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Multiple fixes (issue #1757 , issue #1799 , issue #1842 , etc):
[modules/shaper.git] / src / Model / Model_Objects.cpp
index 1acc948065e3f26542a67dafc4bbff72bc499c2c..0b7678a5d532144cacb2b60ed48d64fe43b01631 100644 (file)
 #include <Model_ResultPart.h>
 #include <Model_ResultConstruction.h>
 #include <Model_ResultBody.h>
+#include <Model_ResultCompSolid.h>
 #include <Model_ResultGroup.h>
 #include <Model_ResultParameter.h>
 #include <ModelAPI_Validator.h>
 #include <ModelAPI_CompositeFeature.h>
+#include <ModelAPI_Tools.h>
 
 #include <Events_Loop.h>
-#include <Events_Error.h>
+#include <Events_InfoMessage.h>
 
 #include <TDataStd_Integer.hxx>
 #include <TDataStd_Comment.hxx>
@@ -29,6 +31,8 @@
 #include <TDF_Reference.hxx>
 #include <TDF_ChildIDIterator.hxx>
 #include <TDF_LabelMapHasher.hxx>
+#include <TDF_LabelMap.hxx>
+#include <TDF_ListIteratorOfLabelList.hxx>
 
 static const int TAG_OBJECTS = 2;  // tag of the objects sub-tree (features, results)
 
@@ -49,7 +53,8 @@ void Model_Objects::setOwner(DocumentPtr theDoc)
 {
   myDoc = theDoc;
   // update all fields and recreate features and result objects if needed
-  synchronizeFeatures(false, true, true);
+  TDF_LabelList aNoUpdated;
+  synchronizeFeatures(aNoUpdated, true, true, true);
   myHistory.clear();
 }
 
@@ -57,16 +62,28 @@ Model_Objects::~Model_Objects()
 {
   // delete all features of this document
   Events_Loop* aLoop = Events_Loop::loop();
-  NCollection_DataMap<TDF_Label, FeaturePtr>::Iterator aFeaturesIter(myFeatures);
-  for(; aFeaturesIter.More(); aFeaturesIter.Next()) {
+  // erase one by one to avoid access from the feature destructor itself from he map
+  // blocks the flush signals to avoid the temporary objects visualization in the viewer
+  // they should not be shown in order to do not lose highlight by erasing them
+  bool isActive = aLoop->activateFlushes(false);
+
+  while(!myFeatures.IsEmpty()) {
+    NCollection_DataMap<TDF_Label, FeaturePtr>::Iterator aFeaturesIter(myFeatures);
     FeaturePtr aFeature = aFeaturesIter.Value();
     static Events_ID EVENT_DISP = aLoop->eventByName(EVENT_OBJECT_TO_REDISPLAY);
     ModelAPI_EventCreator::get()->sendDeleted(myDoc, ModelAPI_Feature::group());
     ModelAPI_EventCreator::get()->sendUpdated(aFeature, EVENT_DISP);
-    aFeature->eraseResults();
+    aFeature->removeResults(0, false);
+    //aFeature->eraseResults();
     aFeature->erase();
+    myFeatures.UnBind(aFeaturesIter.Key());
   }
-  myFeatures.Clear();
+  myHistory.clear();
+  aLoop->activateFlushes(isActive);
+  // erase update, because features are destroyed and update should not performed for them anywhere
+  aLoop->eraseMessages(Events_Loop::eventByName(EVENT_OBJECT_CREATED));
+  aLoop->eraseMessages(Events_Loop::eventByName(EVENT_OBJECT_UPDATED));
+  // deleted and redisplayed is correctly performed: they know that features are destroyed
   aLoop->flush(Events_Loop::eventByName(EVENT_OBJECT_DELETED));
   aLoop->flush(Events_Loop::eventByName(EVENT_OBJECT_TO_REDISPLAY));
 
@@ -117,15 +134,24 @@ void Model_Objects::addFeature(FeaturePtr theFeature, const FeaturePtr theAfterT
     }
     AddToRefArray(aFeaturesLab, aFeatureLab, aPrevFeateureLab);
 
-    initData(theFeature, aFeatureLab, TAG_FEATURE_ARGUMENTS);
     // keep the feature ID to restore document later correctly
     TDataStd_Comment::Set(aFeatureLab, theFeature->getKind().c_str());
     myFeatures.Bind(aFeatureLab, theFeature);
-    // event: feature is added
+    // must be before the event sending: for OB the feature is already added
+    updateHistory(ModelAPI_Feature::group());
+    // do not change the order:
+    // initData()
+    // sendUpdated()
+    // during python script with fillet constraint feature data should be
+    // initialized before using it in GUI
+
+    // must be after binding to the map because of "Box" macro feature that
+    // creates other features in "initData"
+    initData(theFeature, aFeatureLab, TAG_FEATURE_ARGUMENTS);
+    // event: feature is added, mist be before "initData" to update OB correctly on Duplicate:
+    // first new part, then the content
     static Events_ID anEvent = Events_Loop::eventByName(EVENT_OBJECT_CREATED);
     ModelAPI_EventCreator::get()->sendUpdated(theFeature, anEvent);
-    theFeature->setDisabled(false); // by default created feature is enabled
-    updateHistory(ModelAPI_Feature::group());
   } else { // make feature has not-null data anyway
     theFeature->setData(Model_Data::invalidData());
     theFeature->setDoc(myDoc);
@@ -169,15 +195,17 @@ void Model_Objects::refsToFeature(FeaturePtr theFeature,
 {
   // check the feature: it must have no depended objects on it
   // the dependencies can be in the feature results
-  std::list<ResultPtr>::const_iterator aResIter = theFeature->results().cbegin();
-  for(; aResIter != theFeature->results().cend(); aResIter++) {
+  std::list<ResultPtr> aResults;
+  ModelAPI_Tools::allResults(theFeature, aResults);
+  std::list<ResultPtr>::const_iterator aResIter = aResults.cbegin();
+  for (; aResIter != aResults.cend(); aResIter++) {
     ResultPtr aResult = (*aResIter);
     std::shared_ptr<Model_Data> aData = 
-      std::dynamic_pointer_cast<Model_Data>(aResult->data());
+        std::dynamic_pointer_cast<Model_Data>(aResult->data());
     if (aData.get() != NULL) {
       const std::set<AttributePtr>& aRefs = aData->refsToMe();
       std::set<AttributePtr>::const_iterator aRefIt = aRefs.begin(), aRefLast = aRefs.end();
-      for(; aRefIt != aRefLast; aRefIt++) {
+      for (; aRefIt != aRefLast; aRefIt++) {
         FeaturePtr aFeature = std::dynamic_pointer_cast<ModelAPI_Feature>((*aRefIt)->owner());
         if (aFeature.get() != NULL)
           theRefs.insert(aFeature);
@@ -187,10 +215,10 @@ void Model_Objects::refsToFeature(FeaturePtr theFeature,
   // the dependencies can be in the feature itself
   std::shared_ptr<Model_Data> aData = 
       std::dynamic_pointer_cast<Model_Data>(theFeature->data());
-  if (aData && !aData->refsToMe().empty()) {
+  if (aData.get() && !aData->refsToMe().empty()) {
     const std::set<AttributePtr>& aRefs = aData->refsToMe();
     std::set<AttributePtr>::const_iterator aRefIt = aRefs.begin(), aRefLast = aRefs.end();
-    for(; aRefIt != aRefLast; aRefIt++) {
+    for (; aRefIt != aRefLast; aRefIt++) {
       FeaturePtr aFeature = std::dynamic_pointer_cast<ModelAPI_Feature>((*aRefIt)->owner());
       if (aFeature.get() != NULL)
         theRefs.insert(aFeature);
@@ -198,15 +226,15 @@ void Model_Objects::refsToFeature(FeaturePtr theFeature,
   }
 
