Merge ac0249bd13 into b1b60bb7fe

Cargo.lock

@@ -5039,6 +5039,7 @@ dependencies = [
  "clock",
  "collections",
  "convert_case 0.8.0",
+ "criterion",
  "ctor",
  "dap",
  "db",

crates/editor/Cargo.toml

@@ -94,6 +94,7 @@ zed_actions.workspace = true
 workspace-hack.workspace = true
 
 [dev-dependencies]
+criterion.workspace = true
 ctor.workspace = true
 gpui = { workspace = true, features = ["test-support"] }
 language = { workspace = true, features = ["test-support"] }
@@ -119,3 +120,8 @@ util = { workspace = true, features = ["test-support"] }
 workspace = { workspace = true, features = ["test-support"] }
 http_client = { workspace = true, features = ["test-support"] }
 zlog.workspace = true
+
+
+[[bench]]
+name = "editor_render"
+harness = false

crates/editor/benches/editor_render.rs

@@ -0,0 +1,164 @@
+use criterion::{Bencher, BenchmarkId};
+use editor::{
+    Editor, EditorMode, MultiBuffer,
+    actions::{DeleteToPreviousWordStart, SelectAll, SplitSelectionIntoLines},
+};
+use gpui::{AppContext, Focusable as _, TestAppContext, TestDispatcher};
+use project::Project;
+use rand::{Rng as _, SeedableRng as _, rngs::StdRng};
+use settings::SettingsStore;
+use ui::IntoElement;
+use util::RandomCharIter;
+
+fn editor_input_with_1000_cursors(bencher: &mut Bencher<'_>, cx: &TestAppContext) {
+    let mut cx = cx.clone();
+    let text = String::from_iter(["line:\n"; 500]);
+    let buffer = cx.update(|cx| MultiBuffer::build_simple(&text, cx));
+
+    let cx = cx.add_empty_window();
+    let editor = cx.update(|window, cx| {
+        let editor = cx.new(|cx| {
+            let mut editor = Editor::new(EditorMode::full(), buffer, None, window, cx);
+            editor.set_style(editor::EditorStyle::default(), window, cx);
+            editor.select_all(&SelectAll, window, cx);
+            editor.split_selection_into_lines(&SplitSelectionIntoLines, window, cx);
+            editor
+        });
+        window.focus(&editor.focus_handle(cx));
+        editor
+    });
+
+    bencher.iter(|| {
+        cx.update(|window, cx| {
+            editor.update(cx, |editor, cx| {
+                editor.handle_input("hello world", window, cx);
+                editor.delete_to_previous_word_start(
+                    &DeleteToPreviousWordStart {
+                        ignore_newlines: false,
+                    },
+                    window,
+                    cx,
+                );
+                editor.delete_to_previous_word_start(
+                    &DeleteToPreviousWordStart {
+                        ignore_newlines: false,
+                    },
+                    window,
+                    cx,
+                );
+            });
+        })
+    });
+}
+
+fn open_editor_with_one_long_line(bencher: &mut Bencher<'_>, args: &(String, TestAppContext)) {
+    let (text, cx) = args;
+    let mut cx = cx.clone();
+
+    bencher.iter(|| {
+        let buffer = cx.update(|cx| MultiBuffer::build_simple(&text, cx));
+
+        let cx = cx.add_empty_window();
+        let _ = cx.update(|window, cx| {
+            let editor = cx.new(|cx| {
+                let mut editor = Editor::new(EditorMode::full(), buffer, None, window, cx);
+                editor.set_style(editor::EditorStyle::default(), window, cx);
+                editor
+            });
+            window.focus(&editor.focus_handle(cx));
+            editor
+        });
+    });
+}
+
+fn editor_render(bencher: &mut Bencher<'_>, cx: &TestAppContext) {
+    let mut cx = cx.clone();
+    let buffer = cx.update(|cx| {
+        let mut rng = StdRng::seed_from_u64(1);
+        let text_len = rng.gen_range(10000..90000);
+        if rng.r#gen() {
+            let text = RandomCharIter::new(&mut rng)
+                .take(text_len)
+                .collect::<String>();
+            MultiBuffer::build_simple(&text, cx)
+        } else {
+            MultiBuffer::build_random(&mut rng, cx)
+        }
+    });
+
+    let cx = cx.add_empty_window();
+    let editor = cx.update(|window, cx| {
+        let editor = cx.new(|cx| {
+            let mut editor = Editor::new(EditorMode::full(), buffer, None, window, cx);
+            editor.set_style(editor::EditorStyle::default(), window, cx);
+            editor
+        });
+        window.focus(&editor.focus_handle(cx));
+        editor
+    });
+
+    bencher.iter(|| {
+        cx.update(|window, cx| {
+            // editor.update(cx, |editor, cx| editor.move_down(&MoveDown, window, cx));
+            let mut view = editor.clone().into_any_element();
+            let _ = view.request_layout(window, cx);
+            let _ = view.prepaint(window, cx);
+            view.paint(window, cx);
+        });
+    })
+}
+
+pub fn benches() {
+    let dispatcher = TestDispatcher::new(StdRng::seed_from_u64(1));
+    let cx = gpui::TestAppContext::build(dispatcher, None);
+    cx.update(|cx| {
+        let store = SettingsStore::test(cx);
+        cx.set_global(store);
+        assets::Assets.load_test_fonts(cx);
+        theme::init(theme::LoadThemes::JustBase, cx);
+        // release_channel::init(SemanticVersion::default(), cx);
+        client::init_settings(cx);
+        language::init(cx);
+        workspace::init_settings(cx);
+        Project::init_settings(cx);
+        editor::init(cx);
+    });
+
+    let mut criterion: criterion::Criterion<_> =
+        (criterion::Criterion::default()).configure_from_args();
+
+    // setup app context
+    let mut group = criterion.benchmark_group("Time to render");
+    group.bench_with_input(
+        BenchmarkId::new("editor_render", "TestAppContext"),
+        &cx,
+        editor_render,
+    );
+
+    group.finish();
+
+    let text = String::from_iter(["char"; 1000]);
+    let mut group = criterion.benchmark_group("Build buffer with one long line");
+    group.bench_with_input(
+        BenchmarkId::new("editor_with_one_long_line", "(String, TestAppContext )"),
+        &(text, cx.clone()),
+        open_editor_with_one_long_line,
+    );
+
+    group.finish();
+
+    let mut group = criterion.benchmark_group("multi cursor edits");
+    group.bench_with_input(
+        BenchmarkId::new("editor_input_with_1000_cursors", "TestAppContext"),
+        &cx,
+        editor_input_with_1000_cursors,
+    );
+    group.finish();
+}
+
+fn main() {
+    benches();
+    criterion::Criterion::default()
+        .configure_from_args()
+        .final_summary();
+}

crates/editor/src/display_map/block_map.rs

@@ -1737,6 +1737,7 @@ impl<'a> Iterator for BlockChunks<'a> {
 
             return Some(Chunk {
                 text: unsafe { std::str::from_utf8_unchecked(&NEWLINES[..line_count as usize]) },
+                chars: (1 << line_count) - 1,
                 ..Default::default()
             });
         }
@@ -1766,17 +1767,26 @@ impl<'a> Iterator for BlockChunks<'a> {
 
         let (mut prefix, suffix) = self.input_chunk.text.split_at(prefix_bytes);
         self.input_chunk.text = suffix;
+        self.input_chunk.tabs >>= prefix_bytes.saturating_sub(1);
+        self.input_chunk.chars >>= prefix_bytes.saturating_sub(1);
+
+        let mut tabs = self.input_chunk.tabs;
+        let mut chars = self.input_chunk.chars;
 
         if self.masked {
             // Not great for multibyte text because to keep cursor math correct we
             // need to have the same number of bytes in the input as output.
-            let chars = prefix.chars().count();
+            let chars_count = prefix.chars().count();
-            let bullet_len = chars;
+            let bullet_len = chars_count;
             prefix = &BULLETS[..bullet_len];
+            chars = (1 << bullet_len) - 1;
+            tabs = 0;
         }
 
         let chunk = Chunk {
             text: prefix,
+            tabs,
+            chars,
             ..self.input_chunk.clone()
         };
 

crates/editor/src/display_map/custom_highlights.rs

@@ -130,21 +130,37 @@ impl<'a> Iterator for CustomHighlightsChunks<'a> {
             }
         }
 
+        // todo!("Ask if it's ok that i changed the unwraps here")
         let chunk = self
             .buffer_chunk
-            .get_or_insert_with(|| self.buffer_chunks.next().unwrap());
+            .get_or_insert_with(|| self.buffer_chunks.next().unwrap_or_default());
         if chunk.text.is_empty() {
-            *chunk = self.buffer_chunks.next().unwrap();
+            *chunk = self.buffer_chunks.next()?;
         }
 
-        let (prefix, suffix) = chunk
+        let split_idx = chunk.text.len().min(next_highlight_endpoint - self.offset);
-            .text
+        let (prefix, suffix) = chunk.text.split_at(split_idx);
-            .split_at(chunk.text.len().min(next_highlight_endpoint - self.offset));
+
+        let (chars, tabs) = if split_idx == 128 {
+            let output = (chunk.chars, chunk.tabs);
+            chunk.chars = 0;
+            chunk.tabs = 0;
+            output
+        } else {
+            let mask = (1 << split_idx) - 1;
+            let output = (chunk.chars & mask, chunk.tabs & mask);
+            chunk.chars = chunk.chars >> split_idx;
+            chunk.tabs = chunk.tabs >> split_idx;
+            output
+        };
 
