LabelExprFactory label = new LabelExprFactory();
BooleanExprFactory bool = createBooleanExprFactory();
URIExprFactory uri = new URIExprFactory();
SqlExprFactory sql = new SqlExprFactory();
DatatypeExprFactory datatype = new DatatypeExprFactory();
LanguageExprFactory language = new LanguageExprFactory();
sql.setBNodeExprFactory(new BNodeExprFactory());
sql.setBooleanExprFactory(bool);
sql.setDatatypeExprFactory(datatype);
sql.setLabelExprFactory(label);
sql.setLanguageExprFactory(language);