(dired-read-shell-command-default): New function.

(dired-read-shell-command): Use its return value for DEFAULT arg.

diff --git a/lisp/dired-aux.el b/lisp/dired-aux.el
index b9ceb728dbc1a5cafaf427b73d1feb54e11c76dc..321a7f679323ee15b554a14979697ce47e69d2be 100644 (file)
--- a/lisp/dired-aux.el
+++ b/lisp/dired-aux.el
@@ -463,6 +463,50 @@ with a prefix argument."
 \f
 ;;; Shell commands
 
+(defun dired-read-shell-command-default (files)
+  "Return a list of default commands for `dired-read-shell-command'."
+  (require 'mailcap)
+  (mailcap-parse-mailcaps)
+  (mailcap-parse-mimetypes)
+  (let* ((all-mime-type
+         ;; All unique MIME types from file extensions
+         (delete-dups (mapcar (lambda (file)
+                                (mailcap-extension-to-mime
+                                 (file-name-extension file t)))
+                              files)))
+        (all-mime-info
+         ;; All MIME info lists
+         (delete-dups (mapcar (lambda (mime-type)
+                                (mailcap-mime-info mime-type 'all))
+                              all-mime-type)))
+        (common-mime-info
+         ;; Intersection of mime-infos from different mime-types;
+         ;; or just the first MIME info for a single MIME type
+         (if (cdr all-mime-info)
+             (delq nil (mapcar (lambda (mi1)
+                                 (unless (memq nil (mapcar
+                                                    (lambda (mi2)
+                                                      (member mi1 mi2))
+                                                    (cdr all-mime-info)))
+                                   mi1))
+                               (car all-mime-info)))
+           (car all-mime-info)))
+        (commands
+         ;; Command strings from `viewer' field of the MIME info
+         (delq nil (mapcar (lambda (mime-info)
+                             (let ((command (cdr (assoc 'viewer mime-info))))
+                               (if (stringp command)
+                                   (replace-regexp-in-string
+                                    ;; Replace mailcap's `%s' placeholder
+                                    ;; with dired's `?' placeholder
+                                    "%s" "?"
+                                    (replace-regexp-in-string
+                                     ;; Remove the final filename placeholder
+                                     "\s*\\('\\)?%s\\1?\s*\\'" "" command nil t)
+                                    nil t))))
+                           common-mime-info))))
+    commands))
+
 (defun dired-read-shell-command (prompt arg files)
 ;;  "Read a dired shell command prompting with PROMPT (using read-string).
 ;;ARG is the prefix arg and may be used to indicate in the prompt which
@@ -472,7 +516,8 @@ with a prefix argument."
    nil 'shell files
    (function read-string)
    (format prompt (dired-mark-prompt arg files))
-   nil 'shell-command-history))
+   nil 'shell-command-history
+   (dired-read-shell-command-default files)))
 
 ;; The in-background argument is only needed in Emacs 18 where
 ;; shell-command doesn't understand an appended ampersand `&'.