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Bump TREE_SITTER_MATCH_LIMIT to 256 (#4830)

The limit of 64 breaks some highlighting in Erlang files with complicated record definitions. Bumping to 256 seems to work on all files I have seen.

commit0b2bb061b95b60c51f018f541e622b731ddd14ef authorMichael Davis <mcarsondavis@gmail.com> dateMon 21 Nov 2022, 03:13 (4 years ago) parentbbde897
1 file changed+9−8
helix-core/src/syntax.rs+9−8
helix-core/src/syntax.rs+9−8
@@ -354,24 +354,25 @@ impl<'a> CapturedNode<'a> {
354354 }
355355}
356356
357−/// The number of matches a TS cursor can at once to avoid performance problems for medium to large files.
358−/// Set with `set_match_limit`.
359−/// Using such a limit means that we lose valid captures in, so there is fundamentally a tradeoff here.
357+/// The maximum number of in-progress matches a TS cursor can consider at once.
358+/// This is set to a constant in order to avoid performance problems for medium to large files. Set with `set_match_limit`.
359+/// Using such a limit means that we lose valid captures, so there is fundamentally a tradeoff here.
360360///
361361///
362362/// Old tree sitter versions used a limit of 32 by default until this limit was removed in version `0.19.5` (must now be set manually).
363363/// However, this causes performance issues for medium to large files.
364364/// In helix, this problem caused treesitter motions to take multiple seconds to complete in medium-sized rust files (3k loc).
365+///
366+///
365367/// Neovim also encountered this problem and reintroduced this limit after it was removed upstream
366368/// (see <https://github.com/neovim/neovim/issues/14897> and <https://github.com/neovim/neovim/pull/14915>).
367369/// The number used here is fundamentally a tradeoff between breaking some obscure edge cases and performance.
368370///
369371///
370−/// A value of 64 was chosen because neovim uses that value.
371−/// Neovim chose this value somewhat arbitrarily (<https://github.com/neovim/neovim/pull/18397>) adjusting it whenever issues occur in practice.
372−/// However this value has been in use for a long time and due to the large userbase of neovim it is probably a good choice.
373−/// If this limit causes problems for a grammar in the future, it could be increased.
374−const TREE_SITTER_MATCH_LIMIT: u32 = 64;
372+/// Neovim chose 64 for this value somewhat arbitrarily (<https://github.com/neovim/neovim/pull/18397>).
373+/// 64 is too low for some languages though. In particular, it breaks some highlighting for record fields in Erlang record definitions.
374+/// This number can be increased if new syntax highlight breakages are found, as long as the performance penalty is not too high.
375+const TREE_SITTER_MATCH_LIMIT: u32 = 256;
375376
376377impl TextObjectQuery {
377378 /// Run the query on the given node and return sub nodes which match given