lisp/calendar/parse-time.el

   1 ;;; parse-time.el --- parsing time strings -*- lexical-binding: t -*-
   2
   3 ;; Copyright (C) 1996, 2000-2017 Free Software Foundation, Inc.
   4
   5 ;; Author: Erik Naggum <erik@naggum.no>
   6 ;; Keywords: util
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software: you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation, either version 3 of the License, or
  13 ;; (at your option) any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  22
  23 ;;; Commentary:
  24
  25 ;; With the introduction of the `encode-time', `decode-time', and
  26 ;; `format-time-string' functions, dealing with time became simpler in
  27 ;; Emacs.  However, parsing time strings is still largely a matter of
  28 ;; heuristics and no common interface has been designed.
  29
  30 ;; `parse-time-string' parses a time in a string and returns a list of 9
  31 ;; values, just like `decode-time', where unspecified elements in the
  32 ;; string are returned as nil.  `encode-time' may be applied on these
  33 ;; values to obtain an internal time value.
  34
  35 ;;; Code:
  36
  37 (require 'cl-lib)
  38
  39 ;; Byte-compiler warnings
  40 (defvar parse-time-elt)
  41 (defvar parse-time-val)
  42
  43 (defsubst parse-time-string-chars (char)
  44   (cond ((<= ?a char ?z) ?a)
  45         ((<= ?0 char ?9) ?0)
  46         ((eq char ?+) 1)
  47         ((eq char ?-) -1)
  48         ((eq char ?:) ?d)))
  49
  50 (defun parse-time-tokenize (string)
  51   "Tokenize STRING into substrings.
  52 Each substring is a run of \"valid\" characters, i.e., lowercase
  53 letters, digits, plus or minus signs or colons."
  54   (let ((start nil)
  55         (end (length string))
  56         (all-digits nil)
  57         (list ())
  58         (index 0)
  59         (c nil))
  60     (while (< index end)
  61       (while (and (< index end)         ;Skip invalid characters.
  62                   (not (setq c (parse-time-string-chars (aref string index)))))
  63         (cl-incf index))
  64       (setq start index
  65             all-digits (eq c ?0))
  66       (while (and (< (cl-incf index) end)       ;Scan valid characters.
  67                   (setq c (parse-time-string-chars (aref string index))))
  68         (setq all-digits (and all-digits (eq c ?0))))
  69       (if (<= index end)
  70           (push (if all-digits (cl-parse-integer string :start start :end index)
  71                   (substring string start index))
  72                 list)))
  73     (nreverse list)))
  74
  75 (defvar parse-time-months '(("jan" . 1) ("feb" . 2) ("mar" . 3)
  76                             ("apr" . 4) ("may" . 5) ("jun" . 6)
  77                             ("jul" . 7) ("aug" . 8) ("sep" . 9)
  78                             ("oct" . 10) ("nov" . 11) ("dec" . 12)
  79                             ("january" . 1) ("february" . 2)
  80                             ("march" . 3) ("april" . 4) ("june" . 6)
  81                             ("july" . 7) ("august" . 8)
  82                             ("september" . 9) ("october" . 10)
  83                             ("november" . 11) ("december" . 12)))
  84 (defvar parse-time-weekdays '(("sun" . 0) ("mon" . 1) ("tue" . 2)
  85                               ("wed" . 3) ("thu" . 4) ("fri" . 5)
  86                               ("sat" . 6) ("sunday" . 0) ("monday" . 1)
