Materialized view source columns

Hi to all.
How can I extract the all source columns of a mview? In the user_mview_keys are presented only the single source columns, but not those who are included in expression. For example:
CREATE MATERIALIZED VIEW mview1 AS
SELECT emp_no, d.dname||e.ename FROM dept d INNER JOIN emp e ON (d.deptno=e.deptno)
So, in this case, in the user_mview_keys we can see only the emp_no field but not the dname and ename fields. Is there a way to extract this information from Oracle data dictionary without parsing the materialized view query? Also, is there a way to extract all columns that are included in the WHERE clause of the materialized view query?
Any help will be appreciate!

Maybe I'm reading this wrong but if you're just after the column names can't you just select them from user_tab_columns?

e.g.create materialized view testcols as select siteref||sitename from fig.t_jacsite;

17:02:47 jack@JACL> select column_name from user_tab_columns where table_name = 'TESTCOLS';

COLUMN_NAME
------------------------------
SITEREF||SITENAME

But if you type:
Beroetz>CREATE MATERIALIZED VIEW TestCols AS
SELECT SITEREF||SITENAME "Col1" ...
Then we have:
Beroetz> select column_name from user_tab_columns where table_name = 'TESTCOLS';
COLUMN_NAME
------------------
Col1
So we loose the information about the source columns. Also I'm looking for the columns that participate in the WHERE clause!