(enable-flow-control): Use a char-table.

1 files changed, 20 insertions, 17 deletions

diff --git a/lisp/flow-ctrl.el b/lisp/flow-ctrl.el
index c853ae3a767..4bad32a0c11 100644
--- a/lisp/flow-ctrl.el
+++ b/lisp/flow-ctrl.el
@@ -48,6 +48,8 @@
 (defvar flow-control-c-q-replacement ?\036
   "Character that replaces C-q, when flow control handling is enabled.")
 
+(put 'keyboard-translate-table 'char-table-extra-slots 0)
+
 ;;;###autoload
 (defun enable-flow-control (&optional argument)
   "Toggle flow control handling.
@@ -64,27 +66,28 @@ With arg, enable flow control mode if arg is positive, otherwise disable."
         (set-input-mode t nil (nth 2 (current-input-mode)))
         (if keyboard-translate-table
             (progn
-              (aset keyboard-translate-table flow-control-c-s-replacement
-                    flow-control-c-s-replacement)
-              (aset keyboard-translate-table ?\^s ?\^s)
-              (aset keyboard-translate-table flow-control-c-q-replacement
-                    flow-control-c-q-replacement)
-              (aset keyboard-translate-table ?\^q ?\^q))))
+              (aset keyboard-translate-table flow-control-c-s-replacement nil)
+              (aset keyboard-translate-table ?\^s nil)
+              (aset keyboard-translate-table flow-control-c-q-replacement nil)
+              (aset keyboard-translate-table ?\^q nil))))
     ;; Turn flow control on.
     ;; Tell emacs to pass C-s and C-q to OS.
     (set-input-mode nil t (nth 2 (current-input-mode)))
     ;; Initialize translate table, saving previous mappings, if any.
-    (let ((the-table (make-string (max 128 (length keyboard-translate-table))
-                                  0)))
-      (let ((i 0)
-            (j (length keyboard-translate-table)))
-        (while (< i j)
-          (aset the-table i (elt keyboard-translate-table i))
-          (setq i (1+ i)))
-        (while (< i 128)
-          (aset the-table i i)
-          (setq i (1+ i))))
-      (setq keyboard-translate-table the-table))
+    (cond ((null keyboard-translate-table)
+           (setq keyboard-translate-table
+                 (make-char-table 'keyboard-translate-table nil)))
+          ((char-table-p keyboard-translate-table)
+           (setq keyboard-translate-table
+                 (copy-sequence keyboard-translate-table)))
+          (t
+           (let ((the-table (make-char-table 'keyboard-translate-table nil)))
+             (let ((i 0)
+                   (j (length keyboard-translate-table)))
+               (while (< i j)
+                 (aset the-table i (elt keyboard-translate-table i))
+                 (setq i (1+ i))))
+             (setq keyboard-translate-table the-table))))
     ;; Swap C-s and C-\
     (aset keyboard-translate-table flow-control-c-s-replacement ?\^s)
     (aset keyboard-translate-table ?\^s flow-control-c-s-replacement)