master 8728da58ab 2/2: Allow applying Rmail summary filters consecutively

[Eli Zaretskii]

branch: master
commit 8728da58ab319cbffc160b49c716b65429c8d5a6
Author: Andrea Monaco <andrea.monaco@autistici.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Allow applying Rmail summary filters consecutively
    
    * lisp/mail/rmailsum.el (rmail-summary-currently-displayed-msgs):
    New variable.
    (rmail-summary-apply-filters-consecutively): New user option.
    (rmail-summary-fill-displayed-messages, rmail-summary-negate): New
    functions.
    (rmail-summary-by-labels, rmail-summary-by-recipients)
    (rmail-summary-by-regexp, rmail-summary-by-topic)
    (rmail-summary-by-senders): Obey
    'rmail-summary-apply-filters-consecutively'.
    KEEP-FILTERING, to narrow the existing filtered summary.
    
    * etc/NEWS: Announce the change.
---
 etc/NEWS              | 12 +++++++
 lisp/mail/rmailsum.el | 95 +++++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 101 insertions(+), 6 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index cbbf90fde6..530532fa07 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2051,6 +2051,18 @@ Formerly it was a pair of numbers '(A B)' that 
represented 65536*A + B,
 to cater to older Emacs implementations that lacked bignums.
 The older form still works but is undocumented.
 
+** Rmail
+
+---
+*** Rmail partial summaries can now be applied one on top of the other.
+You can now narrow the filtering of messages by the summary's criteria
+(recipients, topic, senders, etc.) by making a summary of the already
+summarized messages.  For example, invoking 'rmail-summary-by-senders',
+followed by 'rmail-summary-by-topic' will produce a summary where both
+the senders and the topic are according to your selection.  The new
+user option 'rmail-summary-apply-filters-consecutively' controls
+whether the stacking of the filters is in effect.
+
 ** EIEIO
 
 +++
diff --git a/lisp/mail/rmailsum.el b/lisp/mail/rmailsum.el
index b959f45250..1ed3664506 100644
--- a/lisp/mail/rmailsum.el
+++ b/lisp/mail/rmailsum.el
@@ -50,6 +50,22 @@ Setting this option to nil might speed up the generation of 
summaries."
   :type 'boolean
   :group 'rmail-summary)
 
+(defcustom rmail-summary-apply-filters-consecutively nil
+  "If non-nil, Rmail summary commands apply filtering on top existing 
filtering.
+When this variable is non-nil, `rmail-summary-by-*' commands work on the
+current summary, and so their filtering can be stacked one on top of another.
+This allows gradual narrowing of the selection of the messages."
+  :type 'boolean
+  :group 'rmail-summary)
+
+(defvar rmail-summary-currently-displayed-msgs nil
+  "String made of `y' and `n'.
+The character at position i tells wether message i is shown in the
+summary or not.  First character is ignored.
+Used when applying `rmail-summary-by-*' commands consecutively.  Filled
+by `rmail-summary-fill-displayed-messages'.")
+(put 'rmail-summary-currently-displayed-msgs 'permanent-local t)
+
 (defvar rmail-summary-font-lock-keywords
   '(("^ *[0-9]+D.*" . font-lock-string-face)                   ; Deleted.
     ("^ *[0-9]+-.*" . font-lock-type-face)                     ; Unread.
@@ -267,6 +283,34 @@ Setting this option to nil might speed up the generation 
of summaries."
 (defun rmail-update-summary (&rest _)
   (apply (car rmail-summary-redo) (cdr rmail-summary-redo)))
 
