@Override
    public Object parse(SourceData sourceData, int rowIndex, Context context) {
        Object stringObj = stringParser.parse(sourceData, rowIndex, context);
        if (stringObj == null) {
            return null;
        }
        String str = OperatorTools.parseString(stringObj);
        if (str == null || str.isEmpty()) {
            return null;
        }
        return (int) str.charAt(0);
    }
ASCIIFunction  ASCII(string)
description:
- Return NULL if string is NULL.
- Return the numeric value of the first character of string.
inlong-sdk/transform-sdk/src/main/java/org/apache/inlong/sdk/transform/process/function/string/AsciiFunction.java