From: Jani Nikula <jani@nikula.org>
Date: Thu, 6 Sep 2012 15:32:37 +0000 (+0300)
Subject: emacs: add helper for tag change list manipulation
X-Git-Tag: 0.15_rc1~245
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=1dc7e66ee7186679e7669f045a4d787f36d26860;p=notmuch.git

emacs: add helper for tag change list manipulation

Add a helper to create (and optionally reverse) a list of tag changes.
---

diff --git a/emacs/notmuch-tag.el b/emacs/notmuch-tag.el
index 0c0fc875..4fce3a98 100644
--- a/emacs/notmuch-tag.el
+++ b/emacs/notmuch-tag.el
@@ -140,6 +140,21 @@ notmuch-after-tag-hook will be run."
   ;; in all cases we return tag-changes as a list
   tag-changes)
 
+(defun notmuch-tag-change-list (tags &optional reverse)
+  "Convert TAGS into a list of tag changes.
+
+Add a \"+\" prefix to any tag in TAGS list that doesn't already
+begin with a \"+\" or a \"-\". If REVERSE is non-nil, replace all
+\"+\" prefixes with \"-\" and vice versa in the result."
+  (mapcar (lambda (str)
+	    (let ((s (if (string-match "^[+-]" str) str (concat "+" str))))
+	      (if reverse
+		  (concat (if (= (string-to-char s) ?-) "+" "-")
+			  (substring s 1))
+		s)))
+	  tags))
+
+
 ;;
 
 (provide 'notmuch-tag)