bug#53126: 29.0.50; [PATCH] Lazy highlight/count when reading query-replace string, etc.

[Juri Linkov]

> Inlined below some further comments.
>
>>>> I meant using simply
>>>>
>>>>   (add-hook 'minibuffer-setup-hook 'isearch-read-with-highlight-setup)
>>>>
>>>> But it seems isearch-read-with-highlight-setup doesn't set
>>>> isearch-lazy-count-display-function.
>
> What used to be 'isearch-read-with-highlight-setup' is now
> 'minibuffer-lazy-highlight-setup'.
>
> Just to make sure I understood you: your suggestion is for this function
> to remove itself automagically from the minibuffer setup hook, to
> dispense with the need of 'minibuffer-with-setup-hook'?  This seems
> handy but unusual, hence my question.
> ...
> - In a previous message, you seemed to suggest making
>   `minibuffer-lazy-highlight-setup' self-cleaning form the
>   minibuffer-setup-hook, so as to dispense with the need for
>   `with-minibuffer-setup-hook'.  I did exactly that, but since I haven't
>   seen this convention before, I wanted to double check.

Actually, my comment was about having the line that you already added
in your latest patch in 'minibuffer-lazy-highlight-setup':

  (add-hook 'lazy-count-update-hook #'minibuffer-lazy-highlight--count)

So I don't see the need to have this line:

  (remove-hook 'minibuffer-setup-hook #'minibuffer-lazy-highlight-setup)

Also I noticed that you changed the function 
'isearch-lazy-count-display-function'
to the hook 'lazy-count-update-hook', and this looks fine,
I see no problem with this.

> - Besides query-replace, I only added lazy highlight to
>   isearch-edit-string for now.

BTW, what is the relation between the minibuffer-lazy-highlight feature
and another proposed feature that immediately updates the search in
the buffer while editing the string in the minibuffer by isearch-edit-string?
Can minibuffer-lazy-highlight be considered as a lightweight version of
the buffer search from the minibuffer?

> There are a few more we could add   (perhaps later),
> such as `occur' and `keep-lines'.

I tried (add-hook 'minibuffer-setup-hook #'minibuffer-lazy-highlight-setup)
in the minibuffer of 'occur' and others, and it works nicely.
Maybe it could even semi-deprecate the package re-builder.el.

Thanks for this generally usable feature.

> - There's no customization variable to enable the minibuffer lazy
>   highlight.  The rationale is that each command that will use it should
>   define its own user option (or use an existing one).  For
>   `isearch-edit-string' it's `isearch-lazy-highlight'; for
>   `query-replace' it's `query-replace-lazy-highlight'; and so on.

A common customizable option to enable this everywhere would be nice too.
Maybe disabling is already possible by customizing
'minibuffer-lazy-count-format' to nil?  Then the checks for
non-nil 'minibuffer-lazy-count-format' could be added to
more places, such as to wrap the whole '(condition-case error'
in query-replace-read-args with the 'when' condition, etc.

> - As to the lazy count during `perform-replace': I would like to leave
>   this for later.  In fact, I think the lazy highlight has some issues
>   that need fixing beforehand.  For instance, if I replace "a" with
>   "aba", then the "a"'s from the replacement text also get lazy
>   highlighted.  We shouldn't refresh the lazy highlight during
>   `preform-replace'.  Then adding lazy count on top should be easy.

Patches welcome.

>>> I guess this could be done.
>>
>> Maybe two separate hooks could be defined?  One highlights like
>> lazy-highlight, and another counts like lazy-count does:
>>
>>   (add-hook 'minibuffer-setup-hook 'isearch-read-with-highlight-setup)
>>   (add-hook 'minibuffer-setup-hook 'isearch-read-with-count-setup)
>
> The highlight without counting can be achieved by binding a suitable new
> variable.  Counting without highlight is not supported by isearch AFAIU.

Counting without highlighting is only possible by redefining the function
'isearch-lazy-highlight-match' to a no-op function.