         chunk.text = suffix;
         self.offset += prefix.len();
+        // FIXME: chunk cloning is wrong because the bitmaps might be off
         let mut prefix = Chunk {
             text: prefix,
+            chars,
+            tabs,
             ..chunk.clone()
         };
         if !self.active_highlights.is_empty() {
@@ -171,3 +187,140 @@ impl Ord for HighlightEndpoint {
             .then_with(|| other.is_start.cmp(&self.is_start))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use std::{any::TypeId, sync::Arc};
+
+    use super::*;
+    use crate::MultiBuffer;
+    use gpui::App;
+    use rand::prelude::*;
+    use util::RandomCharIter;
+
+    #[gpui::test(iterations = 100)]
+    fn test_random_chunk_bitmaps(cx: &mut App, mut rng: StdRng) {
+        // Generate random buffer using existing test infrastructure
+        let len = rng.gen_range(10..10000);
+        let buffer = if rng.r#gen() {
+            let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
+            MultiBuffer::build_simple(&text, cx)
+        } else {
+            MultiBuffer::build_random(&mut rng, cx)
+        };
+
+        let buffer_snapshot = buffer.read(cx).snapshot(cx);
+
+        // Create random highlights
+        let mut highlights = sum_tree::TreeMap::default();
+        let highlight_count = rng.gen_range(1..10);
+
+        for _i in 0..highlight_count {
+            let style = HighlightStyle {
+                color: Some(gpui::Hsla {
+                    h: rng.r#gen::<f32>(),
+                    s: rng.r#gen::<f32>(),
+                    l: rng.r#gen::<f32>(),
+                    a: 1.0,
+                }),
+                ..Default::default()
+            };
+
+            let mut ranges = Vec::new();
+            let range_count = rng.gen_range(1..10);
+            let text = buffer_snapshot.text();
+            for _ in 0..range_count {
+                if buffer_snapshot.len() == 0 {
+                    continue;
+                }
+
+                let mut start = rng.gen_range(0..=buffer_snapshot.len().saturating_sub(10));
+
+                while !text.is_char_boundary(start) {
+                    start = start.saturating_sub(1);
+                }
+
+                let end_end = buffer_snapshot.len().min(start + 100);
+                let mut end = rng.gen_range(start..=end_end);
+                while !text.is_char_boundary(end) {
+                    end = end.saturating_sub(1);
+                }
+
+                if start < end {
+                    start = end;
+                }
+                let start_anchor = buffer_snapshot.anchor_before(start);
+                let end_anchor = buffer_snapshot.anchor_after(end);
+                ranges.push(start_anchor..end_anchor);
+            }
+
+            let type_id = TypeId::of::<()>(); // Simple type ID for testing
+            highlights.insert(HighlightKey::Type(type_id), Arc::new((style, ranges)));
+        }
+
+        // Get all chunks and verify their bitmaps
+        let chunks =
+            CustomHighlightsChunks::new(0..buffer_snapshot.len(), false, None, &buffer_snapshot);
+
+        for chunk in chunks {
+            let chunk_text = chunk.text;
+            let chars_bitmap = chunk.chars;
+            let tabs_bitmap = chunk.tabs;
+
+            // Check empty chunks have empty bitmaps
+            if chunk_text.is_empty() {
+                assert_eq!(
+                    chars_bitmap, 0,
+                    "Empty chunk should have empty chars bitmap"
+                );
+                assert_eq!(tabs_bitmap, 0, "Empty chunk should have empty tabs bitmap");
+                continue;
+            }
+
+            // Verify that chunk text doesn't exceed 128 bytes
+            assert!(
+                chunk_text.len() <= 128,
+                "Chunk text length {} exceeds 128 bytes",
+                chunk_text.len()
+            );
+
+            // Verify chars bitmap
+            let char_indices = chunk_text
+                .char_indices()
+                .map(|(i, _)| i)
+                .collect::<Vec<_>>();
+
+            for byte_idx in 0..chunk_text.len() {
+                let should_have_bit = char_indices.contains(&byte_idx);
+                let has_bit = chars_bitmap & (1 << byte_idx) != 0;
+
+                if has_bit != should_have_bit {
+                    eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
+                    eprintln!("Char indices: {:?}", char_indices);
+                    eprintln!("Chars bitmap: {:#b}", chars_bitmap);
+                    assert_eq!(
+                        has_bit, should_have_bit,
+                        "Chars bitmap mismatch at byte index {} in chunk {:?}. Expected bit: {}, Got bit: {}",
+                        byte_idx, chunk_text, should_have_bit, has_bit
+                    );
+                }
+            }
+
+            // Verify tabs bitmap
+            for (byte_idx, byte) in chunk_text.bytes().enumerate() {
+                let is_tab = byte == b'\t';
+                let has_bit = tabs_bitmap & (1 << byte_idx) != 0;
+
+                if has_bit != is_tab {
+                    eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
+                    eprintln!("Tabs bitmap: {:#b}", tabs_bitmap);
+                    assert_eq!(
+                        has_bit, is_tab,
+                        "Tabs bitmap mismatch at byte index {} in chunk {:?}. Byte: {:?}, Expected bit: {}, Got bit: {}",
+                        byte_idx, chunk_text, byte as char, is_tab, has_bit
+                    );
+                }
+            }
+        }
+    }
+}

crates/editor/src/display_map/fold_map.rs

@@ -529,6 +529,7 @@ impl FoldMap {
                                 },
                                 placeholder: Some(TransformPlaceholder {
                                     text: ELLIPSIS,
+                                    chars: 1,
                                     renderer: ChunkRenderer {
                                         id: ChunkRendererId::Fold(fold.id),
                                         render: Arc::new(move |cx| {
@@ -872,6 +873,14 @@ impl FoldSnapshot {
         .flat_map(|chunk| chunk.text.chars())
     }
 
+    pub fn chunks_at(&self, start: FoldPoint) -> FoldChunks<'_> {
+        self.chunks(
+            start.to_offset(self)..self.len(),
+            false,
+            Highlights::default(),
+        )
+    }
+
     #[cfg(test)]
     pub fn clip_offset(&self, offset: FoldOffset, bias: Bias) -> FoldOffset {
         if offset > self.len() {
@@ -1034,6 +1043,7 @@ struct Transform {
 #[derive(Clone, Debug)]
 struct TransformPlaceholder {
     text: &'static str,
+    chars: u128,
     renderer: ChunkRenderer,
 }
 
@@ -1274,6 +1284,10 @@ pub struct Chunk<'a> {
     pub is_inlay: bool,
     /// An optional recipe for how the chunk should be presented.
     pub renderer: Option<ChunkRenderer>,
+    /// Bitmap of tab character locations in chunk
+    pub tabs: u128,
+    /// Bitmap of character locations in chunk
+    pub chars: u128,
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
@@ -1391,6 +1405,7 @@ impl<'a> Iterator for FoldChunks<'a> {
             self.output_offset.0 += placeholder.text.len();
             return Some(Chunk {
                 text: placeholder.text,
+                chars: placeholder.chars,
                 renderer: Some(placeholder.renderer.clone()),
                 ..Default::default()
             });
@@ -1429,6 +1444,16 @@ impl<'a> Iterator for FoldChunks<'a> {
             chunk.text = &chunk.text
                 [(self.inlay_offset - buffer_chunk_start).0..(chunk_end - buffer_chunk_start).0];
 
+            let bit_end = (chunk_end - buffer_chunk_start).0;
+            let mask = if bit_end >= 128 {
+                u128::MAX
+            } else {
+                (1u128 << bit_end) - 1
+            };
+
+            chunk.tabs = (chunk.tabs >> (self.inlay_offset - buffer_chunk_start).0) & mask;
+            chunk.chars = (chunk.chars >> (self.inlay_offset - buffer_chunk_start).0) & mask;
+
             if chunk_end == transform_end {
                 self.transform_cursor.next();
             } else if chunk_end == buffer_chunk_end {
@@ -1439,6 +1464,8 @@ impl<'a> Iterator for FoldChunks<'a> {
             self.output_offset.0 += chunk.text.len();
             return Some(Chunk {
                 text: chunk.text,
+                tabs: chunk.tabs,
+                chars: chunk.chars,
                 syntax_highlight_id: chunk.syntax_highlight_id,
                 highlight_style: chunk.highlight_style,
                 diagnostic_severity: chunk.diagnostic_severity,
@@ -2068,6 +2095,97 @@ mod tests {
         );
     }
 
+    #[gpui::test(iterations = 100)]
+    fn test_random_chunk_bitmaps(cx: &mut gpui::App, mut rng: StdRng) {
+        init_test(cx);
+
+        // Generate random buffer using existing test infrastructure
+        let text_len = rng.gen_range(0..10000);
+        let buffer = if rng.r#gen() {
+            let text = RandomCharIter::new(&mut rng)
+                .take(text_len)
+                .collect::<String>();
+            MultiBuffer::build_simple(&text, cx)
+        } else {
+            MultiBuffer::build_random(&mut rng, cx)
+        };
+        let buffer_snapshot = buffer.read(cx).snapshot(cx);
+        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
+        let (mut fold_map, _) = FoldMap::new(inlay_snapshot.clone());
+
+        // Perform random mutations
+        let mutation_count = rng.gen_range(1..10);
+        for _ in 0..mutation_count {
+            fold_map.randomly_mutate(&mut rng);
+        }
+
+        let (snapshot, _) = fold_map.read(inlay_snapshot, vec![]);
+
+        // Get all chunks and verify their bitmaps
+        let chunks = snapshot.chunks(
+            FoldOffset(0)..FoldOffset(snapshot.len().0),
+            false,
+            Highlights::default(),
+        );
+
+        for chunk in chunks {
+            let chunk_text = chunk.text;
+            let chars_bitmap = chunk.chars;
+            let tabs_bitmap = chunk.tabs;
+
+            // Check empty chunks have empty bitmaps
+            if chunk_text.is_empty() {
+                assert_eq!(
+                    chars_bitmap, 0,
+                    "Empty chunk should have empty chars bitmap"
+                );
+                assert_eq!(tabs_bitmap, 0, "Empty chunk should have empty tabs bitmap");
+                continue;
+            }
+
+            // Verify that chunk text doesn't exceed 128 bytes
+            assert!(
+                chunk_text.len() <= 128,
+                "Chunk text length {} exceeds 128 bytes",
+                chunk_text.len()
+            );
+
+            // Verify chars bitmap
+            let char_indices = chunk_text
+                .char_indices()
+                .map(|(i, _)| i)
+                .collect::<Vec<_>>();
+
+            for byte_idx in 0..chunk_text.len() {
+                let should_have_bit = char_indices.contains(&byte_idx);
+                let has_bit = chars_bitmap & (1 << byte_idx) != 0;
+
+                if has_bit != should_have_bit {
+                    eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
+                    eprintln!("Char indices: {:?}", char_indices);
+                    eprintln!("Chars bitmap: {:#b}", chars_bitmap);
+                    assert_eq!(
+                        has_bit, should_have_bit,
+                        "Chars bitmap mismatch at byte index {} in chunk {:?}. Expected bit: {}, Got bit: {}",
+                        byte_idx, chunk_text, should_have_bit, has_bit
+                    );
+                }
+            }
+
+            // Verify tabs bitmap
+            for (byte_idx, byte) in chunk_text.bytes().enumerate() {
+                let is_tab = byte == b'\t';
+                let has_bit = tabs_bitmap & (1 << byte_idx) != 0;
+
+                assert_eq!(
+                    has_bit, is_tab,
+                    "Tabs bitmap mismatch at byte index {} in chunk {:?}. Byte: {:?}, Expected bit: {}, Got bit: {}",
+                    byte_idx, chunk_text, byte as char, is_tab, has_bit
+                );
+            }
+        }
+    }
+
     fn init_test(cx: &mut gpui::App) {
         let store = SettingsStore::test(cx);
         cx.set_global(store);

crates/editor/src/display_map/inlay_map.rs

@@ -11,7 +11,7 @@ use std::{
     sync::Arc,
 };
 use sum_tree::{Bias, Cursor, Dimensions, SumTree};
-use text::{Patch, Rope};
+use text::{ChunkBitmaps, Patch, Rope};
 use ui::{ActiveTheme, IntoElement as _, ParentElement as _, Styled as _, div};
 
 use super::{Highlights, custom_highlights::CustomHighlightsChunks, fold_map::ChunkRendererId};
@@ -245,8 +245,9 @@ pub struct InlayChunks<'a> {
     transforms: Cursor<'a, Transform, Dimensions<InlayOffset, usize>>,
     buffer_chunks: CustomHighlightsChunks<'a>,
     buffer_chunk: Option<Chunk<'a>>,
-    inlay_chunks: Option<text::Chunks<'a>>,
+    inlay_chunks: Option<text::ChunkWithBitmaps<'a>>,
-    inlay_chunk: Option<&'a str>,
+    /// text, char bitmap, tabs bitmap
+    inlay_chunk: Option<ChunkBitmaps<'a>>,
     output_offset: InlayOffset,
     max_output_offset: InlayOffset,
     highlight_styles: HighlightStyles,
@@ -316,11 +317,26 @@ impl<'a> Iterator for InlayChunks<'a> {
 
                 let (prefix, suffix) = chunk.text.split_at(split_index);
 
