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Fix off-by-one bug in ISO 8601 BC years

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* lisp/calendar/iso8601.el (iso8601--year-match)
(iso8601--full-date-match, iso8601--without-day-match)
(iso8601--week-date-match, iso8601--ordinal-date-match)
(iso8601-parse-date):
Don’t bother to separate the year’s sign from the year,
as that distinction is not needed: ISO 8601 uses
astronomical year numbering with a year zero, which
is what the Emacs time functions use, so there’s no
need to treat nonpositive years specially.
(iso8601--adjust-year): Remove; no longer needed
since callers can just use string-to-number.
* test/lisp/calendar/iso8601-tests.el (test-iso8601-date-years):
Adjust test case to match fixed behavior.
This commit is contained in:
Paul Eggert 2019-10-05 21:23:15 -07:00
parent aadf721676
commit 9d829b8be5
2 changed files with 18 additions and 33 deletions
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49
lisp/calendar/iso8601.el
View file

@ -62,17 +62,17 @@
regexps "\\|"))
(defconst iso8601--year-match
"\\([+-]\\)?\\([0-9][0-9][0-9][0-9]\\)")
"\\([+-]?[0-9][0-9][0-9][0-9]\\)")
(defconst iso8601--full-date-match
"\\([+-]\\)?\\([0-9][0-9][0-9][0-9]\\)-?\\([0-9][0-9]\\)-?\\([0-9][0-9]\\)")
"\\([+-]?[0-9][0-9][0-9][0-9]\\)-?\\([0-9][0-9]\\)-?\\([0-9][0-9]\\)")
(defconst iso8601--without-day-match
"\\([+-]\\)?\\([0-9][0-9][0-9][0-9]\\)-\\([0-9][0-9]\\)")
"\\([+-]?[0-9][0-9][0-9][0-9]\\)-\\([0-9][0-9]\\)")
(defconst iso8601--outdated-date-match
"--\\([0-9][0-9]\\)-?\\([0-9][0-9]\\)")
(defconst iso8601--week-date-match
"\\([+-]\\)?\\([0-9][0-9][0-9][0-9]\\)-?W\\([0-9][0-9]\\)-?\\([0-9]\\)?")
"\\([+-]?[0-9][0-9][0-9][0-9]\\)-?W\\([0-9][0-9]\\)-?\\([0-9]\\)?")
(defconst iso8601--ordinal-date-match
"\\([+-]\\)?\\([0-9][0-9][0-9][0-9]\\)-?\\([0-9][0-9][0-9]\\)")
"\\([+-]?[0-9][0-9][0-9][0-9]\\)-?\\([0-9][0-9][0-9]\\)")
(defconst iso8601--date-match
(iso8601--concat-regexps
(list iso8601--year-match
@ -145,21 +145,18 @@ See `decode-time' for the meaning of FORM."
;; Just a year: [+-]YYYY.
((iso8601--match iso8601--year-match string)
(iso8601--decoded-time
:year (iso8601--adjust-year (match-string 1 string)
(match-string 2 string))))
:year (string-to-number string)))
;; Calendar dates: YYYY-MM-DD and variants.
((iso8601--match iso8601--full-date-match string)
(iso8601--decoded-time
:year (iso8601--adjust-year (match-string 1 string)
(match-string 2 string))
:month (match-string 3 string)
:day (match-string 4 string)))
:year (string-to-number (match-string 1 string))
:month (match-string 2 string)
:day (match-string 3 string)))
;; Calendar date without day: YYYY-MM.
((iso8601--match iso8601--without-day-match string)
(iso8601--decoded-time
:year (iso8601--adjust-year (match-string 1 string)
(match-string 2 string))
:month (match-string 3 string)))
:year (string-to-number string)
:month (match-string 2 string)))
;; Outdated date without year: --MM-DD
((iso8601--match iso8601--outdated-date-match string)
(iso8601--decoded-time
@ -167,11 +164,10 @@ See `decode-time' for the meaning of FORM."
:day (match-string 2 string)))
;; Week dates: YYYY-Www-D
((iso8601--match iso8601--week-date-match string)
(let* ((year (iso8601--adjust-year (match-string 1 string)
(match-string 2 string)))
(week (string-to-number (match-string 3 string)))
(day-of-week (and (match-string 4 string)
(string-to-number (match-string 4 string))))
(let* ((year (string-to-number string))
(week (string-to-number (match-string 2 string)))
(day-of-week (and (match-string 3 string)
(string-to-number (match-string 3 string))))
(jan-start (decoded-time-weekday
(decode-time
(iso8601--encode-time
@ -199,9 +195,8 @@ See `decode-time' for the meaning of FORM."
:day (decoded-time-day month-day)))))
;; Ordinal dates: YYYY-DDD
((iso8601--match iso8601--ordinal-date-match string)
(let* ((year (iso8601--adjust-year (match-string 1 string)
(match-string 2 string)))
(ordinal (string-to-number (match-string 3 string)))
(let* ((year (string-to-number (match-string 1 string)))
(ordinal (string-to-number (match-string 2 string)))
(month-day (date-ordinal-to-time year ordinal)))
(iso8601--decoded-time :year year
:month (decoded-time-month month-day)
@ -209,16 +204,6 @@ See `decode-time' for the meaning of FORM."
(t
(signal 'wrong-type-argument string))))
(defun iso8601--adjust-year (sign year)
(save-match-data
(let ((year (if (stringp year)
(string-to-number year)
year)))
(if (string= sign "-")
;; -0001 is 2 BCE.
(1- (- year))
year))))
(defun iso8601-parse-time (string &optional form)
"Parse STRING, which should be an ISO 8601 time string.
The return value will be a `decode-time' structure with just the

2
test/lisp/calendar/iso8601-tests.el
View file

@ -26,7 +26,7 @@
(should (equal (iso8601-parse-date "1985")
'(nil nil nil nil nil 1985 nil nil nil)))
(should (equal (iso8601-parse-date "-0003")
'(nil nil nil nil nil -4 nil nil nil)))
'(nil nil nil nil nil -3 nil nil nil)))
(should (equal (iso8601-parse-date "+1985")
'(nil nil nil nil nil 1985 nil nil nil))))