(rmail-next-same-subject): New command.

(rmail-previous-same-subject): Likewise.
(rmail-mode-map): Add bindings for C-c C-n and C-c C-p.

1 files changed, 50 insertions, 0 deletions

diff --git a/lisp/mail/rmail.el b/lisp/mail/rmail.el
index 0bc70936edb..deb5547efb3 100644
--- a/lisp/mail/rmail.el
+++ b/lisp/mail/rmail.el
@@ -414,6 +414,8 @@ Note:    it means the file has no messages in it.\n\^_")))
   (define-key rmail-mode-map "\C-c\C-s\C-c" 'rmail-sort-by-correspondent)
   (define-key rmail-mode-map "\C-c\C-s\C-l" 'rmail-sort-by-lines)
   (define-key rmail-mode-map "\C-c\C-s\C-k" 'rmail-sort-by-keywords)
+  (define-key rmail-mode-map "\C-c\C-n" 'rmail-next-same-subject)
+  (define-key rmail-mode-map "\C-c\C-p" 'rmail-previous-same-subject)
   )
 
 (define-key rmail-mode-map [menu-bar] (make-sparse-keymap))
@@ -1747,6 +1749,54 @@ Interactively, empty argument means use same regexp used last time."
 ;;    (if found
 ;;      (rmail-show-message found))
     found))
+
+(defun rmail-next-same-subject (n)
+  "Go to the next mail message having the same subject header.
+With prefix argument N, do this N times.
+If N is negative, go backwards instead."
+  (interactive "p")
+  (let* ((subject (mail-fetch-field "Subject"))
+         (search-regexp (concat "^Subject: *\\(Re: *\\)?"
+                                (regexp-quote subject)
+                                "\n"))
+         (forward (> n 0))
+         (i rmail-current-message)
+         found)
+    (if (string-match "Re:[ \t]*" subject)
+        (setq subject (substring subject (match-end 0))))
+    (save-excursion
+      (save-restriction
+        (widen)
+        (while (and (/= n 0)
+                    (if forward
+                        (< i rmail-total-messages)
+                      (> i 1)))
+          (let (done)
+            (while (and (not done)
+                        (if forward
+                            (< i rmail-total-messages)
+                          (> i 1)))
+              (setq i (if forward (1+ i) (1- i)))
+              (goto-char (rmail-msgbeg i))
+              (search-forward "\n*** EOOH ***\n")
+              (let ((beg (point)) end)
+                (search-forward "\n\n")
+                (setq end (point))
+                (goto-char beg)
+                (setq done (re-search-forward search-regexp end t))))
+            (if done (setq found i)))
+          (setq n (if forward (1- n) (1+ n))))))
+    (if found
+        (rmail-show-message found)
+      (error "No %s message with same subject"
+             (if forward "following" "previous")))))
+
+(defun rmail-previous-same-subject (n)
+  "Go to the previous mail message having the same subject header.
+With prefix argument N, do this N times.
+If N is negative, go forwards instead."
+  (interactive "p")
+  (rmail-next-same-subject (- n)))
 
 ;;;; *** Rmail Message Deletion Commands ***