X-Git-Url: https://code.delx.au/gnu-emacs/blobdiff_plain/a30a106b8d481116ed9fa4d6969bf41a1c663581..d18a808f42266d6a1873373e6fef9ca6e74a5226:/lisp/help.el diff --git a/lisp/help.el b/lisp/help.el index 42fd5d2911..45d84b8897 100644 --- a/lisp/help.el +++ b/lisp/help.el @@ -1,6 +1,6 @@ ;;; help.el --- help commands for Emacs -;; Copyright (C) 1985, 1986, 1993, 1994 Free Software Foundation, Inc. +;; Copyright (C) 1985, 1986, 1993, 1994, 1998 Free Software Foundation, Inc. ;; Maintainer: FSF ;; Keywords: help, internal @@ -66,6 +66,7 @@ (define-key help-map "F" 'view-emacs-FAQ) (define-key help-map "i" 'info) +(define-key help-map "4i" 'info-other-window) (define-key help-map "\C-f" 'Info-goto-emacs-command-node) (define-key help-map "\C-k" 'Info-goto-emacs-key-command-node) (define-key help-map "\C-i" 'info-lookup-symbol) @@ -91,27 +92,51 @@ (define-key help-map "q" 'help-quit) -(defvar help-font-lock-keywords - (eval-when-compile - (let ((name-char "[-+a-zA-Z0-9_*]") (sym-char "[-+a-zA-Z0-9_:*]")) - (list - ;; - ;; The symbol itself. - (list (concat "\\`\\(" name-char "+\\)\\(\\(:\\)\\|\\('\\)\\)") - '(1 (if (match-beginning 3) - font-lock-function-name-face - font-lock-variable-name-face))) - ;; - ;; Words inside `' which tend to be symbol names. - (list (concat "`\\(" sym-char sym-char "+\\)'") - 1 'font-lock-reference-face t) - ;; - ;; CLisp `:' keywords as references. - (list (concat "\\<:" sym-char "+\\>") 0 'font-lock-reference-face t)))) - "Default expressions to highlight in Help mode.") +(define-key help-mode-map [mouse-2] 'help-follow-mouse) +(define-key help-mode-map "\C-c\C-b" 'help-go-back) +(define-key help-mode-map "\C-c\C-c" 'help-follow) +(define-key help-mode-map "\t" 'help-next-ref) +(define-key help-mode-map [backtab] 'help-previous-ref) +(define-key help-mode-map [(shift tab)] 'help-previous-ref) +;; Documentation only, since we use minor-mode-overriding-map-alist. +(define-key help-mode-map "\r" 'help-follow) + +;; Font-locking is incompatible with the new xref stuff. +;(defvar help-font-lock-keywords +; (eval-when-compile +; (let ((name-char "[-+a-zA-Z0-9_*]") (sym-char "[-+a-zA-Z0-9_:*]")) +; (list +; ;; +; ;; The symbol itself. +; (list (concat "\\`\\(" name-char "+\\)\\(\\(:\\)\\|\\('\\)\\)") +; '(1 (if (match-beginning 3) +; font-lock-function-name-face +; font-lock-variable-name-face))) +; ;; +; ;; Words inside `' which tend to be symbol names. +; (list (concat "`\\(" sym-char sym-char "+\\)'") +; 1 'font-lock-constant-face t) +; ;; +; ;; CLisp `:' keywords as references. +; (list (concat "\\<:" sym-char "+\\>") 0 'font-lock-builtin-face t)))) +; "Default expressions to highlight in Help mode.") + +(defvar help-xref-stack nil + "A stack of ways by which to return to help buffers after following xrefs. +Used by `help-follow' and `help-xref-go-back'. +An element looks like (POSITION FUNCTION ARGS...). +To use the element, do (apply FUNCTION ARGS) then (goto-char POSITION).") +(put 'help-xref-stack 'permanent-local t) + +(defvar help-xref-stack-item nil + "An item for `help-follow' in this buffer to push onto `help-xref-stack'. +The format is (FUNCTION ARGS...).") +(put 'help-xref-stack-item 'permanent-local t) + +(setq-default help-xref-stack nil help-xref-stack-item nil) (defun help-mode () - "Major mode for viewing help text. + "Major mode for viewing help text and navigating references in it. Entry to this mode runs the normal hook `help-mode-hook'. Commands: \\{help-mode-map}" @@ -121,27 +146,45 @@ Commands: (setq mode-name "Help") (setq major-mode 'help-mode) (make-local-variable 'font-lock-defaults) - (setq font-lock-defaults '(help-font-lock-keywords)) + (setq font-lock-defaults nil) ; font-lock would defeat xref (view-mode) + (make-local-variable 