mu4e: add command mu4e-sexp-at-point

Add command ~mu4e-sexp-at-point~ for showing/hiding the s-expression for the
message-at-point. Useful for development / debugging. Bound to ~,~ in headers and
view mode.

NEWS.org

@@ -119,6 +119,10 @@
    - Removed header-fields ~:attachments~, ~:signature~, ~:encryption~ and
  ~:user-agent~. They're obsolete with the Gnus-based message viewer.
 
+   - Add command ~mu4e-sexp-at-point~ for showing/hiding the s-expression for the
+     message-at-point. Useful for development / debugging. Bound to ~,~ in headers
+     and view mode.
+
    - undo is now supported across message-saves
 
    - a lot of the internals have been changed:

mu4e/mu4e-headers.el

@@ -932,6 +932,8 @@ after the end of the search results."
           (define-key map "t" 'mu4e-headers-mark-subthread)
           (define-key map "T" 'mu4e-headers-mark-thread)
 
+	  (define-key map "," #'mu4e-sexp-at-point)
+
           ;; navigation between messages
           (define-key map "p" 'mu4e-headers-prev)
           (define-key map "n" 'mu4e-headers-next)

mu4e/mu4e-message.el

@@ -30,6 +30,7 @@
 (require 'mu4e-contacts)
 (require 'flow-fill)
 (require 'shr)
+(require 'pp)
 
 (declare-function mu4e-error "mu4e-helpers")
 (declare-function mu4e-warn  "mu4e-helpers")
@@ -47,9 +48,9 @@
 
 (defsubst mu4e-message-field-raw (msg field)
   "Retrieve FIELD from message plist MSG.
-FIELD is one of :from, :to, :cc, :bcc, :subject, :data,
-:message-id, :path, :maildir, :priority, :attachments,
-:references, :in-reply-to, :body-txt, :body-html
+
+See \"mu fields\" for the full list of field, in particular the
+\"sexp\" column.
 
 Returns nil if the field does not exist.
 
@@ -66,13 +67,6 @@ A message plist looks something like:
  :maildir \"/INBOX\"
  :priority normal
  :flags (seen)
- :attachments
-     ((:index 2 :name \"photo.jpg\" :mime-type \"image/jpeg\" :size 147331)
-      (:index 3 :name \"book.pdf\" :mime-type \"application/pdf\" :size 192220))
- :references  (\"238C8384574032D81EE81AF0114E4E74@123213.mail.example.com\"
- \"6BDC23465F79238203498230942D81EE81AF0114E4E74@123213.mail.example.com\")
- :in-reply-to \"238203498230942D81EE81AF0114E4E74@123213.mail.example.com\"
- :body-txt \"Hi Tom, ...\"
 \)).
 Some notes on the format:
 - The address fields are lists of plist (:name NAME :email EMAIL),
@@ -228,6 +222,19 @@ If MSG is nil, use `mu4e-message-at-point'."
     (kill-new path)
     (mu4e-message "Saved '%s' to kill-ring" path)))
 
+(defconst mu4e--sexp-buffer-name " *mu4e-sexp-at-point"
+  "Buffer name for sexp buffers.")
+
+(defun mu4e-sexp-at-point ()
+  "Show or hide the s-expression for the message-at-point, if any."
+  (interactive)
+  (if-let ((win (get-buffer-window mu4e--sexp-buffer-name)))
+      (delete-window win)
+    (when-let ((msg (mu4e-message-at-point 'noerror)))
+      (with-current-buffer-window mu4e--sexp-buffer-name nil nil
+	;; the "pretty-printing" is not very pretty...
+	(insert (pp-to-string msg))))))
+
 ;;;
 (provide 'mu4e-message)
 ;;; mu4e-message.el ends here

mu4e/mu4e-view.el

@@ -887,6 +887,7 @@ This is useful for advising some Gnus-functionality that does not work in mu4e."
     (define-key map "E" #'mu4e-compose-edit)
 
     (define-key map "." #'mu4e-view-raw-message)
+    (define-key map "," #'mu4e-sexp-at-point)
     (define-key map "|" #'mu4e-view-pipe)
     (define-key map "a" #'mu4e-view-action)
     (define-key map "A" #'mu4e-view-mime-part-action)