Add a freeze() method to QQmlPropertyMap

After freezing a QQmlPropertyMap you cannot add any more properties, but
in turn the property access is cached, and therefore faster.

Task-number: QTBUG-57792
Change-Id: I2c6d768039c3b59eb2411194e463ee0de55f8bed
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

5 files changed, 60 insertions, 9 deletions

diff --git a/src/qml/qml/qqmlopenmetaobject.cpp b/src/qml/qml/qqmlopenmetaobject.cpp
index b5264fcdfc..ec2d57013f 100644
--- a/src/qml/qml/qqmlopenmetaobject.cpp
+++ b/src/qml/qml/qqmlopenmetaobject.cpp
@@ -172,8 +172,8 @@ void QQmlOpenMetaObjectTypePrivate::init(const QMetaObject *metaObj)
 class QQmlOpenMetaObjectPrivate
 {
 public:
-    QQmlOpenMetaObjectPrivate(QQmlOpenMetaObject *_q, bool _autoCreate, QObject *obj)
-        : q(_q), object(obj), autoCreate(_autoCreate) {}
+    QQmlOpenMetaObjectPrivate(QQmlOpenMetaObject *_q, QObject *obj)
+        : q(_q), object(obj) {}
 
     struct Property {
     private:
@@ -243,12 +243,12 @@ public:
     QObject *object;
     QQmlRefPointer<QQmlOpenMetaObjectType> type;
     QVector<QByteArray> *deferredPropertyNames = nullptr;
-    bool autoCreate;
+    bool autoCreate = true;
     bool cacheProperties = false;
 };
 
-QQmlOpenMetaObject::QQmlOpenMetaObject(QObject *obj, const QMetaObject *base, bool automatic)
-: d(new QQmlOpenMetaObjectPrivate(this, automatic, obj))
+QQmlOpenMetaObject::QQmlOpenMetaObject(QObject *obj, const QMetaObject *base)
+: d(new QQmlOpenMetaObjectPrivate(this, obj))
 {
     d->type.adopt(new QQmlOpenMetaObjectType(base ? base : obj->metaObject()));
     d->type->d->referers.insert(this);
@@ -259,8 +259,8 @@ QQmlOpenMetaObject::QQmlOpenMetaObject(QObject *obj, const QMetaObject *base, bo
     op->metaObject = this;
 }
 
-QQmlOpenMetaObject::QQmlOpenMetaObject(QObject *obj, QQmlOpenMetaObjectType *type, bool automatic)
-: d(new QQmlOpenMetaObjectPrivate(this, automatic, obj))
+QQmlOpenMetaObject::QQmlOpenMetaObject(QObject *obj, QQmlOpenMetaObjectType *type)
+: d(new QQmlOpenMetaObjectPrivate(this, obj))
 {
     d->type = type;
     d->type->d->referers.insert(this);
@@ -438,6 +438,16 @@ void QQmlOpenMetaObject::setCached(bool c)
     }
 }
 
+bool QQmlOpenMetaObject::autoCreatesProperties() const
+{
+    return d->autoCreate;
+}
+
+void QQmlOpenMetaObject::setAutoCreatesProperties(bool autoCreate)
+{
+    d->autoCreate = autoCreate;
+}
+
 
 int QQmlOpenMetaObject::createProperty(const char *name, const char *)
 {
diff --git a/src/qml/qml/qqmlopenmetaobject_p.h b/src/qml/qml/qqmlopenmetaobject_p.h
index f6397c8c59..47bba085b5 100644
--- a/src/qml/qml/qqmlopenmetaobject_p.h
+++ b/src/qml/qml/qqmlopenmetaobject_p.h
@@ -93,8 +93,8 @@ class QQmlOpenMetaObjectPrivate;
 class Q_QML_PRIVATE_EXPORT QQmlOpenMetaObject : public QAbstractDynamicMetaObject
 {
 public:
-    QQmlOpenMetaObject(QObject *, const QMetaObject * = nullptr, bool = true);
-    QQmlOpenMetaObject(QObject *, QQmlOpenMetaObjectType *, bool = true);
+    QQmlOpenMetaObject(QObject *, const QMetaObject * = nullptr);
+    QQmlOpenMetaObject(QObject *, QQmlOpenMetaObjectType *);
     ~QQmlOpenMetaObject() override;
 
