regex - Regular expression for contents of parenthesis in Racket -

how can contents of parenthesis in racket? contents may have more parenthesis. tried:

(regexp-match #rx"((.*))" "(check)") 

but output has "(check)" 3 times rather one:

'("(check)" "(check)" "(check)") 

and want "check" , not "(check)".

edit: nested parenthesis, inner block should returned. hence (a (1 2) c) should return "a (1 2) c".

parentheses capturing , not matching.. #rx"((.*))" makes 2 captures of everything. thus:

(regexp-match #rx"((.*))" "any text") ; ==> ("any text" "any text" "any text") 

the resulting list has first whole match, first set of acpturnig paren , ones inside second.. if want match parentheses need escape them:

(regexp-match #rx"\\((.*)\\)" "any text") ; ==> #f (regexp-match #rx"\\((.*)\\)" "(a (1 2) c)") ; ==> ("(a (1 2) c)" "a (1 2) c") 

now see first element whole match, since match might start @ location in search string , end match largest. second element 1 capture.

this fail if string has additional sets of parentheses. eg.

(regexp-match #rx"\\((.*)\\)" "(1 2 3) (a (1 2) c)") ; ==> ("(1 2 3) (a (1 2) c)" "1 2 3) (a (1 2) c") 

it's because expression isn't nesting aware. aware of need recursive reguler expression in perl (?r) syntax , friends, racket doesn't have (yet???)