(describe-register-1): Use window-width

to truncate string in a register.  Check whether the string
in a register is an empty string or a sequence of white spaces.

diff --git a/lisp/register.el b/lisp/register.el
index d149dee200e72b967084e43d9f85072e9c055141..ad65d4b7401e82f7c9cff0784d60031d91cd86b9 100644 (file)
--- a/lisp/register.el
+++ b/lisp/register.el
@@ -233,9 +233,18 @@ The Lisp value REGISTER is a character."
          (progn
            (princ "the text:\n")
            (princ val))
-       (princ "text starting with\n    ")
-       (string-match "[^ \t\n].\\{,20\\}" val)
-       (princ (match-string 0 val))))
+       (cond 
+        ;; Extract first N characters starting with first non-whitespace.
+        ((string-match (format "[^ \t\n].\\{,%d\\}"
+                               ;; Deduct 6 for the spaces inserted below.
+                               (min 20 (max 0 (- (window-width) 6))))
+                       val)
+         (princ "text starting with\n    ")
+         (princ (match-string 0 val)))
+        ((string-match "^[ \t\n]+$" val)
+         (princ "whitespace"))
+        (t
+         (princ "the empty string")))))
      (t
       (princ "Garbage:\n")
       (if verbose (prin1 val))))))