fuzzy_nucleo: Add a tail proximity bonus to fix the double hits not sorted higher bonus.

crates/file_finder/src/file_finder_tests.rs

@@ -447,6 +447,55 @@ async fn test_complex_path(cx: &mut TestAppContext) {
     });
 }
 
+#[gpui::test]
+async fn test_tail_proximity_bonus_prefers_later_match(cx: &mut TestAppContext) {
+    let app_state = init_test(cx);
+
+    cx.update(|cx| {
+        let settings = *ProjectPanelSettings::get_global(cx);
+        ProjectPanelSettings::override_global(
+            ProjectPanelSettings {
+                hide_root: true,
+                ..settings
+            },
+            cx,
+        );
+    });
+
+    app_state
+        .fs
+        .as_fake()
+        .insert_tree(
+            path!("/root"),
+            json!({
+                "zzz": { "zed": { "Cargo.toml": "" } },
+                "zed": { "zzz": { "Cargo.toml": "" } },
+            }),
+        )
+        .await;
+
+    let project = Project::test(app_state.fs.clone(), [path!("/root").as_ref()], cx).await;
+    let (picker, _, cx) = build_find_picker(project, cx);
+
+    picker
+        .update_in(cx, |picker, window, cx| {
+            picker
+                .delegate
+                .update_matches("zed cargo".to_string(), window, cx)
+        })
+        .await;
+
+    picker.update(cx, |picker, _| {
+        assert_eq!(
+            collect_search_matches(picker).search_paths_only(),
+            vec![
+                rel_path("zzz/zed/Cargo.toml").into(),
+                rel_path("zed/zzz/Cargo.toml").into(),
+            ],
+        );
+    });
+}
+
 #[gpui::test]
 async fn test_row_column_numbers_query_inside_file(cx: &mut TestAppContext) {
     let app_state = init_test(cx);

crates/fuzzy_nucleo/src/paths.rs

@@ -134,6 +134,19 @@ fn get_filename_match_bonus(
     score as f64 / filename.len().max(1) as f64
 }
 
+const TAIL_REWARD_SCALE: f64 = 1.5;
+
+#[inline]
+fn get_tail_proximity_bonus(matched_chars: &[u32], haystack_len: u32) -> f64 {
+    debug_assert!(
+        haystack_len != 0 && matched_chars.len() != 0,
+        "This should only be called on a successful match."
+    );
+    let trailing: u32 = matched_chars.iter().map(|&i| haystack_len - 1 - i).sum();
+    let mean_trailing = trailing as f64 / matched_chars.len() as f64;
+    (1.0 / (1.0 + mean_trailing)) * TAIL_REWARD_SCALE
+}
+
 fn path_match_helper<'a>(
     matcher: &mut nucleo::Matcher,
     query: &Query,
@@ -193,7 +206,9 @@ fn path_match_helper<'a>(
 
         let length_penalty = candidate_buf.len() as f64 * LENGTH_PENALTY;
         let filename_bonus = get_filename_match_bonus(&candidate_buf, &query.pattern, matcher);
-        let positive = (score as f64 + filename_bonus) * case_penalty(case_mismatches);
+        let tail_proximity_bonus = get_tail_proximity_bonus(&matched_chars, haystack.len() as u32);
+        let positive =
+            (score as f64 + filename_bonus + tail_proximity_bonus) * case_penalty(case_mismatches);
         let adjusted_score = positive - length_penalty;
         let positions = positions_from_sorted(&candidate_buf, &matched_chars);