Add support in todo-mode.el for ISO date format

* lisp/calendar/todo-mode.el (todo--date-pattern-groups): New defconst.
(todo-date-pattern): Use it to extend pattern matching of
`calendar-date-display-form' to support the ISO date format in
todo item date headers (bug#66395, bug#55284).
(todo-edit-item--header): Make it work with ISO date strings.

diff --git a/lisp/calendar/todo-mode.el b/lisp/calendar/todo-mode.el
index c27bae8439e1ff625d15f366d0b6b683be451045..dbd1388848ed6b72a480e06ca3699dce31abb113 100644 (file)
--- a/lisp/calendar/todo-mode.el
+++ b/lisp/calendar/todo-mode.el
@@ -189,20 +189,53 @@ The final element is \"*\", indicating an unspecified month.")
   "Array of abbreviated month names, in order.
 The final element is \"*\", indicating an unspecified month.")
 
+(defconst todo--date-pattern-groups
+  (pcase calendar-date-style
+          ('american '((monthname . "6") (month . "7") (day . "8") (year . "9")))
+          ('european '((day . "6") (monthname . "7") (month . "8") (year . "9")))
+          ('iso '((year . "6") (monthname . "7") (month . "8") (day . "9"))))
+  "Alist for grouping date components in `todo-date-pattern'.")
+
 (defconst todo-date-pattern
-  (let ((dayname (diary-name-pattern calendar-day-name-array nil t)))
-    (concat "\\(?4:\\(?5:" dayname "\\)\\|"
-           (calendar-dlet
-                ((dayname)
-                (monthname (format "\\(?6:%s\\)" (diary-name-pattern
-                                                  todo-month-name-array
-                                                  todo-month-abbrev-array)))
-                (month "\\(?7:[0-9]+\\|\\*\\)")
-                (day "\\(?8:[0-9]+\\|\\*\\)")
-                (year "-?\\(?9:[0-9]+\\|\\*\\)"))
-             (mapconcat #'eval calendar-date-display-form))
-           "\\)"))
-  "Regular expression matching a todo item date header.")
+  (let* ((dayname (diary-name-pattern calendar-day-name-array nil t))
+         (d (concat "\\(?" (alist-get 'day todo--date-pattern-groups)
+                    ":[0-9]+\\|\\*\\)"))
+         (mn (format (concat "\\(?" (alist-get 'monthname
+                                               todo--date-pattern-groups)
+                             ":%s\\)")
+                     (diary-name-pattern todo-month-name-array
+                                         todo-month-abbrev-array)))
+         (m (concat "\\(?" (alist-get 'month todo--date-pattern-groups)
+                    ":[0-9]+\\|\\*\\)"))
+         (y (concat "\\(?" (alist-get 'year todo--date-pattern-groups)
+                    ":[0-9]+\\|\\*\\)"))
+         (dd "1111111")
+         (mm "2222222")
+         (yy "3333333")
+         (s (concat "\\(?4:\\(?5:" dayname "\\)\\|"
+                   (calendar-dlet
+                        ((dayname)
+                        (monthname mn)
+                        (year yy)
+                        (month mm)
+                        (day dd))
+                      (mapconcat #'eval calendar-date-display-form))
+                   "\\)")))
+    ;; The default value of calendar-iso-date-display-form calls
+    ;; `string-to-number' on the values of `month' and `day', so we
+    ;; gave them placeholder values above and now replace these with
+    ;; the necessary regexps with appropriately numbered groups, because
+    ;; `todo-edit-item--header' uses these groups.
+    (when (string-match dd s nil t)
+      (setq s (string-replace dd d s)))
+    (when (string-match mm s nil t)
+      (setq s (string-replace mm m s)))
+    (when (string-match yy s nil t)
+      (setq s (string-replace yy y s)))
+    s)
+  "Regular expression matching a todo item date header.
+The value of `calendar-date-display-form' determines the form of
+the date header.")
 
 ;; By itself this matches anything, because of the `?'; however, it's only
 ;; used in the context of `todo-date-pattern' (but Emacs Lisp lacks
@@ -2350,10 +2383,18 @@ made in the number or names of categories."
                             (line-end-position) t)
          (let* ((otime (match-string-no-properties 2))
                 (odayname (match-string-no-properties 5))
-                (omonthname (match-string-no-properties 6))
-                (omonth (match-string-no-properties 7))
-                (oday (match-string-no-properties 8))
-                (oyear (match-string-no-properties 9))
+                 (mngroup (string-to-number
+                           (alist-get 'monthname todo--date-pattern-groups)))
+                (omonthname (match-string-no-properties mngroup))
+                 (mgroup (string-to-number
+                          (alist-get 'month todo--date-pattern-groups)))
+                (omonth (match-string-no-properties mgroup))
+                 (dgroup (string-to-number
+                          (alist-get 'day todo--date-pattern-groups)))
+                (oday (match-string-no-properties dgroup))
+                 (ygroup (string-to-number
+                          (alist-get 'year todo--date-pattern-groups)))
+                (oyear (match-string-no-properties ygroup))
                 (tmn-array todo-month-name-array)
                 (mlist (append tmn-array nil))
                 (tma-array todo-month-abbrev-array)
@@ -2399,11 +2440,23 @@ made in the number or names of categories."
                 ((eq what 'month)
                  (setf day oday
                        year oyear
-                       (if (memq 'month calendar-date-display-form)
+                        ;; With default ISO style, 'month is in a
+                        ;; sublist of c-d-d-f, so we flatten it.
+                       (if (memq 'month (flatten-tree
+                                          calendar-date-display-form))
                            month
                          monthname)
                        (cond ((not current-prefix-arg)
-                              (todo-read-date 'month))
+                              (let ((nmonth (todo-read-date 'month)))
+                                 ;; If old month is given as a number,
+                                 ;; have to convert new month name to
+                                 ;; the corresponding number.
+                                 (when omonth
+                                   (setq nmonth
+                                         (number-to-string
+                                          (1+ (seq-position tma-array
+                                                            nmonth)))))
+                                 nmonth))
                              ((or (string= omonth "*") (= mm 13))
                               (user-error "Cannot increment *"))
                              (t