+                let (chars, tabs) = if split_index == 128 {
+                    let output = (chunk.chars, chunk.tabs);
+                    chunk.chars = 0;
+                    chunk.tabs = 0;
+                    output
+                } else {
+                    let mask = (1 << split_index) - 1;
+                    let output = (chunk.chars & mask, chunk.tabs & mask);
+                    chunk.chars = chunk.chars >> split_index;
+                    chunk.tabs = chunk.tabs >> split_index;
+                    output
+                };
                 chunk.text = suffix;
                 self.output_offset.0 += prefix.len();
+                // FIXME: chunk cloning is wrong because the bitmaps might be off
                 InlayChunk {
                     chunk: Chunk {
                         text: prefix,
+                        chars,
+                        tabs,
                         ..chunk.clone()
                     },
                     renderer: None,
@@ -397,9 +413,14 @@ impl<'a> Iterator for InlayChunks<'a> {
                     let start = offset_in_inlay;
                     let end = cmp::min(self.max_output_offset, self.transforms.end().0)
                         - self.transforms.start().0;
-                    inlay.text.chunks_in_range(start.0..end.0)
+                    let chunks = inlay.text.chunks_in_range(start.0..end.0);
+                    text::ChunkWithBitmaps(chunks)
                 });
-                let inlay_chunk = self
+                let ChunkBitmaps {
+                    text: inlay_chunk,
+                    chars,
+                    tabs,
+                } = self
                     .inlay_chunk
                     .get_or_insert_with(|| inlay_chunks.next().unwrap());
 
@@ -421,6 +442,20 @@ impl<'a> Iterator for InlayChunks<'a> {
 
                 let (chunk, remainder) = inlay_chunk.split_at(split_index);
                 *inlay_chunk = remainder;
+
+                let (chars, tabs) = if split_index == 128 {
+                    let output = (*chars, *tabs);
+                    *chars = 0;
+                    *tabs = 0;
+                    output
+                } else {
+                    let mask = (1 << split_index as u32) - 1;
+                    let output = (*chars & mask, *tabs & mask);
+                    *chars = *chars >> split_index;
+                    *tabs = *tabs >> split_index;
+                    output
+                };
+
                 if inlay_chunk.is_empty() {
                     self.inlay_chunk = None;
                 }
@@ -430,6 +465,8 @@ impl<'a> Iterator for InlayChunks<'a> {
                 InlayChunk {
                     chunk: Chunk {
                         text: chunk,
+                        chars,
+                        tabs,
                         highlight_style,
                         is_inlay: true,
                         ..Chunk::default()
@@ -1220,6 +1257,7 @@ mod tests {
     use std::{any::TypeId, cmp::Reverse, env, sync::Arc};
     use sum_tree::TreeMap;
     use text::Patch;
+    use util::RandomCharIter;
     use util::post_inc;
 
     #[test]
@@ -1962,6 +2000,102 @@ mod tests {
         }
     }
 
+    #[gpui::test(iterations = 100)]
+    fn test_random_chunk_bitmaps(cx: &mut gpui::App, mut rng: StdRng) {
+        init_test(cx);
+
+        // Generate random buffer using existing test infrastructure
+        let text_len = rng.gen_range(0..10000);
+        let buffer = if rng.r#gen() {
+            let text = RandomCharIter::new(&mut rng)
+                .take(text_len)
+                .collect::<String>();
+            MultiBuffer::build_simple(&text, cx)
+        } else {
+            MultiBuffer::build_random(&mut rng, cx)
+        };
+
+        let buffer_snapshot = buffer.read(cx).snapshot(cx);
+        let (mut inlay_map, _) = InlayMap::new(buffer_snapshot.clone());
+
+        // Perform random mutations to add inlays
+        let mut next_inlay_id = 0;
+        let mutation_count = rng.gen_range(1..10);
+        for _ in 0..mutation_count {
+            inlay_map.randomly_mutate(&mut next_inlay_id, &mut rng);
+        }
+
+        let (snapshot, _) = inlay_map.sync(buffer_snapshot, vec![]);
+
+        // Get all chunks and verify their bitmaps
+        let chunks = snapshot.chunks(
+            InlayOffset(0)..InlayOffset(snapshot.len().0),
+            false,
+            Highlights::default(),
+        );
+
+        for chunk in chunks.into_iter().map(|inlay_chunk| inlay_chunk.chunk) {
+            let chunk_text = chunk.text;
+            let chars_bitmap = chunk.chars;
+            let tabs_bitmap = chunk.tabs;
+
+            // Check empty chunks have empty bitmaps
+            if chunk_text.is_empty() {
+                assert_eq!(
+                    chars_bitmap, 0,
+                    "Empty chunk should have empty chars bitmap"
+                );
+                assert_eq!(tabs_bitmap, 0, "Empty chunk should have empty tabs bitmap");
+                continue;
+            }
+
+            // Verify that chunk text doesn't exceed 128 bytes
+            assert!(
+                chunk_text.len() <= 128,
+                "Chunk text length {} exceeds 128 bytes",
+                chunk_text.len()
+            );
+
+            // Verify chars bitmap
+            let char_indices = chunk_text
+                .char_indices()
+                .map(|(i, _)| i)
+                .collect::<Vec<_>>();
+
+            for byte_idx in 0..chunk_text.len() {
+                let should_have_bit = char_indices.contains(&byte_idx);
+                let has_bit = chars_bitmap & (1 << byte_idx) != 0;
+
+                if has_bit != should_have_bit {
+                    eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
+                    eprintln!("Char indices: {:?}", char_indices);
+                    eprintln!("Chars bitmap: {:#b}", chars_bitmap);
+                    assert_eq!(
+                        has_bit, should_have_bit,
+                        "Chars bitmap mismatch at byte index {} in chunk {:?}. Expected bit: {}, Got bit: {}",
+                        byte_idx, chunk_text, should_have_bit, has_bit
+                    );
+                }
+            }
+
+            // Verify tabs bitmap
+            for (byte_idx, byte) in chunk_text.bytes().enumerate() {
+                let is_tab = byte == b'\t';
+                let has_bit = tabs_bitmap & (1 << byte_idx) != 0;
+
+                if has_bit != is_tab {
+                    eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
+                    eprintln!("Tabs bitmap: {:#b}", tabs_bitmap);
+                    assert_eq!(
+                        has_bit, is_tab,
+                        "Tabs bitmap mismatch at byte index {} in chunk {:?}. Byte: {:?}, Expected bit: {}, Got bit: {}",
+                        byte_idx, chunk_text, byte as char, is_tab, has_bit
+                    );
+                }
+            }
+        }
+    }
+
     fn init_test(cx: &mut App) {
         let store = SettingsStore::test(cx);
         cx.set_global(store);

crates/editor/src/display_map/tab_map.rs

@@ -2,6 +2,7 @@ use super::{
     Highlights,
     fold_map::{self, Chunk, FoldChunks, FoldEdit, FoldPoint, FoldSnapshot},
 };
+
 use language::Point;
 use multi_buffer::MultiBufferSnapshot;
 use std::{cmp, mem, num::NonZeroU32, ops::Range};
@@ -72,6 +73,7 @@ impl TabMap {
                     false,
                     Highlights::default(),
                 ) {
+                    // todo!(performance use tabs bitmask)
                     for (ix, _) in chunk.text.match_indices('\t') {
                         let offset_from_edit = offset_from_edit + (ix as u32);
                         if first_tab_offset.is_none() {
@@ -299,21 +301,29 @@ impl TabSnapshot {
     }
 
     pub fn to_tab_point(&self, input: FoldPoint) -> TabPoint {
-        let chars = self.fold_snapshot.chars_at(FoldPoint::new(input.row(), 0));
+        let chunks = self.fold_snapshot.chunks_at(FoldPoint::new(input.row(), 0));
-        let expanded = self.expand_tabs(chars, input.column());
+        let tab_cursor = TabStopCursor::new(chunks);
+        let expanded = self.expand_tabs(tab_cursor, input.column());
         TabPoint::new(input.row(), expanded)
     }
 
     pub fn to_fold_point(&self, output: TabPoint, bias: Bias) -> (FoldPoint, u32, u32) {
-        let chars = self.fold_snapshot.chars_at(FoldPoint::new(output.row(), 0));
+        let chunks = self
+            .fold_snapshot
+            .chunks_at(FoldPoint::new(output.row(), 0));
+
+        let tab_cursor = TabStopCursor::new(chunks);
         let expanded = output.column();
         let (collapsed, expanded_char_column, to_next_stop) =
-            self.collapse_tabs(chars, expanded, bias);
+            self.collapse_tabs(tab_cursor, expanded, bias);
-        (
+
+        let result = (
             FoldPoint::new(output.row(), collapsed),
             expanded_char_column,
             to_next_stop,
-        )
+        );
+
+        result
     }
 
     pub fn make_tab_point(&self, point: Point, bias: Bias) -> TabPoint {
@@ -330,72 +340,80 @@ impl TabSnapshot {
             .to_buffer_point(inlay_point)
     }
 
-    fn expand_tabs(&self, chars: impl Iterator<Item = char>, column: u32) -> u32 {
+    /// todo!(performance use tabs bitmask)
+    fn expand_tabs(&self, mut cursor: TabStopCursor, column: u32) -> u32 {
         let tab_size = self.tab_size.get();
 
-        let mut expanded_chars = 0;
-        let mut expanded_bytes = 0;
-        let mut collapsed_bytes = 0;
         let end_column = column.min(self.max_expansion_column);
-        for c in chars {
+        let mut seek_target = end_column;
-            if collapsed_bytes >= end_column {
+        let mut tab_count = 0;
-                break;
+        let mut expanded_tab_len = 0;
-            }
+
-            if c == '\t' {
+        while let Some(tab_stop) = cursor.seek(seek_target) {
-                let tab_len = tab_size - expanded_chars % tab_size;
+            let expanded_chars_old = tab_stop.char_offset + expanded_tab_len - tab_count;
-                expanded_bytes += tab_len;
+            let tab_len = tab_size - ((expanded_chars_old - 1) % tab_size);
-                expanded_chars += tab_len;
+            tab_count += 1;
-            } else {
+            expanded_tab_len += tab_len;
-                expanded_bytes += c.len_utf8() as u32;
+
-                expanded_chars += 1;
+            seek_target = end_column - cursor.byte_offset;
-            }
-            collapsed_bytes += c.len_utf8() as u32;
         }
+
+        let left_over_char_bytes = if !cursor.is_char_boundary() {
+            cursor.bytes_until_next_char().unwrap_or(0) as u32
+        } else {
+            0
+        };
+
+        let collapsed_bytes = cursor.byte_offset() + left_over_char_bytes;
+        let expanded_bytes =
+            cursor.byte_offset() + expanded_tab_len - tab_count + left_over_char_bytes;
+
         expanded_bytes + column.saturating_sub(collapsed_bytes)
     }
 
-    fn collapse_tabs(
+    fn collapse_tabs(&self, mut cursor: TabStopCursor, column: u32, bias: Bias) -> (u32, u32, u32) {
-        &self,
-        chars: impl Iterator<Item = char>,
-        column: u32,
-        bias: Bias,
-    ) -> (u32, u32, u32) {
         let tab_size = self.tab_size.get();
+        let mut collapsed_column = column;
+        let mut seek_target = column.min(self.max_expansion_column);
+        let mut tab_count = 0;
+        let mut expanded_tab_len = 0;
 
