emacs/show: Accommodate the lack of part header buttons

Various pieces of code assumed (reasonably) that part header buttons
are present. Modify them to avoid problems if no part headers were
inserted.

diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
index ddb9c65c6d05c43319df0e08752f0f44bbdcffc9..8222f0d1e784821a4bae3345cdf732a07f7f731c 100644 (file)
--- a/emacs/notmuch-show.el
+++ b/emacs/notmuch-show.el
@@ -501,36 +501,37 @@ message at DEPTH in the current thread."
 
 (defun notmuch-show-toggle-part-invisibility (&optional button)
   (interactive)
-  (let* ((button (or button (button-at (point))))
-        (overlay (button-get button 'overlay))
-        (lazy-part (button-get button :notmuch-lazy-part)))
-    ;; We have a part to toggle if there is an overlay or if there is a lazy part.
-    ;; If neither is present we cannot toggle the part so we just return nil.
-    (when (or overlay lazy-part)
-      (let* ((show (button-get button :notmuch-part-hidden))
-            (new-start (button-start button))
-            (button-label (button-get button :base-label))
-            (old-point (point))
-            (properties (text-properties-at (button-start button)))
-            (inhibit-read-only t))
-       ;; Toggle the button itself.
-       (button-put button :notmuch-part-hidden (not show))
-       (goto-char new-start)
-       (insert "[ " button-label (if show " ]" " (hidden) ]"))
-       (set-text-properties new-start (point) properties)
-       (let ((old-end (button-end button)))
-         (move-overlay button new-start (point))
-         (delete-region (point) old-end))
-       (goto-char (min old-point (1- (button-end button))))
-       ;; Return nil if there is a lazy-part, it is empty, and we are
-       ;; trying to show it.  In all other cases return t.
-       (if lazy-part
-           (when show
-             (button-put button :notmuch-lazy-part nil)
-             (notmuch-show-lazy-part lazy-part button))
-         ;; else there must be an overlay.
-         (overlay-put overlay 'invisible (not show))
-         t)))))
+  (let ((button (or button (button-at (point)))))
+    (when button
+      (let ((overlay (button-get button 'overlay))
+           (lazy-part (button-get button :notmuch-lazy-part)))
+       ;; We have a part to toggle if there is an overlay or if there is a lazy part.
+       ;; If neither is present we cannot toggle the part so we just return nil.
+       (when (or overlay lazy-part)
+         (let* ((show (button-get button :notmuch-part-hidden))
+                (new-start (button-start button))
+                (button-label (button-get button :base-label))
+                (old-point (point))
+                (properties (text-properties-at (button-start button)))
+                (inhibit-read-only t))
+           ;; Toggle the button itself.
+           (button-put button :notmuch-part-hidden (not show))
+           (goto-char new-start)
+           (insert "[ " button-label (if show " ]" " (hidden) ]"))
+           (set-text-properties new-start (point) properties)
+           (let ((old-end (button-end button)))
+             (move-overlay button new-start (point))
+             (delete-region (point) old-end))
+           (goto-char (min old-point (1- (button-end button))))
+           ;; Return nil if there is a lazy-part, it is empty, and we are
+           ;; trying to show it.  In all other cases return t.
+           (if lazy-part
+               (when show
+                 (button-put button :notmuch-lazy-part nil)
+                 (notmuch-show-lazy-part lazy-part button))
+             ;; else there must be an overlay.
+             (overlay-put overlay 'invisible (not show))
+             t)))))))
 
 ;; Part content ID handling
 
@@ -639,14 +640,17 @@ will return nil if the CID is unknown or cannot be retrieved."
   t)
 
 (defun notmuch-show-insert-part-multipart/signed (msg part content-type nth depth button)
-  (button-put button 'face 'notmuch-crypto-part-header)
-  ;; add signature status button if sigstatus provided
+  (when button
+    (button-put button 'face 'notmuch-crypto-part-header))
+  ;; Add signature status button if sigstatus provided.
   (if (plist-member part :sigstatus)
       (let* ((from (notmuch-show-get-header :From msg))
             (sigstatus (car (plist-get part :sigstatus))))
        (notmuch-crypto-insert-sigstatus-button sigstatus from))
-    ;; if we're not adding sigstatus, tell the user how they can get it
-    (button-put button 'help-echo "Set notmuch-crypto-process-mime to process cryptographic MIME parts."))
+    ;; If we're not adding the signature status, tell the user how
+    ;; they can get it.
+    (when button
+      (button-put button 'help-echo "Set notmuch-crypto-process-mime to process cryptographic MIME parts.")))
 
   (let ((inner-parts (plist-get part :content))
        (start (point)))
@@ -660,17 +664,20 @@ will return nil if the CID is unknown or cannot be retrieved."
   t)
 
 (defun notmuch-show-insert-part-multipart/encrypted (msg part content-type nth depth button)
-  (button-put button 'face 'notmuch-crypto-part-header)
-  ;; add encryption status button if encstatus specified
+  (when button
+    (button-put button 'face 'notmuch-crypto-part-header))
+  ;; Add encryption status button if encryption status is specified.
   (if (plist-member part :encstatus)
       (let ((encstatus (car (plist-get part :encstatus))))
        (notmuch-crypto-insert-encstatus-button encstatus)
-       ;; add signature status button if sigstatus specified
+       ;; Add signature status button if signature status is
+       ;; specified.
        (if (plist-member part :sigstatus)
            (let* ((from (notmuch-show-get-header :From msg))
                   (sigstatus (car (plist-get part :sigstatus))))
              (notmuch-crypto-insert-sigstatus-button sigstatus from))))
-    ;; if we're not adding encstatus, tell the user how they can get it
+    ;; If we're not adding the encryption status, tell the user how
+    ;; they can get it.
     (button-put button 'help-echo "Set notmuch-crypto-process-mime to process cryptographic MIME parts."))
 
   (let ((inner-parts (plist-get part :content))
@@ -980,8 +987,9 @@ useful for quoting in replies)."
 
     (if show-part
         (notmuch-show-insert-bodypart-internal msg part mime-type nth depth button)
-      (button-put button :notmuch-lazy-part
-                  (list msg part mime-type nth depth button)))
+      (when button
+       (button-put button :notmuch-lazy-part
+                   (list msg part mime-type nth depth button))))
 
     ;; Some of the body part handlers leave point somewhere up in the
     ;; part, so we make sure that we're down at the end.