[Patch v3 4/4] emacs: allow notmuch-show-line-faces to use flags for colouring

[Mark Walters <markwalters1009@gmail.com>]

This allows header-lines `notmuch-show-mode' buffers to be coloured
based on the flags (match/excluded) of the message. It supplies the
line colouring function with a list of tags each prefixed with "tag:"
and a list of flags ("match" or "excluded") each prefixed with
"flag:".

The match flag is obviously not equivalent to a tag; the excluded flag
looks equivalent but is subtly different: a message is not marked
excluded if that tag appeared in the query.
---
 emacs/notmuch-show.el |   28 ++++++++++++++++++++++------
 1 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
index e62f0a0..94399c5 100644
--- a/emacs/notmuch-show.el
+++ b/emacs/notmuch-show.el
@@ -96,17 +96,24 @@ any given message."
 (defcustom notmuch-show-line-faces nil
   "Tag to face mapping for header line highlighting in `notmuch-show-mode'.
 
-Here is an example of how to color search results based on tags.
+Here is an example of how to color search results based on tags
+and flags (match and excluded).
  (the following text would be placed in your ~/.emacs file):
 
- (setq notmuch-show-line-faces '((\"deleted\" . (:foreground \"red\"
+ (setq notmuch-show-line-faces '((\"tag:deleted\" . (:foreground \"red\"
 						  :background \"blue\"))
-                                   (\"unread\" . (:foreground \"green\"))))
+                                   (\"tag:unread\" . (:foreground \"green\"))
+                                   (\"flag:excluded\" . (:background \"grey\"))))
 
-The attributes defined for matching tags are merged, with later
+The attributes defined for matching tags/flags are merged, with later
 attributes overriding earlier. A message having both \"delete\"
 and \"unread\" tags with the above settings would have a green
-foreground and blue background."
+foreground and blue background.
+
+Alternatively, here is an example of colouring using the same
+criteria as for search results:
+ (setq notmuch-show-line-faces notmuch-search-line-faces)"
+
   :type '(alist :key-type (string) :value-type (custom-face-edit))
   :group 'notmuch-show
   :group 'notmuch-faces)
@@ -871,11 +878,20 @@ current buffer, if possible."
 	 content-start content-end
 	 headers-start headers-end
 	 body-start body-end
+	 tags-and-flags
 	 (headers-invis-spec (notmuch-show-make-symbol "header"))
 	 (message-invis-spec (notmuch-show-make-symbol "message"))
 	 (bare-subject (notmuch-show-strip-re (plist-get headers :Subject)))
 	 (tags (plist-get msg :tags)))
 
+    (mapc (lambda (tag)
+	    (setq tags-and-flags (cons (concat "tag:" tag) tags-and-flags)))
+	  tags)
+    (if (plist-get msg :match)
+	(setq tags-and-flags (cons "flag:match" tags-and-flags)))
+    (if (plist-get msg :excluded)
+	(setq tags-and-flags (cons "flag:excluded" tags-and-flags)))
+
     ;; Set `buffer-invisibility-spec' to `nil' (a list), otherwise
     ;; removing items from `buffer-invisibility-spec' (which is what
     ;; `notmuch-show-headers-visible' and
@@ -904,8 +920,7 @@ current buffer, if possible."
     (setq content-start (point-marker))
 
     ;; Colour the header line according to the tags of the message.
-    (notmuch-color-line message-start content-start tags notmuch-show-line-faces)
+    (notmuch-color-line message-start content-start tags-and-flags notmuch-show-line-faces)
 
     (plist-put msg :headers-invis-spec headers-invis-spec)
     (plist-put msg :message-invis-spec message-invis-spec)
-- 
1.7.9.1