Add timestamp selector.

README.org

@@ -210,6 +210,7 @@ These selectors take one argument alone, or multiple arguments in a list.
 +  =:tag= :: Group items that match any of the given tags.  Argument may be a string or list of strings.
 +  =:time-grid= :: Group items that appear on the time grid.
 +  =:todo= :: Group items that match any of the given TODO keywords.  Argument may be a string or list of strings, or ~t~ to match any keyword, or ~nil~ to match only non-todo items.
++  =:timestamp= :: Select items whose body contains an active timestamp.  Argument is either ~future~ or ~any~.  The former will only match headlines with a timestamp at a future date, the latter will match any active timestamp.
 
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org-super-agenda.el

@@ -628,6 +628,31 @@ section name for this group."
             (cl-loop for regexp in args
                      thereis (string-match-p regexp heading)))))
 
+(org-super-agenda--defgroup timestamp
+  "Group items whose bodies contain an active timestamp.
+Argument is either `future' or `any'. The former will only match headlines
+with a timestamp at a future date, the latter will match any active timestamp."
+  :section-name (pcase-exhaustive args
+                  (`(any) "Active timestamps: ")
+                  (`(future) "Active future timestamps: "))
+  :test (org-super-agenda--when-with-marker-buffer (org-super-agenda--get-marker item)
+          (let* ((now (ts-now))
+                 (now-year (ts-year now))
+                 (now-day (ts-doy now))
+                 (limit (org-entry-end-position))
+                 (test (pcase-exhaustive args
+                         (`(any)
+                          (lambda (_) t))
+                         (`(future)
+                          (lambda (it) (and it (>= (ts-year it) now-year) (>= (ts-doy it) now-day))))))
+                 (next-ts))
+            (cl-macrolet ((next-timestamp ()
+                                          `(when (re-search-forward org-element--timestamp-regexp limit :no-error)
+                                             (ts-parse-org (match-string 1)))))
+              (cl-loop for next-ts = (next-timestamp)
+                       while next-ts
+                       thereis (funcall test next-ts))))))
+
 (org-super-agenda--defgroup pred
   "Group items that match a predicate.
 Argument can be one or a list of functions, to match items that