;;; parse-time.el --- parsing time strings -*- lexical-binding: t -*-
;; Copyright (C) 1996, 2000-2020 Free Software Foundation, Inc.
;; Author: Erik Naggum <erik@naggum.no>
;; Keywords: util
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;; With the introduction of the `encode-time', `decode-time', and
;; `format-time-string' functions, dealing with time became simpler in
;; Emacs. However, parsing time strings is still largely a matter of
;; heuristics and no common interface has been designed.
;; `parse-time-string' parses a time in a string and returns a list of
;; values, just like `decode-time', where unspecified elements in the
;; string are returned as nil (except unspecfied DST is returned as -1).
;; `encode-time' may be applied on these values to obtain an internal
;; time value.
;;; Code:
(require 'cl-lib)
(require 'iso8601)
(eval-when-compile (require 'subr-x))
;; Byte-compiler warnings
(defvar parse-time-elt)
(defvar parse-time-val)
(defsubst parse-time-string-chars (char)
(cond ((<= ?a char ?z) ?a)
((<= ?0 char ?9) ?0)
((eq char ?+) 1)
((eq char ?-) -1)
((eq char ?:) ?d)))
(defun parse-time-tokenize (string)
"Tokenize STRING into substrings.
Each substring is a run of \"valid\" characters, i.e., lowercase
letters, digits, plus or minus signs or colons."
(let ((start nil)
(end (length string))
(all-digits nil)
(list ())
(index 0)
(c nil))
(while (< index end)
(while (and (< index end) ;Skip invalid characters.
(not (setq c (parse-time-string-chars (aref string index)))))
(cl-incf index))
(setq start index
all-digits (eq c ?0))
(while (and (< (cl-incf index) end) ;Scan valid characters.
(setq c (parse-time-string-chars (aref string index))))
(setq all-digits (and all-digits (eq c ?0))))
(if (<= index end)
(push (if all-digits (cl-parse-integer string :start start :end index)
(substring string start index))
list)))
(nreverse list)))
(defvar parse-time-months '(("jan" . 1) ("feb" . 2) ("mar" . 3)
("apr" . 4) ("may" . 5) ("jun" . 6)
("jul" . 7) ("aug" . 8) ("sep" . 9)
("oct" . 10) ("nov" . 11) ("dec" . 12)
("january" . 1) ("february" . 2)
("march" . 3) ("april" . 4) ("june" . 6)
("july" . 7) ("august" . 8)
("september" . 9) ("october" . 10)
("november" . 11) ("december" . 12)))
(defvar parse-time-weekdays '(("sun" . 0) ("mon" . 1) ("tue" . 2)
("wed" . 3) ("thu" . 4) ("fri" . 5)
("sat" . 6) ("sunday" . 0) ("monday" . 1)
("tuesday" . 2) ("wednesday" . 3)
("thursday" . 4) ("friday" . 5)
("saturday" . 6)))
(defvar parse-time-zoneinfo `(("z" 0) ("ut" 0) ("gmt" 0)
("pst" ,(* -8 3600)) ("pdt" ,(* -7 3600) t)
("mst" ,(* -7 3600)) ("mdt" ,(* -6 3600) t)
("cst" ,(* -6 3600)) ("cdt" ,(* -5 3600) t)
("est" ,(* -5 3600)) ("edt" ,(* -4 3600) t))
"(zoneinfo seconds-off daylight-savings-time-p)")
(defvar parse-time-rules
`(((6) parse-time-weekdays)
((3) (1 31))
((4) parse-time-months)
((5) (100))
((2 1 0)
,#'(lambda () (and (stringp parse-time-elt)
(= (length parse-time-elt) 8)
(= (aref parse-time-elt 2) ?:)
(= (aref parse-time-elt 5) ?:)))
[0 2] [3 5] [6 8])
((8 7) parse-time-zoneinfo
,#'(lambda () (car parse-time-val))
,#'(lambda () (cadr parse-time-val)))
((8)
,#'(lambda ()
