create view dept_view as 
select d.dname, f1(e.sal), f2(e.name), f3(d.loc), f4(1)
from emp e, dept d
where e.deptno = d.deptno
group by d.dname

create view dept_view as
select d.dname, f1(e.sal), f2(e.name), f3(d.loc) loc, f4(1) sal
from emp e, dept d
where e.deptno = d.deptno
group by d.dname

create or replace force view emp_view as 
select d.dname, f1(e.sal) e_sal, f2(e.name) e_name, f3(d.loc) d_loc, f4(sal) sal, f5(1) 
from emp e, dept d
where e.deptno = d.deptno
group by d.dname

create or replace function get_text (p_view in varchar2) return varchar2
as
  ret long;
begin
  select text into ret from user_views where view_name = upper(p_view);
  return ret;
end;
/

SQL> with
  2    names as (select upper('&view') view_name, upper('&column') col from dual),
  3    text as (select get_text(view_name) text from names),
  4    nbcol as (select count(*) nbcol from user_tab_columns, names where table_name=view_name)
  5  select regexp_substr(
  6           regexp_substr(text, '\w+\((\w+\.)?'||col||'(\W|$)', 1, column_value, 'i'),
  7           '^\w+') func
  8  from names, text,
  9       table(cast(multiset(select level from dual
 10                           connect by level <= (select nbcol from nbcol))
 11                   as sys.odciNumberList))
 12  where regexp_substr(text, '\w+\((\w+\.)?'||col||'(\W|$)', 1, column_value, 'i') is not null
 13  /
Enter value for view: emp_view
Enter value for column: name
FUNC
--------------------------------------------------------------------------------------------------
f2

1 row selected.

SQL> /
Enter value for view: emp_view
Enter value for column: loc
FUNC
--------------------------------------------------------------------------------------------------
f3

1 row selected.

SQL> /
Enter value for view: emp_view
Enter value for column: sal
FUNC
--------------------------------------------------------------------------------------------------
f1
f4

2 rows selected.

SQL> with
  2    names as (select upper('&view') view_name, upper('&column') col from dual),
  3    text as (select get_text(view_name) text from names),
  4    nbcol as (select count(*) nbcol from user_tab_columns, names where table_name=view_name)
  5  select regexp_substr(
  6           regexp_substr(text, '\w+\s*\(\s*(\w+\.)?'||col||'\W', 1, column_value, 'i'),
  7           '^\w+') func
  8  from names, text,
  9       table(cast(multiset(select level from dual
 10                           connect by level <= (select nbcol from nbcol))
 11                   as sys.odciNumberList))
 12  where regexp_substr(text, '\w+\s*\(\s*(\w+\.)?'||col||'\W', 1, column_value, 'i') is not null
 13  /
Enter value for view: emp_view
Enter value for column: name
FUNC
-------------------------------------------------------------------------------------------------------
f2

1 row selected.

SQL> /
Enter value for view: emp_view
Enter value for column: loc
FUNC
-------------------------------------------------------------------------------------------------------
f3

1 row selected.

SQL> /
Enter value for view: emp_view
Enter value for column: sal
FUNC
-------------------------------------------------------------------------------------------------------
f1
f4

2 rows selected.

SQL> def view=emp_view
SQL> with
  2    names as (select upper('&view') view_name, upper('&column') col from dual),
  3    text as (select get_text(view_name) text from names),
  4    nbcol as (select count(*) nbcol from user_tab_columns, names where table_name=view_name)
  5  select regexp_substr(
  6           regexp_substr(text, '[[:alnum:]$_#]+\s*\(\s*([[:alnum:]$_#]+\.)?'||col||'[^[:alnum:]$_#]',
  7                               1, column_value, 'i'),
  8           '^[[:alnum:]$_#]+', 1, 1, 'i') func
  9  from names, text,
 10       table(cast(multiset(select level from dual
 11                           connect by level <= (select nbcol from nbcol))
 12                   as sys.odciNumberList))
 13  where regexp_substr(text, '[[:alnum:]$_#]+\s*\(\s*([[:alnum:]$_#]+\.)?'||col||'[^[:alnum:]$_#]',
 14                            1, column_value, 'i')
 15         is not null
 16  /
Enter value for column: name
FUNC
------------------------------------------------------------------------------------------------------------
f2

1 row selected.

SQL> /
Enter value for column: loc
FUNC
------------------------------------------------------------------------------------------------------------
f3

1 row selected.

SQL> /
Enter value for column: sal
FUNC
------------------------------------------------------------------------------------------------------------
f1
f4

2 rows selected.

