public XmlNSDescriptor getNSDescriptor(final String namespace, boolean strict) {
    final XmlTag parentTag = getParentTag();

    if (parentTag == null && namespace.equals(XmlUtil.XHTML_URI)) {
      final XmlNSDescriptor descriptor = getDtdDescriptor(XmlUtil.getContainingFile(this));
      if (descriptor != null) {
        return descriptor;
      }
    }

    Map<String, CachedValue<XmlNSDescriptor>> map = initNSDescriptorsMap();
    final CachedValue<XmlNSDescriptor> descriptor = map.get(namespace);
    if (descriptor != null) {
      final XmlNSDescriptor value = descriptor.getValue();
      if (value != null) {
        return value;
      }
    }

    if (parentTag == null) {
      final XmlDocument parentOfType = PsiTreeUtil.getParentOfType(this, XmlDocument.class);
      if (parentOfType == null) {
        return null;
      }
      return parentOfType.getDefaultNSDescriptor(namespace, strict);
    }

    return parentTag.getNSDescriptor(namespace, strict);
  }
  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);
    }
  }