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;;; help.el --- help commands for Emacs  -*- lexical-binding:t -*-
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;; Copyright (C) 1985-1986, 1993-1994, 1998-2019 Free Software
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;; Foundation, Inc.
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;; Maintainer: emacs-devel@gnu.org
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;; Keywords: help, internal
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;; Package: emacs
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;; This file is part of GNU Emacs.

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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:

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;; This code implements GNU Emacs's built-in help system, the one invoked by
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;; `M-x help-for-help'.
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;;; Code:

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;; Get the macro make-help-screen when this is compiled,
;; or run interpreted, but not when the compiled code is loaded.
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(eval-when-compile (require 'help-macro))
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;; This makes `with-output-to-temp-buffer' buffers use `help-mode'.
(add-hook 'temp-buffer-setup-hook 'help-mode-setup)
(add-hook 'temp-buffer-show-hook 'help-mode-finish)

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;; `help-window-point-marker' is a marker you can move to a valid
;; position of the buffer shown in the help window in order to override
;; the standard positioning mechanism (`point-min') chosen by
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;; `with-output-to-temp-buffer' and `with-temp-buffer-window'.
;; `with-help-window' has this point nowhere before exiting.  Currently
;; used by `view-lossage' to assert that the last keystrokes are always
;; visible.
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(defvar help-window-point-marker (make-marker)
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  "Marker to override default `window-point' in help windows.")
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(defvar help-window-old-frame nil
  "Frame selected at the time `with-help-window' is invoked.")

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(defvar help-map
  (let ((map (make-sparse-keymap)))
    (define-key map (char-to-string help-char) 'help-for-help)
    (define-key map [help] 'help-for-help)
    (define-key map [f1] 'help-for-help)
    (define-key map "." 'display-local-help)
    (define-key map "?" 'help-for-help)

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    (define-key map "\C-a" 'about-emacs)
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    (define-key map "\C-c" 'describe-copying)
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    (define-key map "\C-d" 'view-emacs-debugging)
    (define-key map "\C-e" 'view-external-packages)
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    (define-key map "\C-f" 'view-emacs-FAQ)
    (define-key map "\C-m" 'view-order-manuals)
    (define-key map "\C-n" 'view-emacs-news)
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    (define-key map "\C-o" 'describe-distribution)
    (define-key map "\C-p" 'view-emacs-problems)
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    (define-key map "\C-s" 'search-forward-help-for-help)
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    (define-key map "\C-t" 'view-emacs-todo)
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    (define-key map "\C-w" 'describe-no-warranty)

    ;; This does not fit the pattern, but it is natural given the C-\ command.
    (define-key map "\C-\\" 'describe-input-method)

    (define-key map "C" 'describe-coding-system)
    (define-key map "F" 'Info-goto-emacs-command-node)
    (define-key map "I" 'describe-input-method)
    (define-key map "K" 'Info-goto-emacs-key-command-node)
    (define-key map "L" 'describe-language-environment)
    (define-key map "S" 'info-lookup-symbol)

    (define-key map "a" 'apropos-command)
    (define-key map "b" 'describe-bindings)
    (define-key map "c" 'describe-key-briefly)
    (define-key map "d" 'apropos-documentation)
    (define-key map "e" 'view-echo-area-messages)
    (define-key map "f" 'describe-function)
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    (define-key map "g" 'describe-gnu-project)
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    (define-key map "h" 'view-hello-file)

    (define-key map "i" 'info)
    (define-key map "4i" 'info-other-window)

    (define-key map "k" 'describe-key)
    (define-key map "l" 'view-lossage)
    (define-key map "m" 'describe-mode)
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    (define-key map "o" 'describe-symbol)
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    (define-key map "n" 'view-emacs-news)
    (define-key map "p" 'finder-by-keyword)
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    (define-key map "P" 'describe-package)
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    (define-key map "r" 'info-emacs-manual)
    (define-key map "s" 'describe-syntax)
    (define-key map "t" 'help-with-tutorial)
    (define-key map "w" 'where-is)
    (define-key map "v" 'describe-variable)
    (define-key map "q" 'help-quit)
    map)
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  "Keymap for characters following the Help key.")

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(define-key global-map (char-to-string help-char) 'help-command)
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(define-key global-map [help] 'help-command)
(define-key global-map [f1] 'help-command)
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(fset 'help-command help-map)

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;; insert-button makes the action nil if it is not store somewhere
(defvar help-button-cache nil)

120

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(defun help-quit ()
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  "Just exit from the Help command's command loop."
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  (interactive)
  nil)

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(defvar help-return-method nil
  "What to do to \"exit\" the help buffer.
This is a list
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 (WINDOW . t)              delete the selected window (and possibly its frame,
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                           see `quit-window'), go to WINDOW.
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 (WINDOW . quit-window)    do quit-window, then select WINDOW.
 (WINDOW BUF START POINT)  display BUF at START, POINT, then select WINDOW.")

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(define-obsolete-function-alias 'print-help-return-message 'help-print-return-message "23.2")
(defun help-print-return-message (&optional function)
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  "Display or return message saying how to restore windows after help command.
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This function assumes that `standard-output' is the help buffer.
It computes a message, and applies the optional argument FUNCTION to it.
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If FUNCTION is nil, it applies `message', thus displaying the message.
In addition, this function sets up `help-return-method', which see, that
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specifies what to do when the user exits the help buffer.