'view-no-disable-on-exit) + (setq view-no-disable-on-exit t) + ;; `help-make-xrefs' would be run here if not invoked from + ;; `help-mode-maybe'. (run-hooks 'help-mode-hook)) +(defun help-mode-maybe () + (if (eq major-mode 'fundamental-mode) + (help-mode)) + (when (eq major-mode 'help-mode) + ;; View mode's read-only status of existing *Help* buffer is lost + ;; by with-output-to-temp-buffer. + (toggle-read-only 1) + (help-make-xrefs (current-buffer))) + (setq view-return-to-alist + (list (cons (selected-window) help-return-method)))) + +(add-hook 'temp-buffer-show-hook 'help-mode-maybe) + (defun help-quit () (interactive) nil) (defun help-with-tutorial (&optional arg) "Select the Emacs learn-by-doing tutorial. -A tutorial written in the current primary language is selected. -If there's no tutorial in the language, \"TUTORIAL\" is selected. -With arg, users are asked to select language." +If there is a tutorial version written in the language +of the selected language environment, that version is used. +If there's no tutorial in that language, `TUTORIAL' is selected. +With arg, you are asked to choose which language." (interactive "P") - (let (lang filename file) - (if arg - (or (setq lang (read-language-name 'tutorial "Language: ")) - (error "No tutorial file of the specified language")) - (setq lang primary-language)) - (setq filename (or (get-language-info lang 'tutorial) - "TUTORIAL")) + (let ((lang (if arg + (read-language-name 'tutorial "Language: " "English") + (if (get-language-info current-language-environment 'tutorial) + current-language-environment + "English"))) + file filename) + (setq filename (get-language-info lang 'tutorial)) (setq file (expand-file-name (concat "~/" filename))) (delete-other-windows) (if (get-file-buffer file) @@ -172,14 +215,6 @@ With arg, users are asked to select language." "Print the name of the function KEY invokes. KEY is a string. If INSERT (the prefix arg) is non-nil, insert the message in the buffer." (interactive "kDescribe key briefly: \nP") - ;; If this key seq ends with a down event, discard the - ;; following click or drag event. Otherwise that would - ;; erase the message. - (let ((type (aref key (1- (length key))))) - (if (listp type) (setq type (car type))) - (and (symbolp type) - (memq 'down (event-modifiers type)) - (read-event))) (save-excursion (let ((modifiers (event-modifiers (aref key 0))) (standard-output (if insert (current-buffer) t)) @@ -201,13 +236,20 @@ If INSERT (the prefix arg) is non-nil, insert the message in the buffer." (if (or (null defn) (integerp defn)) (princ (format "%s is undefined" key-desc)) (princ (format (if insert - "%s (%s)" + "`%s' (`%s')" (if (windowp window) "%s at that spot runs the command %s" "%s runs the command %s")) key-desc (if (symbolp defn) defn (prin1-to-string defn))))))))) +(defvar help-return-method nil + "What to do to \"exit\" the help buffer. +This is a list + (WINDOW . t) delete the selected window, go to WINDOW. + (WINDOW . quit-window) do quit-window, then select WINDOW. + (WINDOW BUF START POINT) display BUF at START, POINT, then select WINDOW.") + (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 optional argument FUNCTION to it. @@ -215,6 +257,7 @@ If FUNCTION is nil, applies `message' to it, thus printing it." (and (not (get-buffer-window standard-output)) (let ((first-message (cond ((special-display-p (buffer-name standard-output)) + (setq help-return-method (cons (selected-window) t)) ;; 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 @@ -223,10 +266,16 @@ If FUNCTION is nil, applies `message' to it, thus printing it." ;; so we don't know whether its frame will be selected. nil) ((not (one-window-p t)) + (setq help-return-method + (cons (selected-window) 'quit-window)) "Type \\[switch-to-buffer-other-window] RET to restore the other window.") (pop-up-windows + (setq help-return-method (cons (selected-window) t)) "Type \\[delete-other-windows] to remove help window.") (t + (setq help-return-method + (list (selected-window) (window-buffer) + (window-start) (window-point))) "Type \\[switch-to-buffer] RET to remove help window.")))) (funcall (or function 'message) (concat @@ -249,14 +298,6 @@ If FUNCTION is nil, applies `message' to it, thus printing it." (defun describe-key (key) "Display documentation of the function invoked by KEY. KEY is a string." (interactive "kDescribe key: ") - ;; If this key seq ends with a down event, discard the - ;; following click or drag event. Otherwise that would - ;; erase the message. - (let ((type (aref key (1- (length key))))) - (if (listp type) (setq type (car type))) - (and (symbolp type) - (memq 'down (event-modifiers type)) - (read-event))) (save-excursion (let ((modifiers (event-modifiers (aref key 0))) window position) @@ -280,15 +321,8 @@ If FUNCTION is nil, applies `message' to it, thus printing it." (princ " at that spot")) (princ " runs the command ") (prin1 defn) - (princ ":\n") - (let ((doc (documentation defn))) - (if doc - (progn (terpri) - (princ doc)) - (princ "not documented"))) - (save-excursion - (set-buffer standard-output) - (help-mode)) + (princ "\n which is ") + (describe-function-1 defn nil) (print-help-return-message))))))) (defun describe-mode () @@ -331,9 +365,7 @@ followed by the major mode, which is described on the last page.\n\f\n")) (princ mode-name) (princ " mode:\n") (princ (documentation major-mode)) - (save-excursion - (set-buffer standard-output) - (help-mode)) + (help-setup-xref (list #'help-xref-mode (current-buffer)) (interactive-p)) (print-help-return-message))) ;; So keyboard macro definitions are documented correctly @@ -386,10 +418,14 @@ of the key sequence that ran this command." ;; run describe-prefix-bindings. (setq prefix-help-command 'describe-prefix-bindings) -(defun view-emacs-news () - "Display info on recent changes to Emacs." - (interactive) - (find-file-read-only (expand-file-name "NEWS" data-directory))) +(defun view-emacs-news (&optional arg) + "Display info on recent changes to Emacs. +With numeric argument display information on correspondingly older changes." + (interactive "P") + (let* ((arg (if arg (prefix-numeric-value arg) 0))) + (find-file-read-only + (expand-file-name (concat (make-string arg ?O) "NEWS") + data-directory)))) (defun view-emacs-FAQ () "Display the Emacs Frequently Asked Questions (FAQ) file." @@ -414,7 +450,8 @@ of the key sequence that ran this command." (while (progn (move-to-column 50) (not (eobp))) (search-forward " " nil t) (insert "\n")) - (help-mode)) + (setq help-xref-stack nil + help-xref-stack-item nil)) (print-help-return-message))) (defalias 'help 'help-for-help) @@ -446,8 +483,8 @@ l view-lossage. Shows last 100 characters you typed. L describe-language-environment. This describes either the a specific language environment (if you type its name) or the current language environment (if you type just RET). -m describe-mode. Print documentation of current major mode, - which describes the commands peculiar to it. +m describe-mode. Print documentation of current minor modes, + and the current major mode, including their special commands. n view-emacs-news. Shows emacs news file. p finder-by-keyword. Find packages matching a given topic keyword. s describe-syntax. Display contents of syntax table, plus explanations @@ -470,21 +507,26 @@ C-w Display information on absence of warranty for GNU Emacs." ;; If that gives no function, return a function whose name is around point. ;; If that doesn't give a function, return nil. (defun