4.4BSD/usr/src/contrib/emacs-18.57/lisp/help.el
;; Help commands for Emacs
;; Copyright (C) 1985, 1986 Free Software Foundation, Inc.
;; This file is part of GNU Emacs.
;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 1, or (at your option)
;; any later version.
;; 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
;; along with GNU Emacs; see the file COPYING. If not, write to
;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
(defvar help-map (make-sparse-keymap)
"Keymap for characters following the Help key.")
(define-key global-map "\C-h" 'help-command)
(fset 'help-command help-map)
(define-key help-map "\C-h" 'help-for-help)
(define-key help-map "?" 'help-for-help)
(define-key help-map "\C-c" 'describe-copying)
(define-key help-map "\C-d" 'describe-distribution)
(define-key help-map "\C-w" 'describe-no-warranty)
(define-key help-map "a" 'command-apropos)
(define-key help-map "b" 'describe-bindings)
(define-key help-map "c" 'describe-key-briefly)
(define-key help-map "k" 'describe-key)
(define-key help-map "d" 'describe-function)
(define-key help-map "f" 'describe-function)
(define-key help-map "i" 'info)
(define-key help-map "l" 'view-lossage)
(define-key help-map "m" 'describe-mode)
(define-key help-map "\C-n" 'view-emacs-news)
(define-key help-map "n" 'view-emacs-news)
(define-key help-map "s" 'describe-syntax)
(define-key help-map "t" 'help-with-tutorial)
(define-key help-map "w" 'where-is)
(define-key help-map "v" 'describe-variable)
(defun help-with-tutorial ()
"Select the Emacs learn-by-doing tutorial."
(interactive)
(let ((file (expand-file-name "~/TUTORIAL")))
(delete-other-windows)
(if (get-file-buffer file)
(switch-to-buffer (get-file-buffer file))
(switch-to-buffer (create-file-buffer file))
(setq buffer-file-name file)
(setq default-directory (expand-file-name "~/"))
(setq auto-save-file-name nil)
(insert-file-contents (expand-file-name "TUTORIAL" exec-directory))
(goto-char (point-min))
(search-forward "\n<<")
(beginning-of-line)
(delete-region (point) (progn (end-of-line) (point)))
(newline (- (window-height (selected-window))
(count-lines (point-min) (point))
6))
(goto-char (point-min))
(set-buffer-modified-p nil))))
(defun describe-key-briefly (key)
"Print the name of the function KEY invokes. KEY is a string."
(interactive "kDescribe key briefly: ")
(let ((defn (key-binding key)))
(if (or (null defn) (integerp defn))
(message "%s is undefined" (key-description key))
(message "%s runs the command %s"
(key-description key)
(if (symbolp defn) defn (prin1-to-string defn))))))
(defun print-help-return-message (&optional function)
"Display or return message saying how to restore windows after help command.
Computes a message and applies the argument FUNCTION to it.
If FUNCTION is nil, applies `message' to it, thus printing it."
(and (not (get-buffer-window standard-output))
(funcall (or function 'message)
(substitute-command-keys
(if (one-window-p t)
(if pop-up-windows
"Type \\[delete-other-windows] to remove help window."
"Type \\[switch-to-buffer] RET to remove help window.")
"Type \\[switch-to-buffer-other-window] RET to restore old contents of help window.")))))
(defun describe-key (key)
"Display documentation of the function KEY invokes. KEY is a string."
(interactive "kDescribe key: ")
(let ((defn (key-binding key)))
(if (or (null defn) (integerp defn))
(message "%s is undefined" (key-description key))
(with-output-to-temp-buffer "*Help*"
(prin1 defn)
(princ ":\n")
(if (documentation defn)
(princ (documentation defn))
(princ "not documented"))
(print-help-return-message)))))
(defun describe-mode ()
"Display documentation of current major mode."
(interactive)
(with-output-to-temp-buffer "*Help*"
(princ mode-name)
(princ " Mode:\n")
(princ (documentation major-mode))
(print-help-return-message)))
(defun describe-distribution ()
"Display info on how to obtain the latest version of GNU Emacs."
(interactive)
(find-file-read-only
(expand-file-name "DISTRIB" exec-directory)))
(defun describe-copying ()
"Display info on how you may redistribute copies of GNU Emacs."
(interactive)
(find-file-read-only
(expand-file-name "COPYING" exec-directory))
(goto-char (point-min)))
(defun describe-no-warranty ()
"Display info on all the kinds of warranty Emacs does NOT have."
(interactive)
(describe-copying)
(let (case-fold-search)
(search-forward "NO WARRANTY")
(recenter 0)))
(defun view-emacs-news ()
"Display info on recent changes to Emacs."
(interactive)
(find-file-read-only (expand-file-name "NEWS" exec-directory)))
(defun view-lossage ()
"Display last 100 input keystrokes."