   if (!theRefs.empty() && isSendError) {
-    Events_Error::send(
-      "Feature '" + theFeature->data()->name() + "' is used and can not be deleted");
+    Events_InfoMessage("Model_Objects", 
+      "Feature '%1' is used and can not be deleted").arg(theFeature->data()->name()).send();
   }
 }
 
 void Model_Objects::removeFeature(FeaturePtr theFeature)
 {
   std::shared_ptr<Model_Data> aData = std::static_pointer_cast<Model_Data>(theFeature->data());
-  if (aData && aData->isValid()) {
+  if (aData.get() && aData->isValid()) {
     // checking that the sub-element of composite feature is removed: if yes, inform the owner
     std::set<std::shared_ptr<ModelAPI_Feature> > aRefs;
     refsToFeature(theFeature, aRefs, false);
@@ -214,7 +242,7 @@ void Model_Objects::removeFeature(FeaturePtr theFeature)
     for(; aRefIter != aRefs.end(); aRefIter++) {
       std::shared_ptr<ModelAPI_CompositeFeature> aComposite = 
         std::dynamic_pointer_cast<ModelAPI_CompositeFeature>(*aRefIter);
-      if (aComposite.get()) {
+      if (aComposite.get() && aComposite->isSub(theFeature)) {
         aComposite->removeFeature(theFeature);
       }
     }
@@ -237,8 +265,6 @@ void Model_Objects::removeFeature(FeaturePtr theFeature)
     RemoveFromRefArray(featuresLabel(), aFeatureLabel);
     // event: feature is deleted
     ModelAPI_EventCreator::get()->sendDeleted(theFeature->document(), ModelAPI_Feature::group());
-    // the redisplay signal should be flushed in order to erase the feature presentation in the viewer
-    Events_Loop::loop()->flush(EVENT_DISP);
     updateHistory(ModelAPI_Feature::group());
   }
 }
@@ -278,10 +304,10 @@ void Model_Objects::moveFeature(FeaturePtr theMoved, FeaturePtr theAfterThis)
   if (!aPassedMovedFrom || !aPassedMovedTo) {// not found: unknown situation
     if (!aPassedMovedFrom) {
       static std::string aMovedFromError("The moved feature is not found");
-      Events_Error::send(aMovedFromError);
+      Events_InfoMessage("Model_Objects", aMovedFromError).send();
     } else {
       static std::string aMovedToError("The 'after' feature for movement is not found");
-      Events_Error::send(aMovedToError);
+      Events_InfoMessage("Model_Objects", aMovedToError).send();
     }
     return;
   }
@@ -289,13 +315,15 @@ void Model_Objects::moveFeature(FeaturePtr theMoved, FeaturePtr theAfterThis)
   aRefs->SetInternalArray(aNewArray);
   // update the feature and the history
   clearHistory(theMoved);
-  static Events_ID EVENT_UPD = Events_Loop::loop()->eventByName(EVENT_OBJECT_UPDATED);
-  ModelAPI_EventCreator::get()->sendUpdated(theMoved, EVENT_UPD);
+  // make sure all (selection) attributes of moved feature will be updated
+  static Events_ID kUpdateSelection = Events_Loop::loop()->eventByName(EVENT_UPDATE_SELECTION);
+  ModelAPI_EventCreator::get()->sendUpdated(theMoved, kUpdateSelection, false);
+  ModelAPI_EventCreator::get()->sendReordered(theMoved);
 }
 
 void Model_Objects::clearHistory(ObjectPtr theObj)
 {
-  if (theObj) {
+  if (theObj.get()) {
     const std::string aGroup = theObj->groupName();
     std::map<std::string, std::vector<ObjectPtr> >::iterator aHIter = myHistory.find(aGroup);
     if (aHIter != myHistory.end())
@@ -317,8 +345,7 @@ void Model_Objects::createHistory(const std::string& theGroupID)
 {
   std::map<std::string, std::vector<ObjectPtr> >::iterator aHIter = myHistory.find(theGroupID);
   if (aHIter == myHistory.end()) {
-    myHistory[theGroupID] = std::vector<ObjectPtr>();
-    std::vector<ObjectPtr>& aResult = myHistory[theGroupID];
+    std::vector<ObjectPtr> aResult = std::vector<ObjectPtr>();
     // iterate the array of references and get feature by feature from the array
     bool isFeature = theGroupID == ModelAPI_Feature::group();
     Handle(TDataStd_ReferenceArray) aRefs;
@@ -326,24 +353,33 @@ void Model_Objects::createHistory(const std::string& theGroupID)
       for(int a = aRefs->Lower(); a <= aRefs->Upper(); a++) {
         FeaturePtr aFeature = feature(aRefs->Value(a));
         if (aFeature.get()) {
+          // if feature is in sub-component, remove it from history: it is in sub-tree of sub-component
+          bool isSub = ModelAPI_Tools::compositeOwner(aFeature).get() != NULL;
           if (isFeature) { // here may be also disabled features
-            if (aFeature->isInHistory()) {
+            if (!isSub && aFeature->isInHistory()) {
               aResult.push_back(aFeature);
             }
           } else if (!aFeature->isDisabled()) { // iterate all results of not-disabled feature
-            const std::list<std::shared_ptr<ModelAPI_Result> >& aResults = aFeature->results();
-            std::list<std::shared_ptr<ModelAPI_Result> >::const_iterator aRIter = aResults.begin();
-            for (; aRIter != aResults.cend(); aRIter++) {
-              ResultPtr aRes = *aRIter;
-              if (aRes->groupName() != theGroupID) break; // feature have only same group results
-              if (!aRes->isDisabled() && aRes->isInHistory() && !aRes->isConcealed()) {
-                aResult.push_back(*aRIter);
+            // construction results of sub-features should not be in the tree
+            if (!isSub || theGroupID != ModelAPI_ResultConstruction::group()) {
+              // do not use reference to the list here since results can be changed by "isConcealed"
+              const std::list<std::shared_ptr<ModelAPI_Result> > aResults = aFeature->results();
+              std::list<std::shared_ptr<ModelAPI_Result> >::const_iterator aRIter = aResults.begin();
+              for (; aRIter != aResults.cend(); aRIter++) {
+                ResultPtr aRes = *aRIter;
+                if (aRes->groupName() != theGroupID) break; // feature have only same group results
+                if (!aRes->isDisabled() && aRes->isInHistory() && !aRes->isConcealed()) {
+                  aResult.push_back(*aRIter);
+                }
               }
             }
           }
         }
       }
     }
+    // to be sure that isConcealed did not update the history (issue 1089) during the iteration
+    if (myHistory.find(theGroupID) == myHistory.end())
+      myHistory[theGroupID] = aResult;
   }
 }
 