-        let mut expanded_bytes = 0;
+        while let Some(tab_stop) = cursor.seek(seek_target) {
-        let mut expanded_chars = 0;
+            // Calculate how much we want to expand this tab stop (into spaces)
-        let mut collapsed_bytes = 0;
+            let expanded_chars_old = tab_stop.char_offset + expanded_tab_len - tab_count;
-        for c in chars {
+            let tab_len = tab_size - ((expanded_chars_old - 1) % tab_size);
-            if expanded_bytes >= column {
+            // Increment tab count
-                break;
+            tab_count += 1;
-            }
+            // The count of how many spaces we've added to this line in place of tab bytes
-            if collapsed_bytes >= self.max_expansion_column {
+            expanded_tab_len += tab_len;
-                break;
-            }
 
-            if c == '\t' {
+            // The count of bytes at this point in the iteration while considering tab_count and previous expansions
-                let tab_len = tab_size - (expanded_chars % tab_size);
+            let expanded_bytes = tab_stop.byte_offset + expanded_tab_len - tab_count;
-                expanded_chars += tab_len;
+
-                expanded_bytes += tab_len;
+            // Did we expand past the search target?
-                if expanded_bytes > column {
+            if expanded_bytes > column {
-                    expanded_chars -= expanded_bytes - column;
+                let mut expanded_chars = tab_stop.char_offset + expanded_tab_len - tab_count;
-                    return match bias {
+                // We expanded past the search target, so need to account for the offshoot
-                        Bias::Left => (collapsed_bytes, expanded_chars, expanded_bytes - column),
+                expanded_chars -= expanded_bytes - column;
-                        Bias::Right => (collapsed_bytes + 1, expanded_chars, 0),
+                return match bias {
-                    };
+                    Bias::Left => (
-                }
+                        cursor.byte_offset() - 1,
+                        expanded_chars,
+                        expanded_bytes - column,
+                    ),
+                    Bias::Right => (cursor.byte_offset(), expanded_chars, 0),
+                };
             } else {
-                expanded_chars += 1;
+                // otherwise we only want to move the cursor collapse column forward
-                expanded_bytes += c.len_utf8() as u32;
+                collapsed_column = collapsed_column - tab_len + 1;
+                seek_target = (collapsed_column - cursor.byte_offset)
+                    .min(self.max_expansion_column - cursor.byte_offset);
             }
-
-            if expanded_bytes > column && matches!(bias, Bias::Left) {
-                expanded_chars -= 1;
-                break;
-            }
-
-            collapsed_bytes += c.len_utf8() as u32;
         }
+
+        let collapsed_bytes = cursor.byte_offset();
+        let expanded_bytes = cursor.byte_offset() + expanded_tab_len - tab_count;
+        let expanded_chars = cursor.char_offset() + expanded_tab_len - tab_count;
         (
             collapsed_bytes + column.saturating_sub(expanded_bytes),
             expanded_chars,
@@ -523,6 +541,8 @@ impl TabChunks<'_> {
         self.chunk = Chunk {
             text: &SPACES[0..(to_next_stop as usize)],
             is_tab: true,
+            // todo!(check that this logic is correct)
+            chars: (1u128 << to_next_stop) - 1,
             ..Default::default()
         };
         self.inside_leading_tab = to_next_stop > 0;
@@ -546,18 +566,37 @@ impl<'a> Iterator for TabChunks<'a> {
             }
         }
 
+        //todo!(improve performance by using tab cursor)
         for (ix, c) in self.chunk.text.char_indices() {
             match c {
                 '\t' => {
                     if ix > 0 {
                         let (prefix, suffix) = self.chunk.text.split_at(ix);
+
+                        let (chars, tabs) = if ix == 128 {
+                            let output = (self.chunk.chars, self.chunk.tabs);
+                            self.chunk.chars = 0;
+                            self.chunk.tabs = 0;
+                            output
+                        } else {
+                            let mask = (1 << ix) - 1;
+                            let output = (self.chunk.chars & mask, self.chunk.tabs & mask);
+                            self.chunk.chars = self.chunk.chars >> ix;
+                            self.chunk.tabs = self.chunk.tabs >> ix;
+                            output
+                        };
+
                         self.chunk.text = suffix;
                         return Some(Chunk {
                             text: prefix,
+                            chars,
+                            tabs,
                             ..self.chunk.clone()
                         });
                     } else {
                         self.chunk.text = &self.chunk.text[1..];
+                        self.chunk.tabs >>= 1;
+                        self.chunk.chars >>= 1;
                         let tab_size = if self.input_column < self.max_expansion_column {
                             self.tab_size.get()
                         } else {
@@ -575,6 +614,8 @@ impl<'a> Iterator for TabChunks<'a> {
                         return Some(Chunk {
                             text: &SPACES[..len as usize],
                             is_tab: true,
+                            chars: (1 << len) - 1,
+                            tabs: 0,
                             ..self.chunk.clone()
                         });
                     }
@@ -603,21 +644,271 @@ mod tests {
     use super::*;
     use crate::{
         MultiBuffer,
-        display_map::{fold_map::FoldMap, inlay_map::InlayMap},
+        display_map::{
+            fold_map::{FoldMap, FoldOffset},
+            inlay_map::InlayMap,
+        },
     };
     use rand::{Rng, prelude::StdRng};
+    use util;
+
+    impl TabSnapshot {
+        fn expected_collapse_tabs(
+            &self,
+            chars: impl Iterator<Item = char>,
+            column: u32,
+            bias: Bias,
+        ) -> (u32, u32, u32) {
+            let tab_size = self.tab_size.get();
+
+            let mut expanded_bytes = 0;
+            let mut expanded_chars = 0;
+            let mut collapsed_bytes = 0;
+            for c in chars {
+                if expanded_bytes >= column {
+                    break;
+                }
+                if collapsed_bytes >= self.max_expansion_column {
+                    break;
+                }
+
+                if c == '\t' {
+                    let tab_len = tab_size - (expanded_chars % tab_size);
+                    expanded_chars += tab_len;
+                    expanded_bytes += tab_len;
+                    if expanded_bytes > column {
+                        expanded_chars -= expanded_bytes - column;
+                        return match bias {
+                            Bias::Left => {
+                                (collapsed_bytes, expanded_chars, expanded_bytes - column)
+                            }
+                            Bias::Right => (collapsed_bytes + 1, expanded_chars, 0),
+                        };
+                    }
+                } else {
+                    expanded_chars += 1;
+                    expanded_bytes += c.len_utf8() as u32;
+                }
+
+                if expanded_bytes > column && matches!(bias, Bias::Left) {
+                    expanded_chars -= 1;
+                    break;
+                }
+
+                collapsed_bytes += c.len_utf8() as u32;
+            }
+
+            (
+                collapsed_bytes + column.saturating_sub(expanded_bytes),
+                expanded_chars,
+                0,
+            )
+        }
+
+        pub fn expected_to_tab_point(&self, input: FoldPoint) -> TabPoint {
+            let chars = self.fold_snapshot.chars_at(FoldPoint::new(input.row(), 0));
+            let expanded = self.expected_expand_tabs(chars, input.column());
+            TabPoint::new(input.row(), expanded)
+        }
+
+        fn expected_expand_tabs(&self, chars: impl Iterator<Item = char>, column: u32) -> u32 {
+            let tab_size = self.tab_size.get();
+
+            let mut expanded_chars = 0;
+            let mut expanded_bytes = 0;
+            let mut collapsed_bytes = 0;
+            let end_column = column.min(self.max_expansion_column);
+            for c in chars {
+                if collapsed_bytes >= end_column {
+                    break;
+                }
+                if c == '\t' {
+                    let tab_len = tab_size - expanded_chars % tab_size;
+                    expanded_bytes += tab_len;
+                    expanded_chars += tab_len;
+                } else {
+                    expanded_bytes += c.len_utf8() as u32;
+                    expanded_chars += 1;
+                }
+                collapsed_bytes += c.len_utf8() as u32;
+            }
+
+            expanded_bytes + column.saturating_sub(collapsed_bytes)
+        }
+
+        fn expected_to_fold_point(&self, output: TabPoint, bias: Bias) -> (FoldPoint, u32, u32) {
+            let chars = self.fold_snapshot.chars_at(FoldPoint::new(output.row(), 0));
+            let expanded = output.column();
+            let (collapsed, expanded_char_column, to_next_stop) =
+                self.expected_collapse_tabs(chars, expanded, bias);
+            (
+                FoldPoint::new(output.row(), collapsed),
+                expanded_char_column,
+                to_next_stop,
+            )
+        }
+    }
 
     #[gpui::test]
     fn test_expand_tabs(cx: &mut gpui::App) {
+        let test_values = [
+            ("κg🏀 f\nwo🏀❌by🍐❎β🍗c\tβ❎ \ncλ🎉", 17),
+            (" \twςe", 4),
+            ("fε", 1),
+            ("i❎\t", 3),
+        ];
         let buffer = MultiBuffer::build_simple("", cx);
         let buffer_snapshot = buffer.read(cx).snapshot(cx);
         let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot);
         let (_, fold_snapshot) = FoldMap::new(inlay_snapshot);
         let (_, tab_snapshot) = TabMap::new(fold_snapshot, 4.try_into().unwrap());
 
