Method nullify

subprojects/groovy-sql/src/main/java/groovy/sql/Sql.java:4696–4718

Hook to allow derived classes to override null handling. Default behavior is to replace ?'"? references with NULLish @param sql the SQL statement @return the modified SQL String

(String sql)

     * @return the modified SQL String
     */
    protected String nullify(String sql) {
        /*
         * Some drivers (Oracle classes12.zip) have difficulty resolving data
         * type if setObject(null). We will modify the query to pass 'null', 'is
         * null', and 'is not null'
         */
        //could be more efficient by compiling expressions in advance.
        int firstWhere = findWhereKeyword(sql);
        if (firstWhere >= 0) {
            Pattern[] patterns = {Pattern.compile("(?is)^(.{" + firstWhere + "}.*?)!=\\s{0,1}(\\s*)\\?'\"\\?(.*)"),
                    Pattern.compile("(?is)^(.{" + firstWhere + "}.*?)<>\\s{0,1}(\\s*)\\?'\"\\?(.*)"),
                    Pattern.compile("(?is)^(.{" + firstWhere + "}.*?[^<>])=\\s{0,1}(\\s*)\\?'\"\\?(.*)"),};
            String[] replacements = {"$1 is not $2null$3", "$1 is not $2null$3", "$1 is $2null$3",};
            for (int i = 0; i < patterns.length; i++) {
                Matcher matcher = patterns[i].matcher(sql);
                while (matcher.matches()) {
                    sql = matcher.replaceAll(replacements[i]);
                    matcher = patterns[i].matcher(sql);
                }
            }
        }
        return sql.replaceAll("\\?'\"\\?", "null");
    }

    /**
     * Hook to allow derived classes to override where clause sniffing.