private static List<PsiElement> getTopLevelRegExpChars(String regExpText, Project project) {
@SuppressWarnings("deprecation")
PsiFile file = PsiFileFactory.getInstance(project).createFileFromText("A.regexp", regExpText);
List<PsiElement> result = null;
final PsiElement[] children = file.getChildren();
for (PsiElement child : children) {
PsiElement[] grandChildren = child.getChildren();
if (grandChildren.length != 1)
return Collections
.emptyList(); // a | b, more than one branch, can not predict in current way
for (PsiElement grandGrandChild : grandChildren[0].getChildren()) {
if (result == null) result = new ArrayList<>();
result.add(grandGrandChild);
}
}
return result != null ? result : Collections.<PsiElement>emptyList();
}
