DocumentObjectGroup: fix deleting of groups in case of malformed links

This one prevents thurther object structure damage if
DocumentObjectGroup::Group connains multiple links to the same feature.
Also minorr changes:
 - Fix some spacing
 - Ask the user if he wants to delete group content

src/App/DocumentObjectGroup.cpp

@@ -29,14 +29,14 @@
 #include "DocumentObjectGroup.h"
 #include "DocumentObjectGroupPy.h"
 #include "Document.h"
-#include "FeaturePythonPyImp.h"
+#include "FeaturePythonPyImp.h"
 
 using namespace App;
 
 PROPERTY_SOURCE(App::DocumentObjectGroup, App::DocumentObject)
 
 
-DocumentObjectGroup::DocumentObjectGroup() 
+DocumentObjectGroup::DocumentObjectGroup()
 {
     ADD_PROPERTY_TYPE(Group,(0),"Base",(App::PropertyType)(Prop_Output),"List of referenced objects");
 }
@@ -63,20 +63,22 @@ void DocumentObjectGroup::addObject(DocumentObject* obj)
 
 void DocumentObjectGroup::removeObject(DocumentObject* obj)
 {
-    std::vector<DocumentObject*> grp = Group.getValues();
-    for (std::vector<DocumentObject*>::iterator it = grp.begin(); it != grp.end(); ++it) {
-        if (*it == obj) {
-            grp.erase(it);
-            Group.setValues(grp);
-            break;
-        }
+    const std::vector<DocumentObject*> & grp = Group.getValues();
+    std::vector<DocumentObject*> newGrp;
+
+    std::remove_copy (grp.begin(), grp.end(), std::back_inserter (newGrp), obj);
+    if (grp.size() != newGrp.size()) {
+        Group.setValues (newGrp);
     }
 }
 
 void DocumentObjectGroup::removeObjectsFromDocument()
 {
-    std::vector<DocumentObject*> grp = Group.getValues();
-    for (std::vector<DocumentObject*>::iterator it = grp.begin(); it != grp.end(); ++it) {
+    const std::vector<DocumentObject*> & grp = Group.getValues();
+    // Use set so iterate on each linked object exactly one time (in case of multiple links to the same document)
+    std::set<DocumentObject*> grpSet (grp.begin(), grp.end());
+
+    for (std::set<DocumentObject*>::iterator it = grpSet.begin(); it != grpSet.end(); ++it) {
         removeObjectFromDocument(*it);
     }
 }
@@ -85,11 +87,9 @@ void DocumentObjectGroup::removeObjectFromDocument(DocumentObject* obj)
 {
     // remove all children
     if (obj->getTypeId().isDerivedFrom(DocumentObjectGroup::getClassTypeId())) {
-        std::vector<DocumentObject*> grp = static_cast<DocumentObjectGroup*>(obj)->Group.getValues();
-        for (std::vector<DocumentObject*>::iterator it = grp.begin(); it != grp.end(); ++it) {
-            // recursive call to remove all subgroups
-            removeObjectFromDocument(*it);
-        }
+        DocumentObjectGroup *grp = static_cast<DocumentObjectGroup*>(obj);
+        // recursive call to remove all subgroups
+        grp->removeObjectsFromDocument();
     }
 
     this->getDocument()->remObject(obj->getNameInDocument());
@@ -177,7 +177,7 @@ PyObject *DocumentObjectGroup::getPyObject()
         // ref counter is set to 1
         PythonObject = Py::Object(new DocumentObjectGroupPy(this),true);
     }
-    return Py::new_reference_to(PythonObject); 
+    return Py::new_reference_to(PythonObject);
 }
 
 // Python feature ---------------------------------------------------------

src/App/DocumentObjectGroup.h

@@ -45,11 +45,11 @@ public:
 
