Function: iso8601-parse-interval

iso8601-parse-interval is a byte-compiled function defined in iso8601.el.gz.

Signature

(iso8601-parse-interval STRING)

Documentation

Parse ISO 8601 intervals.

Probably introduced at or before Emacs version 27.1.

Source Code

;; Defined in /usr/src/emacs/lisp/calendar/iso8601.el.gz
(defun iso8601-parse-interval (string)
  "Parse ISO 8601 intervals."
  (let ((bits (split-string string "/"))
        start end duration)
    (if (not (= (length bits) 2))
        (signal 'wrong-type-argument (list string))
      ;; The intervals may be an explicit start/end times, or either a
      ;; start or an end, and an accompanying duration.
      (cond
       ((and (string-match "\\`P" (car bits))
             (iso8601-valid-p (cadr bits)))
        (setq duration (iso8601-parse-duration (car bits))
              end (iso8601-parse (cadr bits))))
       ((and (string-match "\\`P" (cadr bits))
             (iso8601-valid-p (car bits)))
        (setq duration (iso8601-parse-duration (cadr bits))
              start (iso8601-parse (car bits))))
       ((and (iso8601-valid-p (car bits))
             (iso8601-valid-p (cadr bits)))
        (setq start (iso8601-parse (car bits))
              end (iso8601-parse (cadr bits))))
       (t
        (signal 'wrong-type-argument (list string)))))
    (unless end
      (setq end (decoded-time-add start duration)))
    (unless start
      (setq start (decoded-time-add end
                                    ;; We negate the duration so that
                                    ;; we get a subtraction.
                                    (mapcar (lambda (elem)
                                              (if (numberp elem)
                                                  (- elem)
                                                elem))
                                            duration))))
    (list start end
          (or duration
	      ;; FIXME: Support subseconds.
	      ;; FIXME: It makes no sense to decode a time difference
	      ;; according to (decoded-time-zone end), or according to
	      ;; any other time zone for that matter.
              (decode-time (time-subtract (iso8601--encode-time end)
                                          (iso8601--encode-time start))
			   (or (decoded-time-zone end) 0) 'integer)))))