Function: read-char-from-minibuffer
read-char-from-minibuffer is a byte-compiled function defined in
subr.el.gz.
Signature
(read-char-from-minibuffer PROMPT &optional CHARS HISTORY)
Documentation
Read a character from the minibuffer, prompting for it with PROMPT.
Like read-char, but uses the minibuffer to read and return a character.
Optional argument CHARS, if non-nil, should be a list of characters;
the function will ignore any input that is not one of CHARS.
Optional argument HISTORY, if non-nil, should be a symbol that
specifies the history list variable to use for navigating in input
history using \M-p and \M-n, with \RET to select a character from
history.
If you bind the variable help-form to a non-nil value
while calling this function, then pressing help-char
causes it to evaluate help-form and display the result.
There is no need to explicitly add help-char to CHARS;
help-char is bound automatically to help-form-show.
Probably introduced at or before Emacs version 27.1.
Source Code
;; Defined in /usr/src/emacs/lisp/subr.el.gz
(defun read-char-from-minibuffer (prompt &optional chars history)
"Read a character from the minibuffer, prompting for it with PROMPT.
Like `read-char', but uses the minibuffer to read and return a character.
Optional argument CHARS, if non-nil, should be a list of characters;
the function will ignore any input that is not one of CHARS.
Optional argument HISTORY, if non-nil, should be a symbol that
specifies the history list variable to use for navigating in input
history using \\`M-p' and \\`M-n', with \\`RET' to select a character from
history.
If you bind the variable `help-form' to a non-nil value
while calling this function, then pressing `help-char'
causes it to evaluate `help-form' and display the result.
There is no need to explicitly add `help-char' to CHARS;
`help-char' is bound automatically to `help-form-show'."
;; If text conversion is enabled in this buffer, then it will only
;; be disabled the next time `force-mode-line-update' happens.
(when (and (bound-and-true-p overriding-text-conversion-style)
(bound-and-true-p text-conversion-style))
(force-mode-line-update))
(let* ((overriding-text-conversion-style nil)
(map (if (consp chars)
(or (gethash (list help-form (cons help-char chars))
read-char-from-minibuffer-map-hash)
(let ((map (make-sparse-keymap))
(msg help-form))
(set-keymap-parent map read-char-from-minibuffer-map)
;; If we have a dynamically bound `help-form'
;; here, then the `C-h' (i.e., `help-char')
;; character should output that instead of
;; being a command char.
(when help-form
(define-key map (vector help-char)
(lambda ()
(interactive)
(let ((help-form msg)) ; lexically bound msg
(help-form-show)))))
;; FIXME: We use `read-char-from-minibuffer-insert-char'
;; here only as a kind of alias of `self-insert-command'
;; to prevent those keys from being remapped to
;; `read-char-from-minibuffer-insert-other'.
(dolist (char chars)
(define-key map (vector char)
#'read-char-from-minibuffer-insert-char))
(define-key map [remap self-insert-command]
#'read-char-from-minibuffer-insert-other)
(puthash (list help-form (cons help-char chars))
map read-char-from-minibuffer-map-hash)
map))
read-char-from-minibuffer-map))
;; Protect this-command when called from pre-command-hook (bug#45029)
(this-command this-command)
(result (minibuffer-with-setup-hook
(lambda ()
(setq-local post-self-insert-hook nil)
(add-hook 'post-command-hook
(lambda ()
(if (<= (1+ (minibuffer-prompt-end))
(point-max))
(exit-minibuffer)))
nil 'local))
;; Disable text conversion if it is enabled.
;; (bug#65370)
(when (fboundp 'set-text-conversion-style)
(set-text-conversion-style text-conversion-style))
(read-from-minibuffer prompt nil map nil (or history t))))
(char
(if (plusp (length result))
;; We have a string (with one character), so return the first one.
(elt result 0)
;; The default value is RET.
(when history (push "\r" (symbol-value history)))
?\r)))
;; Display the question with the answer.
(message "%s%s" prompt (char-to-string char))
char))