time-calculator.lisp

(in-package :time-calculator)

(defun diff-time (t1-string t2-string)
  (let ((min1 (time-serialize t1-string))
        (min2 (time-serialize t2-string)))
    (values (abs (- min2 min1)) "min")))

(defun time-serialize (time-hhmm-string)
  (let* ((p (search ":" time-hhmm-string))
         (h (parse-integer (subseq time-hhmm-string 0 p)))
         (m (parse-integer (subseq time-hhmm-string (1+ p)))))
    (+ (* h 60) m)))

(defun min-to-hour (min)
  (values (/ min 60.0) "hour"))

(defun hour-to-min (hour min)
  (values (+ min (* hour 60)) "min"))

(defun time-or-num (stream char2 n)
  (declare (ignorable char2 n))
  (let ((value nil)
        (is-time? nil))
    (labels ((read-at-last ()
               (let ((c (read-char stream)))
                 (cond ((digit-char-p c)
                        (push (string c) value)
                        (read-at-last))
                       ((eql #\: c)
                        (setf is-time? t)
                        (push (string c) value)
                        (read-at-last))
                       (t (unread-char c stream)
                        (if is-time?
                            (apply #'concatenate 'string (nreverse value))
                            (multiple-value-bind (n m)
                              (parse-integer (apply #'concatenate 'string (nreverse value)))
                              n)))))))
      (read-at-last))))

(set-dispatch-macro-character #\# #\t #'time-or-num)