Support nil value for dictionary-server

* net/lisp/dictionary.el (dictionary-server): Support choice to select
the dictionary server to use
* net/lisp/dictionary.el (dictionary-check-connection): Support nil
value for dictionary-server

This nil value is the new default value of that variable. When
opening a new connection and dictionary-server is nil the code
behaves the following way:

- it will first try to connect to a dictd server running on localhost
- if that fails, it queries the user if the alternative
  server (dict.org) should be consulted
- if the user agrees, the connection is made to dict.org

This allows the default value of dictionary-server not to connect
a remote server by default. The user is always able to select a
different server by customizing the variable dictionary-search.

diff --git a/lisp/net/dictionary.el b/lisp/net/dictionary.el
index 8d7d97afe0e6335c02f148377c467f2c6c1ce20e..a1d4ac9214e1a837ec30463d0c0e2e5e9c9390b2 100644 (file)
--- a/lisp/net/dictionary.el
+++ b/lisp/net/dictionary.el
@@ -44,13 +44,13 @@
 ;; Stuff for customizing.
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
-(defvar dictionary-server)
+(defvar dictionary-current-server)
 (defun dictionary-set-server-var (name value)
   (if (and (boundp 'dictionary-connection)
           dictionary-connection
           (eq (dictionary-connection-status dictionary-connection) 'up)
           (y-or-n-p
-           (concat "Close existing connection to " dictionary-server "? ")))
+           (concat "Close existing connection to " dictionary-current-server "? ")))
       (dictionary-connection-close dictionary-connection))
   (set-default name value))
 
@@ -63,11 +63,22 @@
   :group 'dictionary)
 
 (defcustom dictionary-server
-  "dict.org"
-  "This server is contacted for searching the dictionary"
+  nil
+  "This server is contacted for searching the dictionary.
+
+You can specify here:
+
+- Automatic: First try localhost, then dict.org after confirmation
+- localhost: Only use localhost
+- dict.org: Only use dict.org
+- User-defined: You can specify your own server here
+"
   :group 'dictionary
   :set 'dictionary-set-server-var
-  :type 'string
+  :type '(choice (const :tag "Automatic" nil)
+                 (const :tag "localhost" "localhost")
+                 (const :tag "dict.org" "dict.org")
+                 (string :tag "User-defined"))
   :version "28.1")
 
 (defcustom dictionary-port
@@ -421,56 +432,71 @@ is utf-8"
   "Return the reply list stored in `reply'."
   (list 'get reply ''reply-list))
 
+(defun dictionary-open-server (server)
+  "Opens a new connection to this server"
+  (let ((wanted 'raw-text)
+        (coding-system nil))
+    (if (member wanted (coding-system-list))
+        (setq coding-system wanted))
+    (let ((coding-system-for-read coding-system)
+          (coding-system-for-write coding-system))
+      (setq dictionary-current-server server)
+      (message "Opening connection to %s:%s" server
+               dictionary-port)
+      (dictionary-connection-close dictionary-connection)
+      (setq dictionary-connection
+            (if dictionary-use-http-proxy
+                (dictionary-connection-open dictionary-proxy-server
+                                            dictionary-proxy-port)
+              (dictionary-connection-open server dictionary-port)))
+      (set-process-query-on-exit-flag
+       (dictionary-connection-process dictionary-connection)
+       nil)
+
+      (when dictionary-use-http-proxy
+        (message "Proxy CONNECT to %s:%d"
+                 dictionary-proxy-server
+                 dictionary-proxy-port)
+        (dictionary-send-command (format "CONNECT %s:%d HTTP/1.1"
+                                         server
+                                         dictionary-port))
+        ;; just a \r\n combination
+        (dictionary-send-command "")
+
+        ;; read first line of reply
+        (let* ((reply (dictionary-read-reply))
+               (reply-list (dictionary-split-string reply)))
+          ;; first item is protocol, second item is code
+          (unless (= (string-to-number (cadr reply-list)) 200)
+            (error "Bad reply from proxy server %s" reply))
+
+          ;; skip the following header lines until empty found
+          (while (not (equal reply ""))
+            (setq reply (dictionary-read-reply)))))
+
+      (dictionary-check-initial-reply)
+      (dictionary-send-command (concat "client " dictionary-identification))
+      (let ((reply (dictionary-read-reply-and-split)))
+        (message nil)
+        (unless (dictionary-check-reply reply 250)
+          (error "Unknown server answer: %s"
+                 (dictionary-reply reply)))))))
+
 (defun dictionary-check-connection ()
   "Check if there is already a connection open"
   (if (not (and dictionary-connection
                (eq (dictionary-connection-status dictionary-connection) 'up)))
-      (let ((wanted 'raw-text)
-           (coding-system nil))
-       (if (member wanted (coding-system-list))
-           (setq coding-system wanted))
-       (let ((coding-system-for-read coding-system)
-             (coding-system-for-write coding-system))
-         (message "Opening connection to %s:%s" dictionary-server
-                  dictionary-port)
-         (dictionary-connection-close dictionary-connection)
-         (setq dictionary-connection
-               (if dictionary-use-http-proxy
-                   (dictionary-connection-open dictionary-proxy-server
-                                                dictionary-proxy-port)
-                 (dictionary-connection-open dictionary-server dictionary-port)))
-         (set-process-query-on-exit-flag
-          (dictionary-connection-process dictionary-connection)
-          nil)
-
-         (when dictionary-use-http-proxy
-           (message "Proxy CONNECT to %s:%d"
-                    dictionary-proxy-server
-                    dictionary-proxy-port)
-           (dictionary-send-command (format "CONNECT %s:%d HTTP/1.1"
-                                            dictionary-server
-                                            dictionary-port))
-           ;; just a \r\n combination
-           (dictionary-send-command "")
-
-           ;; read first line of reply
-           (let* ((reply (dictionary-read-reply))
-                  (reply-list (dictionary-split-string reply)))
-             ;; first item is protocol, second item is code
-             (unless (= (string-to-number (cadr reply-list)) 200)
-               (error "Bad reply from proxy server %s" reply))
-
-             ;; skip the following header lines until empty found
-             (while (not (equal reply ""))
-               (setq reply (dictionary-read-reply)))))
-
-         (dictionary-check-initial-reply)
-         (dictionary-send-command (concat "client " dictionary-identification))
-         (let ((reply (dictionary-read-reply-and-split)))
-           (message nil)
-           (unless (dictionary-check-reply reply 250)
-             (error "Unknown server answer: %s"
-                    (dictionary-reply reply))))))))
+      (if dictionary-server
+          (dictionary-open-server dictionary-server)
+        (let ((server "localhost"))
+          (condition-case nil
+              (dictionary-open-server server)
+            (error
+             (if (y-or-n-p
+                  (format "Failed to open server %s, continue with dict.org?"
+                          server))
+                 (dictionary-open-server "dict.org")
+               (error "Failed automatic server selection, please customize dictionary-server"))))))))
 
 (defun dictionary-mode-p ()
   "Return non-nil if current buffer has dictionary-mode"