function-called-at-point () - (or (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)) - (condition-case () - (let ((stab (syntax-table))) - (unwind-protect + (let ((stab (syntax-table))) + (set-syntax-table emacs-lisp-mode-syntax-table) + (unwind-protect + (or (condition-case () + (save-excursion + (save-restriction + (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) + (setq obj (read (current-buffer))) + (and (symbolp obj) (fboundp obj) obj)))) + (error nil)) + (condition-case () (save-excursion - (set-syntax-table emacs-lisp-mode-syntax-table) (or (not (zerop (skip-syntax-backward "_w"))) (eq (char-syntax (following-char)) ?w) (eq (char-syntax (following-char)) ?_) @@ -492,8 +534,8 @@ C-w Display information on absence of warranty for GNU Emacs." (skip-chars-forward "'") (let ((obj (read (current-buffer)))) (and (symbolp obj) (fboundp obj) obj))) - (set-syntax-table stab))) - (error nil)))) + (error nil))) + (set-syntax-table stab)))) (defun describe-function-find-file (function) (let ((files load-history) @@ -513,76 +555,104 @@ C-w Display information on absence of warranty for GNU Emacs." (setq val (completing-read (if fn (format "Describe function (default %s): " fn) "Describe function: ") - obarray 'fboundp t)) + obarray 'fboundp t nil nil (symbol-name fn))) (list (if (equal val "") fn (intern val))))) (if function (with-output-to-temp-buffer "*Help*" (prin1 function) - (princ ": ") - (let* ((def (symbol-function function)) - file-name - (beg (if (commandp def) "an interactive " "a "))) - (princ (cond ((or (stringp def) - (vectorp def)) - "a keyboard macro") - ((subrp def) - (concat beg "built-in function")) - ((byte-code-function-p def) - (concat beg "compiled Lisp function")) - ((symbolp def) - (format "alias for `%s'" def)) - ((eq (car-safe def) 'lambda) - (concat beg "Lisp function")) - ((eq (car-safe def) 'macro) - "a Lisp macro") - ((eq (car-safe def) 'mocklisp) - "a mocklisp function") - ((eq (car-safe def) 'autoload) - (setq file-name (nth 1 def)) - (format "%s autoloaded Lisp %s" - (if (commandp def) "an interactive" "an") - (if (nth 4 def) "macro" "function") - )) - (t ""))) - (or file-name - (setq file-name (describe-function-find-file function))) - (if file-name - (progn - (princ " in `") - ;; We used to add .el to the file name, - ;; but that's completely wrong when the user used load-file. - (princ file-name) - (princ "'"))) - (princ ".") - (terpri) - (let ((arglist (cond ((byte-code-function-p def) - (car (append def nil))) - ((eq (car-safe def) 'lambda) - (nth 1 def)) - (t t)))) - (if (listp arglist) - (progn - (princ (cons function - (mapcar (lambda (arg) - (if (memq arg '(&optional &rest)) - arg - (intern (upcase (symbol-name arg))))) - arglist))) - (terpri)))) - (let ((doc (documentation function))) - (if doc - (progn (terpri) - (princ doc)) - (princ "not documented")))) + ;; Use " is " instead of a colon so that + ;; it is easier to get out the function name using forward-sexp. + (princ " is ") + (describe-function-1 function nil) (print-help-return-message) (save-excursion (set-buffer standard-output) - (help-mode) ;; Return the text we displayed. (buffer-string))) (message "You didn't specify a function"))) +(defun describe-function-1 (function parens) + (let* ((def (symbol-function function)) + file-name string need-close + (beg (if (commandp def) "an interactive " "a "))) + (setq string + (cond ((or (stringp def) + (vectorp def)) + "a keyboard macro") + ((subrp def) + (concat beg "built-in function")) + ((byte-code-function-p def) + (concat beg "compiled Lisp function")) + ((symbolp def) + (while (symbolp (symbol-function def)) + (setq def (symbol-function def))) + (format "alias for `%s'" def)) + ((eq (car-safe def) 'lambda) + (concat beg "Lisp