Add timestamp selector.

README.org

@@ -193,6 +193,7 @@ These selectors take one argument alone, or multiple arguments in a list.
 +  =:children= :: Select any item that has child entries.  Argument may be ~t~ to match if it has any children, ~nil~ to match if it has no children, ~todo~ to match if it has children with any to-do keywords, or a string to match if it has children with certain to-do keywords.  You might use this to select items that are project top-level headings.  Be aware that this may be very slow in non-daily/weekly agenda views because of its recursive nature.
 +  =:date= :: Group items that have a date associated. Argument can be =t= to match items with any date, =nil= to match items without a date, or =today= to match items with today’s date. The =ts-date= text-property is matched against.
 +  =:deadline= :: Group items that have a deadline. Argument can be ~t~ (to match items with any deadline), ~nil~ (to match items that have no deadline), ~past~ (to match items with a deadline in the past), ~today~ (to match items whose deadline is today), or ~future~ (to match items with a deadline in the future). Argument may also be given like ~before DATE~ or ~after DATE~ where DATE is a date string that ~org-time-string-to-absolute~ can process.
++  =:timestamp= :: Group items whose bodies contain an active timestamp.  Argument can be ~t~ (to match items with any timestamp), ~past~ (to match items with timestamps in the past), ~today~ (to match items with timestamps set to today), or ~future~ (to match items with timestamps in the future).  Argument may also be given like ~before DATE~ or ~after DATE~, where DATE is a date string that ~org-time-string-to-absolute~ can process.
 +  =:effort<= :: Group items that are less than (or equal to) the given effort. Argument is a time-duration string, like ~5~ or ~0:05~ for 5 minutes.
 +  =:effort>= :: Group items that are higher than (or equal to) the given effort. Argument is a time-duration string, like ~5~ or ~0:05~ for 5 minutes.
 +  ~:file-path~ :: Group items whose buffers' filename paths match any of the given regular expressions.

org-super-agenda.el

@@ -396,6 +396,7 @@ returned by :SECTION-NAME as the first item, a list of items not
 matching the :TEST as the second, and a list of items matching as
 the third."
   (declare (indent defun)
+           (doc-string 2)
            (debug (&define symbolp stringp
                            &rest [&or [":section-name" [&or stringp def-form]]
                                       [":test" def-form]
@@ -498,7 +499,7 @@ DATE', where DATE is a date string that
 (org-super-agenda--defgroup scheduled
   "Group items that are scheduled.
 Argument can be `t' (to match items scheduled for any date),
-`nil' (to match items that are not schedule), `past` (to match
+`nil' (to match items that are not scheduled), `past' (to match
 items scheduled for the past), `today' (to match items scheduled
 for today), or `future' (to match items scheduled for the
 future).  Argument may also be given like `before DATE' or `after
@@ -532,6 +533,42 @@ DATE', where DATE is a date string that
                                        ((or 'before 'on 'after) target-date))))
                    (org-super-agenda--compare-dates comparison entry-time compare-date))))))))
 
+(org-super-agenda--defgroup timestamp
+  "Group items whose bodies contain an active timestamp.
+Argument can be `t' (to match items with any timestamps), `past' (to match items
+with timestamps in the past), `today' (to match items with timestamps set to
+today), or `future' (to match items with timestamps in the future).  Argument
+may also be given like `before DATE', `after DATE' or `after DATE', where DATE
+is a date string that `org-read-date' can process.  Note that relative dates are
+supported, e.g. `before +3d' means in the next two days."
+  :section-name (pcase (car args)
+                  ('t "Active timestamps")
+                  ('today "Active timestamps for today")
+                  ('future "Future active timestamps")
+                  ('past "Past active timestamps")
+                  ('before (concat "Active timestamps before " (cadr args)))
+                  ('on (concat "Active timestamps on " (cadr args)))
+                  ('after (concat "Active timestamps after " (cadr args))))
+  :let* ((target-date (pcase (car args)
+                        ((or 'before 'on 'after)
+                         (org-time-string-to-absolute (org-read-date nil nil (cadr args))))))
+         (comparison (car args))
+         (compare-date
+          (pcase comparison
+            ((or 'future 'past 'today) (org-today))
+            ((or 'before 'after 'on) target-date))))
+  :test (org-super-agenda--when-with-marker-buffer (org-super-agenda--get-marker item)
+          (let ((limit (org-entry-end-position)))
+            (cl-macrolet
+                ((next-timestamp
+                  ()
+                  `(when (re-search-forward org-ts-regexp limit :no-error)
+                     (org-time-string-to-absolute (org-read-date nil nil (match-string 1))))))
+              (cl-loop for next-ts = (next-timestamp)
+                       while next-ts
+                       thereis (or (eq comparison 't)
+                                   (org-super-agenda--compare-dates comparison next-ts compare-date)))))))
+
 (defun org-super-agenda--compare-dates (comparison date-a date-b)
   "Compare DATE-A and DATE-B according to COMPARISON.
 COMPARISON should be a symbol, one of: `past' or `before',

