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;;;; Input and display facilities.

+ (defconst read-key-empty-map (make-sparse-keymap))
+ (defvar read-key-delay 0.1)
+
+ (defun read-key (&optional prompt)
+ "Read a key from the keyboard.
+ Contrary to `read-event' this will not return a raw event but instead will
+ obey the input decoding and translations usually done by `read-key-sequence'.
+ So escape sequences and keyboard encoding are taken into account.
+ When there's an ambiguity because the key looks like the prefix of
+ some sort of escape sequence, the ambiguity is resolved via `read-key-delay'."
+ (let ((overriding-terminal-local-map read-key-empty-map)
+ (overriding-local-map nil)
+ (old-global-map (current-global-map))
+ (timer (run-with-idle-timer
+ ;; Wait long enough that Emacs has the time to receive and
+ ;; process all the raw events associated with the single-key.
+ ;; But don't wait too long, or the user may find the delay
+ ;; annoying (or keep hitting more keys which may then get
+ ;; lost or misinterpreted).
+ ;; This is only relevant for keys which Emacs perceives as
+ ;; "prefixes", such as C-x (because of the C-x 8 map in
+ ;; key-translate-table and the C-x @ map in function-key-map)
+ ;; or ESC (because of terminal escape sequences in
+ ;; input-decode-map).
+ read-key-delay t
+ (lambda ()
+ (let ((keys (this-command-keys-vector)))
+ (unless (zerop (length keys))
+ ;; `keys' is non-empty, so the user has hit at least
+ ;; one key; there's no point waiting any longer, even
+ ;; though read-key-sequence thinks we should wait
+ ;; for more input to decide how to interpret the
+ ;; current input.
+ (throw 'read-key keys)))))))
+ (unwind-protect
+ (progn
+ (use-global-map read-key-empty-map)
+ (aref (catch 'read-key (read-key-sequence prompt nil t)) 0))
+ (cancel-timer timer)
+ (use-global-map old-global-map))))
+
(defvar read-quoted-char-radix 8
"*Radix for \\[quoted-insert] and other uses of `read-quoted-char'.
Legitimate radix values are 8, 10 and 16.")