function")) + ((eq (car-safe def) 'macro) + "a Lisp macro") + ((eq (car-safe def) 'mocklisp) + "a mocklisp function") + ((eq (car-safe def) 'autoload) + (setq file-name (nth 1 def)) + (format "%s autoloaded Lisp %s" + (if (commandp def) "an interactive" "an") + (if (nth 4 def) "macro" "function") + )) + (t ""))) + (when (and parens (not (equal string ""))) + (setq need-close t) + (princ "(")) + (princ string) + (or file-name + (setq file-name (describe-function-find-file function))) + (if file-name + (progn + (princ " in `") + ;; We used to add .el to the file name, + ;; but that's completely wrong when the user used load-file. + (princ file-name) + (princ "'") + ;; Make a hyperlink to the library. + (with-current-buffer "*Help*" + (save-excursion + (re-search-backward "`\\([^`']+\\)'" nil t) + (help-xref-button 1 #'(lambda (arg) + (let ((location + (find-function-noselect arg))) + (pop-to-buffer (car location)) + (goto-char (cdr location)))) + function))))) + (if need-close (princ ")")) + (princ ".") + (terpri) + ;; Handle symbols aliased to other symbols. + (setq def (indirect-function def)) + ;; If definition is a macro, find the function inside it. + (if (eq (car-safe def) 'macro) + (setq def (cdr def))) + (let ((arglist (cond ((byte-code-function-p def) + (car (append def nil))) + ((eq (car-safe def) 'lambda) + (nth 1 def)) + (t t)))) + (if (listp arglist) + (progn + (princ (cons function + (mapcar (lambda (arg) + (if (memq arg '(&optional &rest)) + arg + (intern (upcase (symbol-name arg))))) + arglist))) + (terpri)))) + (let ((doc (documentation function))) + (if doc + (progn (terpri) + (princ doc) + (help-setup-xref (list #'describe-function function) (interactive-p))) + (princ "not documented"))))) + ;; We return 0 if we can't find a variable to return. (defun variable-at-point () (condition-case () @@ -611,7 +681,8 @@ Returns the documentation as a string, also." (setq val (completing-read (if (symbolp v) (format "Describe variable (default %s): " v) "Describe variable: ") - obarray 'boundp t)) + obarray 'boundp t nil nil + (if (symbolp v) (symbol-name v)))) (list (if (equal val "") v (intern val))))) (if (symbolp variable) @@ -653,14 +724,48 @@ Returns the documentation as a string, also." (terpri) (let ((doc (documentation-property variable 'variable-documentation))) (princ (or doc "not documented as a variable."))) + (help-setup-xref (list #'describe-variable variable) (interactive-p)) + + ;; Make a link to customize if this variable can be customized. + ;; Note, it is not reliable to test for a custom-type property + ;; because those are only present after the var's definition + ;; has been loaded. + (if (user-variable-p variable) + (let ((customize-label "customize")) + (terpri) + (terpri) + (princ (concat "You can " customize-label " this variable.")) + (with-current-buffer "*Help*" + (save-excursion + (re-search-backward + (concat "\\(" customize-label "\\)") nil t) + (help-xref-button 1 #'(lambda (v) + (customize-variable v)) variable) + )))) + (print-help-return-message) (save-excursion (set-buffer standard-output) - (help-mode) ;; Return the text we displayed. (buffer-string)))) (message "You did not specify a variable"))) +(defun describe-bindings (&optional prefix buffer) + "Show a list of all defined keys, and their definitions. +We put that list in a buffer, and display the buffer. + +The optional argument PREFIX, if non-nil, should be a key sequence; +then we display only bindings that start with that prefix. +The optional argument BUFFER specifies which buffer's bindings +to display (default, the current buffer)." + (interactive "P") + (or buffer (setq buffer (current-buffer))) + (with-current-buffer buffer + (describe-bindings-internal nil prefix)) + (with-current-buffer "*Help*" + (help-setup-xref (list #'describe-bindings prefix buffer) + (interactive-p)))) + (defun where-is (definition &optional insert) "Print message listing key sequences that invoke specified command. Argument is a command definition, usually a symbol with a function definition. @@ -714,19 +819,22 @@ is used instead of `load-path'." (throw 'answer try))))) (if nosuffix '("") - (let ((basic '(".elc" ".el" "")) - (compressed '(".Z" ".gz" ""))) - ;; If autocompression mode is on, - ;; consider all combinations of library suffixes - ;; and compression suffixes. - (if (rassq 'jka-compr-handler file-name-handler-alist) - (apply 'nconc - (mapcar (lambda (compelt) - (mapcar (lambda (baselt) - (concat baselt compelt)) - basic)) - compressed)) - basic))))) + '(".elc" ".el" "") +;;; load doesn't handle this yet. +;;; (let ((basic '(".elc" ".el" "")) +;;; (compressed '(".Z" ".gz" ""))) +;;; ;; If autocompression mode is on, +;;; ;; consider all combinations of library suffixes +;;; ;; and compression suffixes. +;;; (if (rassq 'jka-compr-handler file-name-handler-alist) +;;; (apply 'nconc +;;; (mapcar (lambda (compelt) +;;; (mapcar (lambda (baselt) +;;; (concat baselt compelt)) +;;; basic)) +;;; compressed)) +;;; basic)) + ))) (or path load-path))) (and interactive-call (if result @@ -734,4 +842,283 @@ is used instead of `load-path'." (message "No library %s in search path" library))) result)) + +;;; Grokking cross-reference information in doc strings and +;;; hyperlinking it. + +;; This may have some scope for extension and the same or something +;; similar should be done for widget doc strings, which currently use +;; another mechanism. + +(defcustom help-highlight-p t + "*If non-nil, `help-make-xrefs' highlight cross-references. +Under a window system it highlights them with face defined by +`help-highlight-face'. On a character terminal highlighted +references look like cross-references in info mode." + :group 'help + :version "20.3" + :type 'boolean) + +(defcustom help-highlight-face 'underline + "Face used by `help-make-xrefs' to highlight cross-references. +Must be previously-defined." + :group 'help + :version "20.3" + :type 'face) + +(defvar help-back-label "[back]" + "Label to use by `help-make-xrefs' for the go-back reference.") + +(defvar help-xref-symbol-regexp + (concat "\\(\\<\\(\\(variable\\|option\\)\\|" + "\\(function\\|command\\)\\|" + "\\(symbol\\)\\)\\s-+\\)?" + ;; Note starting with word-syntax character: + "`\\(\\sw\\(\\sw\\|\\s_\\)+\\)'") + "Regexp matching doc string references to symbols. + +The words preceding the quoted symbol can be used in doc strings to +distinguish references to variables, functions and symbols.") + +(defvar help-xref-info-regexp + "\\ (move-to-column col) 0) + (looking-at "\\(\\sw\\|\\s_\\)+$")) + ;; + (let ((sym (intern-soft (match-string 0)))) + (if (fboundp sym) + (help-xref-button + 0 #'describe-function sym)))) + t) + (zerop (forward-line)) + (move-to-column 0))))))) + (set-syntax-table stab)) + ;; Make a back-reference in this buffer if appropriate. + (when help-xref-stack + (goto-char (point-max)) + (save-excursion + (insert "\n\n" help-back-label)) + ;; Just to provide the match data: + (looking-at (concat "\n\n\\(" (regexp-quote help-back-label) "\\)")) + (help-xref-button 1 #'help-xref-go-back (current-buffer)))) + ;; View mode steals RET from us. + (set (make-local-variable 'minor-mode-overriding-map-alist) + (list (cons 'view-mode + (let ((map (make-sparse-keymap))) + (set-keymap-parent map view-mode-map) + (define-key map "\r" 'help-follow) + map)))) + (set-buffer-modified-p old-modified)))) + +(defun help-xref-button (match-number function data) + "Make a hyperlink for cross-reference text previously matched. + +MATCH-NUMBER is the