@@ -370,18 +406,40 @@ ObjectPtr Model_Objects::object(TDF_Label theLabel)
 {
   // try feature by label
   FeaturePtr aFeature = feature(theLabel);
-  if (aFeature)
+  if (aFeature.get())
     return feature(theLabel);
   TDF_Label aFeatureLabel = theLabel.Father().Father();  // let's suppose it is result
   aFeature = feature(aFeatureLabel);
-  if (aFeature) {
+  bool isSubResult = false;
+  if (!aFeature.get() && aFeatureLabel.Depth() > 1) { // let's suppose this is sub-result of result
+    aFeatureLabel = aFeatureLabel.Father().Father();
+    aFeature = feature(aFeatureLabel);
+    isSubResult = true;
+  }
+  if (aFeature.get()) {
     const std::list<std::shared_ptr<ModelAPI_Result> >& aResults = aFeature->results();
     std::list<std::shared_ptr<ModelAPI_Result> >::const_iterator aRIter = aResults.cbegin();
     for (; aRIter != aResults.cend(); aRIter++) {
-      std::shared_ptr<Model_Data> aResData = std::dynamic_pointer_cast<Model_Data>(
-          (*aRIter)->data());
-      if (aResData->label().Father().IsEqual(theLabel))
-        return *aRIter;
+      if (isSubResult) {
+        ResultCompSolidPtr aCompRes = std::dynamic_pointer_cast<ModelAPI_ResultCompSolid>(*aRIter);
+        if (aCompRes.get()) {
+          int aNumSubs = aCompRes->numberOfSubs();
+          for(int a = 0; a < aNumSubs; a++) {
+            ResultPtr aSub = aCompRes->subResult(a);
+            if (aSub.get()) {
+              std::shared_ptr<Model_Data> aSubData = std::dynamic_pointer_cast<Model_Data>(
+                  aSub->data());
+              if (aSubData->label().Father().IsEqual(theLabel))
+                return aSub;
+            }
+          }
+        }
+      } else {
+        std::shared_ptr<Model_Data> aResData = std::dynamic_pointer_cast<Model_Data>(
+            (*aRIter)->data());
+        if (aResData->label().Father().IsEqual(theLabel))
+          return *aRIter;
+      }
     }
   }
   return FeaturePtr();  // not found
@@ -399,11 +457,37 @@ std::shared_ptr<ModelAPI_Object> Model_Objects::objectByName(
     const std::string& theGroupID, const std::string& theName)
 {
   createHistory(theGroupID);
-  std::vector<ObjectPtr>& allObjs = myHistory[theGroupID];
-  std::vector<ObjectPtr>::iterator anObjIter = allObjs.begin();
-  for(; anObjIter != allObjs.end(); anObjIter++) {
-    if ((*anObjIter)->data()->name() == theName)
-      return *anObjIter;
+  if (theGroupID == ModelAPI_Feature::group()) { // searching among features (in history or not)
+    std::list<std::shared_ptr<ModelAPI_Feature> > allObjs = allFeatures();
+    std::list<std::shared_ptr<ModelAPI_Feature> >::iterator anObjIter = allObjs.begin();
+    for(; anObjIter != allObjs.end(); anObjIter++) {
+      if ((*anObjIter)->data()->name() == theName)
+        return *anObjIter;
+    }
+  } else { // searching among results (concealed or not)
+    std::list<std::shared_ptr<ModelAPI_Feature> > allObjs = allFeatures();
+    std::list<std::shared_ptr<ModelAPI_Feature> >::iterator anObjIter = allObjs.begin();
+    for(; anObjIter != allObjs.end(); anObjIter++) {
+      const std::list<std::shared_ptr<ModelAPI_Result> >& aResults = (*anObjIter)->results();
+      std::list<std::shared_ptr<ModelAPI_Result> >::const_iterator aRIter = aResults.cbegin();
+      for (; aRIter != aResults.cend(); aRIter++) {
+        if (aRIter->get() && (*aRIter)->groupName() == theGroupID) {
+          if ((*aRIter)->data()->name() == theName)
+            return *aRIter;
+          ResultCompSolidPtr aCompRes = std::dynamic_pointer_cast<ModelAPI_ResultCompSolid>(*aRIter);
+          if (aCompRes.get()) {
+            int aNumSubs = aCompRes->numberOfSubs();
+            for(int a = 0; a < aNumSubs; a++) {
+              ResultPtr aSub = aCompRes->subResult(a);
+              if (aSub.get() && aSub->groupName() == theGroupID) {
+                if (aSub->data()->name() == theName)
+                  return aSub;
+              }
+            }
+          }
+        }
+      }
+    }
   }
   // not found
   return ObjectPtr();
@@ -426,7 +510,7 @@ const int Model_Objects::index(std::shared_ptr<ModelAPI_Object> theObject)
 int Model_Objects::size(const std::string& theGroupID)
 {
   createHistory(theGroupID);
-  return myHistory[theGroupID].size();
+  return int(myHistory[theGroupID].size());
 }
 
