private static void fillFromSchema(PsiFile file, ElementNames names) {
    if (!(file instanceof XmlFile)) return;
    final XmlFile f = (XmlFile) file;
    final XmlDocument d = f.getDocument();
    if (d == null) return;
    final XmlTag rootTag = d.getRootTag();
    if (rootTag == null) return;

    //noinspection unchecked
    names.dependencies.add(new NSDeclTracker(rootTag));

    try {
      final Map<String, String> namespaceDeclarations = rootTag.getLocalNamespaceDeclarations();
      final Collection<String> prefixes = namespaceDeclarations.keySet();

      //noinspection unchecked
      final Set<XmlElementDescriptor> history = new THashSet<XmlElementDescriptor>();

      final XmlElementFactory ef = XmlElementFactory.getInstance(file.getProject());
      int noSchemaNamespaces = 0;
      for (String prefix : prefixes) {
        final String namespace = namespaceDeclarations.get(prefix);
        if (isIgnoredNamespace(prefix, namespace)) continue;

        final XmlTag tag =
            ef.createTagFromText("<dummy-tag xmlns='" + namespace + "' />", XMLLanguage.INSTANCE);
        final XmlDocument document = PsiTreeUtil.getParentOfType(tag, XmlDocument.class);
        final XmlNSDescriptor rootDescriptor = tag.getNSDescriptor(tag.getNamespace(), true);
        if (rootDescriptor == null
            || (rootDescriptor instanceof XmlNSDescriptorImpl
                && ((XmlNSDescriptorImpl) rootDescriptor).getTag() == null)
            || !rootDescriptor.getDeclaration().isPhysical()) {
          final QName any = QNameUtil.createAnyLocalName(namespace);
          names.elementNames.add(any);
          names.attributeNames.add(any);
          noSchemaNamespaces++;
          continue;
        }

        //noinspection unchecked
        names.dependencies.add(rootDescriptor.getDescriptorFile());

        final XmlElementDescriptor[] e = rootDescriptor.getRootElementsDescriptors(document);
        for (XmlElementDescriptor descriptor : e) {
          processElementDescriptors(descriptor, tag, names, history);
        }
      }

      names.validateNames = names.elementNames.size() > noSchemaNamespaces;

      //            final QName any = QNameUtil.createAnyLocalName("");
      //            names.elementNames.add(any);
      //            names.attributeNames.add(any);
    } catch (IncorrectOperationException e) {
      Logger.getInstance(XsltContextProvider.class.getName()).error(e);
    }
  }
  private CachedValue<ElementNames> createCachedValue(final PsiFile file) {
    return CachedValuesManager.getManager(file.getProject())
        .createCachedValue(
            new CachedValueProvider<ElementNames>() {
              public Result<ElementNames> compute() {
                final ElementNames names = new ElementNames();
                final PsiFile[] associations =
                    myFileAssociationsManager.getAssociationsFor(
                        file, FileAssociationsManager.XML_FILES);

                if (associations.length == 0) {
                  fillFromSchema(file, names);
                } else {
                  names.validateNames = true;
                  //noinspection unchecked
                  ContainerUtil.addAll(names.dependencies, associations);
                }
                //noinspection unchecked
                names.dependencies.add(myFileAssociationsManager);

                for (PsiFile file : associations) {
                  if (!(file instanceof XmlFile)) continue;
                  file.accept(
                      new XmlRecursiveElementVisitor() {
                        @Override
                        public void visitXmlTag(XmlTag tag) {
                          names.elementNames.add(QNameUtil.createQName(tag));
                          super.visitXmlTag(tag);
                        }

                        @Override
                        public void visitXmlAttribute(XmlAttribute attribute) {
                          if (!attribute.isNamespaceDeclaration()) {
                            names.attributeNames.add(QNameUtil.createQName(attribute));
                          }
                          super.visitXmlAttribute(attribute);
                        }
                      });
                }

