Detailed explanation of Oracle custom split function examples

CREATE OR REPLACE TYPE ty_str_split IS TABLE OF VARCHAR2 (4000);
 
CREATE OR REPLACE FUNCTION fn_var_split (
  p_str IN VARCHAR2,
  p_delimiter IN VARCHAR2
)
  RETURN ty_str_split
IS
  j INT := 0;
  len INT := 0;
  str VARCHAR2 (4000);
  str_split ty_str_split := ty_str_split ();
  v_str VARCHAR2 (4000) := RTRIM (LTRIM (p_str, p_delimiter), p_delimiter);
BEGIN
  len := LENGTH (v_str);
 
  WHILE len > 0
  LOOP
    j := INSTR (v_str, p_delimiter, 1);
 
    IF j = 0
    THEN
      str := SUBSTR (v_str, 1);
      len := 0;
      str_split.EXTEND;
      str_split (str_split.COUNT) := str;
    ELSE
      str := SUBSTR (v_str, 1, j - 1);
      v_str := LTRIM (LTRIM (v_str, str), p_delimiter);
      len := LENGTH (v_str);
      str_split.EXTEND;
      str_split (str_split.COUNT) := str;
    END IF;
  END LOOP;
 
  RETURN str_split;
END fn_var_split;
/

1
12
123
1234
12345

DECLARE
  CURSOR c
  IS
    SELECT * FROM TABLE (CAST (fn_var_split (';1;12;;123;;;1234;;;;12345;', ';') AS ty_str_split));
  r c%ROWTYPE;
BEGIN
  OPEN c;
  LOOP
    FETCH c INTO r;
    EXIT WHEN c%NOTFOUND;
    DBMS_OUTPUT.put_line (r.column_value);
  END LOOP;
  CLOSE c;
END;
/