with t (x1, x2, c, flag) as
(
              select 10, 30, 'blue', 'src' from dual
union all select 20, 30, 'red', 'tgt' from dual
union all select 31, 35, 'red', 'tgt' from dual
)
,p as (
select * from (
  select x, flag, decode(z,'X1',c,'-') c, z
    from (select x1, x2+1 x2, c, flag from t) tt
 unpivot (x for z in (x1,x2))) 
 pivot (max(c) for flag in ('src' s,'tgt' t))
),
q as (
select x x1, lead(x) over (order by x) -1 x2, c from (
  select x, c, lag(c) over (order by x) cp from (
    select x, decode(s,'-',t,s) c from (
      select x,
             last_value(s ignore nulls) over (order by x) s,
             last_value(t ignore nulls) over (order by x) t
        from p
      )
    )
  )
 where c != nvl(cp,' ')
)
select x1,x2,c from q
 where x1 <= x2  
/

SQL> /

        X1         X2 C
---------- ---------- ----
        10         30 blue

with t (x1, x2, c, flag) as
(
              select 20, 30, 'red', 'src' from dual
union all select 20, 30, 'red', 'tgt' from dual
)

X1	X2	RESULT
20	30	red
31	30	 - 
Download CSV
2 rows selected.

SQL> ed
Wrote file afiedt.buf

  1  with t (x1, x2, c, flag) as
  2  (
  3                select 10, 30, 'blue', 'src' from dual
  4  union all select 20, 30, 'red', 'tgt' from dual
  5  union all select 31, 35, 'red', 'tgt' from dual
  6  )
  7  ,p as (
  8  select * from (
  9    select x, flag, decode(z,'X1',c,'-') c, z
 10      from (select x1, x2+1 x2, c, flag from t) tt
 11   unpivot (x for z in (x1,x2)))
 12   pivot (max(c) for flag in ('src' s,'tgt' t))
 13  ),
 14  q as (
 15  select x x1, lead(x) over (order by x) -1 x2, c from (
 16    select x, c, lag(c) over (order by x) cp from (
 17      select x, decode(s,'-',t,s) c from (
 18        select x,
 19               last_value(s ignore nulls) over (order by x) s,
 20               last_value(t ignore nulls) over (order by x) t
 21          from p
 22        )
 23      )
 24    )
 25   where c != nvl(cp,' ')
 26  )
 27  select x1,x2,c from q
 28*  where x1 <= x2
SQL> /

        X1         X2 C
---------- ---------- ----
        10         30 blue

SQL>

SQL> create or replace package dropme_pkg as
  2      type res_rec_t is record (x1 t.x1%type, x2 t.x2%type, res t.c%type);
  3      type res_tab_t is table of res_rec_t;
  4      type refcur_t is ref cursor return t%rowtype;
  5      function f_superimpose return res_tab_t pipelined;
  6  end dropme_pkg;
  7  /

Package created.

...
104  end dropme_pkg;
105  /

Warning: Package Body created with compilation errors.

SQL> show err
Errors for PACKAGE BODY DROPME_PKG:

LINE/COL ERROR
-------- -----------------------------------------------------------------
16/9     PL/SQL: Statement ignored
16/18    PLS-00222: no function with name 'RES_REC_T' exists in this scope
SQL> l 16
 16*         l_res := res_rec_t(l_src.x1, l_src.x2, l_src.c);
SQL>