Do not call this in the scope of `with-help-window'."
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  (and (not (get-buffer-window standard-output))
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       (let ((first-message
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	      (cond ((or
		      pop-up-frames
		      (special-display-p (buffer-name standard-output)))
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		     (setq help-return-method (cons (selected-window) t))
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		     ;; If the help output buffer is a special display buffer,
		     ;; don't say anything about how to get rid of it.
		     ;; First of all, the user will do that with the window
		     ;; manager, not with Emacs.
		     ;; Secondly, the buffer has not been displayed yet,
		     ;; so we don't know whether its frame will be selected.
		     nil)
		    ((not (one-window-p t))
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		     (setq help-return-method
			   (cons (selected-window) 'quit-window))
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		     "Type \\[display-buffer] RET to restore the other window.")
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		    (pop-up-windows
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		     (setq help-return-method (cons (selected-window) t))
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		     "Type \\[delete-other-windows] to remove help window.")
		    (t
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		     (setq help-return-method
			   (list (selected-window) (window-buffer)
				 (window-start) (window-point)))
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		     "Type \\[switch-to-buffer] RET to remove help window."))))
	 (funcall (or function 'message)
		  (concat
		   (if first-message
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		       (substitute-command-keys first-message))
		   (if first-message "  ")
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		   ;; If the help buffer will go in a separate frame,
		   ;; it's no use mentioning a command to scroll, so don't.
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		   (if (or pop-up-windows
			   (special-display-p (buffer-name standard-output)))
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		       nil
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		     (if (same-window-p (buffer-name standard-output))
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			 ;; Say how to scroll this window.
			 (substitute-command-keys
			  "\\[scroll-up] to scroll the help.")
		       ;; Say how to scroll some other window.
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		       (substitute-command-keys
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			"\\[scroll-other-window] to scroll the help."))))))))
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;; So keyboard macro definitions are documented correctly
(fset 'defining-kbd-macro (symbol-function 'start-kbd-macro))

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(defalias 'help 'help-for-help-internal)
;; find-function can find this.
(defalias 'help-for-help 'help-for-help-internal)
;; It can't find this, but nobody will look.
(make-help-screen help-for-help-internal
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  (purecopy "Type a help option: [abcCdefFgiIkKlLmnprstvw.] C-[cdefmnoptw] or ?")
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  ;; Don't purecopy this one, because it's not evaluated (it's
  ;; directly used as a docstring in a function definition, so it'll
  ;; be moved to the DOC file anyway: no need for purecopying it).
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  "You have typed %THIS-KEY%, the help character.  Type a Help option:
\(Use SPC or DEL to scroll through this text.  Type \\<help-map>\\[help-quit] to exit the Help command.)

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a PATTERN   Show commands whose name matches the PATTERN (a list of words
              or a regexp).  See also the `apropos' command.
b           Display all key bindings.
c KEYS      Display the command name run by the given key sequence.
C CODING    Describe the given coding system, or RET for current ones.
d PATTERN   Show a list of functions, variables, and other items whose
              documentation matches the PATTERN (a list of words or a regexp).
e           Go to the *Messages* buffer which logs echo-area messages.
f FUNCTION  Display documentation for the given function.
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F COMMAND   Show the Emacs manual's section that describes the command.
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g           Display information about the GNU project.
h           Display the HELLO file which illustrates various scripts.
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i           Start the Info documentation reader: read included manuals.
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I METHOD    Describe a specific input method, or RET for current.
k KEYS      Display the full documentation for the key sequence.
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K KEYS      Show the Emacs manual's section for the command bound to KEYS.
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l           Show last 300 input keystrokes (lossage).
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L LANG-ENV  Describes a specific language environment, or RET for current.
m           Display documentation of current minor modes and current major mode,
              including their special commands.
n           Display news of recent Emacs changes.
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o SYMBOL    Display the given function or variable's documentation and value.
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p TOPIC     Find packages matching a given topic keyword.
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P PACKAGE   Describe the given Emacs Lisp package.
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r           Display the Emacs manual in Info mode.
s           Display contents of current syntax table, plus explanations.
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S SYMBOL    Show the section for the given symbol in the Info manual
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              for the programming language used in this buffer.
t           Start the Emacs learn-by-doing tutorial.
v VARIABLE  Display the given variable's documentation and value.
w COMMAND   Display which keystrokes invoke the given command (where-is).
.           Display any available local help at point in the echo area.

