public static int getBaseType(ResultNode arg) {
        if (arg instanceof IntegerResultNode) {
            return IntegerResultNode.classId;
        } else if (arg instanceof FloatResultNode) {
            return FloatResultNode.classId;
        } else if (arg instanceof StringResultNode) {
            return StringResultNode.classId;
        } else if (arg instanceof RawResultNode) {
            return RawResultNode.classId;
        } else {
            return ResultNode.classId;
        }
    }
This class implements a lookup table for result node type conversion.

@author Ulf Lilleengen
searchlib/src/main/java/com/yahoo/searchlib/expression/ArithmeticTypeConversion.java