Restore predicate for detecting date stamps in ERC

* etc/ERC-NEWS: Mention function `erc-stamp-inserting-date-stamp-p'.
* lisp/erc/erc-stamp.el (erc-stamp-inserting-date-stamp-p): New
function for third parties to detect whether the message being
inserted is a date stamp.  Date stamps as independent messages were
originally introduced as part of bug#60936.

1 files changed, 7 insertions, 0 deletions

diff --git a/lisp/erc/erc-stamp.el b/lisp/erc/erc-stamp.el
index a65b564ba6c..cfd756ce625 100644
--- a/lisp/erc/erc-stamp.el
+++ b/lisp/erc/erc-stamp.el
@@ -678,6 +678,13 @@ value of t means the option's value doesn't require trimming.")
                                             0 erc-stamp--date-format-end)
                                erc-timestamp-format-left))))
 
+(defun erc-stamp-inserting-date-stamp-p ()
+  "Return non-nil if the narrowed buffer contains a date stamp.
+Expect to be called by members of `erc-insert-modify-hook' and
+`erc-insert-post-hook' to detect whether the message being
+inserted is a date stamp."
+  (erc--check-msg-prop 'erc--msg 'datestamp))
+
 ;; Calling `erc-display-message' from within a hook it's currently
 ;; running is roundabout, but it's a definite means of ensuring hooks
 ;; can act on the date stamp as a standalone message to do things like