C-a         Information about Emacs.
C-c         Emacs copying permission (GNU General Public License).
C-d         Instructions for debugging GNU Emacs.
C-e         External packages and information about Emacs.
C-f         Emacs FAQ.
C-m         How to order printed Emacs manuals.
C-n         News of recent Emacs changes.
C-o         Emacs ordering and distribution information.
C-p         Info about known Emacs problems.
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C-s         Search forward \"help window\".
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C-t         Emacs TODO list.
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C-w         Information on absence of warranty for GNU Emacs."
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  help-map)



(defun function-called-at-point ()
  "Return a function around point or else called by the list containing point.
If that doesn't give a function, return nil."
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  (with-syntax-table emacs-lisp-mode-syntax-table
    (or (condition-case ()
            (save-excursion
              (or (not (zerop (skip-syntax-backward "_w")))
                  (eq (char-syntax (following-char)) ?w)
                  (eq (char-syntax (following-char)) ?_)
                  (forward-sexp -1))
              (skip-chars-forward "'")
              (let ((obj (read (current-buffer))))
                (and (symbolp obj) (fboundp obj) obj)))
          (error nil))
        (condition-case ()
            (save-excursion
              (save-restriction
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                (let ((forward-sexp-function nil)) ;Use elisp-mode's value
                  (narrow-to-region (max (point-min)
                                         (- (point) 1000))
                                    (point-max))
                  ;; Move up to surrounding paren, then after the open.
                  (backward-up-list 1)
                  (forward-char 1)
                  ;; If there is space here, this is probably something
                  ;; other than a real Lisp function call, so ignore it.
                  (if (looking-at "[ \t]")
                      (error "Probably not a Lisp function call"))
                  (let ((obj (read (current-buffer))))
                    (and (symbolp obj) (fboundp obj) obj)))))
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          (error nil))
        (let* ((str (find-tag-default))
               (sym (if str (intern-soft str))))
          (if (and sym (fboundp sym))
              sym
            (save-match-data
              (when (and str (string-match "\\`\\W*\\(.*?\\)\\W*\\'" str))
                (setq sym (intern-soft (match-string 1 str)))
                (and (fboundp sym) sym))))))))
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;;; `User' help functions

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(defun view-help-file (file &optional dir)
  (view-file (expand-file-name file (or dir data-directory)))
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  (goto-address-mode 1)
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  (goto-char (point-min)))

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(defun describe-distribution ()
  "Display info on how to obtain the latest version of GNU Emacs."
  (interactive)
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  (view-help-file "DISTRIB"))
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(defun describe-copying ()
  "Display info on how you may redistribute copies of GNU Emacs."
  (interactive)
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  (view-help-file "COPYING"))
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;; Maybe this command should just be removed.
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(defun describe-gnu-project ()
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  "Browse online information on the GNU project."
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  (interactive)
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  (browse-url "https://www.gnu.org/gnu/thegnuproject.html"))
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(defun describe-no-warranty ()
  "Display info on all the kinds of warranty Emacs does NOT have."
  (interactive)
  (describe-copying)
  (let (case-fold-search)
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    (search-forward "Disclaimer of Warranty")
    (forward-line 0)
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    (recenter 0)))

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(defun describe-prefix-bindings ()
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  "Describe the bindings of the prefix used to reach this command.
The prefix described consists of all but the last event
of the key sequence that ran this command."
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  (interactive)
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  (let ((key (this-command-keys)))
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    (describe-bindings
     (if (stringp key)
	 (substring key 0 (1- (length key)))
       (let ((prefix (make-vector (1- (length key)) nil))
	     (i 0))
	 (while (< i (length prefix))
	   (aset prefix i (aref key i))
	   (setq i (1+ i)))
	 prefix)))))
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;; Make C-h after a prefix, when not specifically bound,
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;; run describe-prefix-bindings.
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(setq prefix-help-command 'describe-prefix-bindings)

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(defun view-emacs-news (&optional version)
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  "Display info on recent changes to Emacs.
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With argument, display info only for the selected version."
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  (interactive "P")
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  (unless version
    (setq version emacs-major-version))
  (when (consp version)
    (let* ((all-versions
	    (let (res)
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	      (mapc
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	       (lambda (file)
		 (with-temp-buffer
		   (insert-file-contents
		    (expand-file-name file data-directory))
		   (while (re-search-forward
			   (if (member file '("NEWS.18" "NEWS.1-17"))
			       "Changes in \\(?:Emacs\\|version\\)?[ \t]*\\([0-9]+\\(?:\\.[0-9]+\\)?\\)"
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			     "^\\* [^0-9\n]*\\([0-9]+\\.[0-9]+\\)") nil t)
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		     (setq res (cons (match-string-no-properties 1) res)))))
	       (cons "NEWS"
		     (directory-files data-directory nil
				      "^NEWS\\.[0-9][-0-9]*$" nil)))
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	      (sort (delete-dups res) #'string>)))
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	   (current (car all-versions)))
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      (setq version (completing-read
		     (format "Read NEWS for the version (default %s): " current)
		     all-versions nil nil nil nil current))
      (if (integerp (string-to-number version))
	  (setq version (string-to-number version))
	(unless (or (member version all-versions)
		    (<= (string-to-number version) (string-to-number current)))
	  (error "No news about version %s" version)))))
  (when (integerp version)
    (cond ((<= version 12)
	   (setq version (format "1.%d" version)))
	  ((<= version 18)
	   (setq version (format "%d" version)))
	  ((> version emacs-major-version)
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	   (error "No news about Emacs %d (yet)" version))))
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  (let* ((vn (if (stringp version)
		 (string-to-number version)
	       version))
	 (file (cond
		((>= vn emacs-major-version) "NEWS")
		((< vn 18) "NEWS.1-17")
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		(t (format "NEWS.%d" vn))))
	 res)
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    (view-file (expand-file-name file data-directory))
    (widen)
    (goto-char (point-min))
    (when (stringp version)
      (when (re-search-forward
	     (concat (if (< vn 19)
			 "Changes in Emacs[ \t]*"
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		       "^\\* [^0-9\n]*") version "$")
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	     nil t)
	(beginning-of-line)
	(narrow-to-region
	 (point)
	 (save-excursion
	   (while (and (setq res
			     (re-search-forward
			      (if (< vn 19)
				  "Changes in \\(?:Emacs\\|version\\)?[ \t]*\\([0-9]+\\(?:\\.[0-9]+\\)?\\)"
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				"^\\* [^0-9\n]*\\([0-9]+\\.[0-9]+\\)") nil t))
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		       (equal (match-string-no-properties 1) version)))
	   (or res (goto-char (point-max)))
	   (beginning-of-line)
	   (point)))))))

