oracle xe wm_concat

CREATE OR REPLACE TYPE wm_concat_impl AUTHID CURRENT_USER
  AS OBJECT (
    curr_str   VARCHAR2 (32767),
    STATIC FUNCTION odciaggregateinitialize (sctx IN OUT wm_concat_impl) RETURN NUMBER,
    
    MEMBER FUNCTION odciaggregateiterate (
    SELF   IN OUT   wm_concat_impl,
    p1     IN       VARCHAR2
  ) RETURN NUMBER,
  
  MEMBER FUNCTION odciaggregateterminate (
    SELF          IN       wm_concat_impl,
    returnvalue   OUT      VARCHAR2,
    flags         IN       NUMBER
  ) RETURN NUMBER,
  
  MEMBER FUNCTION odciaggregatemerge (
    SELF    IN OUT   wm_concat_impl,
    sctx2   IN       wm_concat_impl
  ) RETURN NUMBER
);

CREATE OR REPLACE TYPE BODY wm_concat_impl
  IS
  STATIC FUNCTION odciaggregateinitialize (sctx IN OUT wm_concat_impl)
  RETURN NUMBER
    IS
    BEGIN
      sctx := wm_concat_impl (NULL);
      RETURN odciconst.success;
    END;
  MEMBER FUNCTION odciaggregateiterate (
    SELF   IN OUT   wm_concat_impl,
    p1     IN       VARCHAR2
  ) RETURN NUMBER
    IS
    BEGIN
      IF (curr_str IS NOT NULL)
        THEN
        curr_str := curr_str || ',' || p1;
      ELSE
        curr_str := p1;
      END IF;
      RETURN odciconst.success;
    END;
  MEMBER FUNCTION odciaggregateterminate (
    SELF          IN       wm_concat_impl,
    returnvalue   OUT      VARCHAR2,
    flags         IN       NUMBER
  ) RETURN NUMBER
    IS
    BEGIN
      returnvalue := curr_str;
      RETURN odciconst.success;
    END;
  MEMBER FUNCTION odciaggregatemerge (
    SELF    IN OUT   wm_concat_impl,
    sctx2   IN       wm_concat_impl
  )
  RETURN NUMBER
    IS
    BEGIN
    IF (sctx2.curr_str IS NOT NULL)
      THEN
      SELF.curr_str := SELF.curr_str || ',' || sctx2.curr_str;
    END IF;
    RETURN odciconst.success;
  END;
END;

CREATE OR REPLACE FUNCTION wm_concat (p1 VARCHAR2)
RETURN VARCHAR2
AGGREGATE USING wm_concat_impl;