-        assert_eq!(tab_snapshot.expand_tabs("\t".chars(), 0), 0);
+        for (text, column) in test_values {
-        assert_eq!(tab_snapshot.expand_tabs("\t".chars(), 1), 4);
+            let mut tabs = 0u128;
-        assert_eq!(tab_snapshot.expand_tabs("\ta".chars(), 2), 5);
+            let mut chars = 0u128;
+            for (idx, c) in text.char_indices() {
+                if c == '\t' {
+                    tabs |= 1 << idx;
+                }
+                chars |= 1 << idx;
+            }
+
+            let chunks = [Chunk {
+                text,
+                tabs,
+                chars,
+                ..Default::default()
+            }];
+
+            let cursor = TabStopCursor::new(chunks);
+
+            assert_eq!(
+                tab_snapshot.expected_expand_tabs(text.chars(), column),
+                tab_snapshot.expand_tabs(cursor, column)
+            );
+        }
+    }
+
+    #[gpui::test]
+    fn test_collapse_tabs(cx: &mut gpui::App) {
+        let input = "A\tBC\tDEF\tG\tHI\tJ\tK\tL\tM";
+
+        let buffer = MultiBuffer::build_simple(input, cx);
+        let buffer_snapshot = buffer.read(cx).snapshot(cx);
+        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
+        let (_, fold_snapshot) = FoldMap::new(inlay_snapshot);
+        let (_, tab_snapshot) = TabMap::new(fold_snapshot, 4.try_into().unwrap());
+
+        for (ix, _) in input.char_indices() {
+            let range = TabPoint::new(0, ix as u32)..tab_snapshot.max_point();
+
+            assert_eq!(
+                tab_snapshot.expected_to_fold_point(range.start, Bias::Left),
+                tab_snapshot.to_fold_point(range.start, Bias::Left),
+                "Failed with tab_point at column {ix}"
+            );
+            assert_eq!(
+                tab_snapshot.expected_to_fold_point(range.start, Bias::Right),
+                tab_snapshot.to_fold_point(range.start, Bias::Right),
+                "Failed with tab_point at column {ix}"
+            );
+
+            assert_eq!(
+                tab_snapshot.expected_to_fold_point(range.end, Bias::Left),
+                tab_snapshot.to_fold_point(range.end, Bias::Left),
+                "Failed with tab_point at column {ix}"
+            );
+            assert_eq!(
+                tab_snapshot.expected_to_fold_point(range.end, Bias::Right),
+                tab_snapshot.to_fold_point(range.end, Bias::Right),
+                "Failed with tab_point at column {ix}"
+            );
+        }
+    }
+
+    // todo!(We should have a randomized test here as well)
+    #[gpui::test]
+    fn test_to_fold_point_panic_reproduction(cx: &mut gpui::App) {
+        // This test reproduces a specific panic where to_fold_point returns incorrect results
+        let _text = "use macro_rules_attribute::apply;\nuse serde_json::Value;\nuse smol::{\n    io::AsyncReadExt,\n    process::{Command, Stdio},\n};\nuse smol_macros::main;\nuse std::io;\n\nfn test_random() {\n    // Generate a random value\n    let random_value = std::time::SystemTime::now()\n        .duration_since(std::time::UNIX_EPOCH)\n        .unwrap()\n        .as_secs()\n        % 100;\n\n    // Create some complex nested data structures\n    let mut vector = Vec::new();\n    for i in 0..random_value {\n        vector.push(i);\n    }\n    ";
+
+        let text = "γ\tw⭐\n🍐🍗 \t";
+        let buffer = MultiBuffer::build_simple(text, cx);
+        let buffer_snapshot = buffer.read(cx).snapshot(cx);
+        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
+        let (_, fold_snapshot) = FoldMap::new(inlay_snapshot);
+        let (_, tab_snapshot) = TabMap::new(fold_snapshot, 4.try_into().unwrap());
+
+        // This should panic with the expected vs actual mismatch
+        let tab_point = TabPoint::new(0, 9);
+        let result = tab_snapshot.to_fold_point(tab_point, Bias::Left);
+        let expected = tab_snapshot.expected_to_fold_point(tab_point, Bias::Left);
+
+        assert_eq!(result, expected);
+    }
+
+    #[gpui::test(iterations = 100)]
+    fn test_collapse_tabs_random(cx: &mut gpui::App, mut rng: StdRng) {
+        // Generate random input string with up to 200 characters including tabs
+        // to stay within the MAX_EXPANSION_COLUMN limit of 256
+        let len = rng.gen_range(0..=2048);
+        let tab_size = NonZeroU32::new(rng.gen_range(1..=4)).unwrap();
+        let mut input = String::with_capacity(len);
+
+        for _ in 0..len {
+            if rng.gen_bool(0.1) {
+                // 10% chance of inserting a tab
+                input.push('\t');
+            } else {
+                // 90% chance of inserting a random ASCII character (excluding tab, newline, carriage return)
+                let ch = loop {
+                    let ascii_code = rng.gen_range(32..=126); // printable ASCII range
+                    let ch = ascii_code as u8 as char;
+                    if ch != '\t' {
+                        break ch;
+                    }
+                };
+                input.push(ch);
+            }
+        }
+
+        let buffer = MultiBuffer::build_simple(&input, cx);
+        let buffer_snapshot = buffer.read(cx).snapshot(cx);
+        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
+        let (_, fold_snapshot) = FoldMap::new(inlay_snapshot);
+        let (_, mut tab_snapshot) = TabMap::new(fold_snapshot, 4.try_into().unwrap());
+        tab_snapshot.max_expansion_column = rng.gen_range(0..323);
+        tab_snapshot.tab_size = tab_size;
+
+        for (ix, _) in input.char_indices() {
+            let range = TabPoint::new(0, ix as u32)..tab_snapshot.max_point();
+
+            assert_eq!(
+                tab_snapshot.expected_to_fold_point(range.start, Bias::Left),
+                tab_snapshot.to_fold_point(range.start, Bias::Left),
+                "Failed with input: {}, with idx: {ix}",
+                input
+            );
+            assert_eq!(
+                tab_snapshot.expected_to_fold_point(range.start, Bias::Right),
+                tab_snapshot.to_fold_point(range.start, Bias::Right),
+                "Failed with input: {}, with idx: {ix}",
+                input
+            );
+
+            assert_eq!(
+                tab_snapshot.expected_to_fold_point(range.end, Bias::Left),
+                tab_snapshot.to_fold_point(range.end, Bias::Left),
+                "Failed with input: {}, with idx: {ix}",
+                input
+            );
+            assert_eq!(
+                tab_snapshot.expected_to_fold_point(range.end, Bias::Right),
+                tab_snapshot.to_fold_point(range.end, Bias::Right),
+                "Failed with input: {}, with idx: {ix}",
+                input
+            );
+        }
     }
 