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(defun view-emacs-todo (&optional _arg)
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  "Display the Emacs TODO list."
  (interactive "P")
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  (view-help-file "TODO"))
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(defun view-echo-area-messages ()
  "View the log of recent echo-area messages: the `*Messages*' buffer.
The number of messages retained in that buffer
is specified by the variable `message-log-max'."
  (interactive)
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  (with-current-buffer (messages-buffer)
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    (goto-char (point-max))
    (display-buffer (current-buffer))))
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(defun view-order-manuals ()
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  "Display information on how to buy printed copies of Emacs manuals."
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  (interactive)
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  (info "(emacs)Printed Books"))
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(defun view-emacs-FAQ ()
  "Display the Emacs Frequently Asked Questions (FAQ) file."
  (interactive)
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  (info "(efaq)"))
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(defun view-emacs-problems ()
  "Display info on known problems with Emacs and possible workarounds."
  (interactive)
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  (view-help-file "PROBLEMS"))

(defun view-emacs-debugging ()
  "Display info on how to debug Emacs problems."
  (interactive)
  (view-help-file "DEBUG"))

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;; This used to visit a plain text file etc/MORE.STUFF;
;; maybe this command should just be removed.
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(defun view-external-packages ()
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  "Display info on where to get more Emacs packages."
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  (interactive)
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  (info "(efaq)Packages that do not come with Emacs"))
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(defun view-lossage ()
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  "Display last few input keystrokes and the commands run.
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For convenience this uses the same format as
`edit-last-kbd-macro'.
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To record all your input, use `open-dribble-file'."
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  (interactive)
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  (help-setup-xref (list #'view-lossage)
		   (called-interactively-p 'interactive))
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  (with-help-window (help-buffer)
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    (princ " ")
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    (princ (mapconcat (lambda (key)
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			(cond
			 ((and (consp key) (null (car key)))
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			  (format ";; %s\n" (if (symbolp (cdr key)) (cdr key)
					      "anonymous-command")))
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			 ((or (integerp key) (symbolp key) (listp key))
			  (single-key-description key))
			 (t
			  (prin1-to-string key nil))))
		      (recent-keys 'include-cmds)
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		      " "))
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    (with-current-buffer standard-output
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      (goto-char (point-min))
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      (let ((comment-start ";; ")
            (comment-column 24))
        (while (not (eobp))
          (comment-indent)
	  (forward-line 1)))
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      ;; jidanni wants to see the last keystrokes immediately.
      (set-marker help-window-point-marker (point)))))
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;; Key bindings
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(defun describe-bindings (&optional prefix buffer)
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  "Display a buffer showing a list of all defined keys, and their definitions.
The keys are displayed in order of precedence.
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The optional argument PREFIX, if non-nil, should be a key sequence;
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then we display only bindings that start with that prefix.
The optional argument BUFFER specifies which buffer's bindings
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to display (default, the current buffer).  BUFFER can be a buffer
or a buffer name."
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  (interactive)
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  (or buffer (setq buffer (current-buffer)))
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  (help-setup-xref (list #'describe-bindings prefix buffer)
		   (called-interactively-p 'interactive))
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  (with-help-window (help-buffer)
    ;; Be aware that `describe-buffer-bindings' puts its output into
    ;; the current buffer.
    (with-current-buffer (help-buffer)
      (describe-buffer-bindings buffer prefix))))
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;; This function used to be in keymap.c.
(defun describe-bindings-internal (&optional menus prefix)
  "Show a list of all defined keys, and their definitions.
We put that list in a buffer, and display the buffer.