     /** @name Object handling  */
     //@{
-    /** Adds an object of \a sType with \a pObjectName to the document this group belongs to and 
+    /** Adds an object of \a sType with \a pObjectName to the document this group belongs to and
      * append it to this group as well.
      */
     DocumentObject *addObject(const char* sType, const char* pObjectName);
-    /* Adds the object \a obj to this group. 
+    /* Adds the object \a obj to this group.
      */
     void addObject(DocumentObject* obj);
     /** Removes an object from this group.

src/App/DocumentObjectGroupPy.xml

@@ -45,4 +45,4 @@
     </Methode>
     <CustomAttributes />
   </PythonExport>
-</GenerateModel>
+</GenerateModel>

src/Gui/ViewProviderDocumentObjectGroup.cpp

@@ -26,6 +26,7 @@
 #ifndef _PreComp_
 # include <QApplication>
 # include <QPixmap>
+# include <QMessageBox>
 #endif
 
 #include <App/DocumentObjectGroup.h>
@@ -131,7 +132,10 @@ bool ViewProviderDocumentObjectGroup::canDragObjects() const
 
 void ViewProviderDocumentObjectGroup::dragObject(App::DocumentObject* obj)
 {
-    static_cast<App::DocumentObjectGroup*>(getObject())->removeObject(obj);
+    Gui::Command::doCommand(Gui::Command::Doc,"App.getDocument(\"%s\").getObject(\"%s\").removeObject("
+            "App.getDocument(\"%s\").getObject(\"%s\"))",
+            getObject()->getDocument()->getName(), getObject()->getNameInDocument(), 
+            obj->getDocument()->getName(), obj->getNameInDocument() );
 }
 
 bool ViewProviderDocumentObjectGroup::canDropObjects() const
@@ -141,7 +145,10 @@ bool ViewProviderDocumentObjectGroup::canDropObjects() const
 
 void ViewProviderDocumentObjectGroup::dropObject(App::DocumentObject* obj)
 {
-    static_cast<App::DocumentObjectGroup*>(getObject())->addObject(obj);
+    Gui::Command::doCommand(Gui::Command::Doc,"App.getDocument(\"%s\").getObject(\"%s\").addObject("
+            "App.getDocument(\"%s\").getObject(\"%s\"))",
+            getObject()->getDocument()->getName(), getObject()->getNameInDocument(), 
+            obj->getDocument()->getName(), obj->getNameInDocument() );
 }
 
 std::vector<std::string> ViewProviderDocumentObjectGroup::getDisplayModes(void) const
@@ -152,8 +159,22 @@ std::vector<std::string> ViewProviderDocumentObjectGroup::getDisplayModes(void)
 
 bool ViewProviderDocumentObjectGroup::onDelete(const std::vector<std::string> &)
 {
-    Gui::Command::doCommand(Gui::Command::Doc,"App.getDocument(\"%s\").getObject(\"%s\").removeObjectsFromDocument()"
-                                     ,getObject()->getDocument()->getName(), getObject()->getNameInDocument());
+    assert ( getObject ()->isDerivedFrom ( App::DocumentObjectGroup::getClassTypeId () ) );
+    App::DocumentObjectGroup *group = static_cast<App::DocumentObjectGroup *> (getObject());
+    // If the group is nonempty ask the user if he wants to delete it's content
+    if ( group->Group.getSize () ) {
+        QMessageBox::StandardButton choice = 
+            QMessageBox::question ( 0, QObject::tr ( "Delete group content?" ), 
+                QObject::tr ( "The group %1 is not empty, delete it's content as well?")
+                    .arg ( QString::fromUtf8 ( group->Label.getValue () ) ), 
+                QMessageBox::Yes | QMessageBox::No, QMessageBox::Yes );
+
+        if ( choice == QMessageBox::Yes ) {
+            Gui::Command::doCommand(Gui::Command::Doc,
+                    "App.getDocument(\"%s\").getObject(\"%s\").removeObjectsFromDocument()"
+                    ,getObject()->getDocument()->getName(), getObject()->getNameInDocument());
+        }
+    }
     return true;
 }