notedeck

commit 352ace0ec1352981d669baee0f211c2f4bdf3839
parent 23b2817320e75791ace9e7aa5d0d6900fbb7c932
Author: William Casarin <jb55@jb55.com>
Date:   Fri, 13 Feb 2026 13:31:10 -0800

egui-md-stream: fix O(n²) collapse_text_elements

Replace Vec::remove loop with single-pass read/write pointer
approach. Vec::remove shifts all subsequent elements on each
call, making it quadratic. The new approach swaps in place and
truncates once at the end.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Diffstat:
M
crates/egui-md-stream/src/inline.rs
 | 
21
+++++++++++++++------

1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/crates/egui-md-stream/src/inline.rs b/crates/egui-md-stream/src/inline.rs
@@ -371,16 +371,25 @@ fn parse_link(text: &str) -> Option<(String, String, usize)> {
 
 /// Collapse adjacent Text elements into one.
 fn collapse_text_elements(elements: &mut Vec<InlineElement>) {
-    let mut i = 0;
-    while i + 1 < elements.len() {
-        if let (InlineElement::Text(a), InlineElement::Text(b)) = (&elements[i], &elements[i + 1]) {
+    if elements.len() < 2 {
+        return;
+    }
+
+    let mut write = 0;
+    for read in 1..elements.len() {
+        if let (InlineElement::Text(a), InlineElement::Text(b)) =
+            (&elements[write], &elements[read])
+        {
             let combined = format!("{}{}", a, b);
-            elements[i] = InlineElement::Text(combined);
-            elements.remove(i + 1);
+            elements[write] = InlineElement::Text(combined);
         } else {
-            i += 1;
+            write += 1;
+            if write != read {
+                elements.swap(write, read);
+            }
         }
     }
+    elements.truncate(write + 1);
 }
 
 /// Streaming inline parser state.