test/results.el

@@ -2199,4 +2199,19 @@ Wednesday   5 July 2017
   ambition:   In  77 d.:  TODO Visit Mars                                                     :universe:ambition::space:travel:planet:
   test:       Scheduled:  TODO [#C] Get haircut                                                                       :personal:@town:
   ambition:   TODO Practice leaping tall                     !                                           :universe:ambition::personal:
-"))
+" "98d4ed62b31456728bdfc66c8210b1ea" "Day-agenda (W27):
+Wednesday   5 July 2017
+
+ Future timestamps
+  test:          NEXT Meet with the Elder Council
+" "7b77cb34ad6f2bf523dc25b647310fd0" "Day-agenda (W27):
+Wednesday   5 July 2017
+
+ Past timestamps
+  test:          NEXT Time Travellers' Convention
+" "7b77cb34ad6f2bf523dc25b647310fd0" "Day-agenda (W27):
+Wednesday   5 July 2017
+
+ Relative timestamps
+  test:          NEXT Release the Kraken
+"))

test/test.el

@@ -728,23 +728,44 @@ already loaded."
   (should (org-super-agenda-test--run
            :groups '((:not (:todo t))))))
 
-(ert-deftest org-super-agenda-test--with-retained-sorting ()
+(ert-deftest org-super-agenda-test--with-kept-order ()
   (should (org-super-agenda-test--run
            :groups '((:name "Ambitions vs Bills with retained sorting"
                             :and (:todo "TODO" :priority>= "B" :tag "ambition")
                             :and (:todo "TODO" :priority>= "B" :tag "bills")
                             :discard (:anything)))
            :let* ((org-agenda-sorting-strategy '(priority-down tag-down))
-                  (org-super-agenda-retain-sorting t)))))
+                  (org-super-agenda-keep-order t)))))
 
-(ert-deftest org-super-agenda-test--without-retained-sorting ()
+(ert-deftest org-super-agenda-test--without-kept-order ()
   (should (org-super-agenda-test--run
            :groups '((:name "Ambitions vs Bills without retained sorting"
                             :and (:todo "TODO" :priority>= "B" :tag "ambition")
                             :and (:todo "TODO" :priority>= "B" :tag "bills")
                             :discard (:anything)))
            :let* ((org-agenda-sorting-strategy '(priority-down tag-down))
-                  (org-super-agenda-retain-sorting nil)))))
+                  (org-super-agenda-keep-order nil)))))
+
+(ert-deftest org-super-agenda-test--future-timestamps ()
+  (should (org-super-agenda-test--run
+           :groups '((:name "Future timestamps"
+                            :and (:tag "appointment" :timestamp future)
+                            :discard (:anything)))
+           :let* ((org-agenda-sorting-strategy '(priority-down tag-down))))))
+
+(ert-deftest org-super-agenda-test--past-timestamps ()
+  (should (org-super-agenda-test--run
+           :groups '((:name "Past timestamps"
+                            :and (:tag "appointment" :timestamp past)
+                            :discard (:anything)))
+           :let* ((org-agenda-sorting-strategy '(priority-down tag-down))))))
+
+(ert-deftest org-super-agenda-test--past-timestamps ()
+  (should (org-super-agenda-test--run
+           :groups '((:name "Relative timestamps"
+                            :and (:tag "appointment" :timestamp (on "+3d"))
+                            :discard (:anything)))
+           :let* ((org-agenda-sorting-strategy '(priority-down tag-down))))))
 
 (ert-deftest org-super-agenda-test--:order ()
   ;; DONE: Works.

test/test.org

@@ -78,6 +78,12 @@ If I don't, the frobnicator will probably fall off halfway to Mars...
 
 Gotta buy one first, though.
 
+** NEXT Meet with the Elder Council                            :appointment:
+<2021-10-03 So>
+** NEXT Time Travellers' Convention                            :appointment:
+<1566-10-05 Mo>
+** NEXT Release the Kraken                                     :appointment:
+<2017-07-08 Mo>
 ** Recurring
 :PROPERTIES:
 :agenda-group: recurring