g is.  It is
        very difficult to use part of Elsa without the whole front-end.  For
        example, you cannot use Elsa to parse C/ObjC code without building an
        AST.  You can do this in Clang and it is much faster than building an
        AST.</li>
    <li>Elsa does not have an integrated preprocessor, which makes it extremely
        difficult to accurately map from a source location in the AST back to
        its original position before preprocessing.  Like GCC, it does not keep
  