@Override
    public Object parse(SourceData sourceData, int rowIndex, Context context) {
        if (inputStringParser == null || patternStringParser == null) {
            return null;
        }
        String inputString = OperatorTools.parseString(inputStringParser.parse(sourceData, rowIndex, context));
        String patternString = OperatorTools.parseString(patternStringParser.parse(sourceData, rowIndex, context));
        Pattern pattern = Pattern.compile(patternString);
        Matcher matcher = pattern.matcher(inputString);
        int count = 0;
        while (matcher.find()) {
            count++;
        }
        return count;
    }
RegexpCountFunction  ->  regexp_count(str, regexp)
description:
- Return NULL if any of the arguments are NULL or 'regexp' is invalid
- Return the number of times 'str' matches the 'regexp' pattern
Note: 'regexp' must be a Java regular expression.
inlong-sdk/transform-sdk/src/main/java/org/apache/inlong/sdk/transform/process/function/string/RegexpCountFunction.java