The optional argument MENUS, if non-nil, says to mention menu bindings.
\(Ordinarily these are omitted from the output.)
The optional argument PREFIX, if non-nil, should be a key sequence;
then we display only bindings that start with that prefix."
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  (declare (obsolete describe-buffer-bindings "24.4"))
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  (let ((buf (current-buffer)))
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    (with-help-window (help-buffer)
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      ;; Be aware that `describe-buffer-bindings' puts its output into
      ;; the current buffer.
      (with-current-buffer (help-buffer)
	(describe-buffer-bindings buf prefix menus)))))
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(defun where-is (definition &optional insert)
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  "Print message listing key sequences that invoke the command DEFINITION.
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Argument is a command definition, usually a symbol with a function definition.
If INSERT (the prefix arg) is non-nil, insert the message in the buffer."
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  (interactive
   (let ((fn (function-called-at-point))
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	 (enable-recursive-minibuffers t)
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	 val)
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     (setq val (completing-read
		(if fn
		    (format "Where is command (default %s): " fn)
		  "Where is command: ")
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		obarray 'commandp t nil nil
		(and fn (symbol-name fn))))
     (list (unless (equal val "") (intern val))
	   current-prefix-arg)))
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  (unless definition (error "No command"))
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  (let ((func (indirect-function definition))
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        (defs nil)
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        (standard-output (if insert (current-buffer) standard-output)))
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    ;; In DEFS, find all symbols that are aliases for DEFINITION.
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    (mapatoms (lambda (symbol)
		(and (fboundp symbol)
		     (not (eq symbol definition))
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		     (eq func (condition-case ()
				  (indirect-function symbol)
				(error symbol)))
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		     (push symbol defs))))
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    ;; Look at all the symbols--first DEFINITION,
    ;; then its aliases.
    (dolist (symbol (cons definition defs))
      (let* ((remapped (command-remapping symbol))
	     (keys (where-is-internal
		    symbol overriding-local-map nil nil remapped))
	     (keys (mapconcat 'key-description keys ", "))
	     string)
	(setq string
	      (if insert
		  (if (> (length keys) 0)
		      (if remapped
			  (format "%s (%s) (remapped from %s)"
				  keys remapped symbol)
			(format "%s (%s)" keys symbol))
		    (format "M-x %s RET" symbol))
		(if (> (length keys) 0)
		    (if remapped
			(format "%s is remapped to %s which is on %s"
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				symbol remapped keys)
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		      (format "%s is on %s" symbol keys))
		  ;; If this is the command the user asked about,
		  ;; and it is not on any key, say so.
		  ;; For other symbols, its aliases, say nothing
		  ;; about them unless they are on keys.
		  (if (eq symbol definition)
		      (format "%s is not on any key" symbol)))))
	(when string
	  (unless (eq symbol definition)
	    (princ ";\n its alias "))
	  (princ string)))))
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  nil)

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(defun help-key-description (key untranslated)
  (let ((string (key-description key)))
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    (if (or (not untranslated)
	    (and (eq (aref untranslated 0) ?\e) (not (eq (aref key 0) ?\e))))
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	string
      (let ((otherstring (key-description untranslated)))
	(if (equal string otherstring)
	    string
	  (format "%s (translated from %s)" string otherstring))))))
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(defun help--binding-undefined-p (defn)
  (or (null defn) (integerp defn) (equal defn 'undefined)))

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(defun help--analyze-key (key untranslated)
  "Get information about KEY its corresponding UNTRANSLATED events.
Returns a list of the form (BRIEF-DESC DEFN EVENT MOUSE-MSG)."
  (if (numberp untranslated)
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      (error "Missing `untranslated'!"))
  (let* ((event (when (> (length key) 0)
                  (aref key (if (and (symbolp (aref key 0))
		                     (> (length key) 1)
		                     (consp (aref key 1)))
                                ;; Look at the second event when the first
                                ;; is a pseudo-event like `mode-line' or
                                ;; `left-fringe'.
		                1
	                      0))))
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	 (modifiers (event-modifiers event))
	 (mouse-msg (if (or (memq 'click modifiers) (memq 'down modifiers)
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			    (memq 'drag modifiers))
                        " at that spot" ""))
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	 (defn (key-binding key t)))
    ;; Handle the case where we faked an entry in "Select and Paste" menu.
    (when (and (eq defn nil)
	       (stringp (aref key (1- (length key))))
	       (eq (key-binding (substring key 0 -1)) 'yank-menu))
      (setq defn 'menu-bar-select-yank))
    ;; Don't bother user with strings from (e.g.) the select-paste menu.
    (when (stringp (aref key (1- (length key))))
      (aset key (1- (length key)) "(any string)"))
    (when (and untranslated
               (stringp (aref untranslated (1- (length untranslated)))))
      (aset untranslated (1- (length untranslated)) "(any string)"))
    (list
     ;; Now describe the key, perhaps as changed.
     (let ((key-desc (help-key-description key untranslated)))
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       (if (help--binding-undefined-p defn)
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           (format "%s%s is undefined" key-desc mouse-msg)
         (format "%s%s runs the command %S" key-desc mouse-msg defn)))
     defn event mouse-msg)))

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(defun help--filter-info-list (info-list i)
  "Drop the undefined keys."
  (or
   ;; Remove all `undefined' keys.
   (delq nil (mapcar (lambda (x)
                       (unless (help--binding-undefined-p (nth i x)) x))
                     info-list))
   ;; If nothing left, then keep one (the last one).
   (last info-list)))

(defun describe-key-briefly (&optional key-list insert untranslated)
  "Print the name of the functions KEY-LIST invokes.
KEY-LIST is a list of pairs (SEQ . RAW-SEQ) of key sequences, where
RAW-SEQ is the untranslated form of the key sequence SEQ.
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If INSERT (the prefix arg) is non-nil, insert the message in the buffer.

