1;;; time-date.el --- Date and time handling functions 2 3;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 4;; Free Software Foundation, Inc. 5 6;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org> 7;; Masanobu Umeda <umerin@mse.kyutech.ac.jp> 8;; Keywords: mail news util 9 10;; This file is part of GNU Emacs. 11 12;; GNU Emacs is free software; you can redistribute it and/or modify 13;; it under the terms of the GNU General Public License as published by 14;; the Free Software Foundation; either version 2, or (at your option) 15;; any later version. 16 17;; GNU Emacs is distributed in the hope that it will be useful, 18;; but WITHOUT ANY WARRANTY; without even the implied warranty of 19;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 20;; GNU General Public License for more details. 21 22;; You should have received a copy of the GNU General Public License 23;; along with GNU Emacs; see the file COPYING. If not, write to the 24;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 25;; Boston, MA 02110-1301, USA. 26 27;;; Commentary: 28 29;; Time values come in three formats. The oldest format is a cons 30;; cell of the form (HIGH . LOW). This format is obsolete, but still 31;; supported. The two other formats are the lists (HIGH LOW) and 32;; (HIGH LOW MICRO). The first two formats specify HIGH * 2^16 + LOW 33;; seconds; the third format specifies HIGH * 2^16 + LOW + MICRO / 34;; 1000000 seconds. We should have 0 <= MICRO < 1000000 and 0 <= LOW 35;; < 2^16. If the time value represents a point in time, then HIGH is 36;; nonnegative. If the time value is a time difference, then HIGH can 37;; be negative as well. The macro `with-decoded-time-value' and the 38;; function `encode-time-value' make it easier to deal with these 39;; three formats. See `time-subtract' for an example of how to use 40;; them. 41 42;;; Code: 43 44(defmacro with-decoded-time-value (varlist &rest body) 45 "Decode a time value and bind it according to VARLIST, then eval BODY. 46 47The value of the last form in BODY is returned. 48 49Each element of the list VARLIST is a list of the form 50\(HIGH-SYMBOL LOW-SYMBOL MICRO-SYMBOL [TYPE-SYMBOL] TIME-VALUE). 51The time value TIME-VALUE is decoded and the result it bound to 52the symbols HIGH-SYMBOL, LOW-SYMBOL and MICRO-SYMBOL. 53 54The optional TYPE-SYMBOL is bound to the type of the time value. 55Type 0 is the cons cell (HIGH . LOW), type 1 is the list (HIGH 56LOW), and type 3 is the list (HIGH LOW MICRO)." 57 (declare (indent 1) 58 (debug ((&rest (symbolp symbolp symbolp &or [symbolp form] form)) 59 body))) 60 (if varlist 61 (let* ((elt (pop varlist)) 62 (high (pop elt)) 63 (low (pop elt)) 64 (micro (pop elt)) 65 (type (unless (eq (length elt) 1) 66 (pop elt))) 67 (time-value (car elt)) 68 (gensym (make-symbol "time"))) 69 `(let* ,(append `((,gensym ,time-value) 70 (,high (pop ,gensym)) 71 ,low ,micro) 72 (when type `(,type))) 73 (if (consp ,gensym) 74 (progn 75 (setq ,low (pop ,gensym)) 76 (if ,gensym 77 ,(append `(setq ,micro (car ,gensym)) 78 (when type `(,type 2))) 79 ,(append `(setq ,micro 0) 80 (when type `(,type 1))))) 81 ,(append `(setq ,low ,gensym ,micro 0) 82 (when type `(,type 0)))) 83 (with-decoded-time-value ,varlist ,@body))) 84 `(progn ,@body))) 85 86(defun encode-time-value (high low micro type) 87 "Encode HIGH, LOW, and MICRO into a time value of type TYPE. 88Type 0 is the cons cell (HIGH . LOW), type 1 is the list (HIGH LOW), 89and type 3 is the list (HIGH LOW MICRO)." 90 (cond 91 ((eq type 0) (cons high low)) 92 ((eq type 1) (list high low)) 93 ((eq type 2) (list high low micro)))) 94 95(autoload 'parse-time-string "parse-time") 96(autoload 'timezone-make-date-arpa-standard "timezone") 97 98;;;###autoload 99(defun date-to-time (date) 100 "Parse a string that represents a date-time and return a time value." 101 (condition-case () 102 (apply 'encode-time 103 (parse-time-string 104 ;; `parse-time-string' isn't sufficiently general or 105 ;; robust. It fails to grok some of the formats that 106 ;; timezone does (e.g. dodgy post-2000 stuff from some 107 ;; Elms) and either fails or returns bogus values. Lars 108 ;; reverted this change, but that loses non-trivially 109 ;; often for me. -- fx 110 (timezone-make-date-arpa-standard date))) 111 (error (error "Invalid date: %s" date)))) 112 113;;;###autoload 114(defun time-to-seconds (time) 115 "Convert time value TIME to a floating point number. 116You can use `float-time' instead." 