  87                               ("tuesday" . 2) ("wednesday" . 3)
  88                               ("thursday" . 4) ("friday" . 5)
  89                               ("saturday" . 6)))
  90 (defvar parse-time-zoneinfo `(("z" 0) ("ut" 0) ("gmt" 0)
  91                               ("pst" ,(* -8 3600)) ("pdt" ,(* -7 3600) t)
  92                               ("mst" ,(* -7 3600)) ("mdt" ,(* -6 3600) t)
  93                               ("cst" ,(* -6 3600)) ("cdt" ,(* -5 3600) t)
  94                               ("est" ,(* -5 3600)) ("edt" ,(* -4 3600) t))
  95   "(zoneinfo seconds-off daylight-savings-time-p)")
  96
  97 (defvar parse-time-rules
  98   `(((6) parse-time-weekdays)
  99     ((3) (1 31))
 100     ((4) parse-time-months)
 101     ((5) (100 ,most-positive-fixnum))
 102     ((2 1 0)
 103      ,#'(lambda () (and (stringp parse-time-elt)
 104                         (= (length parse-time-elt) 8)
 105                         (= (aref parse-time-elt 2) ?:)
 106                         (= (aref parse-time-elt 5) ?:)))
 107      [0 2] [3 5] [6 8])
 108     ((8 7) parse-time-zoneinfo
 109      ,#'(lambda () (car parse-time-val))
 110      ,#'(lambda () (cadr parse-time-val)))
 111     ((8)
 112      ,#'(lambda ()
 113           (and (stringp parse-time-elt)
 114                (= 5 (length parse-time-elt))
 115                (or (= (aref parse-time-elt 0) ?+)
 116                    (= (aref parse-time-elt 0) ?-))))
 117      ,#'(lambda () (* 60 (+ (cl-parse-integer parse-time-elt :start 3 :end 5)
 118                             (* 60 (cl-parse-integer parse-time-elt :start 1 :end 3)))
 119                       (if (= (aref parse-time-elt 0) ?-) -1 1))))
 120     ((5 4 3)
 121      ,#'(lambda () (and (stringp parse-time-elt)
 122                         (= (length parse-time-elt) 10)
 123                         (= (aref parse-time-elt 4) ?-)
 124                         (= (aref parse-time-elt 7) ?-)))
 125      [0 4] [5 7] [8 10])
 126     ((2 1 0)
 127      ,#'(lambda () (and (stringp parse-time-elt)
 128                         (= (length parse-time-elt) 5)
 129                         (= (aref parse-time-elt 2) ?:)))
 130      [0 2] [3 5] ,#'(lambda () 0))
 131     ((2 1 0)
 132      ,#'(lambda () (and (stringp parse-time-elt)
 133                         (= (length parse-time-elt) 4)
 134                         (= (aref parse-time-elt 1) ?:)))
 135      [0 1] [2 4] ,#'(lambda () 0))
 136     ((2 1 0)
 137      ,#'(lambda () (and (stringp parse-time-elt)
 138                         (= (length parse-time-elt) 7)
 139                         (= (aref parse-time-elt 1) ?:)))
 140      [0 1] [2 4] [5 7])
 141     ((5) (50 110) ,#'(lambda () (+ 1900 parse-time-elt)))
 142     ((5) (0 49) ,#'(lambda () (+ 2000 parse-time-elt))))
 143   "(slots predicate extractor...)")
 144 ;;;###autoload(put 'parse-time-rules 'risky-local-variable t)
 145
 146 ;;;###autoload
 147 (defun parse-time-string (string)
 148   "Parse the time-string STRING into (SEC MIN HOUR DAY MON YEAR DOW DST TZ).
 149 STRING should be on something resembling an RFC2822 string, a la
 150 \"Fri, 25 Mar 2016 16:24:56 +0100\", but this function is
 151 somewhat liberal in what format it accepts, and will attempt to
 152 return a \"likely\" value even for somewhat malformed strings.
 153 The values returned are identical to those of `decode-time', but
 154 any values that are unknown are returned as nil."