                //noinspection unchecked
                return new Result<ElementNames>(names, ArrayUtil.toObjectArray(names.dependencies));
              }
            },
            false);
  }
  @Nullable
  @Override
  public MyValidationMessageConsumer collectInformation(@NotNull final PsiFile file) {
    final FileType type = file.getFileType();
    if (type != StdFileTypes.XML && type != RncFileType.getInstance()) {
      return null;
    }
    final XmlFile xmlfile = (XmlFile) file;
    final XmlDocument document = xmlfile.getDocument();
    if (document == null) {
      return null;
    }
    if (type == StdFileTypes.XML) {
      final XmlTag rootTag = document.getRootTag();
      if (rootTag == null) {
        return null;
      }
      if (!ApplicationLoader.RNG_NAMESPACE.equals(rootTag.getNamespace())) {
        return null;
      }
    } else {
      if (!ApplicationManager.getApplication().isUnitTestMode()
          && MyErrorFinder.hasError(xmlfile)) {
        return null;
      }
    }
    final Document doc = PsiDocumentManager.getInstance(file.getProject()).getDocument(file);

    final MyValidationMessageConsumer consumer = new MyValidationMessageConsumer();
    ErrorHandler eh =
        new DefaultHandler() {
          @Override
          public void warning(SAXParseException e) {
            handleError(e, file, doc, consumer.warning());
          }

          @Override
          public void error(SAXParseException e) {
            handleError(e, file, doc, consumer.error());
          }
        };

    RngParser.parsePattern(file, eh, true);
    return consumer;
  }
  @NotNull
  @Override
  public Runnable processFile(final PsiFile file) {
    VirtualFile vFile = file.getVirtualFile();
    if (vFile instanceof VirtualFileWindow) vFile = ((VirtualFileWindow) vFile).getDelegate();
    final Project project = file.getProject();
    if (vFile == null
        || !ProjectRootManager.getInstance(project).getFileIndex().isInSourceContent(vFile)) {
      return EmptyRunnable.INSTANCE;
    }
    final List<Pair<String, Boolean>> names = new ArrayList<Pair<String, Boolean>>();
    final Set<String> demandedForNested = new HashSet<>();
    collectNamesToImport(names, demandedForNested, (XmlFile) file);
    Collections.sort(names, (o1, o2) -> StringUtil.compare(o1.first, o2.first, true));
    final CodeStyleSettings settings = CodeStyleSettingsManager.getSettings(project);
    final List<Pair<String, Boolean>> sortedNames =
        ImportHelper.sortItemsAccordingToSettings(names, settings);
    final HashSet<String> onDemand = new HashSet<String>();
    ImportHelper.collectOnDemandImports(sortedNames, onDemand, settings);
    onDemand.addAll(demandedForNested);
    final Set<String> imported = new HashSet<String>();
    final List<String> imports = new ArrayList<String>();
    for (Pair<String, Boolean> pair : sortedNames) {
      final String qName = pair.first;
      final String packageName = StringUtil.getPackageName(qName);
      if (imported.contains(packageName) || imported.contains(qName)) {
        continue;
      }
      if (onDemand.contains(packageName)) {
        imported.add(packageName);
        imports.add("<?import " + packageName + ".*?>");
      } else {
        imported.add(qName);
        imports.add("<?import " + qName + "?>");
      }
    }
    final PsiFileFactory factory = PsiFileFactory.getInstance(file.getProject());

    final XmlFile dummyFile =
        (XmlFile)
            factory.createFileFromText(
                "_Dummy_.fxml", StdFileTypes.XML, StringUtil.join(imports, "\n"));
    final XmlDocument document = dummyFile.getDocument();
    final XmlProlog newImportList = document != null ? document.getProlog() : null;
    if (newImportList == null) return EmptyRunnable.getInstance();
    return () -> {
      final XmlDocument xmlDocument = ((XmlFile) file).getDocument();
      final XmlProlog prolog = xmlDocument != null ? xmlDocument.getProlog() : null;
      if (prolog != null) {
        final Collection<XmlProcessingInstruction> instructions =
            PsiTreeUtil.findChildrenOfType(prolog, XmlProcessingInstruction.class);
        for (final XmlProcessingInstruction instruction : instructions) {
          final ASTNode node = instruction.getNode();
          final ASTNode nameNode = node.findChildByType(XmlTokenType.XML_NAME);
          if (nameNode != null && nameNode.getText().equals("import")) {
            instruction.delete();
          }
        }
        prolog.add(newImportList);
      } else {
        document.addBefore(newImportList, document.getRootTag());
      }
    };
  }