QmlDesigner: Add is singleton to NodeMetaInfo

Change-Id: Icb657fd326b25a6d9c7f2e73dc35df5c4df42c1e
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmldesigner/libs/designercore/include/nodemetainfo.h

@@ -75,6 +75,7 @@ public:
 
     MetaInfoType type() const;
     bool isFileComponent() const;
+    bool isSingleton() const;
     FlagIs canBeContainer() const;
     FlagIs forceClip() const;
     FlagIs doesLayoutChildren() const;

src/plugins/qmldesigner/libs/designercore/metainfo/nodemetainfo.cpp

@@ -1527,6 +1527,26 @@ bool NodeMetaInfo::isFileComponent() const
     }
 }
 
+bool NodeMetaInfo::isSingleton() const
+{
+    if constexpr (useProjectStorage()) {
+        if (!isValid())
+            return {};
+
+        using NanotraceHR::keyValue;
+        NanotraceHR::Tracer tracer{"is singleton", category(), keyValue("type id", m_typeId)};
+
+        auto isSingleton = typeData().traits.isSingleton;
+
+        tracer.end(keyValue("is singleton", isSingleton));
+
+        return isSingleton;
+
+    } else {
+        return false;
+    }
+}
+
 FlagIs NodeMetaInfo::canBeContainer() const
 {
     if constexpr (useProjectStorage()) {

tests/unit/tests/unittests/metainfo/nodemetainfo-test.cpp

@@ -236,6 +236,43 @@ TEST_F(NodeMetaInfo, component_is_file_component)
     ASSERT_TRUE(isFileComponent);
 }
 
+TEST_F(NodeMetaInfo, object_is_not_singleton)
+{
+    bool isSingleton = objectMetaInfo.isSingleton();
+
+    ASSERT_FALSE(isSingleton);
+}
+
+TEST_F(NodeMetaInfo, default_is_not_ingleton)
+{
+    bool isSingleton = QmlDesigner::NodeMetaInfo{}.isFileComponent();
+
+    ASSERT_FALSE(isSingleton);
+}
+
+TEST_F(NodeMetaInfo, invalid_is_not_singleton)
+{
+    auto node = model.createModelNode("Foo");
+    auto metaInfo = node.metaInfo();
+
+    bool isSingleton = metaInfo.isSingleton();
+
+    ASSERT_FALSE(isSingleton);
+}
+
+TEST_F(NodeMetaInfo, component_is_singleton)
+{
+    auto moduleId = projectStorageMock.createModule("/path/to/project", ModuleKind::PathLibrary);
+    TypeTraits traits{TypeTraitsKind::Reference};
+    traits.isSingleton = true;
+    auto typeId = projectStorageMock.createType(moduleId, "Foo", traits);
+    QmlDesigner::NodeMetaInfo metaInfo{typeId, &projectStorageMock};
+
+    bool isSingleton = metaInfo.isSingleton();
+
+    ASSERT_TRUE(isSingleton);
+}
+
 TEST_F(NodeMetaInfo, has_property)
 {
     auto metaInfo = model.qtQuickItemMetaInfo();