emacs: Factor out useful functions into notmuch-lib

Move a few functions related to handling multipart/alternative parts
into notmuch-lib.el, so they can be used by future reply code.

emacs/notmuch-lib.el

@@ -21,6 +21,8 @@
 
 ;; This is an part of an emacs-based interface to the notmuch mail system.
 
+(eval-when-compile (require 'cl))
+
 (defvar notmuch-command "notmuch"
   "Command to run the notmuch binary.")
 
@@ -173,6 +175,37 @@ the user hasn't set this variable with the old or new value."
   (list 'when (< emacs-major-version 23)
 	form))
 
+(defun notmuch-split-content-type (content-type)
+  "Split content/type into 'content' and 'type'"
+  (split-string content-type "/"))
+
+(defun notmuch-match-content-type (t1 t2)
+  "Return t if t1 and t2 are matching content types, taking wildcards into account"
+  (let ((st1 (notmuch-split-content-type t1))
+	(st2 (notmuch-split-content-type t2)))
+    (if (or (string= (cadr st1) "*")
+	    (string= (cadr st2) "*"))
+	(string= (car st1) (car st2))
+      (string= t1 t2))))
+
+(defvar notmuch-multipart/alternative-discouraged
+  '(
+    ;; Avoid HTML parts.
+    "text/html"
+    ;; multipart/related usually contain a text/html part and some associated graphics.
+    "multipart/related"
+    ))
+
+(defun notmuch-multipart/alternative-choose (types)
+  "Return a list of preferred types from the given list of types"
+  ;; Based on `mm-preferred-alternative-precedence'.
+  (let ((seq types))
+    (dolist (pref (reverse notmuch-multipart/alternative-discouraged))
+      (dolist (elem (copy-sequence seq))
+	(when (string-match pref elem)
+	  (setq seq (nconc (delete elem seq) (list elem))))))
+    seq))
+
 ;; Compatibility functions for versions of emacs before emacs 23.
 ;;
 ;; Both functions here were copied from emacs 23 with the following copyright:

emacs/notmuch-show.el

@@ -542,30 +542,13 @@ current buffer, if possible."
 	    (mm-display-part handle)
 	    t))))))
 
-(defvar notmuch-show-multipart/alternative-discouraged
-  '(
-    ;; Avoid HTML parts.
-    "text/html"
-    ;; multipart/related usually contain a text/html part and some associated graphics.
-    "multipart/related"
-    ))
-
 (defun notmuch-show-multipart/*-to-list (part)
   (mapcar (lambda (inner-part) (plist-get inner-part :content-type))
 	  (plist-get part :content)))
 
-(defun notmuch-show-multipart/alternative-choose (types)
-  ;; Based on `mm-preferred-alternative-precedence'.
-  (let ((seq types))
-    (dolist (pref (reverse notmuch-show-multipart/alternative-discouraged))
-      (dolist (elem (copy-sequence seq))
-	(when (string-match pref elem)
-	  (setq seq (nconc (delete elem seq) (list elem))))))
-    seq))
-
 (defun notmuch-show-insert-part-multipart/alternative (msg part content-type nth depth declared-type)
   (notmuch-show-insert-part-header nth declared-type content-type nil)
-  (let ((chosen-type (car (notmuch-show-multipart/alternative-choose (notmuch-show-multipart/*-to-list part))))
+  (let ((chosen-type (car (notmuch-multipart/alternative-choose (notmuch-show-multipart/*-to-list part))))
 	(inner-parts (plist-get part :content))
 	(start (point)))
     ;; This inserts all parts of the chosen type rather than just one,
@@ -808,9 +791,6 @@ current buffer, if possible."
 
 ;; Functions for determining how to handle MIME parts.
 
-(defun notmuch-show-split-content-type (content-type)
-  (split-string content-type "/"))
-
 (defun notmuch-show-handlers-for (content-type)
   "Return a list of content handlers for a part of type CONTENT-TYPE."
   (let (result)
@@ -821,7 +801,7 @@ current buffer, if possible."
 	  (list (intern (concat "notmuch-show-insert-part-*/*"))
 		(intern (concat
 			 "notmuch-show-insert-part-"
-			 (car (notmuch-show-split-content-type content-type))
+			 (car (notmuch-split-content-type content-type))
 			 "/*"))
 		(intern (concat "notmuch-show-insert-part-" content-type))))
     result))