diff options
Diffstat (limited to 'helix-core/src/syntax.rs')
| -rw-r--r-- | helix-core/src/syntax.rs | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/helix-core/src/syntax.rs b/helix-core/src/syntax.rs index 0f62577f..b320fcda 100644 --- a/helix-core/src/syntax.rs +++ b/helix-core/src/syntax.rs @@ -354,6 +354,25 @@ impl<'a> CapturedNode<'a> { } } +/// The number of matches a TS cursor can at once to avoid performance problems for medium to large files. +/// Set with `set_match_limit`. +/// Using such a limit means that we lose valid captures in, so there is fundamentally a tradeoff here. +/// +/// +/// 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). +/// However, this causes performance issues for medium to large files. +/// In helix, this problem caused treesitter motions to take multiple seconds to complete in medium-sized rust files (3k loc). +/// Neovim also encountered this problem and reintroduced this limit after it was removed upstream +/// (see <https://github.com/neovim/neovim/issues/14897> and <https://github.com/neovim/neovim/pull/14915>). +/// The number used here is fundamentally a tradeoff between breaking some obscure edge cases and performance. +/// +/// +/// A value of 64 was chosen because neovim uses that value. +/// Neovim chose this value somewhat arbitrarily (<https://github.com/neovim/neovim/pull/18397>) adjusting it whenever issues occur in practice. +/// 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. +/// If this limit causes problems for a grammar in the future, it could be increased. +const TREE_SITTER_MATCH_LIMIT: u32 = 64; + impl TextObjectQuery { /// Run the query on the given node and return sub nodes which match given /// capture ("function.inside", "class.around", etc). @@ -394,6 +413,8 @@ impl TextObjectQuery { .iter() .find_map(|cap| self.query.capture_index_for_name(cap))?; + cursor.set_match_limit(TREE_SITTER_MATCH_LIMIT); + let nodes = cursor .captures(&self.query, node, RopeProvider(slice)) .filter_map(move |(mat, _)| { @@ -843,6 +864,7 @@ impl Syntax { let mut cursor = ts_parser.cursors.pop().unwrap_or_else(QueryCursor::new); // TODO: might need to set cursor range cursor.set_byte_range(0..usize::MAX); + cursor.set_match_limit(TREE_SITTER_MATCH_LIMIT); let source_slice = source.slice(..); @@ -1032,6 +1054,7 @@ impl Syntax { // if reusing cursors & no range this resets to whole range cursor_ref.set_byte_range(range.clone().unwrap_or(0..usize::MAX)); + cursor_ref.set_match_limit(TREE_SITTER_MATCH_LIMIT); let mut captures = cursor_ref .captures( |