* @return a find definition scope visitor that has already found some definition
*/
@SuppressWarnings("unchecked")
private FindDefinitionModelVisitor getFindDefinitionsScopeVisitor(String rep, int line, int col) throws Exception {
Tuple3 key = new Tuple3(rep, line, col);
FindDefinitionModelVisitor visitor = this.findDefinitionVisitorCache.getObj(key);
if (visitor == null) {
visitor = new FindDefinitionModelVisitor(rep, line, col, this);
if (ast != null) {
try {
ast.accept(visitor);
} catch (StopVisitingException e) {
//expected exception