* todos.el: Fix and improve item date string editing.

(todos-date-pattern): Make dayname an explicitly numbered group.
(todos-basic-edit-item-header): Set match for dayname and use it
to ensure attempting to edit day, month or year of a date header
containing a day name is a noop, simplifying and fixing buggy code.

2 files changed, 17 insertions, 10 deletions

diff --git a/lisp/calendar/ChangeLog b/lisp/calendar/ChangeLog
index b09cf30f1c7..0d8fda0d147 100644
--- a/lisp/calendar/ChangeLog
+++ b/lisp/calendar/ChangeLog
@@ -1,3 +1,11 @@
+2013-06-09  Stephen Berman  <stephen.berman@gmx.net>
+
+        * todos.el: Fix and improve item date string editing.
+        (todos-date-pattern): Make dayname an explicitly numbered group.
+        (todos-basic-edit-item-header): Set match for dayname and use it
+        to ensure attempting to edit day, month or year of a date header
+        containing a day name is a noop, simplifying and fixing buggy code.
+
 2013-06-08  Stephen Berman  <stephen.berman@gmx.net>
 
         * todos.el: Improve commentary.
diff --git a/lisp/calendar/todos.el b/lisp/calendar/todos.el
index 6d79fadd106..4f83ead0d48 100644
--- a/lisp/calendar/todos.el
+++ b/lisp/calendar/todos.el
@@ -211,7 +211,7 @@ The final element is \"*\", indicating an unspecified month.")
 
 (defconst todos-date-pattern
   (let ((dayname (diary-name-pattern calendar-day-name-array nil t)))
-    (concat "\\(?5:" dayname "\\|"
+    (concat "\\(?4:\\(?5:" dayname "\\)\\|"
             (let ((dayname)
                   (monthname (format "\\(?6:%s\\)" (diary-name-pattern
                                                     todos-month-name-array
@@ -2099,6 +2099,7 @@ otherwise, edit just the item at point."
                              (line-end-position) t)
           (let* ((odate (match-string-no-properties 1))
                  (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))
@@ -2133,9 +2134,8 @@ otherwise, edit just the item at point."
                 (when (> (length ntime) 0)
                   (setq ntime (concat " " ntime))))
                ;; When date string consists only of a day name,
-               ;; passing other date components is a NOP.
-               ((and (memq what '(year month day))
-                     (not (or oyear omonth oday))))
+               ;; passing other date components is a noop.
+               ((and odayname (memq what '(year month day))))
                ((eq what 'year)
                 (setq day oday
                       monthname omonthname
@@ -2220,12 +2220,11 @@ otherwise, edit just the item at point."
                                 (setq monthname (aref tma-array (1- adjmm))))
                               ;; Return changed numerical day as a string.
                               (number-to-string (nth 1 date)))))))))
-            ;; If new year, month or day date string components were
-            ;; calculated, rebuild the whole date string from them.
-            (when (memq what '(year month day))
-              (if (or oyear omonth omonthname oday)
-                  (setq ndate (mapconcat 'eval calendar-date-display-form ""))
-                (message "Cannot edit date component of empty date string")))
+            (unless odayname
+              ;; If year, month or day date string components were
+              ;; changed, rebuild the date string.
+              (when (memq what '(year month day))
+                (setq ndate (mapconcat 'eval calendar-date-display-form ""))))
             (when ndate (replace-match ndate nil nil nil 1))
             ;; Add new time string to the header, if it was supplied.
             (when ntime