@Nullable
  public static Set<String> getEnumValues(Project project, @NotNull String regExp) {
    final PsiFileFactory factory = PsiFileFactory.getInstance(project);
    final PsiFile file = factory.createFileFromText("dummy.regexp", RegExpFileType.INSTANCE, regExp);
    final RegExpPattern pattern = (RegExpPattern)file.getFirstChild();
    if (pattern == null) {
      return null;
    }
    final RegExpBranch[] branches = pattern.getBranches();
    final Set<String> values = new HashSet<>();
    for (RegExpBranch branch : branches) {
      if (analyzeBranch(branch)) {
        values.add(branch.getUnescapedText());
      }
    }
    return values;
  }
@Nullable
  public static Set<String> getEnumValues(Project project, @NotNull String regExp)