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715a2ca2 | 1 | ;;; time-date.el --- date and time handling functions |
c113de23 GM |
2 | ;; Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc. |
3 | ||
4 | ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org> | |
5 | ;; Masanobu Umeda <umerin@mse.kyutech.ac.jp> | |
6 | ;; Keywords: mail news 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 the | |
22 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
23 | ;; Boston, MA 02111-1307, USA. | |
24 | ||
25 | ;;; Commentary: | |
26 | ||
27 | ;;; Code: | |
28 | ||
29 | (require 'parse-time) | |
30 | ||
ce2a8a6a DL |
31 | (autoload 'timezone-make-date-arpa-standard "timezone") |
32 | ||
c113de23 GM |
33 | ;;;###autoload |
34 | (defun date-to-time (date) | |
74fcda73 | 35 | "Parse a string that represents a date-time and return a time value." |
c113de23 | 36 | (condition-case () |
ce2a8a6a DL |
37 | (apply 'encode-time |
38 | (parse-time-string | |
39 | ;; `parse-time-string' isn't sufficiently general or | |
40 | ;; robust. It fails to grok some of the formats that | |
41 | ;; timzeone does (e.g. dodgy post-2000 stuff from some | |
42 | ;; Elms) and either fails or returns bogus values. Lars | |
43 | ;; reverted this change, but that loses non-trivially | |
44 | ;; often for me. -- fx | |
45 | (timezone-make-date-arpa-standard date))) | |
c113de23 GM |
46 | (error (error "Invalid date: %s" date)))) |
47 | ||
48 | (defun time-to-seconds (time) | |
74fcda73 RS |
49 | "Convert time value TIME to a floating point number. |
50 | You can use `float-time' instead." | |
c113de23 GM |
51 | (+ (* (car time) 65536.0) |
52 | (cadr time) | |
53 | (/ (or (nth 2 time) 0) 1000000.0))) | |
54 | ||
74fcda73 | 55 | ;;;###autoload |
c113de23 | 56 | (defun seconds-to-time (seconds) |
74fcda73 | 57 | "Convert SECONDS (a floating point number) to a time value." |
c113de23 GM |
58 | (list (floor seconds 65536) |
59 | (floor (mod seconds 65536)) | |
60 | (floor (* (- seconds (ffloor seconds)) 1000000)))) | |
61 | ||
74fcda73 | 62 | ;;;###autoload |
c113de23 | 63 | (defun time-less-p (t1 t2) |
74fcda73 | 64 | "Say whether time value T1 is less than time value T2." |
c113de23 GM |
65 | (or (< (car t1) (car t2)) |
66 | (and (= (car t1) (car t2)) | |
67 | (< (nth 1 t1) (nth 1 t2))))) | |
68 | ||
74fcda73 | 69 | ;;;###autoload |
c113de23 | 70 | (defun days-to-time (days) |
74fcda73 | 71 | "Convert DAYS into a time value." |
c113de23 GM |
72 | (let* ((seconds (* 1.0 days 60 60 24)) |
73 | (rest (expt 2 16)) | |
74 | (ms (condition-case nil (floor (/ seconds rest)) | |
75 | (range-error (expt 2 16))))) | |
76 | (list ms (condition-case nil (round (- seconds (* ms rest))) | |
77 | (range-error (expt 2 16)))))) | |
78 | ||
74fcda73 | 79 | ;;;###autoload |
c113de23 | 80 | (defun time-since (time) |
74fcda73 RS |
81 | "Return the time elapsed since TIME. |
82 | TIME should be either a time value or a date-time string." | |
c113de23 GM |
83 | (when (stringp time) |
84 | ;; Convert date strings to internal time. | |
85 | (setq time (date-to-time time))) | |
86 | (let* ((current (current-time)) | |
87 | (rest (when (< (nth 1 current) (nth 1 time)) | |
88 | (expt 2 16)))) | |
89 | (list (- (+ (car current) (if rest -1 0)) (car time)) | |
90 | (- (+ (or rest 0) (nth 1 current)) (nth 1 time))))) | |
91 | ||
74fcda73 RS |
92 | ;;;###autoload |
93 | (defalias 'subtract-time 'time-subtract) | |
94 | ||
95 | ;;;###autoload | |
96 | (defun time-subtract (t1 t2) | |
97 | "Subtract two time values. | |
98 | Return the difference in the format of a time value." | |
c113de23 GM |
99 | (let ((borrow (< (cadr t1) (cadr t2)))) |
100 | (list (- (car t1) (car t2) (if borrow 1 0)) | |