 void Model_Objects::allResults(const std::string& theGroupID, std::list<ResultPtr>& theResults)
@@ -442,9 +526,10 @@ void Model_Objects::allResults(const std::string& theGroupID, std::list<ResultPt
         for (; aRIter != aResults.cend(); aRIter++) {
           ResultPtr aRes = *aRIter;
           if (aRes->groupName() != theGroupID) break; // feature have only same group results
-          if (aRes->isInHistory() && !aRes->isConcealed()) {
+          // iterate also concealed: ALL RESULTS (for translation parts undo/redo management)
+          //if (aRes->isInHistory() && !aRes->isConcealed()) {
             theResults.push_back(*aRIter);
-          }
+          //}
         }
       }
     }
@@ -463,7 +548,7 @@ void Model_Objects::setUniqueName(FeaturePtr theFeature)
     return;  // not needed, name is already defined
   std::string aName;  // result
   // first count all features of such kind to start with index = count + 1
-  int aNumObjects = 0;
+  int aNumObjects = -1; // this feature is already in this map
   NCollection_DataMap<TDF_Label, FeaturePtr>::Iterator aFIter(myFeatures);
   for (; aFIter.More(); aFIter.Next()) {
     if (aFIter.Value()->getKind() == theFeature->getKind())
@@ -484,6 +569,7 @@ void Model_Objects::setUniqueName(FeaturePtr theFeature)
         isSameName = (*aRIter)->data()->name() == aName;
       }
     }
+
     if (isSameName) {
       aNumObjects++;
       std::stringstream aNameStream;
@@ -505,14 +591,24 @@ void Model_Objects::initData(ObjectPtr theObj, TDF_Label theLab, const int theTa
   theObj->setDoc(myDoc);
   theObj->setData(aData);
   FeaturePtr aFeature = std::dynamic_pointer_cast<ModelAPI_Feature>(theObj);
-  if (aFeature) {
+  if (aFeature.get()) {
     setUniqueName(aFeature);  // must be before "initAttributes" because duplicate part uses name
   }
   theObj->initAttributes();
 }
 
+std::shared_ptr<ModelAPI_Feature> Model_Objects::featureById(const int theId)
+{
+  if (theId > 0) {
+    TDF_Label aLab = featuresLabel().FindChild(theId, Standard_False);
+    return feature(aLab);
+  }
+  return std::shared_ptr<ModelAPI_Feature>(); // not found
+}
+
 void Model_Objects::synchronizeFeatures(
-  const bool theMarkUpdated, const bool theUpdateReferences, const bool theFlush)
+  const TDF_LabelList& theUpdated, const bool theUpdateReferences, 
+  const bool theOpen, const bool theFlush)
 {
   Model_Document* anOwner = std::dynamic_pointer_cast<Model_Document>(myDoc).get();
   if (!anOwner) // this may happen on creation of document: nothing there, so nothing to synchronize
@@ -527,6 +623,17 @@ void Model_Objects::synchronizeFeatures(
   static Events_ID aToHideEvent = aLoop->eventByName(EVENT_OBJECT_TO_REDISPLAY);
   bool isActive = aLoop->activateFlushes(false);
 
+  // collect all updated labels map
+  TDF_LabelMap anUpdatedMap;
+  TDF_ListIteratorOfLabelList anUpdatedIter(theUpdated);
+  for(; anUpdatedIter.More(); anUpdatedIter.Next()) {
+    TDF_Label& aFeatureLab = anUpdatedIter.Value();
+    while(aFeatureLab.Depth() > 3)
+      aFeatureLab = aFeatureLab.Father();
+    if (myFeatures.IsBound(aFeatureLab))
+      anUpdatedMap.Add(aFeatureLab);
+  }
+
   // update all objects by checking are they on labels or not
   std::set<FeaturePtr> aNewFeatures, aKeptFeatures;
   TDF_ChildIDIterator aLabIter(featuresLabel(), TDataStd_Comment::GetID());
@@ -538,25 +645,41 @@ void Model_Objects::synchronizeFeatures(
       aFeature = std::dynamic_pointer_cast<Model_Session>(ModelAPI_Session::get())->createFeature(
         TCollection_AsciiString(Handle(TDataStd_Comment)::DownCast(aLabIter.Value())->Get())
         .ToCString(), anOwner);
-      if (!aFeature) {  // somethig is wrong, most probably, the opened document has invalid structure
-        Events_Error::send("Invalid type of object in the document");
+      if (!aFeature.get()) {  // somethig is wrong, most probably, the opened document has invalid structure
+        Events_InfoMessage("Model_Objects", "Invalid type of object in the document").send();
         aLabIter.Value()->Label().ForgetAllAttributes();
         continue;
       }
+      aFeature->init();
       // this must be before "setData" to redo the sketch line correctly
       myFeatures.Bind(aFeatureLabel, aFeature);
       aNewFeatures.insert(aFeature);
       initData(aFeature, aFeatureLabel, TAG_FEATURE_ARGUMENTS);
       updateHistory(aFeature);
-      aFeature->setDisabled(false); // by default created feature is enabled (this allows to recreate the results before "setCurrent" is called)
 
       // event: model is updated
       ModelAPI_EventCreator::get()->sendUpdated(aFeature, aCreateEvent);
     } else {  // nothing is changed, both iterators are incremented
       aFeature = myFeatures.Find(aFeatureLabel);
       aKeptFeatures.insert(aFeature);
-      if (theMarkUpdated) {
+      if (anUpdatedMap.Contains(aFeatureLabel)) {
+        if (!theOpen) { // on abort/undo/redo reinitialize attributes is something is changed
+          std::list<std::shared_ptr<ModelAPI_Attribute> > anAttrs = aFeature->data()->attributes("");
+          std::list<std::shared_ptr<ModelAPI_Attribute> >::iterator anAttr = anAttrs.begin();
+          for(; anAttr != anAttrs.end(); anAttr++)
+            (*anAttr)->reinit();
+        }
         ModelAPI_EventCreator::get()->sendUpdated(aFeature, anUpdateEvent);
+        if (aFeature->getKind() == "Parameter") { // if parameters are changed, update the results (issue 937)
+          const std::list<std::shared_ptr<ModelAPI_Result> >& aResults = aFeature->results();
+          std::list<std::shared_ptr<ModelAPI_Result> >::const_iterator aRIter = aResults.begin();
+          for (; aRIter != aResults.cend(); aRIter++) {
+            std::shared_ptr<ModelAPI_Result> aRes = *aRIter;
+            if (aRes->data()->isValid() && !aRes->isDisabled()) {
+              ModelAPI_EventCreator::get()->sendUpdated(aRes, anUpdateEvent);
+            }
+          }
+        }
       }
     }
   }
@@ -576,6 +699,7 @@ void Model_Objects::synchronizeFeatures(
         ModelAPI_EventCreator::get()->sendUpdated(aFeature, aRedispEvent);
         updateHistory(aFeature);
         aFeature->erase();
+
         // unbind after the "erase" call: on abort sketch is removes sub-objects that corrupts aFIter
         myFeatures.UnBind(aFIter.Key());
         // reinitialize iterator because unbind may corrupt the previous order in the map
@@ -597,7 +721,8 @@ void Model_Objects::synchronizeFeatures(
       FeaturePtr aFeature = myFeatures.Find(aFeatureLabel);
       if (std::dynamic_pointer_cast<ModelAPI_CompositeFeature>(aFeature).get())
         aComposites.push_back(aFeature);
-      updateResults(aFeature);
+      else
+        updateResults(aFeature);
     }
   }
   std::list<FeaturePtr>::iterator aComposite = aComposites.begin();
@@ -609,95 +734,146 @@ void Model_Objects::synchronizeFeatures(
   if (theUpdateReferences) {
     synchronizeBackRefs();
   }
-  if (theMarkUpdated) { // this means there is no control what was modified => remove history cash
+  if (!theUpdated.IsEmpty()) { // this means there is no control what was modified => remove history cash
     myHistory.clear();
   }
 
