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bug#46933: Possible bugs in filepos-to-bufferpos / bufferpos-to-filepos
From: |
Lars Ingebrigtsen |
Subject: |
bug#46933: Possible bugs in filepos-to-bufferpos / bufferpos-to-filepos |
Date: |
Mon, 20 Jun 2022 02:59:52 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) |
handa <handa@gnu.org> writes:
> But it seems that the usage in Info-find-node-2 is:
> a byte position in an existing file that may not be created by Emacs
>
> There's a case that they are different. The method I wrote in the
> previous mail works only in the former case. And it seems that the
> current implementation of filepos-to-bufferpos is the same because it
> tries to get byte sequence by encode-coding-region.
>
> For the latter case, perhaps something like the following code works.
>
> ;; Return the buffer position correspoinding to the byte position
> ;; FILEPOS in FILE provided that FILE is decoded by CODING-SYSTEM.
> (defun temp (file filepos coding-system)
> (with-temp-buffer
> (set-buffer-multibyte nil)
> (insert-file-contents-literally file)
> (let ((full (decode-coding-region 1 (point-max) coding-system t))
> partial)
> (while (and (setq partial (decode-coding-region 1 (1+ filepos)
> coding-system t))
> (not (eq (compare-strings full 0 (length partial)
> partial 0 (length partial))
> t)))
> (setq filepos (1+ filepos)))
> (1+ (length partial)))))
>
> If it is too slow, there are a few ways to make it faster.
(I'm going through old bug reports that unfortunately weren't resolved
at the time.)
If I understand correctly, the suggestion here is to use this function
in Info-find-node-2 instead of `filepos-to-bufferpos'?
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
- bug#46933: Possible bugs in filepos-to-bufferpos / bufferpos-to-filepos,
Lars Ingebrigtsen <=