On 05-Jun-2013 09:10 +0200, Christian Brabandt wrote: > On Wed, June 5, 2013 08:56, Ingo Karkat wrote: >> 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.) > > I am not sure, it is intended. I certainly wouldn't expect this (and > the doc is wrong in this regard, as you said). Since > \%V is zero-width, I would expect the \%V to still match the end of the > visual selection.
Zero-width means: Matches at the current position, but does not consume the character; i.e. the next match is made at the same position. What is needed at the final atom is: Matches at the previous position (that has already been consumed). I don't know how difficult that is to implement in the regular expression engine(s), but I think such a new \%<V atom would be helpful. In my opinion it is hard to change the existing \%V in a way to fit both uses: It just matches anywhere inside a selection, and has no notion of start or end of selection. Therefore, it's presumably difficult to change its behavior at the end of the selection without introducing off-by-one errors elsewhere. I'm already struggling to come up with a good and precise documentation for the new behavior; the current one is at least simple to grasp (when you understand zero-width matches). And it would be a compatibility-breaking change. >> The general case is this ugly beast: /\%Vfoobar\%(\%V\|\%(\%V.\)\@<=\). > > Yes, very ugly and not easily understandable. > >> 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 > > I can understand why this happens but nevertheless it is an annoying > corner-case to consider when using the \%V atom, so I'd like to have > this issue resolved. Yes, at least the help should warn about this corner case. I ran into it (and came up with the complex correct regexp) in some of my plugins, but I think \%V is one of the more obscure atoms few people use. Probably more users rely on the vis.vim plugin, which solves the problem in a completely different way. -- regards, ingo -- -- You received this message from the "vim_dev" maillist. Do not top-post! Type your reply below the text you are replying to. For more information, visit http://www.vim.org/maillist.php --- You received this message because you are subscribed to the Google Groups "vim_dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
