bug#40053: 28.0; text-property-search-forward skips first region

bug#40053: 28.0; text-property-search-forward skips first region

[Dustin Lacewell]

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The following code does not do what I would expect:

(with-current-buffer (get-buffer-create "*Test*")
  (erase-buffer)
  (insert "   ")
  (insert-text-button "Button1"
                      'foo 'bar)
  (insert "   ")
  (insert-text-button "Button2"
                      'foo 'bar)
  (beginning-of-buffer)
  (text-property-search-forward 'foo 'bar nil t)
  (display-buffer (current-buffer)))

I would expect the point to land on the first button. However, it lands on
the second.

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bug#40053: 28.0; text-property-search-forward skips first region

[Stephen Berman]

On Fri, 13 Mar 2020 12:35:25 -0500 Dustin Lacewell <dlacewell@gmail.com> wrote:

> The following code does not do what I would expect:
>
> (with-current-buffer (get-buffer-create "*Test*")
>   (erase-buffer)
>   (insert "   ")
>   (insert-text-button "Button1"
>                       'foo 'bar)
>   (insert "   ")
>   (insert-text-button "Button2"
>                       'foo 'bar)
>   (beginning-of-buffer)
>   (text-property-search-forward 'foo 'bar nil t)
>   (display-buffer (current-buffer)))
>
> I would expect the point to land on the first button. However, it
> lands on the second.

Actually, if text-property-search-forward succeeds it moves to the end
of the propertized region, so in this case, just after the first
button.  And that's what happens with this sexp:

(text-property-search-forward 'foo 'bar t t)

But you've called it with the argument PREDICATE nil, which means the
search succeeds if the value of the propertized text does not match the
VALUE argument, i.e. in this case if 'bar does not match 'bar.  Since
this is false, the search stops, leaving point at the last position
where the value of 'foo changed, which is the beginning of the second
button.

Steve Berman

bug#40053: 28.0; text-property-search-forward skips first region

[Lars Ingebrigtsen]

Stephen Berman <stephen.berman@gmx.net> writes:

> But you've called it with the argument PREDICATE nil, which means the
> search succeeds if the value of the propertized text does not match the
> VALUE argument, i.e. in this case if 'bar does not match 'bar.  Since
> this is false, the search stops, leaving point at the last position
> where the value of 'foo changed, which is the beginning of the second
> button.

Yup.  So I don't think there's any bug here, and I'm closing this bug
report.  If there's still something to fix here, respond, and the bug
report will be reopened.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no