Perf improvement wanted for vlime#ui#CurArgPos() about vlime

[phmarek]

Re-indenting 419 lines now gave me

FUNCTION  vlime#ui#CurArgPos()
    Defined: .../vlime/vim/autoload/vlime/ui.vim:1102
Called 1145 times
Total time:  48.109187
 Self time:  48.109187

...
591677             28.625727             let syntax = map(synstack(ln, idx), 'synIDattr(v:val, "name")')

Perhaps a simple per-buffer cache that stores the indentation for each line (or form?) so we don't do O(n²) runs here?

FUNCTIONS SORTED ON TOTAL TIME
count  total (s)   self (s)  function
  399  54.321642   0.074243  vlime#plugin#CalcCurIndent()
  399  54.027148   0.307812  vlime#ui#ParseOuterOperators()
 1145  48.109187             vlime#ui#CurArgPos()
 1145   5.610149   0.124386  vlime#ui#CurOperator()
 1456   5.579339   0.064519  vlime#ui#CurExpr()
 2912   5.461276             vlime#ui#CurExprPos()
  311   0.174020   0.003437  vlime#GetCurrentPackage()
  311   0.170583   0.008193  vlime#ui#GetCurrentPackage()

[phmarek]

Notes:

• b:changedtick for cache invalidation
• replace loops by a searchpairpos('(','',')','nrb', CB) with a suitable callback function that stores the start/end positions of all the parens in the file in a dict (referencing the parent parens as well)
• In the actual CurArgPos() just look at the paren tree and go word-wise backward (B in normal mode), skipping comments

PS: Just found the lua-treesitter reference in the nvim docs... perhaps that might be a future direction. (got https://github.com/nvim-treesitter/nvim-treesitter-refactor resp. https://github.com/nvim-treesitter/playground as links)

[theHamsta]

Yes, a Lisp parser would be really cool. There is one for clojure that could be adapted for Lisp: https://github.com/sogaiu/tree-sitter-clojure. I always wanted to implement it but never found the time to write the grammar rules and the queries.

Tree-sitter-based paredit is also very cool. It also works for non-lisp languages if the parser gives a sufficiently structure syntax tree.

[phmarek]

Well, treesitter is nvim-only right now, so we'd lose quite a lot of compatibility (and users?).

I guess the caching version to fix the perf issue would be the right way, right now.

[theHamsta]

And it's only nvim nightly. This is why I was a bit surprised when you cited it. But it would be possible to use it for some functionality if it's available or just have it in nvim-treesitter for additional support for Lisp