-  anOwner->executeFeatures() = false;
+  if (theOpen)
+    anOwner->executeFeatures() = false;
   aLoop->activateFlushes(isActive);
 
   if (theFlush) {
-    aLoop->flush(aCreateEvent);
     aLoop->flush(aDeleteEvent);
+    aLoop->flush(aCreateEvent); // delete should be emitted before create to reacts to aborted feature
     aLoop->flush(anUpdateEvent);
+    aLoop->flush(aCreateEvent); // after update of features, there could be results created
+    aLoop->flush(aDeleteEvent); // or deleted
     aLoop->flush(aRedispEvent);
     aLoop->flush(aToHideEvent);
   }
-  anOwner->executeFeatures() = true;
+  if (theOpen)
+    anOwner->executeFeatures() = true;
 }
 
-void Model_Objects::synchronizeBackRefs()
+/// synchronises back references for the given object basing on the collected data
+void Model_Objects::synchronizeBackRefsForObject(const std::set<AttributePtr>& theNewRefs,
+  ObjectPtr theObject) 
 {
-  // keeps the concealed flags of result to catch the change and create created/deleted events
-  std::list<std::pair<ResultPtr, bool> > aConcealed;
-  // first cycle: erase all data about back-references
-  NCollection_DataMap<TDF_Label, FeaturePtr>::Iterator aFeatures(myFeatures);
-  for(; aFeatures.More(); aFeatures.Next()) {
-    FeaturePtr aFeature = aFeatures.Value();
-    std::shared_ptr<Model_Data> aFData = 
-      std::dynamic_pointer_cast<Model_Data>(aFeature->data());
-    if (aFData) {
-      aFData->eraseBackReferences();
+  if (!theObject.get() || !theObject->data()->isValid())
+    return; // invalid
+  std::shared_ptr<Model_Data> aData = std::dynamic_pointer_cast<Model_Data>(theObject->data());
+  // iterate new list to compare with curent
+  std::set<AttributePtr>::iterator aNewIter = theNewRefs.begin();
+  for(; aNewIter != theNewRefs.end(); aNewIter++) {
+    if (aData->refsToMe().find(*aNewIter) == aData->refsToMe().end()) {
+      FeaturePtr aRefFeat = std::dynamic_pointer_cast<ModelAPI_Feature>((*aNewIter)->owner());
+      aData->addBackReference(aRefFeat, (*aNewIter)->id());
     }
-    const std::list<std::shared_ptr<ModelAPI_Result> >& aResults = aFeature->results();
-    std::list<std::shared_ptr<ModelAPI_Result> >::const_iterator aRIter = aResults.begin();
-    for (; aRIter != aResults.cend(); aRIter++) {
-      std::shared_ptr<Model_Data> aResData = 
-        std::dynamic_pointer_cast<Model_Data>((*aRIter)->data());
-      if (aResData) {
-        aConcealed.push_back(std::pair<ResultPtr, bool>(*aRIter, (*aRIter)->isConcealed()));
-        aResData->eraseBackReferences();
-      }
+  }
+  if (theNewRefs.size() != aData->refsToMe().size()) { // some back ref must be removed
+    std::set<AttributePtr>::iterator aCurrentIter = aData->refsToMe().begin();
+    while(aCurrentIter != aData->refsToMe().end()) {
+      if (theNewRefs.find(*aCurrentIter) == theNewRefs.end()) {
+        // for external references from other documents this system is not working: refs are collected from
+        // different Model_Objects, so before remove check this external object exists and still referenced
+        bool aLeaveIt = false;
+        if ((*aCurrentIter)->owner().get() && (*aCurrentIter)->owner()->document() != myDoc &&
+            (*aCurrentIter)->owner()->data().get() && (*aCurrentIter)->owner()->data()->isValid()) {
+          std::list<std::pair<std::string, std::list<std::shared_ptr<ModelAPI_Object> > > > aRefs;
+          (*aCurrentIter)->owner()->data()->referencesToObjects(aRefs);
+          std::list<std::pair<std::string, std::list<std::shared_ptr<ModelAPI_Object> > > >::iterator
+            aRefIter = aRefs.begin();
+          for(; aRefIter != aRefs.end(); aRefIter++) {
+            if ((*aCurrentIter)->id() == aRefIter->first) {
+              std::list<std::shared_ptr<ModelAPI_Object> >::iterator anOIt;
+              for(anOIt = aRefIter->second.begin(); anOIt != aRefIter->second.end(); anOIt++) {
+                if (*anOIt == theObject) {
+                  aLeaveIt = true;
+                }
+              }
+            }
+          }
+        }
+        if (!aLeaveIt) {
+          aData->removeBackReference(*aCurrentIter);
+          aCurrentIter = aData->refsToMe().begin(); // reinitialize iteration after delete
+        } else aCurrentIter++;
+      } else aCurrentIter++;
     }
   }
+  aData->updateConcealmentFlag();
+}
 