117 (with-decoded-time-value ((high low micro time)) 118 (+ (* 1.0 high 65536) 119 low 120 (/ micro 1000000.0)))) 121 122;;;###autoload 123(defun seconds-to-time (seconds) 124 "Convert SECONDS (a floating point number) to a time value." 125 (list (floor seconds 65536) 126 (floor (mod seconds 65536)) 127 (floor (* (- seconds (ffloor seconds)) 1000000)))) 128 129;;;###autoload 130(defun time-less-p (t1 t2) 131 "Say whether time value T1 is less than time value T2." 132 (with-decoded-time-value ((high1 low1 micro1 t1) 133 (high2 low2 micro2 t2)) 134 (or (< high1 high2) 135 (and (= high1 high2) 136 (or (< low1 low2) 137 (and (= low1 low2) 138 (< micro1 micro2))))))) 139 140;;;###autoload 141(defun days-to-time (days) 142 "Convert DAYS into a time value." 143 (let* ((seconds (* 1.0 days 60 60 24)) 144 (high (condition-case nil (floor (/ seconds 65536)) 145 (range-error most-positive-fixnum)))) 146 (list high (condition-case nil (floor (- seconds (* 1.0 high 65536))) 147 (range-error 65535))))) 148 149;;;###autoload 150(defun time-since (time) 151 "Return the time elapsed since TIME. 152TIME should be either a time value or a date-time string." 153 (when (stringp time) 154 ;; Convert date strings to internal time. 155 (setq time (date-to-time time))) 156 (time-subtract (current-time) time)) 157 158;;;###autoload 159(defalias 'subtract-time 'time-subtract) 160 161;;;###autoload 162(defun time-subtract (t1 t2) 163 "Subtract two time values. 164Return the difference in the format of a time value." 165 (with-decoded-time-value ((high low micro type t1) 166 (high2 low2 micro2 type2 t2)) 167 (setq high (- high high2) 168 low (- low low2) 169 micro (- micro micro2) 170 type (max type type2)) 171 (when (< micro 0) 172 (setq low (1- low) 173 micro (+ micro 1000000))) 174 (when (< low 0) 175 (setq high (1- high) 176 low (+ low 65536))) 177 (encode-time-value high low micro type))) 178 179;;;###autoload 180(defun time-add (t1 t2) 181 "Add two time values. One should represent a time difference." 182 (with-decoded-time-value ((high low micro type t1) 183 (high2 low2 micro2 type2 t2)) 184 (setq high (+ high high2) 185 low (+ low low2) 186 micro (+ micro micro2) 187 type (max type type2)) 188 (when (>= micro 1000000) 189 (setq low (1+ low) 190 micro (- micro 1000000))) 191 (when (>= low 65536) 192 (setq high (1+ high) 193 low (- low 65536))) 194 (encode-time-value high low micro type))) 195 196;;;###autoload 197(defun date-to-day (date) 198 "Return the number of days between year 1 and DATE. 199DATE should be a date-time string." 200 (time-to-days (date-to-time date))) 201 202;;;###autoload 203(defun days-between (date1 date2) 204 "Return the number of days between DATE1 and DATE2. 205DATE1 and DATE2 should be date-time strings." 206 (- (date-to-day date1) (date-to-day date2))) 207 208;;;###autoload 209(defun date-leap-year-p (year) 210 "Return t if YEAR is a leap year." 211 (or (and (zerop (% year 4)) 212 (not (zerop (% year 100)))) 213 (zerop (% year 400)))) 214 215;;;###autoload 216(defun time-to-day-in-year (time) 217 "Return the day number within the year corresponding to TIME." 218 (let* ((tim (decode-time time)) 219 (month (nth 4 tim)) 220 (day (nth 3 tim)) 221 (year (nth 5 tim)) 222 (day-of-year (+ day (* 31 (1- month))))) 223 (when (> month 2) 224 (setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10))) 225 (when (date-leap-year-p year) 226 (setq day-of-year (1+ day-of-year)))) 227 day-of-year)) 228 229;;;###autoload 230(defun time-to-days (time) 231 "The number of days between the Gregorian date 0001-12-31bce and TIME. 232TIME should be a time value. 233The Gregorian date Sunday, December 31, 1bce is imaginary." 234 (let* ((tim (decode-time time)) 235 (month (nth 4 tim)) 236 (day (nth 3 tim)) 237 (year (nth 5 tim))) 238 (+ (time-to-day-in-year time) ; Days this year 239 (* 365 (1- year)) ; + Days in prior years 240 (/ (1- year) 4) ; + Julian leap years 241 (- (/ (1- year) 100)) ; - century years 242 (/ (1- year) 400)))) ; + Gregorian leap years 243 244(defun time-to-number-of-days (time) 245 "Return the number of days represented by TIME. 246The number of days will be returned as a floating point number." 247 (/ (time-to-seconds time) (* 60 60 24))) 248 249;;;###autoload 250(defun safe-date-to-time (date) 251 "Parse a string that represents a date-time and return a time value. 252If DATE is malformed, return a time value of zeros." 253 (condition-case () 254 (date-to-time date) 255 (error '(0 0)))) 256 257(provide 'time-date) 258 259;;; arch-tag: addcf07b-b20a-465b-af72-550b8ac5190f 260;;; time-date.el ends here 261