Add support for dealing with decoded time structures

* doc/lispref/os.texi (Time Conversion): Document the new
functions that work on decoded time.
(Time Calculations): Document new date/time functions.

* lisp/simple.el (decoded-time-second, decoded-time-minute)
(decoded-time-hour, decoded-time-day, decoded-time-month)
(decoded-time-year, decoded-time-weekday, decoded-time-dst)
(decoded-time-zone): New accessor functions for decoded time values.

* lisp/calendar/time-date.el (date-days-in-month)
(date-ordinal-to-time): New functions.
(decoded-time--alter-month, decoded-time--alter-day)
(decoded-time--alter-second, make-decoded-time): New functions
added to manipulate decoded time structures.

* src/timefns.c (Fdecode_time): Mention the new accessors.

* test/lisp/calendar/time-date-tests.el: New file to test the
decoded time functions and the other new functions.

1 files changed, 109 insertions, 0 deletions

diff --git a/test/lisp/calendar/time-date-tests.el b/test/lisp/calendar/time-date-tests.el
new file mode 100644
index 00000000000..d6cf742bc53
--- /dev/null
+++ b/test/lisp/calendar/time-date-tests.el
@@ -0,0 +1,109 @@
+;;; time-date-tests.el --- tests for calendar/time-date.el    -*- lexical-binding:t -*-
+
+;; Copyright (C) 2019 Free Software Foundation, Inc.
+
+;; 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/>.
+
+;;; Code:
+
+(require 'ert)
+(require 'time-date)
+
+(ert-deftest test-leap-year ()
+  (should-not (date-leap-year-p 1999))
+  (should-not (date-leap-year-p 1900))
+  (should (date-leap-year-p 2000))
+  (should (date-leap-year-p 2004)))
+
+(ert-deftest test-days-in-month ()
+  (should (= (date-days-in-month 2004 2) 29))
+  (should (= (date-days-in-month 2004 3) 31))
+  (should-not (= (date-days-in-month 1900 3) 28)))
+
+(ert-deftest test-ordinal ()
+  (should (equal (date-ordinal-to-time 2008 271)
+                 '(0 0 0 27 9 2008 nil nil nil)))
+  (should (equal (date-ordinal-to-time 2008 1)
+                 '(0 0 0 1 1 2008 nil nil nil)))
+  (should (equal (date-ordinal-to-time 2008 32)
+                 '(0 0 0 1 2 2008 nil nil nil)))
+  (should (equal (date-ordinal-to-time 1981 095)
+                 '(0 0 0 5 4 1981 nil nil nil))))
+
+(cl-defmethod mdec (&key second minute hour
+                         day month year
+                         dst zone)
+  (list second minute hour day month year nil dst zone))
+
+(ert-deftest test-decoded-add ()
+  (let ((time '(12 15 16 8 7 2019 1 t 7200)))
+    (should (equal (decoded-time-add time (mdec :year 1))
+                   '(12 15 16 8 7 2020 1 t 7200)))
+
+    (should (equal (decoded-time-add time (mdec :year -2))
+                   '(12 15 16 8 7 2017 1 t 7200)))
+
+    (should (equal (decoded-time-add time (mdec :month 1))
+                   '(12 15 16 8 8 2019 1 t 7200)))
+
+    (should (equal (decoded-time-add time (mdec :month 10))
+                   '(12 15 16 8 5 2020 1 t 7200)))
+
+    (should (equal (decoded-time-add time (mdec :day 1))
+                   '(12 15 16 9 7 2019 1 t 7200)))
+
+    (should (equal (decoded-time-add time (mdec :day -1))
+                   '(12 15 16 7 7 2019 1 t 7200)))
+
+    (should (equal (decoded-time-add time (mdec :day 30))
+                   '(12 15 16 7 8 2019 1 t 7200)))
+
+    (should (equal (decoded-time-add time (mdec :day -365))
+                   '(12 15 16 8 7 2018 1 t 7200)))
+
+    (should (equal (decoded-time-add time (mdec :day 365))
+                   '(12 15 16 7 7 2020 1 t 7200)))
+
+    ;; 2020 is a leap year.
+    (should (equal (decoded-time-add time (mdec :day 366))
+                   '(12 15 16 8 7 2020 1 t 7200)))
+
+    (should (equal (decoded-time-add time (mdec :second 1))
+                   '(13 15 16 8 7 2019 1 t 7200)))
+
+    (should (equal (decoded-time-add time (mdec :second -1))
+                   '(11 15 16 8 7 2019 1 t 7200)))
+
+    (should (equal (decoded-time-add time (mdec :second 61))
+                   '(13 16 16 8 7 2019 1 t 7200)))
+
+    (should (equal (decoded-time-add time (mdec :hour 1 :minute 2 :second 3))
+                   '(15 17 17 8 7 2019 1 t 7200)))
+
+    (should (equal (decoded-time-add time (mdec :hour 24))
+                   '(12 15 16 9 7 2019 1 t 7200)))
+    ))
+
+(ert-deftest test-decoded-add-zone ()
+  (let ((time '(12 15 16 8 7 2019 1 t 7200)))
+    (should (equal (decoded-time-add time (mdec :zone -3600))
+                   '(12 15 15 8 7 2019 1 t 7200)))
+    (should (equal (decoded-time-add time (mdec :zone -7200))
+                   '(12 15 14 8 7 2019 1 t 7200)))))
+
+(require 'ert)
+
+;;; time-date-tests.el ends here