m_type); }
 private:
     void customTypeInfo(const uint type)
@@ -1813,7 +1824,7 @@ QMetaType QMetaType::typeInfo(const int type)
 {
     TypeInfo typeInfo(type);
     QMetaTypeSwitcher::switcher<void>(typeInfo, type, 0);
-    return typeInfo.info.creator || !type ? QMetaType(QMetaType::NoExtensionFlags
+    return typeInfo.info.creator || type == Void ? QMetaType(QMetaType::NoExtensionFlags
                                  , static_cast<const QMetaTypeInterface *>(0) // typeInfo::info is a temporary variable, we can't return address of it.
                                  , typeInfo.info.creator
                                  , typeInfo.info.deleter
@@ -1824,26 +1835,23 @@ QMetaType QMetaType::typeInfo(const int type)
                                  , typeInfo.info.size
                                  , typeInfo.info.flags
                                  , type)
-                : QMetaType(-1);
+                : QMetaType(UnknownType);
 }
 
 QMetaType::QMetaType(const int typeId)
     : m_typeId(typeId)
 {
-    if (Q_UNLIKELY(typeId == -1)) {
+    if (Q_UNLIKELY(typeId == UnknownType)) {
         // Constructs invalid QMetaType instance.
         m_extensionFlags = 0xffffffff;
         Q_ASSERT(!isValid());
     } else {
         // TODO it can be better.
         *this = QMetaType::typeInfo(typeId);
-        if (m_typeId > 0 && !m_creator) {
+        if (m_typeId == UnknownType)
             m_extensionFlags = 0xffffffff;
-            m_typeId = -1;
-        }
-        if (m_typeId ==  QMetaType::Void) {
+        else if (m_typeId == QMetaType::Void)
             m_extensionFlags = CreateEx | DestroyEx | ConstructEx | DestructEx;
-        }
     }
 }