Allow early-warning anniversaries in agenda.

* lisp/org-bbdb.el (org-bbdb-anniversaries-future, org-bbdb-date-list): New functions.

* doc/org.texi: Document the usage of `org-bbdb-anniversaries-future'.

* etc/ORG-NEWS: Feature description.

Feature requested by Julien Cubizolles:

http://thread.gmane.org/gmane.emacs.orgmode/99344

doc/org.texi

@@ -8046,6 +8046,20 @@ hash with anniversaries.  However, from then on things will be very fast---much
 faster in fact than a long list of @samp{%%(diary-anniversary)} entries
 in an Org or Diary file.
 
+If you would like to see upcoming anniversaries with a bit of forewarning,
+you can use the following instead:
+
+@example
+* Anniversaries
+  :PROPERTIES:
+  :CATEGORY: Anniv
+  :END:
+%%(org-bbdb-anniversaries-future 3)
+@end example
+
+That will give you three days' warning: on the anniversary date itself and the
+two days prior. The argument is optional: if omitted, it defaults to 7.
+
 @subsubheading Appointment reminders
 @cindex @file{appt.el}
 @cindex appointment reminders

etc/ORG-NEWS

@@ -40,6 +40,9 @@ http://orgmode.org/worg/org-contrib/babel/languages/ob-doc-stan.html
 *** New =#+latex_compiler= keyword to set LaTeX compiler.
 PDFLaTeX, XeLaTeX, and LuaLaTeX are supported.  See the manual for
 details.
+*** org-bbdb-anniversaries-future
+Used like org-bbdb-anniversaries, it provides a few days warning
+for upcoming anniversaries (default: 7 days).
 ** New functions
 ~org-show-children~ is a faster implementation of
 ~outline-show-children~.

lisp/org-bbdb.el

@@ -397,6 +397,58 @@ This is used by Org to re-create the anniversary hash table."
         ))
     text))
 
+;;; Return list of anniversaries for today and the next n-1 (default: n=7) days.
+;;; This is meant to be used in an org file instead of org-bbdb-anniversaries:
+;;;
+;;; %%(org-bbdb-anniversaries-future)
+;;;
+;;; or
+;;;
+;;; %%(org-bbdb-anniversaries-future 3)
+;;;
+;;; to override the 7-day default.
+
+(defun org-bbdb-date-list (date n)
+  "Return a list of dates in (m d y) format from the given 'date' to n-1 days hence."
+  (let ((abs (calendar-absolute-from-gregorian date))
+        ret)
+    (dotimes (i n (nreverse ret))
+	       (push (calendar-gregorian-from-absolute (+ abs i)) ret))))
+
+;;;###autoload
+(defun org-bbdb-anniversaries-future (&optional n)
+  "Return list of anniversaries for today and the next n-1 days (default n=7)."
+  (let ((n (or n 7)))
+    (when (<= n 0)
+      (error "The (optional) argument of `org-bbdb-anniversaries-future' must be positive"))
+    (let (
+	  ;; List of relevant dates.
+	  (dates (org-bbdb-date-list date n))
+	  ;; Function to annotate text of each element of l with the anniversary date d.
+	  (annotate-descriptions
+	   (lambda (d l)
+	     (mapcar (lambda (x)
+		       ;; The assumption here is that x is a bbdb link of the form
+		       ;; [[bbdb:name][description]].
+		       ;; This function rather arbitrarily modifies the description
+		       ;; by adding the date to it in a fixed format.
+		       (string-match "]]" x)
+		       (replace-match (format " -- %d-%02d-%02d\\&" (third d) (first d) (second d))
+				      nil nil x))
+		     l))))
+      ;; Map a function that generates anniversaries for each date over the dates
+      ;; and nconc the results into a single list. When it is no longer necessary
+      ;; to support older versions of emacs, this can be done with a cl-mapcan;
+      ;; for now, we use the (apply #'nconc ...) method for compatibility.
+      (apply #'nconc
+	     (lambda (d)
+		   (let ((date d))
+		     ;; Rebind 'date' so that org-bbdb-anniversaries will be
+		     ;; fooled into giving us the list for the given date
+		     ;; and then annotate the descriptions for that date.
+		     (funcall annotate-descriptions d (org-bbdb-anniversaries))))
+		 dates))))
+
 (defun org-bbdb-complete-link ()
   "Read a bbdb link with name completion."
   (require 'bbdb-com)