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While reading KEY-LIST interactively, this command temporarily enables
menu items or tool-bar buttons that are disabled to allow getting help
on them."
  (declare (advertised-calling-convention (key-list &optional insert) "27.1"))
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  (interactive
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   ;; Ignore mouse movement events because it's too easy to miss the
   ;; message while moving the mouse.
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   (let ((key-list (help--read-key-sequence 'no-mouse-movement)))
     `(,key-list ,current-prefix-arg)))
  (when (arrayp key-list)
    ;; Old calling convention, changed
    (setq key-list (list (cons key-list
                               (if (numberp untranslated)
                                   (this-single-command-raw-keys)
                                 untranslated)))))
  (let* ((info-list (mapcar (lambda (kr)
                              (help--analyze-key (car kr) (cdr kr)))
                            key-list))
         (msg (mapconcat #'car (help--filter-info-list info-list 1) "\n")))
    (if insert (insert msg) (message "%s" msg))))
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(defun help--key-binding-keymap (key &optional accept-default no-remap position)
  "Return a keymap holding a binding for KEY within current keymaps.
The effect of the arguments KEY, ACCEPT-DEFAULT, NO-REMAP and
POSITION is as documented in the function `key-binding'."
  (let* ((active-maps (current-active-maps t position))
         map found)
    ;; We loop over active maps like key-binding does.
    (while (and
            (not found)
            (setq map (pop active-maps)))
      (setq found (lookup-key map key accept-default))
      (when (integerp found)
        ;; The first `found' characters of KEY were found but not the
        ;; whole sequence.
        (setq found nil)))
    (when found
      (if (and (symbolp found)
               (not no-remap)
               (command-remapping found))
          ;; The user might want to know in which map the binding is
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          ;; found, or in which map the remapping is found.  The
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          ;; default is to show the latter.
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          (help--key-binding-keymap (vector 'remap found))
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        map))))

(defun help--binding-locus (key position)
  "Describe in which keymap KEY is defined.
Return a symbol pointing to that keymap if one exists ; otherwise
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return nil.  The argument POSITION is as documented in the
function `key-binding'."
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  (let ((map (help--key-binding-keymap key t nil position)))
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    (when map
      (catch 'found
        (let ((advertised-syms (nconc
                                (list 'overriding-terminal-local-map
                                      'overriding-local-map)
                                (delq nil
                                      (mapcar
                                       (lambda (mode-and-map)
                                         (let ((mode (car mode-and-map)))
                                           (when (symbol-value mode)
                                             (intern-soft
                                              (format "%s-map" mode)))))
                                       minor-mode-map-alist))
                                (list 'global-map
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                                      (intern-soft (format "%s-map" major-mode))))))
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          ;; Look into these advertised symbols first.
          (dolist (sym advertised-syms)
            (when (and
                   (boundp sym)
                   (eq map (symbol-value sym)))
              (throw 'found sym)))
          ;; Only look in other symbols otherwise.
          (mapatoms
           (lambda (x)
             (when (and (boundp x)
                        ;; Avoid let-bound symbols.
                        (special-variable-p x)
                        (eq (symbol-value x) map))
               (throw 'found x))))
          nil)))))

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(defun help--read-key-sequence (&optional no-mouse-movement)
  "Read a key sequence from the user.
Usually reads a single key sequence, except when that sequence might
hide another one (e.g. a down event, where the user is interested
in getting info about the up event, or a click event, where the user
wants to get info about the double click).
Return a list of elements of the form (SEQ . RAW-SEQ), where SEQ is a key
sequence, and RAW-SEQ is its untranslated form.
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If NO-MOUSE-MOVEMENT is non-nil, ignore key sequences starting
with `mouse-movement' events."
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  (let ((enable-disabled-menus-and-buttons t)
        (cursor-in-echo-area t)
        saved-yank-menu)
    (unwind-protect
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        (let (last-modifiers key-list)
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          ;; If yank-menu is empty, populate it temporarily, so that
          ;; "Select and Paste" menu can generate a complete event.
          (when (null (cdr yank-menu))
            (setq saved-yank-menu (copy-sequence yank-menu))
            (menu-bar-update-yank-menu "(any string)" nil))
          (while
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              ;; Read at least one key-sequence.
              (or (null key-list)
                  ;; After a down event, also read the (presumably) following
                  ;; up-event.
                  (memq 'down last-modifiers)
                  ;; After a click, see if a double click is on the way.
                  (and (memq 'click last-modifiers)
                       (not (sit-for (/ double-click-time 1000.0) t))))
            (let* ((seq (read-key-sequence "\
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Describe the following key, mouse click, or menu item: "))
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                   (raw-seq (this-single-command-raw-keys))
                   (keyn (when (> (length seq) 0)
                           (aref seq (1- (length seq)))))
                   (base (event-basic-type keyn))
                   (modifiers (event-modifiers keyn)))
              (cond
               ((zerop (length seq)))   ;FIXME: Can this happen?
               ((and no-mouse-movement (eq base 'mouse-movement)) nil)
               ((eq base 'help-echo) nil)
               (t
                (setq last-modifiers modifiers)
                (push (cons seq raw-seq) key-list)))))
          (nreverse key-list))
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      ;; Put yank-menu back as it was, if we changed it.
      (when saved-yank-menu
        (setq yank-menu (copy-sequence saved-yank-menu))
        (fset 'yank-menu (cons 'keymap yank-menu))))))

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(defun describe-key (&optional key-list buffer up-event)
  "Display documentation of the function invoked by KEY-LIST.
KEY-LIST can be any kind of a key sequence; it can include keyboard events,
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mouse events, and/or menu events.  When calling from a program,
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pass KEY-LIST as a list of elements (SEQ . RAW-SEQ) where SEQ is
a key-sequence and RAW-SEQ is its untranslated form.

