editor: Optimize selection overlap checking with binary search (#39773)

Xiaobo Liu created 3 weeks ago

Replace O(n²) linear search with O(log n) binary search for checking
selection overlaps when finding next selection range. Pre-sort selection
ranges and use binary search to significantly improve performance when
working with many selections.

Release Notes:

- N/A

---------

Signed-off-by: Xiaobo Liu <[e-mail]>

Change summary

crates/editor/src/editor.rs | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)

Detailed changes

crates/editor/src/editor.rs

@@ -14448,6 +14448,10 @@ impl Editor {
                 let last_selection = selections.iter().max_by_key(|s| s.id).unwrap();
                 let mut next_selected_range = None;
 
+                // Collect and sort selection ranges for efficient overlap checking
+                let mut selection_ranges: Vec<_> = selections.iter().map(|s| s.range()).collect();
+                selection_ranges.sort_by_key(|r| r.start);
+
                 let bytes_after_last_selection =
                     buffer.bytes_in_range(last_selection.end..buffer.len());
                 let bytes_before_first_selection = buffer.bytes_in_range(0..first_selection.start);
@@ -14469,11 +14473,20 @@ impl Editor {
                         || (!buffer.is_inside_word(offset_range.start, None)
                             && !buffer.is_inside_word(offset_range.end, None))
                     {
-                        // TODO: This is n^2, because we might check all the selections
-                        if !selections
-                            .iter()
-                            .any(|selection| selection.range().overlaps(&offset_range))
-                        {
+                        // Use binary search to check for overlap (O(log n))
+                        let overlaps = selection_ranges
+                            .binary_search_by(|range| {
+                                if range.end <= offset_range.start {
+                                    std::cmp::Ordering::Less
+                                } else if range.start >= offset_range.end {
+                                    std::cmp::Ordering::Greater
+                                } else {
+                                    std::cmp::Ordering::Equal
+                                }
+                            })
+                            .is_ok();
+
+                        if !overlaps {
                             next_selected_range = Some(offset_range);
                             break;
                         }