Long live QML inline components

[ChangeLog][QtQml] It is now possible to declare new QML components in
a QML file via the component keyword. They can be used just as if they
were declared in another file, with the only difference that the type
name needs to be prefixed with the name of the containing type outside
of the file were the inline component has been declared.

Notably, inline components are not closures: In the following
example, the output would be 42

// MyItem.qml
Item {
    property int i: 33
    component IC: Item {
        Component.onCompleted: console.log(i)
    }
}
// user.qml
Item {
    property int i: 42
    MyItem.IC {}
}

Fixes: QTBUG-79382
Change-Id: I6a5ffc43f093a76323f435cfee9bab217781b8f5
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

1 files changed, 26 insertions, 4 deletions

diff --git a/src/qml/qml/qqmlengine.cpp b/src/qml/qml/qqmlengine.cpp
index 3345fcb19e..07d5429423 100644
--- a/src/qml/qml/qqmlengine.cpp
+++ b/src/qml/qml/qqmlengine.cpp
@@ -2383,12 +2383,23 @@ int QQmlEnginePrivate::listType(int t) const
     return QQmlMetaType::listType(t);
 }
 
+
+static QQmlPropertyCache *propertyCacheForPotentialInlineComponentType(int t, const QHash<int, QV4::ExecutableCompilationUnit *>::const_iterator &iter) {
+    if (t != (*iter)->metaTypeId) {
+        // this is an inline component, and what we have in the iterator is currently the parent compilation unit
+        for (auto &&icDatum: (*iter)->inlineComponentData)
+            if (icDatum.typeIds.id == t)
+                return (*iter)->propertyCaches.at(icDatum.objectIndex);
+    }
+    return (*iter)->rootPropertyCache().data();
+}
+
 QQmlMetaObject QQmlEnginePrivate::rawMetaObjectForType(int t) const
 {
     Locker locker(this);
     auto iter = m_compositeTypes.constFind(t);
     if (iter != m_compositeTypes.cend()) {
-        return QQmlMetaObject((*iter)->rootPropertyCache().data());
+        return propertyCacheForPotentialInlineComponentType(t, iter);
     } else {
         QQmlType type = QQmlMetaType::qmlType(t);
         return QQmlMetaObject(type.baseMetaObject());
@@ -2400,7 +2411,7 @@ QQmlMetaObject QQmlEnginePrivate::metaObjectForType(int t) const
     Locker locker(this);
     auto iter = m_compositeTypes.constFind(t);
     if (iter != m_compositeTypes.cend()) {
-        return QQmlMetaObject((*iter)->rootPropertyCache().data());
+        return propertyCacheForPotentialInlineComponentType(t, iter);
     } else {
         QQmlType type = QQmlMetaType::qmlType(t);
         return QQmlMetaObject(type.metaObject());
@@ -2412,7 +2423,7 @@ QQmlPropertyCache *QQmlEnginePrivate::propertyCacheForType(int t)
     Locker locker(this);
     auto iter = m_compositeTypes.constFind(t);
     if (iter != m_compositeTypes.cend()) {
-        return (*iter)->rootPropertyCache().data();
+        return propertyCacheForPotentialInlineComponentType(t, iter);
     } else {
         QQmlType type = QQmlMetaType::qmlType(t);
         locker.unlock();
@@ -2425,7 +2436,7 @@ QQmlPropertyCache *QQmlEnginePrivate::rawPropertyCacheForType(int t, int minorVe
     Locker locker(this);
     auto iter = m_compositeTypes.constFind(t);
     if (iter != m_compositeTypes.cend()) {
-        return (*iter)->rootPropertyCache().data();
+        return propertyCacheForPotentialInlineComponentType(t, iter);
     } else {
         QQmlType type = QQmlMetaType::qmlType(t);
         locker.unlock();
@@ -2445,6 +2456,9 @@ void QQmlEnginePrivate::registerInternalCompositeType(QV4::ExecutableCompilation
     // The QQmlCompiledData is not referenced here, but it is removed from this
     // hash in the QQmlCompiledData destructor
     m_compositeTypes.insert(compilationUnit->metaTypeId, compilationUnit);
+    for (auto &&data: compilationUnit->inlineComponentData) {
+        m_compositeTypes.insert(data.typeIds.id, compilationUnit);
+    }
 }
 
 void QQmlEnginePrivate::unregisterInternalCompositeType(QV4::ExecutableCompilationUnit *compilationUnit)
@@ -2453,6 +2467,14 @@ void QQmlEnginePrivate::unregisterInternalCompositeType(QV4::ExecutableCompilati
 
     Locker locker(this);
     m_compositeTypes.remove(compilationUnit->metaTypeId);
+    for (auto&& icDatum: compilationUnit->inlineComponentData)
+        m_compositeTypes.remove(icDatum.typeIds.id);
+}
+
+QV4::ExecutableCompilationUnit *QQmlEnginePrivate::obtainExecutableCompilationUnit(int typeId)
+{
+    Locker locker(this);
+    return m_compositeTypes.value(typeId, nullptr);
 }
 
 template<>