SQL> create or replace view view_function (view_name, parameter_name, function_name) as
  2  with
  3    -- valid patterns for identifiers and characters in them
  4    -- here Oracle standard identifiers
  5    valid_patterns as (select '[a-z][[:alnum:]$_#]*' ident, '[:alnum:]$_#' chars from dual),
  6    -- retrieve text of user views
  7    view_text as (select view_name, get_text(view_name) text from user_views),
  8    -- retrieve number of columns of user views
  9    view_nbcol as (
 10      select table_name view_name, count(*) nbcol from user_tab_columns group by table_name
 11    ),
 12    -- retrieve all function expressions as defined above in the topic:
 13    --   single parameter which must be a name, possibly prefixed by an alias or a table name
 14    function_exp as (
 15      select t.view_name,
 16             regexp_substr(t.text,
 17                           p.ident||'\s*\(\s*('||p.ident||'\.)?'||p.ident||'[^'||p.chars||']',
 18                           1, column_value, 'i') fct_exp
 19      from valid_patterns p, view_text t, view_nbcol n,
 20           table(cast(multiset(select level from dual connect by level <= n.nbcol)
 21                      as sys.odciNumberList))
 22      where n.view_name = t.view_name
 23        and regexp_substr(t.text,
 24                          p.ident||'\s*\(\s*('||p.ident||'\.)?'||p.ident||'[^'||p.chars||']',
 25                          1, column_value, 'i')
 26             is not null
 27    )
 28  -- break the function expression into parameter name and function name
 29  select f.view_name,
 30         cast(upper(regexp_substr(f.fct_exp,
 31                                  '\(\s*('||p.ident||'\.)?('||p.ident||')[^'||p.chars||']',
 32                                  1, 1, 'i', 2))
 33              as varchar2(30)) parameter_name,
 34         cast(upper(regexp_substr(fct_exp, '^'||p.ident, 1, 1, 'i')) as varchar2(30)) func
 35  from function_exp f, valid_patterns p
 36  /

View created.

SQL> select parameter_name, function_name
  2  from view_function
  3  where view_name='EMP_VIEW'
  4  order by 1, 2
  5  /
PARAMETER_NAME                 FUNCTION_NAME
------------------------------ ------------------------------
LOC                            F3
NAME                           F2
SAL                            F1
SAL                            F4

4 rows selected.

SQL> create or replace function view_function_text (p_view in varchar2) return varchar2
  2  as
  3    text varchar2(32767);
  4  begin
  5    select text into text from user_views
  6      where view_name = upper(p_view) and text_length <= 32767;
  7    text := regexp_replace(text, '\s+', ' ');
  8    return substr(text, 1, 4000);
  9  exception when no_data_found then return null;
 10  end;
 11  /

Function created.

SQL> create or replace view view_function (view_name, parameter_name, function_name) as
  2  with
  3    -- valid patterns for identifiers and characters in them
  4    -- here Oracle standard identifiers
  5    valid_patterns as (select '[a-z][[:alnum:]$_#]*' ident, '[:alnum:]$_#' chars from dual),
  6    -- retrieve text of user views
  7    view_text as (select view_name, view_function_text(view_name) text from user_views),
  8    -- retrieve number of columns of user views
  9    view_nbcol as (
 10      select table_name view_name, count(*) nbcol from user_tab_columns group by table_name
 11    ),
 12    -- retrieve all function expressions as defined above in the topic:
 13    --   single parameter which must be a name, possibly prefixed by an alias or a table name
 14    function_exp as (
 15      select t.view_name,
 16             regexp_substr(t.text,
 17                           p.ident||'\s*\(\s*('||p.ident||'\.)?'||p.ident||'\s*\)',
 18                           1, column_value, 'i') fct_exp
 19      from valid_patterns p, view_text t, view_nbcol n,
 20           table(cast(multiset(select level from dual connect by level <= n.nbcol)
 21                      as sys.odciNumberList))
 22      where n.view_name = t.view_name
 23        and regexp_substr(t.text,
 24                          p.ident||'\s*\(\s*('||p.ident||'\.)?'||p.ident||'\s*\)',
 25                          1, column_value, 'i')
 26             is not null
 27    )
 28  -- break the function expression into parameter name and function name
 29  select f.view_name,
 30         cast(upper(regexp_substr(f.fct_exp,
 31                                  '\(\s*('||p.ident||'\.)?('||p.ident||')\s*\)',
 32                                  1, 1, 'i', 2))
 33              as varchar2(30)) parameter_name,
 34         cast(upper(regexp_substr(fct_exp, '^'||p.ident, 1, 1, 'i')) as varchar2(30)) func
 35  from function_exp f, valid_patterns p
 36  /

View created.

SQL> select parameter_name, function_name
  2  from view_function
  3  where view_name='EMP_VIEW'
  4  order by 1, 2
  5  /
PARAMETER_NAME                 FUNCTION_NAME
------------------------------ ------------------------------
LOC                            F3
NAME                           F2
SAL                            F1
SAL                            F4

4 rows selected.

SQL> create or replace force view emp_view2
  2    (dname, deptno, e_sal, e_name, d_loc, sal, ignore1, valid, ignore2, cnt)
  3  as
  4  select d.dname, d.deptno, f1(e.sal), f2(e.name), f3(d.loc), f4(sal), f5(1),
  5         f6(f7(zzzzzz)), f8(name,sal), count(empno)
  6  from emp e, dept d
  7  where e.deptno = d.deptno
  8    and f9(zzzzzz) = 1
  9  group by d.dname, d.deptno
 10  /

Warning: View created with compilation errors.

SQL> select parameter_name, function_name
  2  from view_function
  3  where view_name='EMP_VIEW2'
  4  order by 1, 2
  5  /
PARAMETER_NAME                 FUNCTION_NAME
------------------------------ ------------------------------
EMPNO                          COUNT
LOC                            F3
NAME                           F2
SAL                            F1
SAL                            F4
ZZZZZZ                         F7
ZZZZZZ                         F9

7 rows selected.