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, 44 insertions, 7 deletions

diff --git a/src/qml/common/qv4compileddata_p.h b/src/qml/common/qv4compileddata_p.h
index 453ade09a7..42c476763e 100644
--- a/src/qml/common/qv4compileddata_p.h
+++ b/src/qml/common/qv4compileddata_p.h
@@ -75,7 +75,7 @@ QT_BEGIN_NAMESPACE
 // Also change the comment behind the number to describe the latest change. This has the added
 // benefit that if another patch changes the version too, it will result in a merge conflict, and
 // not get removed silently.
-#define QV4_DATA_STRUCTURE_VERSION 0x27 // resolved merge
+#define QV4_DATA_STRUCTURE_VERSION 0x28// support inline components
 
 class QIODevice;
 class QQmlTypeNameCache;
@@ -112,6 +112,7 @@ struct TableIterator
     int index;
 
     const ItemType *operator->() { return (container->*IndexedGetter)(index); }
+    ItemType operator*() {return *operator->();}
     void operator++() { ++index; }
     bool operator==(const TableIterator &rhs) const { return index == rhs.index; }
     bool operator!=(const TableIterator &rhs) const { return index != rhs.index; }
@@ -597,6 +598,15 @@ struct Binding
 
 static_assert(sizeof(Binding) == 24, "Binding structure needs to have the expected size to be binary compatible on disk when generated by host compiler and loaded by target");
 
+struct InlineComponent
+{
+    quint32_le objectIndex;
+    quint32_le nameIndex;
+    Location location;
+};
+
+static_assert(sizeof(InlineComponent) == 12, "InlineComponent structure needs to have the expected size to be binary compatible on disk when generated by host compiler and loaded by target");
+
 struct EnumValue
 {
     quint32_le nameIndex;
@@ -721,7 +731,9 @@ struct Object
         NoFlag = 0x0,
         IsComponent = 0x1, // object was identified to be an explicit or implicit component boundary
         HasDeferredBindings = 0x2, // any of the bindings are deferred
-        HasCustomParserBindings = 0x4
+        HasCustomParserBindings = 0x4,
+        IsInlineComponentRoot = 0x8,
+        InPartOfInlineComponent = 0x10
     };
 
     // Depending on the use, this may be the type name to instantiate before instantiating this
@@ -751,12 +763,15 @@ struct Object
     quint32_le offsetToNamedObjectsInComponent;
     Location location;
     Location locationOfIdProperty;
+    quint32_le offsetToInlineComponents;
+    quint16_le nInlineComponents;
 //    Function[]
 //    Property[]
 //    Signal[]
 //    Binding[]
+//    InlineComponent[]
 
-    static int calculateSizeExcludingSignalsAndEnums(int nFunctions, int nProperties, int nAliases, int nEnums, int nSignals, int nBindings, int nNamedObjectsInComponent)
+    static int calculateSizeExcludingSignalsAndEnums(int nFunctions, int nProperties, int nAliases, int nEnums, int nSignals, int nBindings, int nNamedObjectsInComponent, int nInlineComponents)
     {
         return ( sizeof(Object)
                  + nFunctions * sizeof(quint32)
@@ -766,6 +781,7 @@ struct Object
                  + nSignals * sizeof(quint32)
                  + nBindings * sizeof(Binding)
                  + nNamedObjectsInComponent * sizeof(int)
+                 + nInlineComponents * sizeof(InlineComponent)
                  + 0x7
                ) & ~0x7;
     }
@@ -804,11 +820,21 @@ struct Object
         return reinterpret_cast<const Signal*>(reinterpret_cast<const char*>(this) + offset);
     }
 
+    const InlineComponent *inlineComponentAt(int idx) const
+    {
+        return inlineComponentTable() + idx;
+    }
+
     const quint32_le *namedObjectsInComponentTable() const
     {
         return reinterpret_cast<const quint32_le*>(reinterpret_cast<const char *>(this) + offsetToNamedObjectsInComponent);
     }
 
+    const InlineComponent *inlineComponentTable() const
+    {
+        return reinterpret_cast<const InlineComponent*>(reinterpret_cast<const char *>(this) + offsetToInlineComponents);
+    }
+
     // --- QQmlPropertyCacheCreator interface
     int propertyCount() const { return nProperties; }
     int aliasCount() const { return nAliases; }
@@ -833,17 +859,22 @@ struct Object
     SignalIterator signalsBegin() const { return SignalIterator(this, 0); }
     SignalIterator signalsEnd() const { return SignalIterator(this, nSignals); }
 
+    typedef TableIterator<InlineComponent, Object, &Object::inlineComponentAt> InlineComponentIterator;
+    InlineComponentIterator inlineComponentsBegin() const {return InlineComponentIterator(this, 0);}
+    InlineComponentIterator inlineComponentsEnd() const {return InlineComponentIterator(this, nInlineComponents);}
+
     int namedObjectsInComponentCount() const { return nNamedObjectsInComponent; }
     // ---
 };
-static_assert(sizeof(Object) == 68, "Object structure needs to have the expected size to be binary compatible on disk when generated by host compiler and loaded by target");
+static_assert(sizeof(Object) == 76, "Object structure needs to have the expected size to be binary compatible on disk when generated by host compiler and loaded by target");
 
 struct Import
 {
     enum ImportType : unsigned int {
         ImportLibrary = 0x1,
         ImportFile = 0x2,
-        ImportScript = 0x3
+        ImportScript = 0x3,
+        ImportInlineComponent = 0x4
     };
     quint32_le type;
 
@@ -1072,7 +1103,7 @@ struct TypeReferenceMap : QHash<int, TypeReference>
         }
 
         auto prop = obj->propertiesBegin();
-        auto propEnd = obj->propertiesEnd();
+        auto const propEnd = obj->propertiesEnd();
         for ( ; prop != propEnd; ++prop) {
             if (!prop->isBuiltinType) {
                 TypeReference &r = this->add(prop->builtinTypeOrTypeNameIndex, prop->location);
@@ -1081,11 +1112,17 @@ struct TypeReferenceMap : QHash<int, TypeReference>
         }
 
         auto binding = obj->bindingsBegin();
-        auto bindingEnd = obj->bindingsEnd();
+        auto const bindingEnd = obj->bindingsEnd();
         for ( ; binding != bindingEnd; ++binding) {
             if (binding->type == QV4::CompiledData::Binding::Type_AttachedProperty)
                 this->add(binding->propertyNameIndex, binding->location);
         }
+
+        auto ic = obj->inlineComponentsBegin();
+        auto const icEnd = obj->inlineComponentsEnd();
+        for (; ic != icEnd; ++ic) {
+            this->add(ic->nameIndex, ic->location);
+        }
     }
 
     template <typename Iterator>