While reading KEY-LIST interactively, this command temporarily enables
menu items or tool-bar buttons that are disabled to allow getting help
on them.

BUFFER is the buffer in which to lookup those keys; it defaults to the
current buffer."
  (declare (advertised-calling-convention (key-list &optional buffer) "27.1"))
  (interactive (list (help--read-key-sequence)))
  (when (arrayp key-list)
    ;; Compatibility with old calling convention.
    (setq key-list (cons (list key-list) (if up-event (list up-event))))
    (when buffer
      (let ((raw (if (numberp buffer) (this-single-command-raw-keys) buffer)))
        (setf (cdar (last key-list)) raw)))
    (setq buffer nil))
  (let* ((buf (or buffer (current-buffer)))
         (on-link
          (mapcar (lambda (kr)
                    (let ((raw (cdr kr)))
                      (and (not (memq mouse-1-click-follows-link '(nil double)))
                           (> (length raw) 0)
                           (eq (car-safe (aref raw 0)) 'mouse-1)
                           (with-current-buffer buf
                             (mouse-on-link-p (event-start (aref raw 0)))))))
                  key-list))
         (info-list
          (help--filter-info-list
           (with-current-buffer buf
             (mapcar (lambda (x)
                       (pcase-let* ((`(,seq . ,raw-seq) x)
                                    (`(,brief-desc ,defn ,event ,_mouse-msg)
                                     (help--analyze-key seq raw-seq))
                                    (locus
                                     (help--binding-locus
                                      seq (event-start event))))
                         `(,seq ,brief-desc ,defn ,locus)))
                     key-list))
           2)))
    (help-setup-xref (list (lambda (key-list buf)
                             (describe-key key-list
                                           (if (buffer-live-p buf) buf)))
                           key-list buf)
		     (called-interactively-p 'interactive))
    (if (and (<= (length info-list) 1)
             (help--binding-undefined-p (nth 2 (car info-list))))
        (message "%s" (nth 1 (car info-list)))
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      (with-help-window (help-buffer)
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        (when (> (length info-list) 1)
          ;; FIXME: Make this into clickable hyperlinks.
          (princ "There were several key-sequences:\n\n")
          (princ (mapconcat (lambda (info)
                              (pcase-let ((`(,_seq ,brief-desc ,_defn ,_locus)
                                           info))
                                (concat "  " brief-desc)))
                            info-list
                            "\n"))
          (when (delq nil on-link)
            (princ "\n\nThose are influenced by `mouse-1-click-follows-link'"))
          (princ "\n\nThey're all described below."))
        (pcase-dolist (`(,_seq ,brief-desc ,defn ,locus)
                       info-list)
          (when defn
            (when (> (length info-list) 1)
              (with-current-buffer standard-output
                (insert "\n\n"
                        ;; FIXME: Can't use eval-when-compile because purified
                        ;; strings lose their text properties :-(
                        (propertize "\n" 'face '(:height 0.1 :inverse-video t))
                        "\n")))

            (princ brief-desc)
            (when locus
              (princ (format " (found in %s)" locus)))
            (princ ", which is ")
	    (describe-function-1 defn)))))))
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(defun describe-mode (&optional buffer)
  "Display documentation of current major mode and minor modes.
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A brief summary of the minor modes comes first, followed by the
major mode description.  This is followed by detailed
descriptions of the minor modes, each on a separate page.

For this to work correctly for a minor mode, the mode's indicator
variable \(listed in `minor-mode-alist') must also be a function
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whose documentation describes the minor mode.

