@NotNull
 private static Map<PsiElement, FoldingDescriptor> buildRanges(
     @NotNull Editor editor, @NotNull PsiFile psiFile) {
   final FoldingBuilder foldingBuilder =
       LanguageFolding.INSTANCE.forLanguage(psiFile.getLanguage());
   final ASTNode node = psiFile.getNode();
   if (node == null) return Collections.emptyMap();
   final FoldingDescriptor[] descriptors =
       LanguageFolding.buildFoldingDescriptors(
           foldingBuilder, psiFile, editor.getDocument(), true);
   Map<PsiElement, FoldingDescriptor> ranges = new HashMap<PsiElement, FoldingDescriptor>();
   for (FoldingDescriptor descriptor : descriptors) {
     final ASTNode ast = descriptor.getElement();
     final PsiElement psi = ast.getPsi();
     if (psi != null) {
       ranges.put(psi, descriptor);
     }
   }
   return ranges;
 }
  @Override
  public void setToEditor(@NotNull final Editor editor) {
    assertDispatchThread();
    final PsiManager psiManager = PsiManager.getInstance(myProject);
    if (psiManager.isDisposed()) return;

    if (!myFile.isValid()) return;
    final PsiFile psiFile = psiManager.findFile(myFile);
    if (psiFile == null) return;

    if (!mySerializedElements.isEmpty()) {
      // Restore postponed state
      assert myPsiElements.isEmpty() : "Sequential deserialization";
      for (SerializedPsiElement entry : mySerializedElements) {
        PsiElement restoredElement =
            FoldingPolicy.restoreBySignature(psiFile, entry.mySerializedElement);
        if (restoredElement != null && restoredElement.isValid()) {
          myPsiElements.add(
              SmartPointerManager.getInstance(myProject)
                  .createSmartPsiElementPointer(restoredElement));
          restoredElement.putUserData(FOLDING_INFO_KEY, entry.myFoldingInfo);
        }
      }
      mySerializedElements.clear();
    }

    Map<PsiElement, FoldingDescriptor> ranges = null;
    for (SmartPsiElementPointer<PsiElement> ptr : myPsiElements) {
      PsiElement element = ptr.getElement();
      if (element == null || !element.isValid()) {
        continue;
      }

      if (ranges == null) {
        ranges = buildRanges(editor, psiFile);
      }
      FoldingDescriptor descriptor = ranges.get(element);
      if (descriptor == null) {
        continue;
      }

      TextRange range = descriptor.getRange();
      FoldRegion region =
          FoldingUtil.findFoldRegion(editor, range.getStartOffset(), range.getEndOffset());
      if (region != null) {
        FoldingInfo fi = element.getUserData(FOLDING_INFO_KEY);
        boolean state = fi != null && fi.expanded;
        region.setExpanded(state);
      }
    }
    for (RangeMarker marker : myRangeMarkers) {
      if (!marker.isValid()) {
        continue;
      }
      FoldRegion region =
          FoldingUtil.findFoldRegion(editor, marker.getStartOffset(), marker.getEndOffset());
      FoldingInfo info = marker.getUserData(FOLDING_INFO_KEY);
      if (region == null) {
        if (info != null) {
          region =
              editor
                  .getFoldingModel()
                  .addFoldRegion(marker.getStartOffset(), marker.getEndOffset(), info.placeHolder);
        }
        if (region == null) {
          return;
        }
      }

      boolean state = info != null && info.expanded;
      region.setExpanded(state);
    }
  }