On 05-Jun-2013 13:56 +0200, Andy Wokula wrote:

> Am 05.06.2013 08:56, schrieb Ingo Karkat:
>> On 05-Jun-2013 08:03 +0200, Christian Brabandt wrote:
>>
>>> [...] the old engine has an long standing bug with \%V ;(
>>>
>>> e.g:
>>>
>>> vim -u NONE -N
>>> ifoobar<esc>
>>> 0ve<esc>
>>> /\%Vfoobar\%V
>>>
>>> I should have probably provided a fix long ago.
>>
>> Where is the bug, that there's no match?! That's intended, as the last
>> \%V matches zero-width _after_ the end of "foobar", but the visual
>> selection ends on the "r". You'd have to use /\%Vfooba\%Vr here. (The
>> example at :help \%V is wrong about this corner case, too.)
>>
>> The general case is this ugly beast: /\%Vfoobar\%(\%V\|\%(\%V.\)\@<=\).
> 
> Keep it simple ...:
>     /\%Vfoobar\%(\%V.\)\@<=

You're technically right, maybe it was irrational fear of bad
performance (from the help: "For speed it's often much better to avoid
this multi.") that made me introduce the branch for the common case.
Confession: I've never measured this, though.

> (Any actual use case for the /ugly beast/?)

As I've mentioned, when you don't have a hard-coded "foobar", but a
passed regular expression e.g. in a custom command.

>> Since restricting the match to inside the entire selection is such a
>> common use case (see the related vis.vim plugin), I think it would be
>> worthwhile to have a special atom (e.g. \%<V) that matches if the
>> _preceding character_ is inside the selection, allowing this much nicer
>> pattern: /\%Vfoobar\%<V
> 
> Looks like  \%<V  would be the same as  \%(\%V.\)\@<=

Right, but hopefully with better performance. The main benefit would be
that it's easier to remember and type. Bram has just suggested a generic
\@0<= elsewhere in this thread, but I think even that (\%V\@0<=) would
be too hard to remember.

-- regards, ingo

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