     QVariant value(const QByteArray &) const;
@@ -115,6 +115,9 @@ public:
     // longer automatically called for new properties.
     void setCached(bool);
 
+    bool autoCreatesProperties() const;
+    void setAutoCreatesProperties(bool autoCreate);
+
     QQmlOpenMetaObjectType *type() const;
 
     void emitPropertyNotification(const QByteArray &propertyName);
diff --git a/src/qml/util/qqmlpropertymap.cpp b/src/qml/util/qqmlpropertymap.cpp
index e38cf3a2a9..2bf8ab0190 100644
--- a/src/qml/util/qqmlpropertymap.cpp
+++ b/src/qml/util/qqmlpropertymap.cpp
@@ -204,6 +204,22 @@ void QQmlPropertyMap::clear(const QString &key)
 }
 
 /*!
+    \since 6.1
+
+    Disallows any further properties to be added to this property map.
+    Existing properties can be modified or cleared.
+
+    In turn, an internal cache is turned on for the existing properties, which
+    may result in faster access from QML.
+ */
+void QQmlPropertyMap::freeze()
+{
+    Q_D(QQmlPropertyMap);
+    d->mo->setAutoCreatesProperties(false);
+    d->mo->setCached(true);
+}
+
+/*!
     Returns the value associated with \a key.
 
     If no value has been set for this key (or if the value has been cleared),
diff --git a/src/qml/util/qqmlpropertymap.h b/src/qml/util/qqmlpropertymap.h
index 556754c021..de070673d7 100644
--- a/src/qml/util/qqmlpropertymap.h
+++ b/src/qml/util/qqmlpropertymap.h
@@ -62,6 +62,7 @@ public:
     void insert(const QString &key, const QVariant &value);
     void insert(const QVariantHash &values);
     void clear(const QString &key);
+    void freeze();
 
     Q_INVOKABLE QStringList keys() const;
 
diff --git a/tests/auto/qml/qqmlpropertymap/tst_qqmlpropertymap.cpp b/tests/auto/qml/qqmlpropertymap/tst_qqmlpropertymap.cpp
index 82930b3f4a..75ef397bba 100644
--- a/tests/auto/qml/qqmlpropertymap/tst_qqmlpropertymap.cpp
+++ b/tests/auto/qml/qqmlpropertymap/tst_qqmlpropertymap.cpp
@@ -63,6 +63,7 @@ private slots:
     void QTBUG_35906();
     void QTBUG_48136();
     void lookupsInSubTypes();
+    void freeze();
 };
 
 class LazyPropertyMap : public QQmlPropertyMap, public QQmlParserStatus
@@ -574,6 +575,26 @@ void tst_QQmlPropertyMap::lookupsInSubTypes()
     QCOMPARE(object->property("newProperty").toInt(), 42);
 }
 
+void tst_QQmlPropertyMap::freeze()
+{
+    QQmlPropertyMap map;
+
+    map.insert(QLatin1String("key1"),100);
+    map.insert(QLatin1String("key2"),200);
+    QCOMPARE(map.keys().count(), 2);
+    QVERIFY(map.contains(QLatin1String("key1")));
+    QCOMPARE(map.value(QLatin1String("key1")), QVariant(100));
+    QCOMPARE(map.value(QLatin1String("key2")), QVariant(200));
+
+    map.freeze();
+    map.insert(QLatin1String("key3"), 32);
+    QCOMPARE(map.keys().count(), 2);
+    QVERIFY(!map.contains("key3"));
+
+    map.insert(QLatin1String("key1"), QStringLiteral("Hello World"));
+    QCOMPARE(map.value("key1").toString(), QStringLiteral("Hello World"));
+}
+
 QTEST_MAIN(tst_QQmlPropertyMap)
 
 #include "tst_qqmlpropertymap.moc"