syntax: Reuse parser instances. highlight_iter() no longer needs &mut.

helix-core/src/syntax.rs

@@ -2,11 +2,12 @@ use crate::{Change, Rope, RopeSlice, Transaction};
 pub use helix_syntax::Lang;
 pub use helix_syntax::{get_language, get_language_name};
 
+use std::cell::RefCell;
 use std::collections::HashMap;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
-use once_cell::sync::OnceCell;
+use once_cell::sync::{Lazy, OnceCell};
 
 // largely based on tree-sitter/cli/src/loader.rs
 pub struct LanguageConfiguration {
@@ -65,8 +66,6 @@ impl LanguageConfiguration {
     }
 }
 
-use once_cell::sync::Lazy;
-
 pub static LOADER: Lazy<Loader> = Lazy::new(Loader::init);
 
 pub struct Loader {
@@ -145,13 +144,20 @@ impl Loader {
     }
 }
 
-//
+pub struct TSParser {
-
+    parser: tree_sitter::Parser,
-pub struct Syntax {
-    // grammar: Grammar,
-    parser: Parser,
     cursors: Vec<QueryCursor>,
+}
+
+// could also just use a pool, or a single instance?
+thread_local! {
+    pub static PARSER: RefCell<TSParser> = RefCell::new(TSParser {
+        parser: Parser::new(),
+        cursors: Vec::new(),
+    })
+}
 
+pub struct Syntax {
     config: Arc<HighlightConfiguration>,
 
     pub(crate) root_layer: LanguageLayer,
@@ -163,10 +169,6 @@ impl Syntax {
         /*language: Lang,*/ source: &Rope,
         config: Arc<HighlightConfiguration>,
     ) -> Self {
-        // fetch grammar for parser based on language string
-        // let grammar = get_language(&language);
-        let parser = Parser::new();
-
         let root_layer = LanguageLayer { tree: None };
 
         // track markers of injections
@@ -174,15 +176,14 @@ impl Syntax {
 
         let mut syntax = Self {
             // grammar,
-            parser,
-            cursors: Vec::new(),
             config,
             root_layer,
         };
 
         // update root layer
+        PARSER.with(|ts_parser| {
             syntax.root_layer.parse(
-            &mut syntax.parser,
+                &mut ts_parser.borrow_mut(),
                 &syntax.config,
                 source,
                 0,
@@ -193,6 +194,7 @@ impl Syntax {
                     end_point: Point::new(usize::MAX, usize::MAX),
                 }],
             );
+        });
         syntax
     }
 
@@ -202,13 +204,15 @@ impl Syntax {
         source: &Rope,
         changeset: &ChangeSet,
     ) -> Result<(), Error> {
+        PARSER.with(|ts_parser| {
             self.root_layer.update(
-            &mut self.parser,
+                &mut ts_parser.borrow_mut(),
                 &self.config,
                 old_source,
                 source,
                 changeset,
             )
+        })
 
         // TODO: deal with injections and update them too
     }
@@ -229,7 +233,8 @@ impl Syntax {
 
     /// Iterate over the highlighted regions for a given slice of source code.
     pub fn highlight_iter<'a>(
-        &'a mut self,
+        &self,
+        ts_parser: &'a mut TSParser,
         source: &'a [u8],
         range: Option<std::ops::Range<usize>>,
         cancellation_flag: Option<&'a AtomicUsize>,
@@ -283,7 +288,7 @@ impl Syntax {
             byte_offset: range.map(|r| r.start).unwrap_or(0), // TODO: simplify
             injection_callback,
             cancellation_flag,
-            highlighter: self,
+            highlighter: ts_parser,
             iter_count: 0,
             layers: vec![layer],
             next_event: None,
@@ -336,19 +341,21 @@ impl LanguageLayer {
 
     fn parse(
         &mut self,
-        parser: &mut Parser,
+        ts_parser: &mut TSParser,
         config: &HighlightConfiguration,
         source: &Rope,
         mut depth: usize,
         mut ranges: Vec<Range>,
     ) -> Result<(), Error> {
-        if parser.set_included_ranges(&ranges).is_ok() {
+        if ts_parser.parser.set_included_ranges(&ranges).is_ok() {
-            parser
+            ts_parser
+                .parser
                 .set_language(config.language)
                 .map_err(|_| Error::InvalidLanguage)?;
 
