SQL> create or replace
  2  function F(p_query varchar2) return sys.odcivarchar2list pipelined is
  3    l_query varchar2(4000) := replace(upper(p_query),chr(10),' ');
  4    pos pls_integer;
  5    joinpos pls_integer;
  6    len pls_integer;
  7    joins sys.odcivarchar2list :=
  8      sys.odcivarchar2list(
  9        'CROSS JOIN',
 10        'NATURAL JOIN',
 11        'LEFT JOIN',
 12        'LEFT OUTER JOIN',
 13        'RIGHT JOIN',
 14        'RIGHT OUTER JOIN',
 15        'INNER JOIN');
 16  begin
 17    pos := instr(p_query,' FROM ');
 18    if pos = 0 then
 19       pipe row ('ERROR: FROM not found');
 20       return;
 21    end if;
 22
 23    l_query := substr(l_query,pos+5);
 24    pos := instr(l_query,' WHERE ');
 25    if pos = 0 then
 26       pipe row ('INFO: WHERE not found');
 27    else
 28      null;
 29    end if;
 30
 31    for x in 1 .. 999 loop 
 32      joinpos := power(2,20);
 33      for i in 1 .. joins.count loop
 34        pos := instr(l_query,joins(i),2);
 35        if pos > 0 then
 36          if pos < joinpos then
 37            joinpos := pos;
 38            len := length(joins(i));
 39          end if;
 40        end if;
 41      end loop;
 42      if joinpos < power(2,20) then
 43        pipe row ( substr(l_query,1,joinpos-1) );
 44        l_query := substr(l_query,joinpos);
 45      end if;
 46    end loop;
 47
 48    return;
 49  end;
 50  /

Function created.

SQL>
SQL> variable q varchar2(4000)
SQL> exec :q := q'{... your query ...}';

PL/SQL procedure successfully completed.

SQL> select * from table(f(:q));

COLUMN_VALUE
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
INFO: WHERE not found
 COM_MSG_SUM
INNER JOIN RAC_SUG_SUM ON COM_MSG_SUM.CT_KEY = RAC_SUG_SUM.CT_KEY AND COM_MSG_SUM.DT_KEY = RAC_SUG_SUM.DT_KEY AND COM_MSG_SUM.ENT_KEY = RAC_SUG_SUM.ENT_KEY
INNER JOIN GAL_ENTITY_DTU ON RAC_SUG_SUM.RAM_KEY= GAL_ENTITY_DTU.RAM_KEY AND RAC_SUG_SUM.ENT_KEY = GAL_ENTITY_DTU.ENT_KEY AND RAC_SUG_SUM.DATE_KEY = GAL_ENTITY_DTU.DATE_KEY
INNER JOIN DIM_DATES ON DIM_DATES.DATE_KEY = COM_MSG_SUM.DATE_KEY
INNER JOIN ORG_CHART ON ORG_CHART.ENT_KEY = COM_MSG_SUM.ENT_KEY
INNER JOIN RUN ON RUN.RAM_KEY = RAC_SUG_SUM.RAM_KEY
INNER JOIN PROD_TYPE ON COM_MSG_SUM.N_PRODUCT_TYPE = PROD_TYPE.PROD_TYPE_IDT
LEFT OUTER JOIN ISSUER_DTLS ON COM_MSG_SUM.ISSUER_ID = ISSUER_DTLS.ISSUER_ID
LEFT OUTER JOIN PROD_CLAS ON RAC_SUG_SUM.CLASS_KEY = PROD_CLAS.CLASS_KEY
LEFT OUTER JOIN ENTITY_TYPE ON GAL_ENTITY_DTU.TYPE_KEY= ENTITY_TYPE.TYPE_KEY
LEFT OUTER JOIN DEPTH_TYPE ON RAC_SUG_SUM.DEPOSIT_TYPE_ID = DEPTH_TYPE.DEPOSIT_TYPE_ID

12 rows selected.