Clean up QQmlOpenMetaObject property data structure

Use a vector instead of a list for a more compact storage - random
access is a more frequent operation than appending/removal. Also use
a struct instead of a QPair for increased readability of the code and
encapsulate read and write operations.

Clean up the internal API to avoid unnecessary mutable property
extraction. This also helps to ensure that in all cases but intended
mutation we end up using the property getter that returns a QVariant by
value, something that will allow returning a null variant when QObject
tracking gets fixed in the next patch.

Change-Id: I563a930fe959b7636f9e9dc88a28cdcefc196707
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 50 insertions, 36 deletions

diff --git a/src/qml/qml/qqmlopenmetaobject.cpp b/src/qml/qml/qqmlopenmetaobject.cpp
index 1b44bbdda3..ff89278faf 100644
--- a/src/qml/qml/qqmlopenmetaobject.cpp
+++ b/src/qml/qml/qqmlopenmetaobject.cpp
@@ -184,31 +184,55 @@ public:
     QQmlOpenMetaObjectPrivate(QQmlOpenMetaObject *_q)
         : q(_q), parent(nullptr), type(nullptr), cacheProperties(false) {}
 
-    inline QPair<QVariant, bool> &getDataRef(int idx) {
-        while (data.count() <= idx)
-            data << QPair<QVariant, bool>(QVariant(), false);
-        return data[idx];
+    struct Property {
+    private:
+        QVariant m_value;
+    public:
+        bool valueSet = false;
+
+        const QVariant &value() const { return m_value; }
+        QVariant &valueRef() { return m_value; }
+        void setValue(const QVariant &v) {
+            m_value = v;
+            valueSet = true;
+        }
+    };
+
+    inline void setPropertyValue(int idx, const QVariant &value) {
+        if (data.count() <= idx)
+            data.resize(idx + 1);
+        data[idx].setValue(value);
     }
 
-    inline QVariant &getData(int idx) {
-        QPair<QVariant, bool> &prop = getDataRef(idx);
-        if (!prop.second) {
-            prop.first = q->initialValue(idx);
-            prop.second = true;
-        }
-        return prop.first;
+    inline Property &propertyRef(int idx) {
+        if (data.count() <= idx)
+            data.resize(idx + 1);
+        Property &prop = data[idx];
+        if (!prop.valueSet)
+            prop.setValue(q->initialValue(idx));
+        return prop;
+    }
+
+    inline QVariant propertyValue(int idx) {
+        auto &prop = propertyRef(idx);
+        return prop.value();
     }
 
-    inline bool hasData(int idx) const {
+    inline QVariant &propertyValueRef(int idx) {
+        auto &prop = propertyRef(idx);
+        return prop.valueRef();
+    }
+
+    inline bool hasProperty(int idx) const {
         if (idx >= data.count())
             return false;
-        return data[idx].second;
+        return data[idx].valueSet;
     }
 
     bool autoCreate;
     QQmlOpenMetaObject *q;
     QAbstractDynamicMetaObject *parent;
-    QList<QPair<QVariant, bool> > data;
+    QVector<Property> data;
     QObject *object;
     QQmlOpenMetaObjectType *type;
     bool cacheProperties;
@@ -276,13 +300,11 @@ int QQmlOpenMetaObject::metaCall(QObject *o, QMetaObject::Call c, int id, void *
         int propId = id - d->type->d->propertyOffset;
         if (c == QMetaObject::ReadProperty) {
             propertyRead(propId);
-            *reinterpret_cast<QVariant *>(a[0]) = d->getData(propId);
+            *reinterpret_cast<QVariant *>(a[0]) = d->propertyValue(propId);
         } else if (c == QMetaObject::WriteProperty) {
-            if (propId >= d->data.count() || d->data.at(propId).first != *reinterpret_cast<QVariant *>(a[0]))  {
+            if (propId >= d->data.count() || d->data.at(propId).value() != *reinterpret_cast<QVariant *>(a[0]))  {
                 propertyWrite(propId);
-                QPair<QVariant, bool> &prop = d->getDataRef(propId);
-                prop.first = propertyWriteValue(propId, *reinterpret_cast<QVariant *>(a[0]));
-                prop.second = true;
+                d->setPropertyValue(propId, propertyWriteValue(propId, *reinterpret_cast<QVariant *>(a[0])));
                 propertyWritten(propId);
                 activate(o, d->type->d->signalOffset + propId, nullptr);
             }
@@ -303,14 +325,12 @@ QAbstractDynamicMetaObject *QQmlOpenMetaObject::parent() const
 
 QVariant QQmlOpenMetaObject::value(int id) const
 {
-    return d->getData(id);
+    return d->propertyValue(id);
 }
 
 void QQmlOpenMetaObject::setValue(int id, const QVariant &value)
 {
-    QPair<QVariant, bool> &prop = d->getDataRef(id);
-    prop.first = propertyWriteValue(id, value);
-    prop.second = true;
+    d->setPropertyValue(id, propertyWriteValue(id, value));
     activate(d->object, id + d->type->d->signalOffset, nullptr);
 }
 
@@ -320,23 +340,18 @@ QVariant QQmlOpenMetaObject::value(const QByteArray &name) const
     if (iter == d->type->d->names.cend())
         return QVariant();
 
-    return d->getData(*iter);
+    return d->propertyValue(*iter);
 }
 
-QVariant &QQmlOpenMetaObject::operator[](const QByteArray &name)
+QVariant &QQmlOpenMetaObject::valueRef(const QByteArray &name)
 {
     QHash<QByteArray, int>::ConstIterator iter = d->type->d->names.constFind(name);
     Q_ASSERT(iter != d->type->d->names.cend());
 
-    return d->getData(*iter);
-}
-
-QVariant &QQmlOpenMetaObject::operator[](int id)
-{
-    return d->getData(id);
+    return d->propertyValueRef(*iter);
 }
 
-bool QQmlOpenMetaObject::setValue(const QByteArray &name, const QVariant &val)
+bool QQmlOpenMetaObject::setValue(const QByteArray &name, const QVariant &val, bool force)
 {
     QHash<QByteArray, int>::ConstIterator iter = d->type->d->names.constFind(name);
 
@@ -348,11 +363,10 @@ bool QQmlOpenMetaObject::setValue(const QByteArray &name, const QVariant &val)
     }
 
     if (id >= 0) {
-        QVariant &dataVal = d->getData(id);
-        if (dataVal == val)
+        if (!force && d->propertyValue(id) == val)
             return false;
 
-        dataVal = val;
+        d->setPropertyValue(id, val);
         activate(d->object, id + d->type->d->signalOffset, nullptr);
         return true;
     }
@@ -363,7 +377,7 @@ bool QQmlOpenMetaObject::setValue(const QByteArray &name, const QVariant &val)
 // returns true if this value has been initialized by a call to either value() or setValue()
 bool QQmlOpenMetaObject::hasValue(int id) const
 {
-    return d->hasData(id);
+    return d->hasProperty(id);
 }
 
 void QQmlOpenMetaObject::setCached(bool c)