lisp/gnus/parse-time.el

   1 ;;; parse-time.el --- Parsing time strings
   2
   3 ;; Copyright (C) 1996, 2000 by 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 2, or (at your option)
  13 ;; 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; see the file COPYING.  If not, write to
  22 ;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, USA.
  24
  25 ;;; Commentary:
  26
  27 ;; With the introduction of the `encode-time', `decode-time', and
  28 ;; `format-time-string' functions, dealing with time became simpler in
  29 ;; Emacs.  However, parsing time strings is still largely a matter of
  30 ;; heuristics and no common interface has been designed.
  31
  32 ;; `parse-time-string' parses a time in a string and returns a list of 9
  33 ;; values, just like `decode-time', where unspecified elements in the
  34 ;; string are returned as nil.  `encode-time' may be applied on these
  35 ;; valuse to obtain an internal time value.
  36
  37 ;;; Code:
  38
  39 (eval-when-compile (require 'cl))       ;and ah ain't kiddin' 'bout it
  40
  41 (defvar parse-time-syntax (make-vector 256 nil))
  42 (defvar parse-time-digits (make-vector 256 nil))
  43
  44 ;; Byte-compiler warnings
  45 (defvar elt)
  46 (defvar val)
  47
  48 (unless (aref parse-time-digits ?0)
  49   (loop for i from ?0 to ?9
  50     do (aset parse-time-digits i (- i ?0))))
  51
  52 (unless (aref parse-time-syntax ?0)
  53   (loop for i from ?0 to ?9
  54     do (aset parse-time-syntax i ?0))
  55   (loop for i from ?A to ?Z
  56     do (aset parse-time-syntax i ?A))
  57   (loop for i from ?a to ?z
  58     do (aset parse-time-syntax i ?a))
  59   (aset parse-time-syntax ?+ 1)
  60   (aset parse-time-syntax ?- -1)
  61   (aset parse-time-syntax ?: ?d)
  62   )
  63
  64 (defsubst digit-char-p (char)
  65   (aref parse-time-digits char))
  66
  67 (defsubst parse-time-string-chars (char)
  68   (aref parse-time-syntax char))
  69
  70 (put 'parse-error 'error-conditions '(parse-error error))
  71 (put 'parse-error 'error-message "Parsing error")
  72
  73 (defsubst parse-integer (string &optional start end)
  74   "[CL] Parse and return the integer in STRING, or nil if none."
  75   (let ((integer 0)
  76         (digit 0)
  77         (index (or start 0))
  78         (end (or end (length string))))
  79     (when (< index end)
  80       (let ((sign (aref string index)))
  81         (if (or (eq sign ?+) (eq sign ?-))
  82             (setq sign (parse-time-string-chars sign)
  83                   index (1+ index))
  84           (setq sign 1))
  85         (while (and (< index end)
  86                     (setq digit (digit-char-p (aref string index))))
  87           (setq integer (+ (* integer 10) digit)
  88                 index (1+ index)))
  89         (if (/= index end)
  90             (signal 'parse-error `("not an integer"
  91                                    ,(substring string (or start 0) end)))
  92           (* sign integer))))))
  93
  94 (defun parse-time-tokenize (string)
  95   "Tokenize STRING into substrings."
