Saving visual selection gets stuck when selecting big texts

[LpZ_squall]

First of all, I'd like to say a big THANKS for this plugin that I discovered yesterday. It's really easy to use, documentation is precise and quite exhaustive, and the plugin itself is very powerful. Great job !

Well, my problem is that when selecting a quite big amount of text and pressing <tab> to reuse it in a snippet, vim gets stuck in the UltiSnips_SaveLastVisualSelection() function for a while. I don't exactly know what the _visual_content.conserve() function is doing, but an optimization would be welcomed :-).

My use-case is the following very simple C snippet, wrapping the selected text into a vim fold:

  snippet fold "Add a new vim fold" !b
  /*{{{ ${1:topic} */

  ${0:${VISUAL}}

  /*}}} */
  endsnippet

When working on a big C file (> 5k lines) without folds, and that I want to add some with this snippet... well I just can't :-D.

[SirVer (sirver)]

Well, this is not related to visual, it is related to big edits inside a snippet. The problem is here:

https://github.com/SirVer/ultisnips/blob/master/plugin/UltiSnips/__init__.py#L686

The issue is that Vim is not reporting what changed in a buffer when the cursor moved. But UltiSnips needs this information to update its text objects. So it first tries a bunch of heuristics to figure this out - e.g. if the cursor is on the next line, but further to the left it is likely that the user inserted a newline. But if those heuristic fail, we need to do a full diff of the snippet area before and after - unfortunately this is a very costly operation and very slow as well (both the implementation and python). This is the notable freeze you see.

Unfortunately I have no idea how to improve the situation - if you have any suggestions, shoot.

[LpZ_squall (lpz-squall)]

OK, thank you for the explanation.

I'm a C developper and I don't know Python, so if you don't know how to improve the situation, then I probably won't be able to do anything, but I'll may have a look one day...