public Object internalEvaluate(final XExpression it, final Context ctx) { if (it instanceof XBinaryOperation) { return _internalEvaluate((XBinaryOperation)it, ctx); } else if (it instanceof XUnaryOperation) { return _internalEvaluate((XUnaryOperation)it, ctx); } else if (it instanceof XAbstractFeatureCall) { return _internalEvaluate((XAbstractFeatureCall)it, ctx); } else if (it instanceof XBooleanLiteral) { return _internalEvaluate((XBooleanLiteral)it, ctx); } else if (it instanceof XCastedExpression) { return _internalEvaluate((XCastedExpression)it, ctx); } else if (it instanceof XNumberLiteral) { return _internalEvaluate((XNumberLiteral)it, ctx); } else if (it instanceof XStringLiteral) { return _internalEvaluate((XStringLiteral)it, ctx); } else if (it instanceof XTypeLiteral) { return _internalEvaluate((XTypeLiteral)it, ctx); } else if (it instanceof XAnnotation) { return _internalEvaluate((XAnnotation)it, ctx); } else if (it != null) { return _internalEvaluate(it, ctx); } else if (it == null) { return _internalEvaluate((Void)null, ctx); } else { throw new IllegalArgumentException("Unhandled parameter types: " + Arrays.<Object>asList(it, ctx).toString()); } } }