any tools which generates sample data matches for given regular expression?

any tools which generates sample data matches for given regular expression?

I searched on web to find out a tool which will generate sample data which
will match to a given regular expression? Say if my regular Expression
Says: re.match("^\s*//P(?P.*)$"),data) the tool should generate data which
is valid for the above re. If any tool pl let me know.
with regards deepak.t.s