+(defun rmail-summary-fill-displayed-messages ()
+  "Fill the rmail-summary-currently-displayed-msgs string."
+  (with-current-buffer rmail-buffer
+    (with-current-buffer rmail-summary-buffer
+      (setq rmail-summary-currently-displayed-msgs
+           (make-string (1+ rmail-total-messages) ?n))
+      (goto-char (point-min))
+      (while (not (eobp))
+       (aset rmail-summary-currently-displayed-msgs
+             (string-to-number (thing-at-point 'line))
+             ?y)
+       (forward-line 1)))))
+
+(defun rmail-summary-negate ()
+  "Toggle display of messages that match the summary and those which do not."
+  (interactive)
+  (rmail-summary-fill-displayed-messages)
+  (rmail-new-summary "Negate"
+                    '(rmail-summary-by-regexp ".*")
+                    (lambda (msg)
+                      (if
+                          (= (aref rmail-summary-currently-displayed-msgs msg)
+                             ?n)
+                          (progn
+                            (aset rmail-summary-currently-displayed-msgs msg 
?y) t)
+                        (progn
+                          (aset rmail-summary-currently-displayed-msgs msg ?n) 
nil)))))
+
 ;;;###autoload
 (defun rmail-summary ()
   "Display a summary of all messages, one line per message."
@@ -282,9 +326,16 @@ LABELS should be a string containing the desired labels, 
separated by commas."
       (setq labels (or rmail-last-multi-labels
                       (error "No label specified"))))
   (setq rmail-last-multi-labels labels)
+  (if rmail-summary-apply-filters-consecutively
+      (rmail-summary-fill-displayed-messages))
   (rmail-new-summary (concat "labels " labels)
                     (list 'rmail-summary-by-labels labels)
-                    'rmail-message-labels-p
+                    (if rmail-summary-apply-filters-consecutively
+                        (lambda (msg l)
+                          (and (= (aref rmail-summary-currently-displayed-msgs 
msg)
+                                  ?y)
+                               (rmail-message-labels-p msg l)))
+                      'rmail-message-labels-p)
                     (concat " \\("
                             (mail-comma-list-regexp labels)
                             "\\)\\(,\\|\\'\\)")))
@@ -297,10 +348,18 @@ but if PRIMARY-ONLY is non-nil (prefix arg given),
  only look in the To and From fields.
 RECIPIENTS is a regular expression."
   (interactive "sRecipients to summarize by: \nP")
+  (if rmail-summary-apply-filters-consecutively
+      (rmail-summary-fill-displayed-messages))
   (rmail-new-summary
    (concat "recipients " recipients)
    (list 'rmail-summary-by-recipients recipients primary-only)
-   'rmail-message-recipients-p recipients primary-only))
+   (if rmail-summary-apply-filters-consecutively
+       (lambda (msg r &optional po)
+        (and (= (aref rmail-summary-currently-displayed-msgs msg)
+                ?y)
+             (rmail-message-recipients-p msg r po)))
+     'rmail-message-recipients-p)
+   recipients primary-only))
 
 (defun rmail-message-recipients-p (msg recipients &optional primary-only)
   (rmail-apply-in-message msg 'rmail-message-recipients-p-1
@@ -328,9 +387,16 @@ Emacs will list the message in the summary."
       (setq regexp (or rmail-last-regexp
                         (error "No regexp specified"))))
   (setq rmail-last-regexp regexp)
+  (if rmail-summary-apply-filters-consecutively
+      (rmail-summary-fill-displayed-messages))
   (rmail-new-summary (concat "regexp " regexp)
                     (list 'rmail-summary-by-regexp regexp)
-                    'rmail-message-regexp-p
+                    (if rmail-summary-apply-filters-consecutively
+                        (lambda (msg r)
+                          (and (= (aref rmail-summary-currently-displayed-msgs 
msg)
+                                  ?y)
+                               (rmail-message-regexp-p msg r)))
+                      'rmail-message-regexp-p)
                      regexp))
 
 (defun rmail-message-regexp-p (msg regexp)
@@ -365,7 +431,7 @@ Emacs will list the message in the summary."
 ;;;###autoload
 (defun rmail-summary-by-topic (subject &optional whole-message)
   "Display a summary of all messages with the given SUBJECT.
-Normally checks just the Subject field of headers; but with prefix
+Normally checks just the Subject field of headers; but when prefix
 argument WHOLE-MESSAGE is non-nil, looks in the whole message.
 SUBJECT is a regular expression."
   (interactive
@@ -376,10 +442,18 @@ SUBJECT is a regular expression."
                          (if subject ", default current subject" "")
                          "): ")))
      (list (read-string prompt nil nil subject) current-prefix-arg)))
+  (if rmail-summary-apply-filters-consecutively
+      (rmail-summary-fill-displayed-messages))
   (rmail-new-summary
    (concat "about " subject)
    (list 'rmail-summary-by-topic subject whole-message)
-   'rmail-message-subject-p subject whole-message))
+   (if rmail-summary-apply-filters-consecutively
+       (lambda (msg s &optional wm)
+        (and (= (aref rmail-summary-currently-displayed-msgs msg)
+                ?y)
+             (rmail-message-subject-p msg s wm)))
+     'rmail-message-subject-p)
+   subject whole-message))
 
 (defun rmail-message-subject-p (msg subject &optional whole-message)
   (if whole-message
@@ -402,9 +476,18 @@ sender of the current message."
                          (if sender ", default this message's sender" "")
                          "): ")))
      (list (read-string prompt nil nil sender))))
+  (if rmail-summary-apply-filters-consecutively
+      (rmail-summary-fill-displayed-messages))
   (rmail-new-summary
    (concat "senders " senders)
-   (list 'rmail-summary-by-senders senders) 'rmail-message-senders-p senders))
+   (list 'rmail-summary-by-senders senders)
+   (if rmail-summary-apply-filters-consecutively
+       (lambda (msg s)
+        (and (= (aref rmail-summary-currently-displayed-msgs msg)
+                ?y)
+             (rmail-message-senders-p msg s)))
+     'rmail-message-senders-p)
+   senders))
 
 (defun rmail-message-senders-p (msg senders)
   (string-match senders (or (rmail-get-header "From" msg) "")))