[PATCH 2/4] emacs: Record part p-list in a text property

[Austin Clements <amdragon@MIT.EDU>]

This is similar to what we already do with the message p-list, though
we apply the part's text property to the whole part's text, in
contrast with the message p-list, which is (rather obscurely) only
applied to the first character.
---
 emacs/notmuch-lib.el  |   16 ++++++++++++++++
 emacs/notmuch-show.el |   13 ++++++++++++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/emacs/notmuch-lib.el b/emacs/notmuch-lib.el
index 790136e..09ce25e 100644
--- a/emacs/notmuch-lib.el
+++ b/emacs/notmuch-lib.el
@@ -360,6 +360,22 @@ 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."
+  (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))))))
+
 (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 a080134..acd0b55 100644
--- a/emacs/notmuch-show.el
+++ b/emacs/notmuch-show.el
@@ -900,7 +900,10 @@ If HIDE is non-nil then initially hide this part."
     ;; Ensure that the part ends with a carriage return.
     (unless (bolp)
       (insert "\n"))
-    (notmuch-show-create-part-overlays msg beg (point) hide)))
+    (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)))
 
 (defun notmuch-show-insert-body (msg body depth)
   "Insert the body BODY at depth DEPTH in the current thread."
@@ -1404,6 +1407,14 @@ Some useful entries are:
     (notmuch-show-move-to-message-top)
     (get-text-property (point) :notmuch-message-properties)))
 
+(defun notmuch-show-get-part-properties ()
+  "Return the properties of the part containing point.
+
+This is the part property list retrieved from the CLI.  Signals
+an error if there is no part containing point."
+  (or (get-text-property (point) :notmuch-part)
+      (error "No message part here")))
+
 (defun notmuch-show-set-prop (prop val &optional props)
   (let ((inhibit-read-only t)
 	(props (or props
-- 
1.7.10.4