(interactive)
(with-output-to-temp-buffer "*Help*"
(princ (key-description (recent-keys)))
(save-excursion
(set-buffer standard-output)
(goto-char (point-min))
(while (progn (move-to-column 50) (not (eobp)))
(search-forward " " nil t)
(insert "\n")))
(print-help-return-message)))
(defun help-for-help ()
"You have typed C-h, the help character. Type a Help option:
A command-apropos. Give a substring, and see a list of commands
(functions interactively callable) that contain
that substring. See also the apropos command.
B describe-bindings. Display table of all key bindings.
C describe-key-briefly. Type a command key sequence;
it prints the function name that sequence runs.
F describe-function. Type a function name and get documentation of it.
I info. The info documentation reader.
K describe-key. Type a command key sequence;
it displays the full documentation.
L view-lossage. Shows last 100 characters you typed.
M describe-mode. Print documentation of current major mode,
which describes the commands peculiar to it.
N view-emacs-news. Shows emacs news file.
S describe-syntax. Display contents of syntax table, plus explanations
T help-with-tutorial. Select the Emacs learn-by-doing tutorial.
V describe-variable. Type name of a variable;
it displays the variable's documentation and value.
W where-is. Type command name; it prints which keystrokes
invoke that command.
C-c print Emacs copying permission (General Public License).
C-d print Emacs ordering information.
C-n print news of recent Emacs changes.
C-w print information on absence of warranty for GNU Emacs."
(interactive)
(message
"A B C F I K L M N S T V W C-c C-d C-n C-w. Type C-h again for more help: ")
(let ((char (read-char)))
(if (or (= char ?\C-h) (= char ??))
(save-window-excursion
(switch-to-buffer "*Help*")
(erase-buffer)
(insert (documentation 'help-for-help))
(goto-char (point-min))
(while (memq char '(?\C-h ?? ?\C-v ?\ ?\177 ?\M-v))
(if (memq char '(?\C-v ?\ ))
(scroll-up))
(if (memq char '(?\177 ?\M-v))
(scroll-down))
(message "A B C F I K L M N S T V W C-c C-d C-n C-w%s: "
(if (pos-visible-in-window-p (point-max))
"" " or Space to scroll"))
(let ((cursor-in-echo-area t))
(setq char (read-char))))))
(let ((defn (cdr (assq (downcase char) (cdr help-map)))))
(if defn (call-interactively defn) (ding)))))
(defun function-called-at-point ()
(condition-case ()
(save-excursion
(save-restriction
(narrow-to-region (max (point-min) (- (point) 1000)) (point-max))
(backward-up-list 1)
(forward-char 1)
(let (obj)
(setq obj (read (current-buffer)))
(and (symbolp obj) (fboundp obj) obj))))
(error nil)))
(defun describe-function (function)
"Display the full documentation of FUNCTION (a symbol)."
(interactive
(let ((fn (function-called-at-point))
(enable-recursive-minibuffers t)
val)
(setq val (completing-read (if fn
(format "Describe function (default %s): " fn)
"Describe function: ")
obarray 'fboundp t))
(list (if (equal val "")
fn (intern val)))))
(with-output-to-temp-buffer "*Help*"
(prin1 function)
(princ ":
")
(if (documentation function)
(princ (documentation function))
(princ "not documented"))
(print-help-return-message)))
(defun variable-at-point ()
(condition-case ()
(save-excursion
(forward-sexp -1)
(skip-chars-forward "'")
(let ((obj (read (current-buffer))))
(and (symbolp obj) (boundp obj) obj)))
(error nil)))
(defun describe-variable (variable)
"Display the full documentation of VARIABLE (a symbol)."
(interactive
(let ((v (variable-at-point))
(enable-recursive-minibuffers t)
val)
(setq val (completing-read (if v
(format "Describe variable (default %s): " v)
"Describe variable: ")
obarray 'boundp t))
(list (if (equal val "")
v (intern val)))))
(with-output-to-temp-buffer "*Help*"
(prin1 variable)
(princ "'s value is ")
(if (not (boundp variable))
(princ "void.")
(prin1 (symbol-value variable)))
(terpri) (terpri)
(princ "Documentation:")
(terpri)
(let ((doc (documentation-property variable 'variable-documentation)))
(if doc
(princ (substitute-command-keys doc))
(princ "not documented as a variable.")))
(print-help-return-message)))
(defun command-apropos (string)
"Like apropos but lists only symbols that are names of commands
\(interactively callable functions)."
(interactive "sCommand apropos (regexp): ")
(let ((message
(let ((standard-output (get-buffer-create "*Help*")))
(print-help-return-message 'identity))))
(apropos string 'commandp)
(and message (message message))))