(and (stringp parse-time-elt)
(= 5 (length parse-time-elt))
(or (= (aref parse-time-elt 0) ?+)
(= (aref parse-time-elt 0) ?-))))
,#'(lambda () (* 60 (+ (cl-parse-integer parse-time-elt :start 3 :end 5)
(* 60 (cl-parse-integer parse-time-elt :start 1 :end 3)))
(if (= (aref parse-time-elt 0) ?-) -1 1))))
((5 4 3)
,#'(lambda () (and (stringp parse-time-elt)
(= (length parse-time-elt) 10)
(= (aref parse-time-elt 4) ?-)
(= (aref parse-time-elt 7) ?-)))
[0 4] [5 7] [8 10])
((2 1 0)
,#'(lambda () (and (stringp parse-time-elt)
(= (length parse-time-elt) 5)
(= (aref parse-time-elt 2) ?:)))
[0 2] [3 5] ,#'(lambda () 0))
((2 1 0)
,#'(lambda () (and (stringp parse-time-elt)
(= (length parse-time-elt) 4)
(= (aref parse-time-elt 1) ?:)))
[0 1] [2 4] ,#'(lambda () 0))
((2 1 0)
,#'(lambda () (and (stringp parse-time-elt)
(= (length parse-time-elt) 7)
(= (aref parse-time-elt 1) ?:)))
[0 1] [2 4] [5 7])
((5) (50 110) ,#'(lambda () (+ 1900 parse-time-elt)))
((5) (0 49) ,#'(lambda () (+ 2000 parse-time-elt))))
"(slots predicate extractor...)")
;;;###autoload(put 'parse-time-rules 'risky-local-variable t)
;;;###autoload
(defun parse-time-string (string)
"Parse the time in STRING into (SEC MIN HOUR DAY MON YEAR DOW DST TZ).
STRING should be an ISO 8601 time string, e.g., \"2020-01-15T16:12:21-08:00\",
or something resembling an RFC 822 (or later) date-time, e.g.,
\"Wed, 15 Jan 2020 16:12:21 -0800\". This function is
somewhat liberal in what format it accepts, and will attempt to
return a \"likely\" value even for somewhat malformed strings.
The values returned are identical to those of `decode-time', but
any unknown values other than DST are returned as nil, and an
unknown DST value is returned as -1."
(condition-case ()
(iso8601-parse string)
(wrong-type-argument
(let ((time (list nil nil nil nil nil nil nil -1 nil))
(temp (parse-time-tokenize (downcase string))))
(while temp
(let ((parse-time-elt (pop temp))
(rules parse-time-rules)
(exit nil))
(while (and rules (not exit))
(let* ((rule (pop rules))
(slots (pop rule))
(predicate (pop rule))
(parse-time-val))
(when (and (not (nth (car slots) time)) ;not already set
(setq parse-time-val
(cond ((and (consp predicate)
(not (functionp predicate)))
(and (numberp parse-time-elt)
(<= (car predicate) parse-time-elt)
(or (not (cdr predicate))
(<= parse-time-elt
(cadr predicate)))
parse-time-elt))
((symbolp predicate)
(cdr (assoc parse-time-elt
(symbol-value predicate))))
((funcall predicate)))))
(setq exit t)
(while slots
(let ((new-val (if rule
(let ((this (pop rule)))
(if (vectorp this)
(cl-parse-integer
parse-time-elt
:start (aref this 0)
:end (aref this 1))
(funcall this)))
parse-time-val)))
(setf (nth (pop slots) time) new-val))))))))
time))))
(defun parse-iso8601-time-string (date-string)
"Parse an ISO 8601 time string, such as \"2020-01-15T16:12:21-08:00\".
Fall back on parsing something resembling an RFC 822 (or later) date-time.
This function is like `parse-time-string' except that it returns
a Lisp timestamp when successful."
(when-let ((time (parse-time-string date-string)))
(encode-time time)))
(provide 'parse-time)
;;; parse-time.el ends here