101 | (- (+ (if borrow 65536 0) (cadr t1)) (cadr t2))))) | |
102 | ||
74fcda73 RS |
103 | ;;;###autoload |
104 | (defun time-add (t1 t2) | |
105 | "Add two time values. One should represent a time difference." | |
106 | (let ((high (car t1)) | |
107 | (low (if (consp (cdr t1)) (nth 1 t1) (cdr t1))) | |
108 | (micro (if (numberp (car-safe (cdr-safe (cdr t1)))) | |
109 | (nth 2 t1) | |
110 | 0)) | |
111 | (high2 (car t2)) | |
112 | (low2 (if (consp (cdr t2)) (nth 1 t2) (cdr t2))) | |
113 | (micro2 (if (numberp (car-safe (cdr-safe (cdr t2)))) | |
114 | (nth 2 t2) | |
115 | 0))) | |
116 | ;; Add | |
117 | (setq micro (+ micro micro2)) | |
118 | (setq low (+ low low2)) | |
119 | (setq high (+ high high2)) | |
120 | ||
121 | ;; Normalize | |
122 | ;; `/' rounds towards zero while `mod' returns a positive number, | |
123 | ;; so we can't rely on (= a (+ (* 100 (/ a 100)) (mod a 100))). | |
124 | (setq low (+ low (/ micro 1000000) (if (< micro 0) -1 0))) | |
125 | (setq micro (mod micro 1000000)) | |
126 | (setq high (+ high (/ low 65536) (if (< low 0) -1 0))) | |
127 | (setq low (logand low 65535)) | |
128 | ||
129 | (list high low micro))) | |
130 | ||
131 | ;;;###autoload | |
c113de23 | 132 | (defun date-to-day (date) |
74fcda73 RS |
133 | "Return the number of days between year 1 and DATE. |
134 | DATE should be a date-time string." | |
c113de23 GM |
135 | (time-to-days (date-to-time date))) |
136 | ||
74fcda73 | 137 | ;;;###autoload |
c113de23 | 138 | (defun days-between (date1 date2) |
74fcda73 RS |
139 | "Return the number of days between DATE1 and DATE2. |
140 | DATE1 and DATE2 should be date-time strings." | |
c113de23 GM |
141 | (- (date-to-day date1) (date-to-day date2))) |
142 | ||
74fcda73 | 143 | ;;;###autoload |
c113de23 GM |
144 | (defun date-leap-year-p (year) |
145 | "Return t if YEAR is a leap year." | |
146 | (or (and (zerop (% year 4)) | |
147 | (not (zerop (% year 100)))) | |
148 | (zerop (% year 400)))) | |
149 | ||
74fcda73 | 150 | ;;;###autoload |
c113de23 GM |
151 | (defun time-to-day-in-year (time) |
152 | "Return the day number within the year of the date month/day/year." | |
153 | (let* ((tim (decode-time time)) | |
154 | (month (nth 4 tim)) | |
155 | (day (nth 3 tim)) | |
156 | (year (nth 5 tim)) | |
157 | (day-of-year (+ day (* 31 (1- month))))) | |
158 | (when (> month 2) | |
159 | (setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10))) | |
160 | (when (date-leap-year-p year) | |
161 | (setq day-of-year (1+ day-of-year)))) | |
162 | day-of-year)) | |
163 | ||
74fcda73 | 164 | ;;;###autoload |
c113de23 GM |
165 | (defun time-to-days (time) |
166 | "The number of days between the Gregorian date 0001-12-31bce and TIME. | |
74fcda73 | 167 | TIME should be a time value. |
c113de23 GM |
168 | The Gregorian date Sunday, December 31, 1bce is imaginary." |
169 | (let* ((tim (decode-time time)) | |
170 | (month (nth 4 tim)) | |
171 | (day (nth 3 tim)) | |
172 | (year (nth 5 tim))) | |
173 | (+ (time-to-day-in-year time) ; Days this year | |
174 | (* 365 (1- year)) ; + Days in prior years | |
175 | (/ (1- year) 4) ; + Julian leap years | |
176 | (- (/ (1- year) 100)) ; - century years | |
177 | (/ (1- year) 400)))) ; + Gregorian leap years | |
178 | ||
179 | ;;;###autoload | |
180 | (defun safe-date-to-time (date) | |
74fcda73 RS |
181 | "Parse a string that represents a date-time and return a time value. |
182 | If DATE is malformed, return a time value of zeros." | |
c113de23 GM |
183 | (condition-case () |
184 | (date-to-time date) | |
185 | (error '(0 0)))) | |
186 | ||
187 | (provide 'time-date) | |
188 | ||
6b61353c | 189 | ;;; arch-tag: addcf07b-b20a-465b-af72-550b8ac5190f |
c113de23 | 190 | ;;; time-date.el ends here |