-  // second cycle: set new back-references: only features may have reference, iterate only them
-  ModelAPI_ValidatorsFactory* aValidators = ModelAPI_Session::get()->validators();
-  for(aFeatures.Initialize(myFeatures); aFeatures.More(); aFeatures.Next()) {
+void Model_Objects::synchronizeBackRefs()
+{
+  // collect all back references in the separated container: to update everything at once,
+  // without additional Concealment switchin on and off: only the final modification
+
+  // referenced (slave) objects to referencing attirbutes
+  std::map<ObjectPtr, std::set<AttributePtr> > allRefs;
+  NCollection_DataMap<TDF_Label, FeaturePtr>::Iterator aFeatures(myFeatures);
+  for(; aFeatures.More(); aFeatures.Next()) {
     FeaturePtr aFeature = aFeatures.Value();
-    std::shared_ptr<Model_Data> aFData = 
-      std::dynamic_pointer_cast<Model_Data>(aFeature->data());
-    if (aFData) {
+    std::shared_ptr<Model_Data> aFData = std::dynamic_pointer_cast<Model_Data>(aFeature->data());
+    if (aFData.get()) {
       std::list<std::pair<std::string, std::list<ObjectPtr> > > aRefs;
       aFData->referencesToObjects(aRefs);
-      std::list<std::pair<std::string, std::list<ObjectPtr> > >::iterator 
-        aRefsIter = aRefs.begin();
-      for(; aRefsIter != aRefs.end(); aRefsIter++) {
-        std::list<ObjectPtr>::iterator aRefTo = aRefsIter->second.begin();
-        for(; aRefTo != aRefsIter->second.end(); aRefTo++) {
+      std::list<std::pair<std::string, std::list<ObjectPtr> > >::iterator aRefsIt = aRefs.begin();
+      for(; aRefsIt != aRefs.end(); aRefsIt++) {
+        std::list<ObjectPtr>::iterator aRefTo = aRefsIt->second.begin();
+        for(; aRefTo != aRefsIt->second.end(); aRefTo++) {
           if (*aRefTo) {
-            std::shared_ptr<Model_Data> aRefData = 
-              std::dynamic_pointer_cast<Model_Data>((*aRefTo)->data());
-            aRefData->addBackReference(aFeature, aRefsIter->first); // here the Concealed flag is updated
-            // update enable/disable status: the nested status must be equal to the composite
-            CompositeFeaturePtr aComp = 
-              std::dynamic_pointer_cast<ModelAPI_CompositeFeature>(aFeature);
-            if (aComp.get()) {
-              FeaturePtr aReferenced = std::dynamic_pointer_cast<ModelAPI_Feature>(*aRefTo);
-              if (aReferenced.get()) {
-                aReferenced->setDisabled(aComp->isDisabled());
-              }
+            std::map<ObjectPtr, std::set<AttributePtr> >::iterator aFound = allRefs.find(*aRefTo);
+            if (aFound == allRefs.end()) {
+              allRefs[*aRefTo] = std::set<AttributePtr>();
+              aFound = allRefs.find(*aRefTo);
             }
+            aFound->second.insert(aFeature->data()->attribute(aRefsIt->first));
           }
         }
       }
     }
   }
-  std::list<std::pair<ResultPtr, bool> >::iterator aCIter = aConcealed.begin();
-  for(; aCIter != aConcealed.end(); aCIter++) {
-    if (aCIter->first->isConcealed() != aCIter->second) { // somethign is changed => produce event
-      if (aCIter->second) { // was concealed become not => creation event
-        static Events_ID anEvent = Events_Loop::eventByName(EVENT_OBJECT_CREATED);
-        ModelAPI_EventCreator::get()->sendUpdated(aCIter->first, anEvent);
-      } else { // was not concealed become concealed => delete event
-        ModelAPI_EventCreator::get()->sendDeleted(myDoc, aCIter->first->groupName());
-        // redisplay for the viewer (it must be disappeared also)
-        static Events_ID EVENT_DISP = 
-          Events_Loop::loop()->eventByName(EVENT_OBJECT_TO_REDISPLAY);
-        ModelAPI_EventCreator::get()->sendUpdated(aCIter->first, EVENT_DISP);
+  // second iteration: just compare back-references with existing in features and results
+  for(aFeatures.Initialize(myFeatures); aFeatures.More(); aFeatures.Next()) {
+    FeaturePtr aFeature = aFeatures.Value();
+    static std::set<AttributePtr> anEmpty;
+    std::map<ObjectPtr, std::set<AttributePtr> >::iterator aFound = allRefs.find(aFeature);
+    if (aFound == allRefs.end()) { // not found => erase all back references
+      synchronizeBackRefsForObject(anEmpty, aFeature);
+    } else {
+      synchronizeBackRefsForObject(aFound->second, aFeature);
+      allRefs.erase(aFound); // to check that all refs are counted
+    }
+    // also for results
+    std::list<ResultPtr> aResults;
+    ModelAPI_Tools::allResults(aFeature, aResults);
+    std::list<ResultPtr>::iterator aRIter = aResults.begin();
+    for(; aRIter != aResults.cend(); aRIter++) {
+      aFound = allRefs.find(*aRIter);
+      if (aFound == allRefs.end()) { // not found => erase all back references
+        synchronizeBackRefsForObject(anEmpty, *aRIter);
+      } else {
+        synchronizeBackRefsForObject(aFound->second, *aRIter);
+        allRefs.erase(aFound); // to check that all refs are counted
       }
     }
   }
+  for(aFeatures.Initialize(myFeatures); aFeatures.More(); aFeatures.Next()) {
+    FeaturePtr aFeature = aFeatures.Value();
+    std::list<ResultPtr> aResults;
+    ModelAPI_Tools::allResults(aFeature, aResults);
+    // update the concealment status for disply in isConcealed of ResultBody
+    std::list<ResultPtr>::iterator aRIter = aResults.begin();
+    for(; aRIter != aResults.cend(); aRIter++) {
+      (*aRIter)->isConcealed();
+    }
+  }
+  // the rest all refs means that feature references to the external document feature: process also them
+  std::map<ObjectPtr, std::set<AttributePtr> >::iterator anExtIter = allRefs.begin();
+  for(; anExtIter != allRefs.end(); anExtIter++) {
+    synchronizeBackRefsForObject(anExtIter->second, anExtIter->first);
+  }
 }
 
