F-021: perf(services): stream whitespace-stripped comparison via Iterator::eq

src/services/context.rs

@@ -321,18 +321,18 @@ impl ContextBuilder {
 
         // Compare non-whitespace character streams.
         // Correctly handles line wrapping while detecting actual content changes.
-        let old_text: String = removed_in_span
+        // Use streaming Iterator::eq to avoid allocating two full Strings and
+        // to short-circuit on the first differing character.
+        let old_chars = removed_in_span
             .iter()
             .flat_map(|l| l.chars())
-            .filter(|c| !c.is_whitespace())
-            .collect();
-        let new_text: String = added_in_span
+            .filter(|c| !c.is_whitespace());
+        let new_chars = added_in_span
             .iter()
             .flat_map(|l| l.chars())
-            .filter(|c| !c.is_whitespace())
-            .collect();
+            .filter(|c| !c.is_whitespace());
 
-        Some(old_text == new_text)
+        Some(old_chars.eq(new_chars))
     }
 
     /// Classify changes within a symbol span with doc-vs-code distinction.
@@ -393,18 +393,18 @@ impl ContextBuilder {
             return None;
         }
 
-        // Check whitespace-only first (same logic as classify_span_change)
-        let old_text: String = removed_in_span
+        // Check whitespace-only first (same logic as classify_span_change).
+        // Stream the filtered char iterators through Iterator::eq to avoid
+        // allocating intermediate Strings and short-circuit on inequality.
+        let old_chars = removed_in_span
             .iter()
             .flat_map(|l| l.chars())
-            .filter(|c| !c.is_whitespace())
-            .collect();
-        let new_text: String = added_in_span
+            .filter(|c| !c.is_whitespace());
+        let new_chars = added_in_span
             .iter()
             .flat_map(|l| l.chars())
-            .filter(|c| !c.is_whitespace())
-            .collect();
-        if old_text == new_text {
+            .filter(|c| !c.is_whitespace());
+        if old_chars.eq(new_chars) {
             return Some(SpanChangeKind::WhitespaceOnly);
         }
 

src/services/differ.rs

@@ -283,9 +283,13 @@ impl AstDiffer {
     }
 
     fn bodies_semantically_equal(old_body: Option<&str>, new_body: Option<&str>) -> bool {
-        let strip = |s: &str| -> String { s.chars().filter(|c| !c.is_whitespace()).collect() };
         match (old_body, new_body) {
-            (Some(o), Some(n)) => strip(o) == strip(n),
+            // Stream filtered char iterators through Iterator::eq to avoid
+            // allocating intermediate Strings and short-circuit on inequality.
+            (Some(o), Some(n)) => o
+                .chars()
+                .filter(|c| !c.is_whitespace())
+                .eq(n.chars().filter(|c| !c.is_whitespace())),
             (None, None) => true,
             _ => false,
         }