what-page and first line of page?

what-page and first line of page?

[Mario Lang]

Hi.

I am editiing a long document where original page numbers are important.
When I use `what-page' to see to which physical page the position
of point currently corresponds, I notice that it does not
work on the first line which starts with ^L.  I.e.:

line 1 or page 1
\fline 2 of page 1
line 1 of page 2

To make `what-page' return the correct page number I either
always have to immediately follow ^L with a newline, or
remove `beginning-of-line' in the definition of `what-page':

(defun what-page ()
  "Print page and line number of point."
  (interactive)
  (save-restriction
    (widen)
    (save-excursion
      ;(beginning-of-line)
      (let ((count 1)
	    (opoint (point)))
	(goto-char 1)
	(while (re-search-forward page-delimiter opoint t)
	  (setq count (1+ count)))
	(message "Page %d, line %d"
		 count
		 (1+ (count-lines (point) opoint)))))))

I am arguing this is a bug.  Does anyone know why
the `beginning-of-line' is actually in there?

-- 
CYa,
  ⡍⠁⠗⠊⠕

Re: what-page and first line of page?

[Stefan Monnier]

> To make `what-page' return the correct page number I either
> always have to immediately follow ^L with a newline, or
> remove `beginning-of-line' in the definition of `what-page':

I removed the beginning-of-line (has been there since the original
commit 1.1 in 1989).  BTW, such reports should be sent to the
bug-tracker rather than to emacs-devel.


        Stefan

bug#4445: what-page and first line of page?

[Juanma Barranquero]

On Tue, Sep 15, 2009 at 03:22, Stefan Monnier <monnier@iro.umontreal.ca> wrote:

> I removed the beginning-of-line (has been there since the original
> commit 1.1 in 1989).

Strangely enough, that `beginning-of-line' somewhat masked a bug in
`what-page' that happens when `re-search-forward' matches but does not
move the point.

For example,

  emacs -Q lisp/ChangeLog
  M-x what-page <RET>         => "Page 1, line 1"

but

  emacs -Q lisp/ChangeLog
  <right>
  M-x what-page <RET>        => loops until C-g

This happens in ChangeLog files because `page-delimiter' has the value
"^\\<\\|^\f", which matches the empty string at the beginning of the
buffer.

I said the change "somewhat masked" the bug because before it, when
the point was on the first line of a ChangeLog, opoint was 1 (because
of the beginning-of-line), so the match failed and `what-page'
terminated. It only looped from line 2 on, while now it loops from
point 2 on.

    Juanma

Re: what-page and first line of page?

[Juanma Barranquero]

On Tue, Sep 15, 2009 at 03:22, Stefan Monnier <monnier@iro.umontreal.ca> wrote:

> I removed the beginning-of-line (has been there since the original
> commit 1.1 in 1989).

Strangely enough, that `beginning-of-line' somewhat masked a bug in
`what-page' that happens when `re-search-forward' matches but does not
move the point.

For example,

  emacs -Q lisp/ChangeLog
  M-x what-page <RET>         => "Page 1, line 1"

but

  emacs -Q lisp/ChangeLog
  <right>
  M-x what-page <RET>        => loops until C-g

This happens in ChangeLog files because `page-delimiter' has the value
"^\\<\\|^\f", which matches the empty string at the beginning of the
buffer.

I said the change "somewhat masked" the bug because before it, when
the point was on the first line of a ChangeLog, opoint was 1 (because
of the beginning-of-line), so the match failed and `what-page'
terminated. It only looped from line 2 on, while now it loops from
point 2 on.

    Juanma

bug#4447: what-page and first line of page?

[Stefan Monnier]

> Strangely enough, that `beginning-of-line' somewhat masked a bug in
> `what-page' that happens when `re-search-forward' matches but does not
> move the point.

Thanks, fixed,


        Stefan

Re: what-page and first line of page?

[Stefan Monnier]

> Strangely enough, that `beginning-of-line' somewhat masked a bug in
> `what-page' that happens when `re-search-forward' matches but does not
> move the point.

Thanks, fixed,


        Stefan

bug#4445: what-page and first line of page?

[Juanma Barranquero]

On Wed, Sep 16, 2009 at 15:15, Stefan Monnier <monnier@iro.umontreal.ca> wrote:

> Thanks, fixed,

Not yet, I think.

2009-09-16  Stefan Monnier  <monnier@iro.umontreal.ca>
^
Page 1, line 1

2009-09-16  Stefan Monnier  <monnier@iro.umontreal.ca>
 ^
Page 2, line 1

2009-09-16  Stefan Monnier  <monnier@iro.umontreal.ca>
  ^
Page 2, line 2

though I'd say that's a problem with the `page-delimiter' regexp for
change-log-mode, not with `what-page' itself.

    Juanma

Re: what-page and first line of page?

[Juanma Barranquero]

On Wed, Sep 16, 2009 at 15:15, Stefan Monnier <monnier@iro.umontreal.ca> wrote:

> Thanks, fixed,

Not yet, I think.

2009-09-16  Stefan Monnier  <monnier@iro.umontreal.ca>
^
Page 1, line 1

2009-09-16  Stefan Monnier  <monnier@iro.umontreal.ca>
 ^
Page 2, line 1

2009-09-16  Stefan Monnier  <monnier@iro.umontreal.ca>
  ^
Page 2, line 2

though I'd say that's a problem with the `page-delimiter' regexp for
change-log-mode, not with `what-page' itself.

    Juanma