Plaster

common-lisp
(defun scan-list (stream) (let ((depth 0) (chars-read 0)) (labels ((next-char () (prog1 (read-char stream) (incf chars-read)))) (tagbody unescaped (loop :for c = (next-char) :do (case c (#\" (go string)) ; " (#\; (go comment)) (#\\ (go single-escape-character)) (#\| (go multiple-escape-character)) (#\# (go hash)) (#\( (incf depth)) (#\) (decf depth))) (when (zerop depth) (go done))) string (loop :for c = (next-char) :do (case c (#\" (go unescaped)) ;" (#\\ (go single-escape-character)))) comment (loop :for c = (next-char) :when (eql c #\Newline) :do (go unescaped)) block-comment (let ((depth 0)) (loop :for c = (next-char) :do (cond ((and (eql c #\#) (eql #\| (next-char))) (incf depth)) ((and (eql c #\|) (eql #\# (next-char))) (if (zerop depth) (go unescaped) (decf depth)))))) hash (loop :for c = (next-char) :if (eql c #\|) :do (go block-comment) :else :do (go unescaped)) single-escape-character (next-char) (go unescaped) multiple-escape-character (loop :for c = (next-char) :if (eql c #\\) :do (next-char) :else :if (eql c #\|) :do (go unescaped)) done (return-from scan-list chars-read))))) (with-input-from-string (s "(foo (bar \"(\" (qwe) #| ) |# \\) |)| 1))") (scan-list s)) => 38