  96   (let ((start nil)
  97         (end (length string))
  98         (all-digits nil)
  99         (list ())
 100         (index 0)
 101         (c nil))
 102     (while (< index end)
 103       (while (and (< index end)         ;skip invalid characters
 104                   (not (setq c (parse-time-string-chars (aref string index)))))
 105         (incf index))
 106       (setq start index all-digits (eq c ?0))
 107       (while (and (< (incf index) end)  ;scan valid characters
 108                   (setq c (parse-time-string-chars (aref string index))))
 109         (setq all-digits (and all-digits (eq c ?0))))
 110       (if (<= index end)
 111           (push (if all-digits (parse-integer string start index)
 112                   (substring string start index))
 113                 list)))
 114     (nreverse list)))
 115
 116 (defvar parse-time-months '(("jan" . 1) ("feb" . 2) ("mar" . 3)
 117                             ("apr" . 4) ("may" . 5) ("jun" . 6)
 118                             ("jul" . 7) ("aug" . 8) ("sep" . 9)
 119                             ("oct" . 10) ("nov" . 11) ("dec" . 12)))
 120 (defvar parse-time-weekdays '(("sun" . 0) ("mon" . 1) ("tue" . 2)
 121                               ("wed" . 3) ("thu" . 4) ("fri" . 5) ("sat" . 6)))
 122 (defvar parse-time-zoneinfo `(("z" 0) ("ut" 0) ("gmt" 0)
 123                               ("pst" ,(* -8 3600)) ("pdt" ,(* -7 3600) t)
 124                               ("mst" ,(* -7 3600)) ("mdt" ,(* -6 3600) t)
 125                               ("cst" ,(* -6 3600)) ("cdt" ,(* -5 3600) t)
 126                               ("est" ,(* -5 3600)) ("edt" ,(* -4 3600) t))
 127   "(zoneinfo seconds-off daylight-savings-time-p)")
 128
 129 (defvar parse-time-rules
 130   `(((6) parse-time-weekdays)
 131     ((3) (1 31))
 132     ((4) parse-time-months)
 133     ((5) (100 4038))
 134     ((2 1 0)
 135      ,#'(lambda () (and (stringp elt)
 136                         (= (length elt) 8)
 137                         (= (aref elt 2) ?:)
 138                         (= (aref elt 5) ?:)))
 139      [0 2] [3 5] [6 8])
 140     ((8 7) parse-time-zoneinfo
 141      ,#'(lambda () (car val))
 142      ,#'(lambda () (cadr val)))
 143     ((8)
 144      ,#'(lambda ()
 145           (and (stringp elt)
 146                (= 5 (length elt))
 147                (or (= (aref elt 0) ?+) (= (aref elt 0) ?-))))
 148      ,#'(lambda () (* 60 (+ (parse-integer elt 3 5)
 149                             (* 60 (parse-integer elt 1 3)))
 150                       (if (= (aref elt 0) ?-) -1 1))))
 151     ((5 4 3)
 152      ,#'(lambda () (and (stringp elt)
 153                         (= (length elt) 10)
 154                         (= (aref elt 4) ?-)
 155                         (= (aref elt 7) ?-)))
 156      [0 4] [5 7] [8 10])
 157     ((2 1 0)
 158      ,#'(lambda () (and (stringp elt) (= (length elt) 5) (= (aref elt 2) ?:)))
 159      [0 2] [3 5] ,#'(lambda () 0))
 160     ((2 1 0)
 161      ,#'(lambda () (and (stringp elt)
 162                         (= (length elt) 4)
 163                         (= (aref elt 1) ?:)))
 164      [0 1] [2 4] ,#'(lambda () 0))
 165     ((2 1 0)
 166      ,#'(lambda () (and (stringp elt)
 167                         (= (length elt) 7)
 168                         (= (aref elt 1) ?:)))
 169      [0 1] [2 4] [5 7])
 170     ((5) (50 110) ,#'(lambda () (+ 1900 elt)))
 171     ((5) (0 49) ,#'(lambda () (+ 2000 elt))))
 172   "(slots predicate extractor...)")
 173
 174 (defun parse-time-string (string)
 175   "Parse the time-string STRING into (SEC MIN HOUR DAY MON YEAR DOW DST TZ).
 176 The values are identical to those of `decode-time', but any values that are
 177 unknown are returned as nil."
 178   (let ((time (list nil nil nil nil nil nil nil nil nil))
 179         (temp (parse-time-tokenize (downcase string))))
 180     (while temp
 181       (let ((elt (pop temp))
 182             (rules parse-time-rules)
 183             (exit nil))
 184         (while (and (not (null rules)) (not exit))
 185           (let* ((rule (pop rules))
 186                  (slots (pop rule))
 187                  (predicate (pop rule))
 188                  (val))
 189             (when (and (not (nth (car slots) time)) ;not already set
 190                        (setq val (cond ((and (consp predicate)
 191                                              (not (eq (car predicate)
 192                                                       'lambda)))
 193                                         (and (numberp elt)
 194                                              (<= (car predicate) elt)
 195                                              (<= elt (cadr predicate))
 196                                              elt))
 197                                        ((symbolp predicate)
 198                                         (cdr (assoc elt
 199                                                     (symbol-value predicate))))
 200                                        ((funcall predicate)))))
 201               (setq exit t)
 202               (while slots
 203                 (let ((new-val (and rule
 204                                     (let ((this (pop rule)))
 205                                       (if (vectorp this)
 206                                           (parse-integer
 207                                            elt (aref this 0) (aref this 1))
 208                                         (funcall this))))))
 209                   (rplaca (nthcdr (pop slots) time) (or new-val val)))))))))
 210     time))
 211
 212 (provide 'parse-time)
 213
 214 ;;; parse-time.el ends here