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

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

1 files changed, 46 insertions, 1 deletions

diff --git a/lisp/dired-aux.el b/lisp/dired-aux.el
index b9ceb728dbc..321a7f67932 100644
--- a/lisp/dired-aux.el
+++ b/lisp/dired-aux.el
@@ -463,6 +463,50 @@ with a prefix argument."
 
 ;;; 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 `&'.