 TDF_Label Model_Objects::resultLabel(
@@ -712,12 +888,14 @@ void Model_Objects::storeResult(std::shared_ptr<ModelAPI_Data> theFeatureData,
                                  std::shared_ptr<ModelAPI_Result> theResult,
                                  const int theResultIndex)
 {
+  theResult->init();
   theResult->setDoc(myDoc);
   initData(theResult, resultLabel(theFeatureData, theResultIndex), TAG_FEATURE_ARGUMENTS);
   if (theResult->data()->name().empty()) {  // if was not initialized, generate event and set a name
     std::stringstream aNewName;
     aNewName<<theFeatureData->name();
-    if (theResultIndex > 0) // if there are several results, add unique prefix starting from second
+    // if there are several results (issue #899: any number of result), add unique prefix starting from second
+    if (theResultIndex > 0 || theResult->groupName() == ModelAPI_ResultBody::group())
       aNewName<<"_"<<theResultIndex + 1;
     theResult->data()->setName(aNewName.str());
   }
@@ -730,10 +908,10 @@ std::shared_ptr<ModelAPI_ResultConstruction> Model_Objects::createConstruction(
   TDataStd_Comment::Set(aLab, ModelAPI_ResultConstruction::group().c_str());
   ObjectPtr anOldObject = object(aLab);
   std::shared_ptr<ModelAPI_ResultConstruction> aResult;
-  if (anOldObject) {
+  if (anOldObject.get()) {
     aResult = std::dynamic_pointer_cast<ModelAPI_ResultConstruction>(anOldObject);
   }
-  if (!aResult) {
+  if (!aResult.get()) {
     aResult = std::shared_ptr<ModelAPI_ResultConstruction>(new Model_ResultConstruction);
     storeResult(theFeatureData, aResult, theIndex);
   }
@@ -744,14 +922,27 @@ std::shared_ptr<ModelAPI_ResultBody> Model_Objects::createBody(
     const std::shared_ptr<ModelAPI_Data>& theFeatureData, const int theIndex)
 {
   TDF_Label aLab = resultLabel(theFeatureData, theIndex);
-  TDataStd_Comment::Set(aLab, ModelAPI_ResultBody::group().c_str());
-  ObjectPtr anOldObject = object(aLab);
+  // for feature create compsolid, but for result sub create body: 
+  // only one level of recursion is supported now
+  ResultPtr aResultOwner = std::dynamic_pointer_cast<ModelAPI_Result>(theFeatureData->owner());
+  ObjectPtr anOldObject;
+  if (aResultOwner.get()) {
+    TDataStd_Comment::Set(aLab, ModelAPI_ResultBody::group().c_str());
+  } else { // in compsolid (higher level result) old object probably may be found
+    TDataStd_Comment::Set(aLab, ModelAPI_ResultCompSolid::group().c_str());
+    anOldObject = object(aLab);
+  }
   std::shared_ptr<ModelAPI_ResultBody> aResult;
-  if (anOldObject) {
+  if (anOldObject.get()) {
     aResult = std::dynamic_pointer_cast<ModelAPI_ResultBody>(anOldObject);
   }
-  if (!aResult) {
-    aResult = std::shared_ptr<ModelAPI_ResultBody>(new Model_ResultBody);
+  if (!aResult.get()) {
+    // create compsolid anyway; if it is compsolid, it will create sub-bodies internally
+    if (aResultOwner.get()) {
+      aResult = std::shared_ptr<ModelAPI_ResultBody>(new Model_ResultBody);
+    } else {
+      aResult = std::shared_ptr<ModelAPI_ResultBody>(new Model_ResultCompSolid);
+    }
     storeResult(theFeatureData, aResult, theIndex);
   }
   return aResult;
@@ -764,16 +955,25 @@ std::shared_ptr<ModelAPI_ResultPart> Model_Objects::createPart(
   TDataStd_Comment::Set(aLab, ModelAPI_ResultPart::group().c_str());
   ObjectPtr anOldObject = object(aLab);
   std::shared_ptr<ModelAPI_ResultPart> aResult;
-  if (anOldObject) {
+  if (anOldObject.get()) {
     aResult = std::dynamic_pointer_cast<ModelAPI_ResultPart>(anOldObject);
   }
-  if (!aResult) {
+  if (!aResult.get()) {
     aResult = std::shared_ptr<ModelAPI_ResultPart>(new Model_ResultPart);
     storeResult(theFeatureData, aResult, theIndex);
   }
   return aResult;
 }
 
