regexp question

[python_charmer2000]

I want to match several regexps against a large body of text.  What I
have so far is similar to this:

re1 = <some regexp>
re2 = <some regexp>
re3 = <some regexp>

big_re = re.compile(re1 + '|' + re2 + '|' + re3)

matches = big_re.finditer(file_list) 
for match in matches:
    span = match.span()
    print "matched text =", file_list[span[0]:span[1]]
    print "matched re =", match.re.pattern

Now the "match.re.pattern" is the entire regexp, big_re.  But I want
to print out the portion of the big re that was matched -- was it re1?
 re2?  or re3?  Is it possible to determine this, or do I have to make
a second pass through the collection of re's and compare them against
the "matched text" in order to determine which part of the big_re was
matched?

thanks!!