 : make-negative-lookbehind ( string -- )
     <negation> lookbehind boa push-stack ;
 
-DEFER: nested-parse-regexp
 : make-non-capturing-group ( string -- )
     non-capture-group boa push-stack ;
 

MIXIN: node
TUPLE: concatenation seq ; INSTANCE: concatenation node
TUPLE: alternation seq ; INSTANCE: alternation node
! !!!!!!!!
TUPLE: question term ; INSTANCE: question node
TUPLE: kleene-star term ; INSTANCE: kleene-star node

! !!!!!!!!


ERROR: bad-special-group string ;

DEFER: nested-parse-regexp
: (parse-special-group) ( -- )
    read1 {
        { [ dup CHAR: : = ]
