Re: [PATCH] iimage-mode: reset point for each regexp

[Juri Linkov <juri@linkov.net>]

> When creating a minor mode that would replace certain regexp matches
> with inline images, I was glad to find iimage-mode already existed to
> make this process easier; better yet, it's built in to Emacs core.
> However, upon customising the functionality of this mode, by altering
> iimage-mode-image-regex-alist to contain more than one item, I found
> an interesting quirk of the mode's behaviour. If a regular expression
> early in the list matched late in the buffer, then regular expression
> matches later in the list would no longer replace matches early in the
> buffer. I didn't expect the alist to have such strict ordering, and
> I'm not sure if that's intentional, especially as the defaults have
> only one element in this alist.
>
> When peering at the source code, I didn't notice any documentation
> indicating that this behaviour is expected. I also noticed the cause
> of this behaviour: '(goto-char (point-min))' is used outside of the
> 'dolist' iteration that loops over regular expressions to match, which
> means that each regexp search begins at the end of the last... By
> moving this goto-char call one line down, within the 'dolist' body,
> each regexp search begins at, well, the beginning. This gives expected
> behaviour in my minor mode (such that an alphabetized list of exact
> matches can have all occurrences replaced with inline images in a
> buffer). If this behaviour is intended, feel free to ignore this post.
>
> Attached is a patch generated with git that implements the above change.

Thanks for the bug report.  I'm using iimage-mode-image-regex-alist
with a single composite regexp, so I never noticed this problem.

Eli, is it ok to push this fix to the emacs-29 branch?

> diff --git a/lisp/iimage.el b/lisp/iimage.el
> index 96ab963bff..053eb27db7 100644
> --- a/lisp/iimage.el
> +++ b/lisp/iimage.el
> @@ -112,8 +112,8 @@ Examples of image filename patterns to match:
>  	file)
>      (with-silent-modifications
>        (save-excursion
> -        (goto-char (point-min))
>          (dolist (pair iimage-mode-image-regex-alist)
> +          (goto-char (point-min))
>            (while (re-search-forward (car pair) nil t)
>              (when (and (setq file (match-string (cdr pair)))
>                         (setq file (locate-file file image-path)))