             // unsafe { syntax.parser.set_cancellation_flag(cancellation_flag) };
-            let tree = parser
+            let tree = ts_parser
+                .parser
                 .parse_with(
                     &mut |byte, _| {
                         if byte <= source.len_bytes() {
@@ -517,7 +524,7 @@ impl LanguageLayer {
 
     fn update(
         &mut self,
-        parser: &mut Parser,
+        ts_parser: &mut TSParser,
         config: &HighlightConfiguration,
         old_source: &Rope,
         source: &Rope,
@@ -535,7 +542,7 @@ impl LanguageLayer {
         }
 
         self.parse(
-            parser,
+            ts_parser,
             config,
             source,
             0,
@@ -652,7 +659,7 @@ where
 {
     source: &'a [u8],
     byte_offset: usize,
-    highlighter: &'a mut Syntax,
+    highlighter: &'a mut TSParser,
     injection_callback: F,
     cancellation_flag: Option<&'a AtomicUsize>,
     layers: Vec<HighlightIterLayer<'a>>,
@@ -839,7 +846,7 @@ impl<'a> HighlightIterLayer<'a> {
     /// added to the returned vector.
     fn new<F: FnMut(&str) -> Option<&'a HighlightConfiguration> + 'a>(
         source: &'a [u8],
-        highlighter: &mut Syntax,
+        highlighter: &mut TSParser,
         cancellation_flag: Option<&'a AtomicUsize>,
         injection_callback: &mut F,
         mut config: &'a HighlightConfiguration,

helix-term/src/ui/editor.rs

@@ -3,7 +3,11 @@ use crate::compositor::{Component, Compositor, Context, EventResult};
 use crate::keymap::{self, Keymaps};
 use crate::ui::text_color;
 
-use helix_core::{indent::TAB_WIDTH, syntax::HighlightEvent, Position, Range, State};
+use helix_core::{
+    indent::TAB_WIDTH,
+    syntax::{self, HighlightEvent},
+    Position, Range, State,
+};
 use helix_view::{document::Mode, Document, Editor, Theme, View};
 use std::borrow::Cow;
 
@@ -34,7 +38,7 @@ impl EditorView {
     }
     pub fn render_view(
         &self,
-        view: &mut View,
+        view: &View,
         viewport: Rect,
         surface: &mut Surface,
         theme: &Theme,
@@ -61,10 +65,9 @@ impl EditorView {
         self.render_statusline(&view.doc, area, surface, theme, is_focused);
     }
 
-    // TODO: ideally not &mut View but highlights require it because of cursor cache
     pub fn render_buffer(
         &self,
-        view: &mut View,
+        view: &View,
         viewport: Rect,
         surface: &mut Surface,
         theme: &Theme,
@@ -79,7 +82,7 @@ impl EditorView {
         let range = {
             // calculate viewport byte ranges
             let start = text.line_to_byte(view.first_line);
-            let end = text.line_to_byte(last_line + 1); // TODO: double check
+            let end = text.line_to_byte(last_line + 1);
 
             start..end
         };
@@ -87,12 +90,20 @@ impl EditorView {
         // TODO: range doesn't actually restrict source, just highlight range
         // TODO: cache highlight results
         // TODO: only recalculate when state.doc is actually modified
-        let highlights: Vec<_> = match view.doc.syntax.as_mut() {
+        let highlights: Vec<_> = match &view.doc.syntax {
             Some(syntax) => {
+                syntax::PARSER.with(|ts_parser| {
                     syntax
-                    .highlight_iter(source_code.as_bytes(), Some(range), None, |_| None)
+                        .highlight_iter(
+                            &mut ts_parser.borrow_mut(),
+                            source_code.as_bytes(),
+                            Some(range),
+                            None,
+                            |_| None,
+                        )
                         .unwrap()
-                    .collect() // TODO: we collect here to avoid double borrow, fix later
+                        .collect() // TODO: we collect here to avoid holding the lock, fix later
+                })
             }
             None => vec![Ok(HighlightEvent::Source {
                 start: range.start,
@@ -102,7 +113,6 @@ impl EditorView {
         let mut spans = Vec::new();
         let mut visual_x = 0;
         let mut line = 0u16;
-        let text = view.doc.text();
 
         'outer: for event in highlights {
             match event.unwrap() {

helix-term/src/ui/menu.rs

@@ -12,9 +12,6 @@ use std::borrow::Cow;
 use helix_core::Position;
 use helix_view::Editor;
 
-// TODO: factor out a popup component that we can reuse for displaying docs on autocomplete,
-// diagnostics popups, etc.
-
 pub struct Menu<T> {
     options: Vec<T>,