Commit 95f731db authored by Nick Roberts's avatar Nick Roberts
Browse files

(help-xref-forward-stack)

(help-xref-stack-forward-item, help-forward-label): New variables.
(help-forward): New button type.
(help-setup-xref): Initialise help-xref-forward-stack.
(help-make-xrefs): Add forward button, if appropriate.
(help-xref-go-back): Push item on forward stack.
(help-xref-go-forward, help-go-forward): New functions.
parent da38057d
......@@ -40,6 +40,7 @@
(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-f" 'help-go-forward)
(define-key help-mode-map "\C-c\C-c" 'help-follow-symbol)
;; Documentation only, since we use minor-mode-overriding-map-alist.
(define-key help-mode-map "\r" 'help-follow)
......@@ -52,13 +53,28 @@ To use the element, do (apply FUNCTION ARGS) then goto the point.")
(put 'help-xref-stack 'permanent-local t)
(make-variable-buffer-local 'help-xref-stack)
(defvar help-xref-forward-stack nil
"The stack of used to navigate help forwards after using the back button.
Used by `help-follow' and `help-xref-go-forward'.
An element looks like (POSITION FUNCTION ARGS...).
To use the element, do (apply FUNCTION ARGS) then goto the point.")
(put 'help-xref-forward-stack 'permanent-local t)
(make-variable-buffer-local 'help-xref-forward-stack)
(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)
(make-variable-buffer-local 'help-xref-stack-item)
(defvar help-xref-stack-forward-item nil
"An item for `help-go-back' to push onto `help-xref-forward-stack'.
The format is (FUNCTION ARGS...).")
(put 'help-xref-stack-forward-item 'permanent-local t)
(make-variable-buffer-local 'help-xref-stack-forward-item)
(setq-default help-xref-stack nil help-xref-stack-item nil)
(setq-default help-xref-forward-stack nil help-xref-forward-stack-item nil)
(defcustom help-mode-hook nil
"Hook run by `help-mode'."
......@@ -123,6 +139,11 @@ The format is (FUNCTION ARGS...).")
'help-function #'help-xref-go-back
'help-echo (purecopy "mouse-2, RET: go back to previous help buffer"))
(define-button-type 'help-forward
:supertype 'help-xref
'help-function #'help-xref-go-forward
'help-echo (purecopy "mouse-2, RET: move forward to next help buffer"))
(define-button-type 'help-info
:supertype 'help-xref
'help-function #'info
......@@ -242,6 +263,9 @@ Commands:
(defvar help-back-label (purecopy "[back]")
"Label to use by `help-make-xrefs' for the go-back reference.")
(defvar help-forward-label (purecopy "[forward]")
"Label to use by `help-make-xrefs' for the go-forward reference.")
(defconst help-xref-symbol-regexp
(purecopy (concat "\\(\\<\\(\\(variable\\|option\\)\\|" ; Link to var
"\\(function\\|command\\)\\|" ; Link to function
......@@ -286,7 +310,8 @@ because we want to record the \"previous\" position of point so we can
restore it properly when going back."
(with-current-buffer (help-buffer)
(when help-xref-stack-item
(push (cons (point) help-xref-stack-item) help-xref-stack))
(push (cons (point) help-xref-stack-item) help-xref-stack)
(setq help-xref-forward-stack nil))
(when interactive-p
(let ((tail (nthcdr 10 help-xref-stack)))
;; Truncate the stack.
......@@ -480,6 +505,11 @@ that."
(insert "\n")
(help-insert-xref-button help-back-label 'help-back
(current-buffer))
(insert "\t"))
;; Make a forward-reference in this buffer if appropriate.
(when help-xref-forward-stack
(help-insert-xref-button help-forward-label 'help-forward
(current-buffer))
(insert "\n")))
;; View mode steals RET from us.
(set (make-local-variable 'minor-mode-overriding-map-alist)
......@@ -598,6 +628,7 @@ help buffer."
"From BUFFER, go back to previous help buffer text using `help-xref-stack'."
(let (item position method args)
(with-current-buffer buffer
(push (cons (point) help-xref-stack-item) help-xref-forward-stack)
(when help-xref-stack
(setq item (pop help-xref-stack)
;; Clear the current item so that it won't get pushed
......@@ -613,12 +644,39 @@ help buffer."
(set-window-point (get-buffer-window buffer) position)
(goto-char position)))))
(defun help-xref-go-forward (buffer)
"From BUFFER, go forward to next help buffer."
(let (item position method args)
(with-current-buffer buffer
(push (cons (point) help-xref-stack-item) help-xref-stack)
(when help-xref-forward-stack
(setq item (pop help-xref-forward-stack)
;; Clear the current item so that it won't get pushed
;; by the function we're about to call. TODO: We could also
;; push it onto a "forward" stack and add a `forw' button.
help-xref-stack-item nil
position (car item)
method (cadr item)
args (cddr item))))
(apply method args)
(with-current-buffer buffer
(if (get-buffer-window buffer)
(set-window-point (get-buffer-window buffer) position)
(goto-char position)))))
(defun help-go-back ()
"Go back to previous topic in this help buffer."
(interactive)
(if help-xref-stack
(help-xref-go-back (current-buffer))
(error "No previous help buffer")))
(defun help-go-forward ()
"Go back to next topic in this help buffer."
(interactive)
(if help-xref-forward-stack
(help-xref-go-forward (current-buffer))
(error "No next help buffer")))
(defun help-do-xref (pos function args)
"Call the help cross-reference function FUNCTION with args ARGS.
......
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