 155   (let ((time (list nil nil nil nil nil nil nil nil nil))
 156         (temp (parse-time-tokenize (downcase string))))
 157     (while temp
 158       (let ((parse-time-elt (pop temp))
 159             (rules parse-time-rules)
 160             (exit nil))
 161         (while (and rules (not exit))
 162           (let* ((rule (pop rules))
 163                  (slots (pop rule))
 164                  (predicate (pop rule))
 165                  (parse-time-val))
 166             (when (and (not (nth (car slots) time)) ;not already set
 167                        (setq parse-time-val
 168                              (cond ((and (consp predicate)
 169                                          (not (eq (car predicate)
 170                                                   'lambda)))
 171                                     (and (numberp parse-time-elt)
 172                                          (<= (car predicate) parse-time-elt)
 173                                          (<= parse-time-elt (cadr predicate))
 174                                          parse-time-elt))
 175                                    ((symbolp predicate)
 176                                     (cdr (assoc parse-time-elt
 177                                                 (symbol-value predicate))))
 178                                    ((funcall predicate)))))
 179               (setq exit t)
 180               (while slots
 181                 (let ((new-val (if rule
 182                                    (let ((this (pop rule)))
 183                                      (if (vectorp this)
 184                                          (cl-parse-integer
 185                                           parse-time-elt
 186                                           :start (aref this 0)
 187                                           :end (aref this 1))
 188                                        (funcall this)))
 189                                  parse-time-val)))
 190                   (rplaca (nthcdr (pop slots) time) new-val))))))))
 191     time))
 192
 193 (defconst parse-time-iso8601-regexp
 194   (let* ((dash "-?")
 195          (colon ":?")
 196          (4digit "\\([0-9][0-9][0-9][0-9]\\)")
 197          (2digit "\\([0-9][0-9]\\)")
 198          (date-fullyear 4digit)
 199          (date-month 2digit)
 200          (date-mday 2digit)
 201          (time-hour 2digit)
 202          (time-minute 2digit)
 203          (time-second 2digit)
 204          (time-secfrac "\\(\\.[0-9]+\\)?")
 205          (time-numoffset (concat "\\([-+]\\)" time-hour ":?" time-minute "?"))
 206          (partial-time (concat time-hour colon time-minute colon time-second
 207                                time-secfrac))
 208          (full-date (concat date-fullyear dash date-month dash date-mday)))
 209     (list (concat "^" full-date)
 210           (concat "T" partial-time)
 211           (concat "\\(Z\\|" time-numoffset "\\)")))
 212   "List of regular expressions matching ISO 8601 dates.
 213 1st regular expression matches the date.
 214 2nd regular expression matches the time.
 215 3rd regular expression matches the (optional) timezone specification.")
 216
 217 (defun parse-iso8601-time-string (date-string)
 218   "Parse an ISO 8601 time string, such as 2016-12-01T23:35:06-05:00.
 219 If DATE-STRING cannot be parsed, it falls back to
 220 `parse-time-string'."
 221   (let* ((date-re (nth 0 parse-time-iso8601-regexp))
 222          (time-re (nth 1 parse-time-iso8601-regexp))
 223          (tz-re (nth 2 parse-time-iso8601-regexp))
 224          re-start
 225          time seconds minute hour
 226          day month year day-of-week dst tz)
 227     ;; We need to populate 'time' with
 228     ;; (SEC MIN HOUR DAY MON YEAR DOW DST TZ)
 229
 230     ;; Nobody else handles iso8601 correctly, let's do it ourselves.
 231     (when (string-match date-re date-string re-start)
 232       (setq year (string-to-number (match-string 1 date-string))
 233             month (string-to-number (match-string 2 date-string))
 234             day (string-to-number (match-string 3 date-string))
 235             re-start (match-end 0))
 236       (when (string-match time-re date-string re-start)
 237         (setq hour (string-to-number (match-string 1 date-string))
 238               minute (string-to-number (match-string 2 date-string))
 239               seconds (string-to-number (match-string 3 date-string))
 240               re-start (match-end 0))
 241         (when (string-match tz-re date-string re-start)
 242           (if (string= "Z" (match-string 1 date-string))
 243               (setq tz 0)  ;; UTC timezone indicated by Z
 244             (setq tz (+
 245                       (* 3600
 246                          (string-to-number (match-string 3 date-string)))
 247                       (* 60
 248                          (string-to-number
 249                           (or (match-string 4 date-string) "0")))))
 250             (when (string= "-" (match-string 2 date-string))
 251               (setq tz (- tz)))))
 252         (setq time (list seconds minute hour day month year day-of-week dst tz))))
 253
 254     ;; Fall back to having `parse-time-string' do fancy things for us.
 255     (when (not time)
 256       (setq time (parse-time-string date-string)))
 257
 258     (and time
 259          (apply 'encode-time time))))
 260
 261 (provide 'parse-time)
 262
 263 ;;; parse-time.el ends here