DocumentObject: add allowDuplicateLabel/onBeforeChangeLabel()

These two APIs allow an object to control its own labeling rules.
The previous auto re-labeling for uniqueness logic is moved from
ObjectLabelObserver (resides in Application.cpp) to PropertyString.

DocumentObject::allowDuplicateLabel() is used to inform PropertyString
that the object allows duplicate label regardless of application
setting. onBeforeChangeLabel() is called before actual label change to
give object a chance to override the new label.

src/App/Application.cpp

@@ -155,35 +155,6 @@ using namespace Base;
 using namespace App;
 using namespace std;
 
-/** Observer that watches relabeled objects and make sure that the labels inside
- * a document are unique.
- * @note In the FreeCAD design it is explicitly allowed to have duplicate labels
- * (i.e. the user visible text e.g. in the tree view) while the internal names
- * are always guaranteed to be unique.
- */
-class ObjectLabelObserver
-{
-public:
-    /// The one and only instance.
-    static ObjectLabelObserver* instance();
-    /// Destructs the sole instance.
-    static void destruct ();
-
-    /** Checks the new label of the object and relabel it if needed
-     * to make it unique document-wide
-     */
-    void slotRelabelObject(const App::DocumentObject&, const App::Property&);
-
-private:
-    static ObjectLabelObserver* _singleton;
-
-    ObjectLabelObserver();
-    ~ObjectLabelObserver();
-    const App::DocumentObject* current;
-    ParameterGrp::handle _hPGrp;
-};
-
-
 //==========================================================================
 // Application
 //==========================================================================
@@ -1915,7 +1886,6 @@ void Application::initApplication(void)
     try {
         Interpreter().runString(Base::ScriptFactory().ProduceScript("CMakeVariables"));
         Interpreter().runString(Base::ScriptFactory().ProduceScript("FreeCADInit"));
-        ObjectLabelObserver::instance();
     }
     catch (const Base::Exception& e) {
         e.ReportException();
@@ -2862,79 +2832,3 @@ std::string Application::FindHomePath(const char* sCall)
 # error "std::string Application::FindHomePath(const char*) not implemented"
 #endif
 
-ObjectLabelObserver* ObjectLabelObserver::_singleton = 0;
-
-ObjectLabelObserver* ObjectLabelObserver::instance()
-{
-    if (!_singleton)
-        _singleton = new ObjectLabelObserver;
-    return _singleton;
-}
-
-void ObjectLabelObserver::destruct ()
-{
-    delete _singleton;
-    _singleton = 0;
-}
-
-void ObjectLabelObserver::slotRelabelObject(const App::DocumentObject& obj, const App::Property& prop)
-{
-    // observe only the Label property
-    if (&prop == &obj.Label) {
-        // have we processed this (or another?) object right now?
-        if (current) {
-            return;
-        }
-
-        std::string label = obj.Label.getValue();
-        App::Document* doc = obj.getDocument();
-        if (doc && !_hPGrp->GetBool("DuplicateLabels")) {
-            std::vector<std::string> objectLabels;
-            std::vector<App::DocumentObject*>::const_iterator it;
-            std::vector<App::DocumentObject*> objs = doc->getObjects();
-            bool match = false;
-
-            for (it = objs.begin();it != objs.end();++it) {
-                if (*it == &obj)
-                    continue; // don't compare object with itself
-                std::string objLabel = (*it)->Label.getValue();
-                if (!match && objLabel == label)
-                    match = true;
-                objectLabels.push_back(objLabel);
-            }
-
-            // make sure that there is a name conflict otherwise we don't have to do anything
-            if (match && !label.empty()) {
-                // remove number from end to avoid lengthy names
-                size_t lastpos = label.length()-1;
-                while (label[lastpos] >= 48 && label[lastpos] <= 57) {
-                    // if 'lastpos' becomes 0 then all characters are digits. In this case we use
-                    // the complete label again
-                    if (lastpos == 0) {
-                        lastpos = label.length()-1;
-                        break;
-                    }
-                    lastpos--;
-                }
-
-                label = label.substr(0, lastpos+1);
-                label = Base::Tools::getUniqueName(label, objectLabels, 3);
-                this->current = &obj;
-                const_cast<App::DocumentObject&>(obj).Label.setValue(label);
-                this->current = 0;
-            }
-        }
-    }
-}
-
-ObjectLabelObserver::ObjectLabelObserver() : current(0)
-{
-    App::GetApplication().signalChangedObject.connect(boost::bind
-        (&ObjectLabelObserver::slotRelabelObject, this, _1, _2));
-    _hPGrp = App::GetApplication().GetUserParameter().GetGroup("BaseApp");
-    _hPGrp = _hPGrp->GetGroup("Preferences")->GetGroup("Document");
-}
-
-ObjectLabelObserver::~ObjectLabelObserver()
-{
-}

src/App/DocumentObject.h

@@ -341,6 +341,17 @@ class AppExport DocumentObject: public App::TransactionalObject
     /* Return true to cause PropertyView to show linked object's property */
     virtual bool canLinkProperties() const {return true;}
 
+    /* Return true to bypass duplicate label checking */
+    virtual bool allowDuplicateLabel() const {return false;}
+
+    /*** Called to let object itself control relabeling
+     *
+     * @param newLabel: input as the new label, which can be modified by object itself
+     *
+     * This function is is called before onBeforeChange()
+     */
+    virtual void onBeforeChangeLabel(std::string &newLabel) {(void)newLabel;}
+
     friend class Document;
     friend class Transaction;
     friend class ObjectExecution;

src/App/DocumentObjectPy.xml

@@ -262,5 +262,11 @@ or None if the GUI is not up</UserDocu>
             </Documentation>
 			<Parameter Name="Parents" Type="List"/>
         </Attribute>
+        <Attribute Name="OldLabel" ReadOnly="true">
+            <Documentation>
+                <UserDocu>Contains the old label before change</UserDocu>
+            </Documentation>
+			<Parameter Name="OldLabel" Type="String"/>
+        </Attribute>
 	</PythonExport>
 </GenerateModel>

src/App/DocumentObjectPyImp.cpp

@@ -834,3 +834,7 @@ PyObject *DocumentObjectPy::adjustRelativeLinks(PyObject *args) {
                         PyObject_IsTrue(recursive)?&visited:nullptr)));
     }PY_CATCH
 }
+
+Py::String DocumentObjectPy::getOldLabel() const {
+    return Py::String(getDocumentObjectPtr()->getOldLabel());
+}