     #[gpui::test]
@@ -811,4 +1102,475 @@ mod tests {
             );
         }
     }
+
+    #[gpui::test(iterations = 100)]
+    fn test_to_tab_point_random(cx: &mut gpui::App, mut rng: StdRng) {
+        let tab_size = NonZeroU32::new(rng.gen_range(1..=16)).unwrap();
+        let len = rng.gen_range(0..=2000);
+
+        // Generate random text using RandomCharIter
+        let text = util::RandomCharIter::new(&mut rng)
+            .take(len)
+            .collect::<String>();
+
+        // Create buffer and tab map
+        let buffer = MultiBuffer::build_simple(&text, cx);
+        let buffer_snapshot = buffer.read(cx).snapshot(cx);
+        let (mut inlay_map, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
+        let (mut fold_map, fold_snapshot) = FoldMap::new(inlay_snapshot);
+        let (mut tab_map, _) = TabMap::new(fold_snapshot.clone(), tab_size);
+
+        let mut next_inlay_id = 0;
+        let (inlay_snapshot, inlay_edits) = inlay_map.randomly_mutate(&mut next_inlay_id, &mut rng);
+        let (fold_snapshot, fold_edits) = fold_map.read(inlay_snapshot, inlay_edits);
+        let max_fold_point = fold_snapshot.max_point();
+        let (mut tab_snapshot, _) = tab_map.sync(fold_snapshot.clone(), fold_edits, tab_size);
+
+        // Test random fold points
+        for _ in 0..50 {
+            tab_snapshot.max_expansion_column = rng.gen_range(0..=256);
+            // Generate random fold point
+            let row = rng.gen_range(0..=max_fold_point.row());
+            let max_column = if row < max_fold_point.row() {
+                fold_snapshot.line_len(row)
+            } else {
+                max_fold_point.column()
+            };
+            let column = rng.gen_range(0..=max_column + 10);
+            let fold_point = FoldPoint::new(row, column);
+
+            let actual = tab_snapshot.to_tab_point(fold_point);
+            let expected = tab_snapshot.expected_to_tab_point(fold_point);
+
+            assert_eq!(
+                actual, expected,
+                "to_tab_point mismatch for fold_point {:?} in text {:?}",
+                fold_point, text
+            );
+        }
+    }
+
+    #[gpui::test]
+    fn test_tab_stop_cursor_utf8(cx: &mut gpui::App) {
+        let text = "\tfoo\tbarbarbar\t\tbaz\n";
+        let buffer = MultiBuffer::build_simple(text, cx);
+        let buffer_snapshot = buffer.read(cx).snapshot(cx);
+        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
+        let (_, fold_snapshot) = FoldMap::new(inlay_snapshot);
+        let chunks = fold_snapshot.chunks(
+            FoldOffset(0)..fold_snapshot.len(),
+            false,
+            Default::default(),
+        );
+        let mut cursor = TabStopCursor::new(chunks);
+        assert!(cursor.seek(0).is_none());
+        let mut tab_stops = Vec::new();
+
+        let mut all_tab_stops = Vec::new();
+        let mut byte_offset = 0;
+        for (offset, ch) in buffer.read(cx).snapshot(cx).text().char_indices() {
+            byte_offset += ch.len_utf8() as u32;
+
+            if ch == '\t' {
+                all_tab_stops.push(TabStop {
+                    byte_offset,
+                    char_offset: offset as u32 + 1,
+                });
+            }
+        }
+
+        while let Some(tab_stop) = cursor.seek(u32::MAX) {
+            tab_stops.push(tab_stop);
+        }
+        pretty_assertions::assert_eq!(tab_stops.as_slice(), all_tab_stops.as_slice(),);
+
+        assert_eq!(cursor.byte_offset(), byte_offset);
+    }
+
+    #[gpui::test]
+    fn test_tab_stop_with_end_range_utf8(cx: &mut gpui::App) {
+        let input = "A\tBC\t"; // DEF\tG\tHI\tJ\tK\tL\tM
+
+        let buffer = MultiBuffer::build_simple(input, cx);
+        let buffer_snapshot = buffer.read(cx).snapshot(cx);
+        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
+        let (_, fold_snapshot) = FoldMap::new(inlay_snapshot);
+
+        let chunks = fold_snapshot.chunks_at(FoldPoint::new(0, 0));
+        let mut cursor = TabStopCursor::new(chunks);
+
+        let mut actual_tab_stops = Vec::new();
+
+        let mut expected_tab_stops = Vec::new();
+        let mut byte_offset = 0;
+        for (offset, ch) in buffer.read(cx).snapshot(cx).text().char_indices() {
+            byte_offset += ch.len_utf8() as u32;
+
+            if ch == '\t' {
+                expected_tab_stops.push(TabStop {
+                    byte_offset,
+                    char_offset: offset as u32 + 1,
+                });
+            }
+        }
+
+        while let Some(tab_stop) = cursor.seek(u32::MAX) {
+            actual_tab_stops.push(tab_stop);
+        }
+        pretty_assertions::assert_eq!(actual_tab_stops.as_slice(), expected_tab_stops.as_slice(),);
+
+        assert_eq!(cursor.byte_offset(), byte_offset);
+    }
+
+    #[gpui::test(iterations = 100)]
+    fn test_tab_stop_cursor_random_utf8(cx: &mut gpui::App, mut rng: StdRng) {
+        // Generate random input string with up to 512 characters including tabs
+        let len = rng.gen_range(0..=2048);
+        let mut input = String::with_capacity(len);
+
+        let mut skip_tabs = rng.gen_bool(0.10);
+        for idx in 0..len {
+            if idx % 128 == 0 {
+                skip_tabs = rng.gen_bool(0.10);
+            }
+
+            if rng.gen_bool(0.15) && !skip_tabs {
+                input.push('\t');
+            } else {
+                let ch = loop {
+                    let ascii_code = rng.gen_range(32..=126); // printable ASCII range
+                    let ch = ascii_code as u8 as char;
+                    if ch != '\t' {
+                        break ch;
+                    }
+                };
+                input.push(ch);
+            }
+        }
+
+        // Build the buffer and create cursor
+        let buffer = MultiBuffer::build_simple(&input, cx);
+        let buffer_snapshot = buffer.read(cx).snapshot(cx);
+        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
+        let (_, fold_snapshot) = FoldMap::new(inlay_snapshot);
+
+        // First, collect all expected tab positions
+        let mut all_tab_stops = Vec::new();
+        let mut byte_offset = 1;
+        let mut char_offset = 1;
+        for ch in buffer_snapshot.text().chars() {
+            if ch == '\t' {
+                all_tab_stops.push(TabStop {
+                    byte_offset,
+                    char_offset,
+                });
+            }
+            byte_offset += ch.len_utf8() as u32;
+            char_offset += 1;
+        }
+
+        // Test with various distances
+        let distances = vec![1, 5, 10, 50, 100, u32::MAX];
+        // let distances = vec![150];
+
+        for distance in distances {
+            let chunks = fold_snapshot.chunks_at(FoldPoint::new(0, 0));
+            let mut cursor = TabStopCursor::new(chunks);
+
+            let mut found_tab_stops = Vec::new();
+            let mut position = distance;
+            while let Some(tab_stop) = cursor.seek(position) {
+                found_tab_stops.push(tab_stop);
+                position = distance - tab_stop.byte_offset;
+            }
+
+            let expected_found_tab_stops: Vec<_> = all_tab_stops
+                .iter()
+                .take_while(|tab_stop| tab_stop.byte_offset <= distance)
+                .cloned()
+                .collect();
+
+            pretty_assertions::assert_eq!(
+                found_tab_stops,
+                expected_found_tab_stops,
+                "TabStopCursor output mismatch for distance {}. Input: {:?}",
+                distance,
+                input
+            );
+
+            let final_position = cursor.byte_offset();
+            if !found_tab_stops.is_empty() {
+                let last_tab_stop = found_tab_stops.last().unwrap();
+                assert!(
+                    final_position >= last_tab_stop.byte_offset,
+                    "Cursor final position {} is before last tab stop {}. Input: {:?}",
+                    final_position,
+                    last_tab_stop.byte_offset,
+                    input
+                );
+            }
+        }
+    }
+
+    #[gpui::test]
+    fn test_tab_stop_cursor_utf16(cx: &mut gpui::App) {
+        let text = "\r\t😁foo\tb😀arbar🤯bar\t\tbaz\n";
+        let buffer = MultiBuffer::build_simple(text, cx);
+        let buffer_snapshot = buffer.read(cx).snapshot(cx);
+        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
+        let (_, fold_snapshot) = FoldMap::new(inlay_snapshot);
+        let chunks = fold_snapshot.chunks(
+            FoldOffset(0)..fold_snapshot.len(),
+            false,
+            Default::default(),
+        );
+        let mut cursor = TabStopCursor::new(chunks);
+        assert!(cursor.seek(0).is_none());
+
+        let mut expected_tab_stops = Vec::new();
+        let mut byte_offset = 0;
+        for (i, ch) in fold_snapshot.chars_at(FoldPoint::new(0, 0)).enumerate() {
+            byte_offset += ch.len_utf8() as u32;
+
+            if ch == '\t' {
+                expected_tab_stops.push(TabStop {
+                    byte_offset,
+                    char_offset: i as u32 + 1,
+                });
+            }
+        }
+
+        let mut actual_tab_stops = Vec::new();
+        while let Some(tab_stop) = cursor.seek(u32::MAX) {
+            actual_tab_stops.push(tab_stop);
+        }
+
+        pretty_assertions::assert_eq!(actual_tab_stops.as_slice(), expected_tab_stops.as_slice(),);
+
+        assert_eq!(cursor.byte_offset(), byte_offset);
+    }
+
+    #[gpui::test(iterations = 100)]
+    fn test_tab_stop_cursor_random_utf16(cx: &mut gpui::App, mut rng: StdRng) {
+        // Generate random input string with up to 512 characters including tabs
+        let len = rng.gen_range(0..=2048);
+        let input = util::RandomCharIter::new(&mut rng)
+            .take(len)
+            .collect::<String>();
+
+        // Build the buffer and create cursor
+        let buffer = MultiBuffer::build_simple(&input, cx);
+        let buffer_snapshot = buffer.read(cx).snapshot(cx);
+        let (_, inlay_snapshot) = InlayMap::new(buffer_snapshot.clone());
+        let (_, fold_snapshot) = FoldMap::new(inlay_snapshot);
+
+        // First, collect all expected tab positions
+        let mut all_tab_stops = Vec::new();
+        let mut byte_offset = 0;
+        for (i, ch) in buffer_snapshot.text().chars().enumerate() {
+            byte_offset += ch.len_utf8() as u32;
+            if ch == '\t' {
+                all_tab_stops.push(TabStop {
+                    byte_offset,
+                    char_offset: i as u32 + 1,
+                });
+            }
+        }
+
+        // Test with various distances
+        // let distances = vec![1, 5, 10, 50, 100, u32::MAX];
+        let distances = vec![150];
+
+        for distance in distances {
+            let chunks = fold_snapshot.chunks_at(FoldPoint::new(0, 0));
+            let mut cursor = TabStopCursor::new(chunks);
+
+            let mut found_tab_stops = Vec::new();
+            let mut position = distance;
+            while let Some(tab_stop) = cursor.seek(position) {
+                found_tab_stops.push(tab_stop);
+                position = distance - tab_stop.byte_offset;
+            }
+
+            let expected_found_tab_stops: Vec<_> = all_tab_stops
+                .iter()
+                .take_while(|tab_stop| tab_stop.byte_offset <= distance)
+                .cloned()
+                .collect();
+
+            pretty_assertions::assert_eq!(
+                found_tab_stops,
+                expected_found_tab_stops,
+                "TabStopCursor output mismatch for distance {}. Input: {:?}",
+                distance,
+                input
+            );
+
+            let final_position = cursor.byte_offset();
+            if !found_tab_stops.is_empty() {
+                let last_tab_stop = found_tab_stops.last().unwrap();
+                assert!(
+                    final_position >= last_tab_stop.byte_offset,
+                    "Cursor final position {} is before last tab stop {}. Input: {:?}",
+                    final_position,
+                    last_tab_stop.byte_offset,
+                    input
+                );
+            }
+        }
+    }
+}
+
+struct TabStopCursor<'a> {
+    chunks: Box<dyn Iterator<Item = Chunk<'a>> + 'a>,
+    byte_offset: u32,
+    char_offset: u32,
+    /// Chunk
+    /// last tab position iterated through
+    current_chunk: Option<(Chunk<'a>, u32)>,
+}
+
+impl<'a> TabStopCursor<'a> {
+    fn new(chunks: impl IntoIterator<Item = Chunk<'a>> + 'a) -> Self {
+        Self {
+            chunks: Box::new(chunks.into_iter()),
+            byte_offset: 0,
+            char_offset: 0,
+            current_chunk: None,
+        }
+    }
+
+    fn bytes_until_next_char(&self) -> Option<usize> {
+        self.current_chunk.as_ref().and_then(|(chunk, idx)| {
+            let mut idx = *idx;
+            let mut diff = 0;
+            while idx > 0 && chunk.chars & (1 << idx) == 0 {
+                idx -= 1;
+                diff += 1;
+            }
+
+            if chunk.chars & (1 << idx) != 0 {
+                Some(
+                    (chunk.text[idx as usize..].chars().next()?)
+                        .len_utf8()
+                        .saturating_sub(diff),
+                )
+            } else {
+                None
+            }
+        })
+    }
+
+    fn is_char_boundary(&self) -> bool {
+        // FIXME: if idx is 128 should we return false or be at the next chunk?
+        // idx might also be 1-indexed instead of 0-indexed, need to double check
+        self.current_chunk
+            .as_ref()
+            .is_some_and(|(chunk, idx)| (chunk.chars & (1 << *idx.min(&127))) != 0)
+    }
+
+    /// distance: length to move forward while searching for the next tab stop
+    fn seek(&mut self, distance: u32) -> Option<TabStop> {
+        if distance == 0 {
+            return None;
+        }
+
+        let mut distance_traversed = 0;
+
+        while let Some((mut chunk, chunk_position)) = self
+            .current_chunk
+            .take()
+            .or_else(|| self.chunks.next().zip(Some(0)))
+        {
+            if chunk.tabs == 0 {
+                let chunk_distance = chunk.text.len() as u32 - chunk_position;
+                if chunk_distance + distance_traversed >= distance {
+                    let overshoot = distance_traversed.abs_diff(distance);
+
+                    self.byte_offset += overshoot;
+                    self.char_offset += get_char_offset(
+                        chunk_position..(chunk_position + overshoot).saturating_sub(1).min(127),
+                        chunk.chars,
+                    );
+
+                    self.current_chunk = Some((chunk, chunk_position + overshoot));
+
+                    return None;
+                }
+
+                self.byte_offset += chunk_distance;
+                self.char_offset += get_char_offset(
+                    chunk_position..(chunk_position + chunk_distance).saturating_sub(1).min(127),
+                    chunk.chars,
+                );
+                distance_traversed += chunk_distance;
+                continue;
+            }
+            let tab_position = chunk.tabs.trailing_zeros() + 1;
+
+            if distance_traversed + tab_position - chunk_position > distance {
+                let cursor_position = distance_traversed.abs_diff(distance);
+
+                self.char_offset += get_char_offset(
+                    chunk_position..(chunk_position + cursor_position - 1),
+                    chunk.chars,
+                );
+                self.current_chunk = Some((chunk, cursor_position + chunk_position));
+                self.byte_offset += cursor_position;
+
+                return None;
+            }
+
+            self.byte_offset += tab_position - chunk_position;
+            self.char_offset += get_char_offset(chunk_position..(tab_position - 1), chunk.chars);
+
+            let tabstop = TabStop {
+                char_offset: self.char_offset,
+                byte_offset: self.byte_offset,
+            };
+
+            chunk.tabs = (chunk.tabs - 1) & chunk.tabs;
+
+            if tab_position as usize != chunk.text.len() {
+                self.current_chunk = Some((chunk, tab_position));
+            }
+
+            return Some(tabstop);
+        }
+
+        None
+    }
+
+    fn byte_offset(&self) -> u32 {
+        self.byte_offset
+    }
+
+    fn char_offset(&self) -> u32 {
+        self.char_offset
+    }
+}
+
+#[inline(always)]
+fn get_char_offset(range: Range<u32>, bit_map: u128) -> u32 {
+    // This edge case can happen when we're at chunk position 128
+
+    if range.start == range.end {
+        return if (1u128 << range.start) & bit_map == 0 {
+            0
+        } else {
+            1
+        };
+    }
+    let end_shift: u128 = 127u128 - range.end.min(127) as u128;
+    let mut bit_mask = (u128::MAX >> range.start) << range.start;
+    bit_mask = (bit_mask << end_shift) >> end_shift;
+    let bit_map = bit_map & bit_mask;
+
+    bit_map.count_ones()
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+struct TabStop {
+    char_offset: u32,
+    byte_offset: u32,
 }

crates/editor/src/display_map/wrap_map.rs

@@ -970,9 +970,25 @@ impl<'a> Iterator for WrapChunks<'a> {
         }
 
         let (prefix, suffix) = self.input_chunk.text.split_at(input_len);
+
+        let (chars, tabs) = if input_len == 128 {
+            let output = (self.input_chunk.chars, self.input_chunk.tabs);
+            self.input_chunk.chars = 0;
+            self.input_chunk.tabs = 0;
+            output
+        } else {
+            let mask = (1 << input_len) - 1;
+            let output = (self.input_chunk.chars & mask, self.input_chunk.tabs & mask);
+            self.input_chunk.chars = self.input_chunk.chars >> input_len;
+            self.input_chunk.tabs = self.input_chunk.tabs >> input_len;
+            output
+        };
+
         self.input_chunk.text = suffix;
         Some(Chunk {
             text: prefix,
+            chars,
+            tabs,
             ..self.input_chunk.clone()
         })
     }

crates/editor/src/editor.rs

@@ -18424,12 +18424,7 @@ impl Editor {
     }
 
     /// called by the Element so we know what style we were most recently rendered with.
-    pub(crate) fn set_style(
+    pub fn set_style(&mut self, style: EditorStyle, window: &mut Window, cx: &mut Context<Self>) {
-        &mut self,
-        style: EditorStyle,
-        window: &mut Window,
-        cx: &mut Context<Self>,
-    ) {
         // We intentionally do not inform the display map about the minimap style
         // so that wrapping is not recalculated and stays consistent for the editor
         // and its linked minimap.

