src/lib_4_comments.4th

   1 \ Parenthetic comments
   2
   3 : ( IMMEDIATE
   4         1               \ allowed nested parens by keeping track of depth
   5         BEGIN
   6                 >IN @ #IB @ >= IF      \ End of TIB?
   7                         QUERY-INPUT    \ Get next line
   8                 THEN
   9
  10                 IB >IN @ + @ 1 >IN +!
  11                 DUP [CHAR] ( = IF       \ open paren?
  12                         DROP            \ drop the open paren
  13                         1+              \ depth increases
  14                 ELSE
  15                         [CHAR] ) = IF   \ close paren?
  16                                 1-      \ depth decreases
  17                         THEN
  18                 THEN
  19         DUP 0= UNTIL            \ continue until we reach matching close paren, depth 0
  20         DROP            \ drop the depth counter
  21 ;
  22