If called from Lisp with a non-nil BUFFER argument, display
documentation for the major and minor modes of that buffer."
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  (interactive "@")
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  (unless buffer (setq buffer (current-buffer)))
  (help-setup-xref (list #'describe-mode buffer)
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		   (called-interactively-p 'interactive))
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  ;; For the sake of help-do-xref and help-xref-go-back,
  ;; don't switch buffers before calling `help-buffer'.
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  (with-help-window (help-buffer)
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    (with-current-buffer buffer
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      (let (minor-modes)
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	;; Older packages do not register in minor-mode-list but only in
	;; minor-mode-alist.
	(dolist (x minor-mode-alist)
	  (setq x (car x))
	  (unless (memq x minor-mode-list)
	    (push x minor-mode-list)))
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	;; Find enabled minor mode we will want to mention.
	(dolist (mode minor-mode-list)
	  ;; Document a minor mode if it is listed in minor-mode-alist,
	  ;; non-nil, and has a function definition.
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	  (let ((fmode (or (get mode :minor-mode-function) mode)))
	    (and (boundp mode) (symbol-value mode)
		 (fboundp fmode)
		 (let ((pretty-minor-mode
			(if (string-match "\\(\\(-minor\\)?-mode\\)?\\'"
					  (symbol-name fmode))
			    (capitalize
			     (substring (symbol-name fmode)
					0 (match-beginning 0)))
			  fmode)))
		   (push (list fmode pretty-minor-mode
			       (format-mode-line (assq mode minor-mode-alist)))
			 minor-modes)))))
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	;; Narrowing is not a minor mode, but its indicator is part of
	;; mode-line-modes.
	(when (buffer-narrowed-p)
	  (push '(narrow-to-region "Narrow" " Narrow") minor-modes))
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	(setq minor-modes
	      (sort minor-modes
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		    (lambda (a b) (string-lessp (cadr a) (cadr b)))))
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	(when minor-modes
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	  (princ "Enabled minor modes:\n")
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	  (make-local-variable 'help-button-cache)
	  (with-current-buffer standard-output
	    (dolist (mode minor-modes)
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	      (let ((mode-function (nth 0 mode))
		    (pretty-minor-mode (nth 1 mode))
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		    (indicator (nth 2 mode)))
		(save-excursion
		  (goto-char (point-max))
		  (princ "\n\f\n")
		  (push (point-marker) help-button-cache)
		  ;; Document the minor modes fully.
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                  (insert-text-button
                   pretty-minor-mode 'type 'help-function
                   'help-args (list mode-function)
                   'button '(t))
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		  (princ (format " minor mode (%s):\n"
				 (if (zerop (length indicator))
				     "no indicator"
				   (format "indicator%s"
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					   indicator))))
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		  (princ (documentation mode-function)))
		(insert-button pretty-minor-mode
			       'action (car help-button-cache)
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			       'follow-link t
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			       'help-echo "mouse-2, RET: show full information")
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		(newline)))
	    (forward-line -1)
	    (fill-paragraph nil)
	    (forward-line 1))

	  (princ "\n(Information about these minor modes follows the major mode info.)\n\n"))
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	;; Document the major mode.
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	(let ((mode mode-name))
	  (with-current-buffer standard-output
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            (let ((start (point)))
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              (insert (format-mode-line mode nil nil buffer))
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              (add-text-properties start (point) '(face bold)))))
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	(princ " mode")
	(let* ((mode major-mode)
	       (file-name (find-lisp-object-file-name mode nil)))
	  (when file-name
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	    (princ (format-message " defined in `%s'"
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                                   (file-name-nondirectory file-name)))
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	    ;; Make a hyperlink to the library.
	    (with-current-buffer standard-output
	      (save-excursion
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		(re-search-backward (substitute-command-keys "`\\([^`']+\\)'")
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                                    nil t)
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		(help-xref-button 1 'help-function-def mode file-name)))))
	(princ ":\n")
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	(princ (documentation major-mode)))))
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  ;; For the sake of IELM and maybe others
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  nil)
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(defun search-forward-help-for-help ()
  "Search forward \"help window\"."
  (interactive)
  ;; Move cursor to the "help window".
  (pop-to-buffer " *Metahelp*")
  ;; Do incremental search forward.
  (isearch-forward nil t))
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(defun describe-minor-mode (minor-mode)
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  "Display documentation of a minor mode given as MINOR-MODE.
MINOR-MODE can be a minor mode symbol or a minor mode indicator string
appeared on the mode-line."
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  (interactive (list (completing-read
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		      "Minor mode: "
			      (nconc
			       (describe-minor-mode-completion-table-for-symbol)
			       (describe-minor-mode-completion-table-for-indicator)
			       ))))
  (if (symbolp minor-mode)
      (setq minor-mode (symbol-name minor-mode)))
  (let ((symbols (describe-minor-mode-completion-table-for-symbol))
	(indicators (describe-minor-mode-completion-table-for-indicator)))
    (cond
     ((member minor-mode symbols)
      (describe-minor-mode-from-symbol (intern minor-mode)))
     ((member minor-mode indicators)
      (describe-minor-mode-from-indicator minor-mode))
     (t
      (error "No such minor mode: %s" minor-mode)))))

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;; symbol
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(defun describe-minor-mode-completion-table-for-symbol ()
  ;; In order to list up all minor modes, minor-mode-list
  ;; is used here instead of minor-mode-alist.
  (delq nil (mapcar 'symbol-name minor-mode-list)))
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(defun describe-minor-mode-from-symbol (symbol)
  "Display documentation of a minor mode given as a symbol, SYMBOL"
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  (interactive (list (intern (completing-read
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			      "Minor mode symbol: "
			      (describe-minor-mode-completion-table-for-symbol)))))
  (if (fboundp symbol)
      (describe-function symbol)
    (describe-variable symbol)))

;; indicator
(defun describe-minor-mode-completion-table-for-indicator ()
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  (delq nil
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	(mapcar (lambda (x)
		  (let ((i (format-mode-line x)))
		    ;; remove first space if existed
		    (cond
		     ((= 0 (length i))
		      nil)
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		     ((eq (aref i 0) ?\s)
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		      (substring i 1))