crates/language/src/buffer.rs

@@ -27,6 +27,7 @@ use gpui::{
     App, AppContext as _, Context, Entity, EventEmitter, HighlightStyle, SharedString, StyledText,
     Task, TaskLabel, TextStyle,
 };
+
 use lsp::{LanguageServerId, NumberOrString};
 use parking_lot::Mutex;
 use schemars::JsonSchema;
@@ -494,6 +495,10 @@ pub struct Chunk<'a> {
     pub is_unnecessary: bool,
     /// Whether this chunk of text was originally a tab character.
     pub is_tab: bool,
+    /// A bitset of which characters are tabs in this string.
+    pub tabs: u128,
+    /// Bitmap of character indices in this chunk
+    pub chars: u128,
     /// Whether this chunk of text was originally a tab character.
     pub is_inlay: bool,
     /// Whether to underline the corresponding text range in the editor.
@@ -4772,7 +4777,12 @@ impl<'a> Iterator for BufferChunks<'a> {
         }
         self.diagnostic_endpoints = diagnostic_endpoints;
 
-        if let Some(chunk) = self.chunks.peek() {
+        if let Some(ChunkBitmaps {
+            text: chunk,
+            chars: chars_map,
+            tabs,
+        }) = self.chunks.peek_tabs()
+        {
             let chunk_start = self.range.start;
             let mut chunk_end = (self.chunks.offset() + chunk.len())
                 .min(next_capture_start)
@@ -4787,6 +4797,16 @@ impl<'a> Iterator for BufferChunks<'a> {
 
             let slice =
                 &chunk[chunk_start - self.chunks.offset()..chunk_end - self.chunks.offset()];
+            let bit_end = chunk_end - self.chunks.offset();
+
+            let mask = if bit_end >= 128 {
+                u128::MAX
+            } else {
+                (1u128 << bit_end) - 1
+            };
+            let tabs = (tabs >> (chunk_start - self.chunks.offset())) & mask;
+            let chars_map = (chars_map >> (chunk_start - self.chunks.offset())) & mask;
+
             self.range.start = chunk_end;
             if self.range.start == self.chunks.offset() + chunk.len() {
                 self.chunks.next().unwrap();
@@ -4798,6 +4818,8 @@ impl<'a> Iterator for BufferChunks<'a> {
                 underline: self.underline,
                 diagnostic_severity: self.current_diagnostic_severity(),
                 is_unnecessary: self.current_code_is_unnecessary(),
+                tabs,
+                chars: chars_map,
                 ..Chunk::default()
             })
         } else {

crates/language/src/buffer_tests.rs

@@ -3787,3 +3787,80 @@ fn init_settings(cx: &mut App, f: fn(&mut AllLanguageSettingsContent)) {
         settings.update_user_settings::<AllLanguageSettings>(cx, f);
     });
 }
+
+#[gpui::test(iterations = 100)]
+fn test_random_chunk_bitmaps(cx: &mut App, mut rng: StdRng) {
+    use util::RandomCharIter;
+
+    // Generate random text
+    let len = rng.gen_range(0..10000);
+    let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
+
+    let buffer = cx.new(|cx| Buffer::local(text, cx));
+    let snapshot = buffer.read(cx).snapshot();
+
+    // Get all chunks and verify their bitmaps
+    let chunks = snapshot.chunks(0..snapshot.len(), false);
+
+    for chunk in chunks {
+        let chunk_text = chunk.text;
+        let chars_bitmap = chunk.chars;
+        let tabs_bitmap = chunk.tabs;
+
+        // Check empty chunks have empty bitmaps
+        if chunk_text.is_empty() {
+            assert_eq!(
+                chars_bitmap, 0,
+                "Empty chunk should have empty chars bitmap"
+            );
+            assert_eq!(tabs_bitmap, 0, "Empty chunk should have empty tabs bitmap");
+            continue;
+        }
+
+        // Verify that chunk text doesn't exceed 128 bytes
+        assert!(
+            chunk_text.len() <= 128,
+            "Chunk text length {} exceeds 128 bytes",
+            chunk_text.len()
+        );
+
+        // Verify chars bitmap
+        let char_indices = chunk_text
+            .char_indices()
+            .map(|(i, _)| i)
+            .collect::<Vec<_>>();
+
+        for byte_idx in 0..chunk_text.len() {
+            let should_have_bit = char_indices.contains(&byte_idx);
+            let has_bit = chars_bitmap & (1 << byte_idx) != 0;
+
+            if has_bit != should_have_bit {
+                eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
+                eprintln!("Char indices: {:?}", char_indices);
+                eprintln!("Chars bitmap: {:#b}", chars_bitmap);
+            }
+
+            assert_eq!(
+                has_bit, should_have_bit,
+                "Chars bitmap mismatch at byte index {} in chunk {:?}. Expected bit: {}, Got bit: {}",
+                byte_idx, chunk_text, should_have_bit, has_bit
+            );
+        }
+
+        // Verify tabs bitmap
+        for (byte_idx, byte) in chunk_text.bytes().enumerate() {
+            let is_tab = byte == b'\t';
+            let has_bit = tabs_bitmap & (1 << byte_idx) != 0;
+
+            if has_bit != is_tab {
+                eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
+                eprintln!("Tabs bitmap: {:#b}", tabs_bitmap);
+                assert_eq!(
+                    has_bit, is_tab,
+                    "Tabs bitmap mismatch at byte index {} in chunk {:?}. Byte: {:?}, Expected bit: {}, Got bit: {}",
+                    byte_idx, chunk_text, byte as char, is_tab, has_bit
+                );
+            }
+        }
+    }
+}

crates/language_tools/src/lsp_log.rs

@@ -433,7 +433,7 @@ impl LogStore {
             log_lines,
             id,
             LogMessage {
-                message: message.trim_end().to_string(),
+                message: message.trim().to_string(),
                 typ,
             },
             language_server_state.log_level,

crates/languages/src/typescript.rs

@@ -780,8 +780,8 @@ pub struct EsLintLspAdapter {
 }
 
 impl EsLintLspAdapter {
-    const CURRENT_VERSION: &'static str = "2.4.4";
+    const CURRENT_VERSION: &'static str = "3.0.10";
-    const CURRENT_VERSION_TAG_NAME: &'static str = "release/2.4.4";
+    const CURRENT_VERSION_TAG_NAME: &'static str = "release/3.0.10";
 
     #[cfg(not(windows))]
     const GITHUB_ASSET_KIND: AssetKind = AssetKind::TarGz;

crates/multi_buffer/src/multi_buffer.rs

@@ -7723,12 +7723,24 @@ impl<'a> Iterator for MultiBufferChunks<'a> {
                 let diff_transform_end = diff_transform_end.min(self.range.end);
 
                 if diff_transform_end < chunk_end {
-                    let (before, after) =
+                    let split_idx = diff_transform_end - self.range.start;
-                        chunk.text.split_at(diff_transform_end - self.range.start);
+                    let (before, after) = chunk.text.split_at(split_idx);
                     self.range.start = diff_transform_end;
+                    let mask = (1 << split_idx) - 1;
+                    let chars = chunk.chars & mask;
+                    let tabs = chunk.tabs & mask;
+
                     chunk.text = after;
+                    chunk.chars = chunk.chars >> split_idx;
+                    chunk.tabs = chunk.tabs >> split_idx;
+
+                    // FIXME: We should be handling bitmap for tabs and chars here
+                    // Because we do a split at operation the bitmaps will be off
+
                     Some(Chunk {
                         text: before,
+                        chars,
+                        tabs,
                         ..chunk.clone()
                     })
                 } else {
@@ -7772,6 +7784,7 @@ impl<'a> Iterator for MultiBufferChunks<'a> {
                     self.range.start += "\n".len();
                     Chunk {
                         text: "\n",
+                        chars: 1u128,
                         ..Default::default()
                     }
                 };
@@ -7868,9 +7881,11 @@ impl<'a> Iterator for ExcerptChunks<'a> {
 
         if self.footer_height > 0 {
             let text = unsafe { str::from_utf8_unchecked(&NEWLINES[..self.footer_height]) };
+            let chars = (1 << self.footer_height) - 1;
             self.footer_height = 0;
             return Some(Chunk {
                 text,
+                chars,
                 ..Default::default()
             });
         }

crates/multi_buffer/src/multi_buffer_tests.rs

@@ -7,6 +7,7 @@ use parking_lot::RwLock;
 use rand::prelude::*;
 use settings::SettingsStore;
 use std::env;
+use util::RandomCharIter;
 use util::test::sample_text;
 
