From 9b0cb4ec205197daf2cfc532934583bd67553702 Mon Sep 17 00:00:00 2001
From: Marco Mihai Condrache <52580954+marcocondrache@users.noreply.github.com>
Date: Fri, 20 Feb 2026 17:29:09 +0100
Subject: [PATCH] text: Store fragment's deletions on stack (#49726)

Helps #38927

- In the common case, each fragment has at most one deletion, so we can
skip the heap allocation
- SmallVec is smaller than an empty HashSet
- Makes cloning cheaper
- From my analysis of the code it's not possible to have duplicate ticks
(I may be wrong tho)

Before you mark this PR as ready for review, make sure that you have:
- [ ] Added a solid test coverage and/or screenshots from doing manual
testing
- [x] Done a self-review taking into account security and performance
aspects
- [ ] Aligned any UI changes with the [UI
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)

Release Notes:

- N/A
---
 crates/text/src/text.rs | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/crates/text/src/text.rs b/crates/text/src/text.rs
index 43e41fd4d289dbd6dd5dc0c49f368ac2385b518a..38ebc2148722d625718d38062fd61c043db62aed 100644
--- a/crates/text/src/text.rs
+++ b/crates/text/src/text.rs
@@ -23,6 +23,7 @@ use postage::{oneshot, prelude::*};
 use regex::Regex;
 pub use rope::*;
 pub use selection::*;
+use smallvec::SmallVec;
 use std::{
     borrow::Cow,
     cmp::{self, Ordering, Reverse},
@@ -541,7 +542,7 @@ pub struct Fragment {
     pub insertion_offset: usize,
     pub len: usize,
     pub visible: bool,
-    pub deletions: HashSet<clock::Lamport>,
+    pub deletions: SmallVec<[clock::Lamport; 2]>,
     pub max_undos: clock::Global,
 }
 
@@ -948,7 +949,7 @@ impl Buffer {
                     intersection.insertion_offset += fragment_start - old_fragments.start().visible;
                     intersection.id =
                         Locator::between(&new_fragments.summary().max_id, &intersection.id);
-                    intersection.deletions.insert(timestamp);
+                    intersection.deletions.push(timestamp);
                     intersection.visible = false;
                 }
                 if intersection.len > 0 {
@@ -1197,7 +1198,7 @@ impl Buffer {
                         fragment_start - old_fragments.start().0.full_offset();
                     intersection.id =
                         Locator::between(&new_fragments.summary().max_id, &intersection.id);
-                    intersection.deletions.insert(timestamp);
+                    intersection.deletions.push(timestamp);
                     intersection.visible = false;
                     insertion_slices.push(InsertionSlice::from_fragment(timestamp, &intersection));
                 }