Improve progressive summaries in Rmail

* lisp/mail/rmailsum.el (rmail-summary-progressively-narrow):
Renamed from 'rmail-summary-apply-filters-consecutively'.  Doc
fix.
(rmail-summary-invert): Renamed from 'rmail-summary-negate'.  Doc
fix.
(rmail-summary-currently-displayed-msgs): Doc fix.
(rmail-summary--exists-1): New function.
(rmail-summary-by-labels, rmail-summary-by-recipients)
(rmail-summary-by-regexp, rmail-summary-by-topic)
(rmail-summary-by-senders): Call 'rmail-summary-exists' to verify
that the summary is usable.

1 files changed, 79 insertions, 57 deletions

diff --git a/lisp/mail/rmailsum.el b/lisp/mail/rmailsum.el
index 0144a34e5e7..d72464cb81a 100644
--- a/lisp/mail/rmailsum.el
+++ b/lisp/mail/rmailsum.el
@@ -50,21 +50,26 @@ 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."
+(defcustom rmail-summary-progressively-narrow nil
+  "Non-nil means progressively narrow the set of messages produced by summary.
+This allows to apply the summary criteria on top one another,
+thus progressively narrowing the selection of the messages produced
+by each summary criteria.
+For example, applying `rmail-summary-by-senders' on top
+of `rmail-summary-by-topic' produces a summary of messages
+with the specified Subjects that were sent from specified
+sending addresses.
+This way, the user can apply one summary on top of another,
+and keep narrowing the resulting list of messages."
   :type 'boolean
   :version "29.1"
   :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'.")
+  "Boolean vector that tells which messages are displayed in the summary.
+First element is ignored.  Used when applying rmail-summary-by-*
+commands consecutively.  Filled by
+`rmail-summary-populate-displayed-messages'.")
 (put 'rmail-summary-currently-displayed-msgs 'permanent-local t)
 
 (defvar rmail-summary-font-lock-keywords
@@ -284,33 +289,40 @@ by `rmail-summary-fill-displayed-messages'.")
 (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."
+(defun rmail-summary-populate-displayed-messages ()
+  "Populate the `rmail-summary-currently-displayed-msgs' vector."
   (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."
+    (let ((totmsgs rmail-total-messages))
+      (with-current-buffer rmail-summary-buffer
+	(setq rmail-summary-currently-displayed-msgs
+	      (make-bool-vector (1+ totmsgs) nil))
+	(goto-char (point-min))
+	(while (not (eobp))
+	  (aset rmail-summary-currently-displayed-msgs
+		(string-to-number (thing-at-point 'line))
+		t)
+	  (forward-line 1))))))
+
+(defun rmail-summary-invert ()
+  "Invert the criteria of the current summary.
+That is, show the messages that are not displayed, and hide
+the messages that are displayed."
   (interactive)
-  (rmail-summary-fill-displayed-messages)
-  (rmail-new-summary "Negate"
+  (rmail-summary-populate-displayed-messages)
+  (rmail-new-summary "Invert"
 		     '(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)))))
+			   (eq (aref rmail-summary-currently-displayed-msgs msg)
+			       nil)
+			   (aset rmail-summary-currently-displayed-msgs msg t)
+			 (aset rmail-summary-currently-displayed-msgs msg nil)))))
+
+(defun rmail-summary--exists-1 ()
+  "Like `rmail-summary-exists', but works in both main and summary buffers."
+  (with-current-buffer rmail-buffer
+    (and rmail-summary-buffer (buffer-name rmail-summary-buffer)
+	 rmail-summary-buffer)))
 
 ;;;###autoload
 (defun rmail-summary ()
@@ -327,14 +339,16 @@ 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))
+  (if (and rmail-summary-progressively-narrow
+	   (rmail-summary--exists-1))
+      (rmail-summary-populate-displayed-messages))
   (rmail-new-summary (concat "labels " labels)
 		     (list 'rmail-summary-by-labels labels)
-		     (if rmail-summary-apply-filters-consecutively
+		     (if (and rmail-summary-progressively-narrow
+			      (rmail-summary--exists-1))
 			 (lambda (msg l)
-			   (and (= (aref rmail-summary-currently-displayed-msgs msg)
-				   ?y)
+			   (and (eq (aref rmail-summary-currently-displayed-msgs msg)
+				    t)
 				(rmail-message-labels-p msg l)))
 		       'rmail-message-labels-p)
 		     (concat " \\("
@@ -349,15 +363,17 @@ 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))
+  (if (and rmail-summary-progressively-narrow
+	   (rmail-summary--exists-1))
+      (rmail-summary-populate-displayed-messages))
   (rmail-new-summary
    (concat "recipients " recipients)
    (list 'rmail-summary-by-recipients recipients primary-only)
-   (if rmail-summary-apply-filters-consecutively
+   (if (and rmail-summary-progressively-narrow
+	    (rmail-summary--exists-1))
        (lambda (msg r &optional po)
-	 (and (= (aref rmail-summary-currently-displayed-msgs msg)
-		 ?y)
+	 (and (eq (aref rmail-summary-currently-displayed-msgs msg)
+		  t)
 	      (rmail-message-recipients-p msg r po)))
      'rmail-message-recipients-p)
    recipients primary-only))
@@ -388,14 +404,16 @@ 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))
+  (if (and rmail-summary-progressively-narrow
+	   (rmail-summary--exists-1))
+      (rmail-summary-populate-displayed-messages))
   (rmail-new-summary (concat "regexp " regexp)
 		     (list 'rmail-summary-by-regexp regexp)
-		     (if rmail-summary-apply-filters-consecutively
+		     (if (and rmail-summary-progressively-narrow
+			      (rmail-summary--exists-1))
 			 (lambda (msg r)
-			   (and (= (aref rmail-summary-currently-displayed-msgs msg)
-				   ?y)
+			   (and (eq (aref rmail-summary-currently-displayed-msgs msg)
+				    t)
 				(rmail-message-regexp-p msg r)))
 		       'rmail-message-regexp-p)
                      regexp))
@@ -443,15 +461,17 @@ 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))
+  (if (and rmail-summary-progressively-narrow
+	   (rmail-summary--exists-1))
+      (rmail-summary-populate-displayed-messages))
   (rmail-new-summary
    (concat "about " subject)
    (list 'rmail-summary-by-topic subject whole-message)
-   (if rmail-summary-apply-filters-consecutively
+   (if (and rmail-summary-progressively-narrow
+	    (rmail-summary--exists-1))
        (lambda (msg s &optional wm)
-	 (and (= (aref rmail-summary-currently-displayed-msgs msg)
-		 ?y)
+	 (and (eq (aref rmail-summary-currently-displayed-msgs msg)
+		  t)
 	      (rmail-message-subject-p msg s wm)))
      'rmail-message-subject-p)
    subject whole-message))
@@ -477,15 +497,17 @@ 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))
+  (if (and rmail-summary-progressively-narrow
+	   (rmail-summary--exists-1))
+      (rmail-summary-populate-displayed-messages))
   (rmail-new-summary
    (concat "senders " senders)
    (list 'rmail-summary-by-senders senders)
-   (if rmail-summary-apply-filters-consecutively
+   (if (and rmail-summary-progressively-narrow
+	    (rmail-summary--exists-1))
        (lambda (msg s)
-	 (and (= (aref rmail-summary-currently-displayed-msgs msg)
-		 ?y)
+	 (and (eq (aref rmail-summary-currently-displayed-msgs msg)
+		  t)
 	      (rmail-message-senders-p msg s)))
      'rmail-message-senders-p)
    senders))