 #[ctor::ctor]
@@ -3712,3 +3713,235 @@ fn test_new_empty_buffers_title_can_be_set(cx: &mut App) {
     });
     assert_eq!(multibuffer.read(cx).title(cx), "Hey");
 }
+
+#[gpui::test(iterations = 100)]
+fn test_random_chunk_bitmaps(cx: &mut App, mut rng: StdRng) {
+    let multibuffer = if rng.r#gen() {
+        let len = rng.gen_range(0..10000);
+        let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
+        let buffer = cx.new(|cx| Buffer::local(text, cx));
+        cx.new(|cx| MultiBuffer::singleton(buffer, cx))
+    } else {
+        MultiBuffer::build_random(&mut rng, cx)
+    };
+
+    let snapshot = multibuffer.read(cx).snapshot(cx);
+
+    let chunks = snapshot.chunks(0..snapshot.len(), false);
+
+    for chunk in chunks {
+        let chunk_text = chunk.text;
+        let chars_bitmap = chunk.chars;
+        let tabs_bitmap = chunk.tabs;
+
+        if chunk_text.is_empty() {
+            assert_eq!(
+                chars_bitmap, 0,
+                "Empty chunk should have empty chars bitmap"
+            );
+            assert_eq!(tabs_bitmap, 0, "Empty chunk should have empty tabs bitmap");
+            continue;
+        }
+
+        assert!(
+            chunk_text.len() <= 128,
+            "Chunk text length {} exceeds 128 bytes",
+            chunk_text.len()
+        );
+
+        // Verify chars bitmap
+        let char_indices = chunk_text
+            .char_indices()
+            .map(|(i, _)| i)
+            .collect::<Vec<_>>();
+
+        for byte_idx in 0..chunk_text.len() {
+            let should_have_bit = char_indices.contains(&byte_idx);
+            let has_bit = chars_bitmap & (1 << byte_idx) != 0;
+
+            if has_bit != should_have_bit {
+                eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
+                eprintln!("Char indices: {:?}", char_indices);
+                eprintln!("Chars bitmap: {:#b}", chars_bitmap);
+            }
+
+            assert_eq!(
+                has_bit, should_have_bit,
+                "Chars bitmap mismatch at byte index {} in chunk {:?}. Expected bit: {}, Got bit: {}",
+                byte_idx, chunk_text, should_have_bit, has_bit
+            );
+        }
+
+        for (byte_idx, byte) in chunk_text.bytes().enumerate() {
+            let is_tab = byte == b'\t';
+            let has_bit = tabs_bitmap & (1 << byte_idx) != 0;
+
+            if has_bit != is_tab {
+                eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
+                eprintln!("Tabs bitmap: {:#b}", tabs_bitmap);
+                assert_eq!(
+                    has_bit, is_tab,
+                    "Tabs bitmap mismatch at byte index {} in chunk {:?}. Byte: {:?}, Expected bit: {}, Got bit: {}",
+                    byte_idx, chunk_text, byte as char, is_tab, has_bit
+                );
+            }
+        }
+    }
+}
+
+#[gpui::test(iterations = 100)]
+fn test_random_chunk_bitmaps_with_diffs(cx: &mut App, mut rng: StdRng) {
+    use buffer_diff::BufferDiff;
+    use util::RandomCharIter;
+
+    let multibuffer = if rng.r#gen() {
+        let len = rng.gen_range(100..10000);
+        let text = RandomCharIter::new(&mut rng).take(len).collect::<String>();
+        let buffer = cx.new(|cx| Buffer::local(text, cx));
+        cx.new(|cx| MultiBuffer::singleton(buffer, cx))
+    } else {
+        MultiBuffer::build_random(&mut rng, cx)
+    };
+
+    let _diff_count = rng.gen_range(1..5);
+    let mut diffs = Vec::new();
+
+    multibuffer.update(cx, |multibuffer, cx| {
+        for buffer_id in multibuffer.excerpt_buffer_ids() {
+            if rng.gen_bool(0.7) {
+                if let Some(buffer_handle) = multibuffer.buffer(buffer_id) {
+                    let buffer_text = buffer_handle.read(cx).text();
+                    let mut base_text = String::new();
+
+                    for line in buffer_text.lines() {
+                        if rng.gen_bool(0.3) {
+                            continue;
+                        } else if rng.gen_bool(0.3) {
+                            let line_len = rng.gen_range(0..50);
+                            let modified_line = RandomCharIter::new(&mut rng)
+                                .take(line_len)
+                                .collect::<String>();
+                            base_text.push_str(&modified_line);
+                            base_text.push('\n');
+                        } else {
+                            base_text.push_str(line);
+                            base_text.push('\n');
+                        }
+                    }
+
+                    if rng.gen_bool(0.5) {
+                        let extra_lines = rng.gen_range(1..5);
+                        for _ in 0..extra_lines {
+                            let line_len = rng.gen_range(0..50);
+                            let extra_line = RandomCharIter::new(&mut rng)
+                                .take(line_len)
+                                .collect::<String>();
+                            base_text.push_str(&extra_line);
+                            base_text.push('\n');
+                        }
+                    }
+
+                    let diff =
+                        cx.new(|cx| BufferDiff::new_with_base_text(&base_text, &buffer_handle, cx));
+                    diffs.push(diff.clone());
+                    multibuffer.add_diff(diff, cx);
+                }
+            }
+        }
+    });
+
+    multibuffer.update(cx, |multibuffer, cx| {
+        if rng.gen_bool(0.5) {
+            multibuffer.set_all_diff_hunks_expanded(cx);
+        } else {
+            let snapshot = multibuffer.snapshot(cx);
+            let text = snapshot.text();
+
+            let mut ranges = Vec::new();
+            for _ in 0..rng.gen_range(1..5) {
+                if snapshot.len() == 0 {
+                    break;
+                }
+
+                let diff_size = rng.gen_range(5..1000);
+                let mut start = rng.gen_range(0..snapshot.len());
+
+                while !text.is_char_boundary(start) {
+                    start = start.saturating_sub(1);
+                }
+
+                let mut end = rng.gen_range(start..snapshot.len().min(start + diff_size));
+
+                while !text.is_char_boundary(end) {
+                    end = end.saturating_add(1);
+                }
+                let start_anchor = snapshot.anchor_after(start);
+                let end_anchor = snapshot.anchor_before(end);
+                ranges.push(start_anchor..end_anchor);
+            }
+            multibuffer.expand_diff_hunks(ranges, cx);
+        }
+    });
+
+    let snapshot = multibuffer.read(cx).snapshot(cx);
+
+    let chunks = snapshot.chunks(0..snapshot.len(), false);
+
+    for chunk in chunks {
+        let chunk_text = chunk.text;
+        let chars_bitmap = chunk.chars;
+        let tabs_bitmap = chunk.tabs;
+
+        if chunk_text.is_empty() {
+            assert_eq!(
+                chars_bitmap, 0,
+                "Empty chunk should have empty chars bitmap"
+            );
+            assert_eq!(tabs_bitmap, 0, "Empty chunk should have empty tabs bitmap");
+            continue;
+        }
+
+        assert!(
+            chunk_text.len() <= 128,
+            "Chunk text length {} exceeds 128 bytes",
+            chunk_text.len()
+        );
+
+        let char_indices = chunk_text
+            .char_indices()
+            .map(|(i, _)| i)
+            .collect::<Vec<_>>();
+
+        for byte_idx in 0..chunk_text.len() {
+            let should_have_bit = char_indices.contains(&byte_idx);
+            let has_bit = chars_bitmap & (1 << byte_idx) != 0;
+
+            if has_bit != should_have_bit {
+                eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
+                eprintln!("Char indices: {:?}", char_indices);
+                eprintln!("Chars bitmap: {:#b}", chars_bitmap);
+            }
+
+            assert_eq!(
+                has_bit, should_have_bit,
+                "Chars bitmap mismatch at byte index {} in chunk {:?}. Expected bit: {}, Got bit: {}",
+                byte_idx, chunk_text, should_have_bit, has_bit
+            );
+        }
+
+        for (byte_idx, byte) in chunk_text.bytes().enumerate() {
+            let is_tab = byte == b'\t';
+            let has_bit = tabs_bitmap & (1 << byte_idx) != 0;
+
+            if has_bit != is_tab {
+                eprintln!("Chunk text bytes: {:?}", chunk_text.as_bytes());
+                eprintln!("Tabs bitmap: {:#b}", tabs_bitmap);
+                assert_eq!(
+                    has_bit, is_tab,
+                    "Tabs bitmap mismatch at byte index {} in chunk {:?}. Byte: {:?}, Expected bit: {}, Got bit: {}",
+                    byte_idx, chunk_text, byte as char, is_tab, has_bit
+                );
+            }
+        }
+    }
+}

crates/rope/src/chunk.rs

@@ -13,7 +13,7 @@ pub struct Chunk {
     chars: u128,
     chars_utf16: u128,
     newlines: u128,
-    tabs: u128,
+    pub tabs: u128,
     pub text: ArrayString<MAX_BASE>,
 }
 
@@ -67,6 +67,11 @@ impl Chunk {
     pub fn slice(&self, range: Range<usize>) -> ChunkSlice<'_> {
         self.as_slice().slice(range)
     }
+
+    #[inline(always)]
+    pub fn chars(&self) -> u128 {
+        self.chars
+    }
 }
 
 #[derive(Clone, Copy, Debug)]

crates/rope/src/rope.rs

@@ -594,6 +594,15 @@ impl<'a> Cursor<'a> {
     }
 }
 
+pub struct ChunkBitmaps<'a> {
+    /// A slice of text up to 128 bytes in size
+    pub text: &'a str,
+    /// Bitmap of character locations in text. LSB ordered
+    pub chars: u128,
+    /// Bitmap of tab locations in text. LSB ordered
+    pub tabs: u128,
+}
+
 #[derive(Clone)]
 pub struct Chunks<'a> {
     chunks: sum_tree::Cursor<'a, Chunk, usize>,
@@ -755,6 +764,36 @@ impl<'a> Chunks<'a> {
         self.offset < initial_offset && self.offset == 0
     }
 
+    /// Returns bitmaps that represent character positions and tab positions
+    pub fn peak_with_bitmaps(&self) -> Option<ChunkBitmaps<'a>> {
+        if !self.offset_is_valid() {
+            return None;
+        }
+
+        let chunk = self.chunks.item()?;
+        let chunk_start = *self.chunks.start();
+        let slice_range = if self.reversed {
+            let slice_start = cmp::max(chunk_start, self.range.start) - chunk_start;
+            let slice_end = self.offset - chunk_start;
+            slice_start..slice_end
+        } else {
+            let slice_start = self.offset - chunk_start;
+            let slice_end = cmp::min(self.chunks.end(), self.range.end) - chunk_start;
+            slice_start..slice_end
+        };
+
+        let bitmask = (1u128 << slice_range.end as u128).saturating_sub(1);
+
+        let chars = (chunk.chars() & bitmask) >> slice_range.start;
+        let tabs = (chunk.tabs & bitmask) >> slice_range.start;
+
+        Some(ChunkBitmaps {
+            text: &chunk.text[slice_range.clone()],
+            chars,
+            tabs,
+        })
+    }
+
     pub fn peek(&self) -> Option<&'a str> {
         if !self.offset_is_valid() {
             return None;
@@ -775,6 +814,36 @@ impl<'a> Chunks<'a> {
         Some(&chunk.text[slice_range])
     }
 
+    pub fn peek_tabs(&self) -> Option<ChunkBitmaps<'a>> {
+        if !self.offset_is_valid() {
+            return None;
+        }
+
+        let chunk = self.chunks.item()?;
+        let chunk_start = *self.chunks.start();
+        let slice_range = if self.reversed {
+            let slice_start = cmp::max(chunk_start, self.range.start) - chunk_start;
+            let slice_end = self.offset - chunk_start;
+            slice_start..slice_end
+        } else {
+            let slice_start = self.offset - chunk_start;
+            let slice_end = cmp::min(self.chunks.end(), self.range.end) - chunk_start;
+            slice_start..slice_end
+        };
+        let chunk_start_offset = slice_range.start;
+        let slice_text = &chunk.text[slice_range];
+
+        // Shift the tabs to align with our slice window
+        let shifted_tabs = chunk.tabs >> chunk_start_offset;
+        let shifted_chars = chunk.chars() >> chunk_start_offset;
+
+        Some(ChunkBitmaps {
+            text: slice_text,
+            chars: shifted_chars,
+            tabs: shifted_tabs,
+        })
+    }
+
     pub fn lines(self) -> Lines<'a> {
         let reversed = self.reversed;
         Lines {
@@ -820,6 +889,30 @@ impl<'a> Chunks<'a> {
     }
 }
 
+pub struct ChunkWithBitmaps<'a>(pub Chunks<'a>);
+
+impl<'a> Iterator for ChunkWithBitmaps<'a> {
+    /// text, chars bitmap, tabs bitmap
+    type Item = ChunkBitmaps<'a>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let chunk_bitmaps = self.0.peak_with_bitmaps()?;
+        if self.0.reversed {
+            self.0.offset -= chunk_bitmaps.text.len();
+            if self.0.offset <= *self.0.chunks.start() {
+                self.0.chunks.prev();
+            }
+        } else {
+            self.0.offset += chunk_bitmaps.text.len();
+            if self.0.offset >= self.0.chunks.end() {
+                self.0.chunks.next();
+            }
+        }
+
+        Some(chunk_bitmaps)
+    }
+}
+
 impl<'a> Iterator for Chunks<'a> {
     type Item = &'a str;