assert (d1.getFeature() == d2.getFeature());
AbstractLiteral lhsLit = d1.getLiteral();
AbstractLiteral rhsLit = d2.getLiteral();
Operator lhsOp = d1.getOperator();
Operator rhsOp = d2.getOperator();
if (rhsOp == Operator.EQUALS) {
// If the rhs operator is =, then the expression will only match
// if the lhs operator is also = and the literal values are the
// same.