+std::shared_ptr<ModelAPI_ResultPart> Model_Objects::copyPart(
+    const std::shared_ptr<ModelAPI_ResultPart>& theOrigin,
+    const std::shared_ptr<ModelAPI_Data>& theFeatureData, const int theIndex)
+{
+  std::shared_ptr<ModelAPI_ResultPart> aResult = createPart(theFeatureData, theIndex);
+  aResult->data()->reference(Model_ResultPart::BASE_REF_ID())->setValue(theOrigin);
+  return aResult;
+}
+
 std::shared_ptr<ModelAPI_ResultGroup> Model_Objects::createGroup(
     const std::shared_ptr<ModelAPI_Data>& theFeatureData, const int theIndex)
 {
@@ -781,10 +981,10 @@ std::shared_ptr<ModelAPI_ResultGroup> Model_Objects::createGroup(
   TDataStd_Comment::Set(aLab, ModelAPI_ResultGroup::group().c_str());
   ObjectPtr anOldObject = object(aLab);
   std::shared_ptr<ModelAPI_ResultGroup> aResult;
-  if (anOldObject) {
+  if (anOldObject.get()) {
     aResult = std::dynamic_pointer_cast<ModelAPI_ResultGroup>(anOldObject);
   }
-  if (!aResult) {
+  if (!aResult.get()) {
     aResult = std::shared_ptr<ModelAPI_ResultGroup>(new Model_ResultGroup(theFeatureData));
     storeResult(theFeatureData, aResult, theIndex);
   }
@@ -798,10 +998,10 @@ std::shared_ptr<ModelAPI_ResultParameter> Model_Objects::createParameter(
   TDataStd_Comment::Set(aLab, ModelAPI_ResultParameter::group().c_str());
   ObjectPtr anOldObject = object(aLab);
   std::shared_ptr<ModelAPI_ResultParameter> aResult;
-  if (anOldObject) {
+  if (anOldObject.get()) {
     aResult = std::dynamic_pointer_cast<ModelAPI_ResultParameter>(anOldObject);
   }
-  if (!aResult) {
+  if (!aResult.get()) {
     aResult = std::shared_ptr<ModelAPI_ResultParameter>(new Model_ResultParameter);
     storeResult(theFeatureData, aResult, theIndex);
   }
@@ -812,9 +1012,14 @@ std::shared_ptr<ModelAPI_Feature> Model_Objects::feature(
     const std::shared_ptr<ModelAPI_Result>& theResult)
 {
   std::shared_ptr<Model_Data> aData = std::dynamic_pointer_cast<Model_Data>(theResult->data());
-  if (aData) {
+  if (aData.get()) {
     TDF_Label aFeatureLab = aData->label().Father().Father().Father();
-    return feature(aFeatureLab);
+    FeaturePtr aFeature = feature(aFeatureLab);
+    if (!aFeature.get() && aFeatureLab.Depth() > 1) { // this may be sub-result of result
+      aFeatureLab = aFeatureLab.Father().Father();
+      aFeature = feature(aFeatureLab);
+    }
+    return aFeature;
   }
   return FeaturePtr();
 }
@@ -844,7 +1049,8 @@ void Model_Objects::updateResults(FeaturePtr theFeature)
   while(aResIter != theFeature->results().cend()) {
     ResultPtr aBody = std::dynamic_pointer_cast<ModelAPI_Result>(*aResIter);
     if (aBody.get()) {
-      if (!aBody->data()->isValid()) { 
+      std::shared_ptr<Model_Data> aData = std::dynamic_pointer_cast<Model_Data>(aBody->data());
+      if (!aData.get() || !aData->isValid() || (!aBody->isDisabled() && aData->isDeleted())) { 
         // found a disappeared result => remove it
         theFeature->eraseResultFromList(aBody);
         // start iterate from beginning because iterator is corrupted by removing
@@ -858,7 +1064,7 @@ void Model_Objects::updateResults(FeaturePtr theFeature)
   if (!theFeature->data() || !theFeature->data()->isValid() || theFeature->isDisabled())
     return;
   // check that results are presented on all labels
-  int aResSize = theFeature->results().size();
+  int aResSize = int(theFeature->results().size());
   TDF_ChildIterator aLabIter(resultLabel(theFeature->data(), 0).Father());
   for(; aLabIter.More(); aLabIter.Next()) {
     // here must be GUID of the feature
@@ -868,7 +1074,8 @@ void Model_Objects::updateResults(FeaturePtr theFeature)
       TDF_Label anArgLab = aLabIter.Value();
       Handle(TDataStd_Comment) aGroup;
       if (anArgLab.FindAttribute(TDataStd_Comment::GetID(), aGroup)) {
-        if (aGroup->Get() == ModelAPI_ResultBody::group().c_str()) {
+        if (aGroup->Get() == ModelAPI_ResultBody::group().c_str() || 
+            aGroup->Get() == ModelAPI_ResultCompSolid::group().c_str()) {
           aNewBody = createBody(theFeature->data(), aResIndex);
         } else if (aGroup->Get() == ModelAPI_ResultPart::group().c_str()) {
           std::shared_ptr<ModelAPI_ResultPart> aNewP = createPart(theFeature->data(), aResIndex); 
@@ -885,11 +1092,11 @@ void Model_Objects::updateResults(FeaturePtr theFeature)
           theFeature->attributeChanged("expression"); // just produce a value
           break;
         } else {
-          Events_Error::send(std::string("Unknown type of result is found in the document:") +
-            TCollection_AsciiString(aGroup->Get()).ToCString());
+          Events_InfoMessage("Model_Objects", "Unknown type of result is found in the document:")
+            .arg(TCollection_AsciiString(aGroup->Get()).ToCString()).send();
         }
       }
-      if (aNewBody) {
+      if (aNewBody && !aNewBody->data()->isDeleted()) {
         theFeature->setResult(aNewBody, aResIndex);
       }
     }
@@ -903,9 +1110,10 @@ ResultPtr Model_Objects::findByName(const std::string theName)
     FeaturePtr& aFeature = anObjIter.ChangeValue();
     if (!aFeature.get() || aFeature->isDisabled()) // may be on close
       continue;
-    const std::list<std::shared_ptr<ModelAPI_Result> >& aResults = aFeature->results();
-    std::list<std::shared_ptr<ModelAPI_Result> >::const_iterator aRIter = aResults.begin();
-    for (; aRIter != aResults.cend(); aRIter++) {
+    std::list<ResultPtr> allResults;
+    ModelAPI_Tools::allResults(aFeature, allResults);
+    std::list<ResultPtr>::iterator aRIter = allResults.begin();
+    for (; aRIter != allResults.cend(); aRIter++) {
       ResultPtr aRes = *aRIter;
       if (aRes.get() && aRes->data() && aRes->data()->isValid() && !aRes->isDisabled() &&
           aRes->data()->name() == theName) {
@@ -920,12 +1128,13 @@ ResultPtr Model_Objects::findByName(const std::string theName)
 FeaturePtr Model_Objects::nextFeature(FeaturePtr theCurrent, const bool theReverse)
 {
   std::shared_ptr<Model_Data> aData = std::static_pointer_cast<Model_Data>(theCurrent->data());
-  if (aData && aData->isValid()) {
+  if (aData.get() && aData->isValid()) {
     TDF_Label aFeatureLabel = aData->label().Father();
     Handle(TDataStd_ReferenceArray) aRefs;
     if (featuresLabel().FindAttribute(TDataStd_ReferenceArray::GetID(), aRefs)) {
       for(int a = aRefs->Lower(); a <= aRefs->Upper(); a++) { // iterate all existing features
-        if (aRefs->Value(a).IsEqual(aFeatureLabel)) {
+        TDF_Label aCurLab = aRefs->Value(a);
+        if (aCurLab.IsEqual(aFeatureLabel)) {
           a += theReverse ? -1 : 1;
           if (a >= aRefs->Lower() && a <= aRefs->Upper())
             return feature(aRefs->Value(a));
@@ -955,6 +1164,31 @@ FeaturePtr Model_Objects::lastFeature()
   return FeaturePtr(); // no features at all
 }
 
+bool Model_Objects::isLater(FeaturePtr theLater, FeaturePtr theCurrent) const
+{
+  std::shared_ptr<Model_Data> aLaterD = std::static_pointer_cast<Model_Data>(theLater->data());
+  std::shared_ptr<Model_Data> aCurrentD = std::static_pointer_cast<Model_Data>(theCurrent->data());
+  if (aLaterD.get() && aLaterD->isValid() && aCurrentD.get() && aCurrentD->isValid()) {
+    TDF_Label aLaterL = aLaterD->label().Father();
+    TDF_Label aCurrentL = aCurrentD->label().Father();
+    int aLaterI = -1, aCurentI = -1; // not found yet state
+    Handle(TDataStd_ReferenceArray) aRefs;
+    if (featuresLabel().FindAttribute(TDataStd_ReferenceArray::GetID(), aRefs)) {
+      for(int a = aRefs->Lower(); a <= aRefs->Upper(); a++) { // iterate all existing features
+        TDF_Label aCurLab = aRefs->Value(a);
+        if (aCurLab.IsEqual(aLaterL)) {
+          aLaterI = a;
+        } else if (aCurLab.IsEqual(aCurrentL)) {
+          aCurentI = a;
+        } else continue;
+        if (aLaterI != -1 && aCurentI != -1) // both are found
+          return aLaterI > aCurentI;
+      }
+    }
+  }
+  return false; // not found, or something is wrong
+}
+
 std::list<std::shared_ptr<ModelAPI_Feature> > Model_Objects::allFeatures()
 {
   std::list<std::shared_ptr<ModelAPI_Feature> > aResult;