subexpression of interest in the last matched +regexp. FUNCTION is a function to invoke when the button is +activated, applied to DATA. DATA may be a single value or a list. +See `help-make-xrefs'." + (add-text-properties (match-beginning match-number) + (match-end match-number) + (list 'mouse-face 'highlight + 'help-xref (cons function + (if (listp data) + data + (list data))))) + (if help-highlight-p + (put-text-property (match-beginning match-number) + (match-end match-number) + 'face help-highlight-face))) + + +;; Additional functions for (re-)creating types of help buffers. +(defun help-xref-interned (symbol) + "Follow a hyperlink which appeared to be an arbitrary interned SYMBOL. + +Both variable and function documentation are extracted into a single +help buffer." + (let ((fdoc (describe-function symbol))) + (describe-variable symbol) + ;; We now have a help buffer on the variable. Insert the function + ;; text after it. + (goto-char (point-max)) + (insert "\n\n" fdoc)) + (goto-char (point-min)) + (help-setup-xref (list #'help-xref-interned symbol) nil)) + +(defun help-xref-mode (buffer) + "Do a `describe-mode' for the specified BUFFER." + (save-excursion + (set-buffer buffer) + (describe-mode))) + +;;; Navigation/hyperlinking with xrefs + +(defun help-follow-mouse (click) + "Follow the cross-reference that you click on." + (interactive "e") + (let* ((start (event-start click)) + (window (car start)) + (pos (car (cdr start)))) + (with-current-buffer (window-buffer window) + (help-follow pos)))) + +(defun help-xref-go-back (buffer) + "Go back to the previous help buffer text using info on `help-xref-stack'." + (interactive) + (let (item position method args) + (with-current-buffer buffer + (when help-xref-stack + (setq help-xref-stack (cdr help-xref-stack)) ; due to help-follow + (setq item (car help-xref-stack) + position (car item) + method (cadr item) + args (cddr item)) + (setq help-xref-stack (cdr help-xref-stack)))) + (apply method args) + (goto-char position))) + +(defun help-go-back () + (interactive) + (help-follow (1- (point-max)))) + +(defun help-follow (&optional pos) + "Follow cross-reference at POS, defaulting to point. + +For the cross-reference format, see `help-make-xrefs'." + (interactive "d") + (let* ((help-data (or (and (not (= pos (point-max))) + (get-text-property pos 'help-xref)) + (and (not (= pos (point-min))) + (get-text-property (1- pos) 'help-xref)))) + (method (car help-data)) + (args (cdr help-data))) + (setq help-xref-stack (cons (cons (point) help-xref-stack-item) + help-xref-stack)) + (setq help-xref-stack-item nil) + (when help-data + ;; There is a reference at point. Follow it. + (apply method args)))) + +;; For tabbing through buffer. +(defun help-next-ref () + "Find the next help cross-reference in the buffer." + (interactive) + (let (pos) + (while (not pos) + (if (get-text-property (point) 'help-xref) ; move off reference + (goto-char (or (next-single-property-change (point) 'help-xref) + (point)))) + (cond ((setq pos (next-single-property-change (point) 'help-xref)) + (if pos (goto-char pos))) + ((bobp) + (message "No cross references in the buffer.") + (setq pos t)) + (t ; be circular + (goto-char (point-min))))))) + +(defun help-previous-ref () + "Find the previous help cross-reference in the buffer." + (interactive) + (let (pos) + (while (not pos) + (if (get-text-property (point) 'help-xref) ; move off reference + (goto-char (or (previous-single-property-change (point) 'help-xref) + (point)))) + (cond ((setq pos (previous-single-property-change (point) 'help-xref)) + (if pos (goto-char pos))) + ((bobp) + (message "No cross references in the buffer.") + (setq pos t)) + (t ; be circular + (goto-char (point-max))))))) + ;;; help.el ends here