Re: Texinfo Mode: node-based movement functions.

[Alan Mackenzie]

Sorry!

I forgot to save the match data.  Here's a corrected version of the code.

On Sat, 6 Nov 2004, Alan Mackenzie wrote:

>Hi, Emacs!
>
>In Texinfo Mode we have functions for moving to the beginning and end of
>a "page" (i.e. a @chapter) and for narrowing to a @chapter (together with
>its @sections).
>
>I think there should also be functions for moving to the beginning and
>end of an individual @node, and for narrowing to it.  "Obviously", a
>@node in a file.texi is analogous to a defun in a file.el.  So the
>natural key bindings are C-M-a, C-M-e, and C-x n d.
>
>The following code is a first shot at implementing this functionality.
>It is currently not bullet proof - in particular, it doesn't take account
>of @ignore commands.  That would not, however, be hard to remedy.
>
>Should I develop this into a production quality patch, complete with an
>amendment to texinfo.txi, ChangeLog entry, etc.?

Corrected code:
########################################################################
(defconst acm-texinfo-node-start "address@hidden .")

(defun acm-texinfo-beginning-of-node (&optional count)
  "Move backward to the beginning of a node.
With COUNT, do it that many times.  A negative COUNT will move forward.

A node starts at the \"@node\" command."
  (interactive "p")
  (if (< count 0)
      (acm-texinfo-end-of-node (- count))
    (save-match-data
      (unless (bolp) (end-of-line))     ; in case we're already inside "@node"
      (search-backward-regexp acm-texinfo-node-start nil 'limit count))))

(defun acm-texinfo-end-of-node (&optional count)
  "Move forward to the end of the current node.
With COUNT, do it that many times.  A negative COUNT will move backwards.

The end of a node is the \"@node\" which begins the next node or EOF."
  (interactive "p")
  (if (< count 0)
      (acm-texinfo-beginning-of-node (- count))
    (save-match-data
      (end-of-line)                     ; to make sure we move.
      (search-forward-regexp acm-texinfo-node-start nil 'limit count)
      (beginning-of-line))))

(defun acm-texinfo-narrow-to-node ()
  "Make the text outside the current node invisible.
This node is the one that contains point or follows point."
  (interactive)
  (widen)
  (save-excursion
    (save-match-data
      (let ((start
             (progn
               (end-of-line)
               (search-backward-regexp acm-texinfo-node-start nil 'limit)
               (point))))
        (end-of-line)
        (if (search-forward-regexp acm-texinfo-node-start nil 'limit)
            (beginning-of-line))
        (narrow-to-region start (point))))))

(eval-after-load "texinfo"
  '(progn
     (define-key texinfo-mode-map "\C-\M-a" 'acm-texinfo-beginning-of-node)
     (define-key texinfo-mode-map "\C-\M-e" 'acm-texinfo-end-of-node)
     (define-key texinfo-mode-map "\C-xnd" 'acm-texinfo-narrow-to-node)))

#########################################################################

-- 
Alan Mackenzie (Munich, Germany)