[PATCH v2 0/5] emacs: Part command improvements

[Austin Clements <amdragon@MIT.EDU>]

This is v2 of id:87zjvghx82.fsf@qmul.ac.uk.  In addition to some
general improvements, this fixes the handling of part overlays in
indented messages, removes the special part button map entirely in
favor of the "." submap, and adds a NEWS patch.

The diff from v1 follows

diff --git a/NEWS b/NEWS
index a7f2ec6..23f4c6a 100644
--- a/NEWS
+++ b/NEWS
@@ -61,6 +61,22 @@ notmuch-vim, but of course that is their decision.
 Emacs Interface
 ---------------
 
+New keymap to view/save parts
+
+  To view or save a single MIME part of a message, use the new "."
+  submap (e.g., ". s" to save, ". v" to view).  Previously, these keys
+  were only available when point was on a part button and they did not
+  have the "." prefix, so they were difficult to invoke (impossible if
+  a part did not have a button) and clashed with other bindings.
+  These new bindings also appear in show's help, so you don't have to
+  memorize them.
+
+Default part save directory is now `mm-default-directory`
+
+  Previously, notmuch offered to save parts and attachments to a mix
+  of `mm-default-directory`, `mailcap-download-directory`, and `~/`.
+  This has been standardized on `mm-default-directory`.
+
 No Emacs 22 support
 
   The Emacs 22 support added late 2010 was sufficient only for a short
diff --git a/emacs/notmuch-lib.el b/emacs/notmuch-lib.el
index 09ce25e..2186783 100644
--- a/emacs/notmuch-lib.el
+++ b/emacs/notmuch-lib.el
@@ -360,21 +360,17 @@ OBJECT."
    below
    string))
 
-(defun notmuch-put-text-property-if-nil (start end property value
-					       &optional object)
-  "Like `put-text-property', but only set the property where it is nil."
+(defun notmuch-map-text-property (start end prop func &optional object)
+  "Transform text property PROP using FUNC.
+
+Applies FUNC to each distinct value of the text property PROP
+between START and END of OBJECT, setting PROP to the value
+returned by FUNC."
   (while (< start end)
-    (let ((start-nil (text-property-any start end property nil object)))
-      (if (null start-nil)
-	  ;; There are no more nil regions; exit the loop
-	  (setq start end)
-	;; Find the end of the nil region
-	(let ((end-nil
-	       (or (text-property-not-all start-nil end property nil object)
-		   end)))
-	  ;; Set the property
-	  (put-text-property start-nil end-nil property value object)
-	  (setq start end-nil))))))
+    (let ((value (get-text-property start prop object))
+	  (next (next-single-property-change start prop object end)))
+      (put-text-property start next prop (funcall func value) object)
+      (setq start next))))
 
 (defun notmuch-logged-error (msg &optional extra)
   "Log MSG and EXTRA to *Notmuch errors* and signal MSG.
diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
index 380b144..613e666 100644
--- a/emacs/notmuch-show.el
+++ b/emacs/notmuch-show.el
@@ -466,7 +466,6 @@ message at DEPTH in the current thread."
 
 (define-button-type 'notmuch-show-part-button-type
   'action 'notmuch-show-part-button-default
-  'keymap 'notmuch-show-part-button-map
   'follow-link t
   'face 'message-mml
   :supertype 'notmuch-button-type)
@@ -843,8 +842,15 @@ If HIDE is non-nil then initially hide this part."
       (insert "\n"))
     (notmuch-show-create-part-overlays msg beg (point) hide)
     ;; Record part information.  Since we already inserted subparts,
-    ;; don't override exiting :notmuch-part properties.
-    (notmuch-put-text-property-if-nil beg (point) :notmuch-part part)))
+    ;; don't override existing :notmuch-part properties.
+    (notmuch-map-text-property beg (point) :notmuch-part
+			       (lambda (v) (or v part)))
+    ;; Make :notmuch-part front sticky and rear non-sticky so it stays
+    ;; applied to the beginning of each line when we indent the message.
+    (notmuch-map-text-property beg (point) 'front-sticky
+			       (lambda (v) (pushnew :notmuch-part v)))
+    (notmuch-map-text-property beg (point) 'rear-nonsticky
+			       (lambda (v) (pushnew :notmuch-part v)))))
 
 (defun notmuch-show-insert-body (msg body depth)
   "Insert the body BODY at depth DEPTH in the current thread."
@@ -1194,11 +1200,6 @@ reset based on the original query."
   "Submap for part commands")
 (fset 'notmuch-show-part-map notmuch-show-part-map)
 
-(defvar notmuch-show-part-button-map
-  (make-composed-keymap notmuch-show-part-map button-map)
-  "Keymap for part button commands")
-(fset 'notmuch-show-part-button-map notmuch-show-part-button-map)
-
 (defvar notmuch-show-mode-map
       (let ((map (make-sparse-keymap)))
 	(define-key map "?" 'notmuch-help)
@@ -1365,7 +1366,7 @@ Some useful entries are:
     (get-text-property (point) :notmuch-message-properties)))
 
 (defun notmuch-show-get-part-properties ()
-  "Return the properties of the part containing point.
+  "Return the properties of the innermost part containing point.
 
 This is the part property list retrieved from the CLI.  Signals
 an error if there is no part containing point."