;;; 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
(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-constant-face t)
- ;;
- ;; CLisp `:' keywords as builtins.
- (list (concat "\\<:" sym-char "+\\>") 0 'font-lock-builtin-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)
+;; 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'.")
+(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'.")
+(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}"
(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))))
(let ((doc (documentation defn)))
(if doc
(progn (terpri)
- (princ doc))
+ (princ doc)
+ (help-setup-xref (cons #'describe-key key) (interactive-p)))
(princ "not documented")))
(print-help-return-message)))))))
(princ mode-name)
(princ " mode:\n")
(princ (documentation major-mode))
+ (help-setup-xref (cons #'help-xref-mode (current-buffer)) (interactive-p))
(print-help-return-message)))
;; So keyboard macro definitions are documented correctly
(while (progn (move-to-column 50) (not (eobp)))
(search-forward " " nil t)
(insert "\n")))
+ (setq help-xref-stack nil
+ help-xref-stack-item nil)
(print-help-return-message)))
(defalias 'help 'help-for-help)
(let ((doc (documentation function)))
(if doc
(progn (terpri)
- (princ doc))
+ (princ doc)
+ (help-setup-xref (cons #'describe-function function) (interactive-p)))
(princ "not documented"))))
(print-help-return-message)
(save-excursion
(terpri)
(let ((doc (documentation-property variable 'variable-documentation)))
(princ (or doc "not documented as a variable.")))
+ (help-setup-xref (cons #'describe-variable variable) (interactive-p))
(print-help-return-message)
(save-excursion
(set-buffer standard-output)
The optional argument PREFIX, if non-nil, should be a key sequence;
then we display only bindings that start with that prefix."
(interactive "P")
+ (setq help-xref-stack nil
+ help-xref-stack-item nil)
(describe-bindings-internal nil prefix))
(defun where-is (definition &optional insert)
(message "No library %s in search path" library)))
result))
+\f
+;;; 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 'symbol)
+
+(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
+ "\\<info\\s-+node\\s-`\\([^']+\\)'"
+ "Regexp matching doc string references to an Info node.")
+
+(defun help-setup-xref (item interactive-p)
+ "Invoked from commands using the \"*Help*\" buffer to install some xref info.
+
+ITEM is a (function . args) pair appropriate for recreating the help
+buffer after following a reference. INTERACTIVE-P is non-nil if the
+calling command was invoked interactively. In this case the stack of
+items for help buffer \"back\" buttons is cleared."
+ (if interactive-p
+ (setq help-xref-stack nil))
+ (setq help-xref-stack-item item))
+
+(defun help-make-xrefs (&optional buffer)
+ "Parse and hyperlink documentation cross-references in the given BUFFER.
+
+Find cross-reference information in a buffer and, if
+`help-highlight-p' is non-nil, highlight it with face defined by
+`help-highlight-face'; activate such cross references for selection
+with `help-follow'. Cross-references have the canonical form `...'
+and the type of reference may be disambiguated by the preceding
+word(s) used in `help-xref-symbol-regexp'.
+
+A special reference `back' is made to return back through a stack of
+help buffers. Variable `help-back-label' specifies the text for
+that."
+ (interactive "b")
+ (save-excursion
+ (set-buffer (or buffer (current-buffer)))
+ (goto-char (point-min))
+ ;; Skip the header-type info, though it might be useful to parse
+ ;; it at some stage (e.g. "function in `library'").
+ (forward-paragraph)
+ (let ((old-modified (buffer-modified-p)))
+ (let ((stab (syntax-table))
+ (case-fold-search t)
+ (inhibit-read-only t))
+ (set-syntax-table emacs-lisp-mode-syntax-table)
+ ;; The following should probably be abstracted out.
+ (unwind-protect
+ (progn
+ ;; Quoted symbols
+ (save-excursion
+ (while (re-search-forward help-xref-symbol-regexp nil t)
+ (let* ((data (match-string 6))
+ (sym (intern-soft data)))
+ (if sym
+ (cond
+ ((match-string 3) ; `variable' &c
+ (and (boundp sym) ; `variable' doesn't ensure
+ ; it's actually bound
+ (help-xref-button 6 #'describe-variable sym)))
+ ((match-string 4) ; `function' &c
+ (and (fboundp sym) ; similarly
+ (help-xref-button 6 #'describe-function sym)))
+ ((match-string 5)) ; nothing for symbol
+ ((and (boundp sym) (fboundp sym))
+ ;; We can't intuit whether to use the
+ ;; variable or function doc -- supply both.
+ (help-xref-button 6 #'help-xref-interned sym))
+ ((boundp sym)
+ (help-xref-button 6 #'describe-variable sym))
+ ((fboundp sym)
+ (help-xref-button 6 #'describe-function sym)))))))
+ ;; Info references
+ (save-excursion
+ (while (re-search-forward help-xref-info-regexp nil t)
+ (help-xref-button 1 #'Info-goto-node (list (match-data 1)))))
+ ;; An obvious case of a key substitution:
+ (save-excursion
+ (while (re-search-forward
+ "\\<M-x\\s-+\\(\\sw\\(\\sw\\|\\s_\\)+\\)" nil t)
+ (let ((sym (intern-soft (match-string 1))))
+ (if (fboundp sym)
+ (help-xref-button 1 #'describe-function sym))))))
+ (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 nil)))
+ ;; View mode steals RET from us.
+ (set (make-local-variable 'minor-mode-overriding-map-alist)
+ (list (cons 'view-mode
+ (let ((map (make-sparse-keymap)))
+ (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'."
+ (put-text-property (match-beginning match-number)
+ (match-end match-number)
+ 'mouse-face 'highlight)
+ (if help-highlight-p
+ (put-text-property (match-beginning match-number)
+ (match-end match-number)
+ 'face help-highlight-face))
+ (put-text-property (match-beginning match-number)
+ (match-end match-number)
+ 'help-xref (cons function
+ (if (listp data)
+ data
+ (list data)))))
+
+\f
+;; 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 (cons #'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)))
+\f
+;;; Navigation/hyperlinking with xrefs
+
+(defun help-follow-mouse (click)
+ "Follow the cross-reference that you click on."
+ (interactive "e")
+ (save-excursion
+ (let* ((start (event-start click))
+ (window (car start))
+ (pos (car (cdr start))))
+ (set-buffer (window-buffer window))
+ (help-follow pos))))
+
+(defun help-xref-go-back ()
+ "Go back to the previous help buffer using info on `help-xref-stack'."
+ (interactive)
+ (when help-xref-stack
+ (setq help-xref-stack (cdr help-xref-stack)) ; due to help-follow
+ (let* ((item (car help-xref-stack))
+ (method (car item))
+ (args (cdr item)))
+ (setq help-xref-stack (cdr help-xref-stack))
+ (if (listp args)
+ (apply method args)
+ (funcall method args)))))
+
+(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 (get-text-property pos 'help-xref))
+ (method (car help-data))
+ (args (cdr help-data)))
+ (setq help-xref-stack (cons 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
+ (or (goto-char (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
projects / emacs.git / commitdiff