⚡ Bolt: [performance improvement] optimize string concatenation to avoid intermediate allocations

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2024-07-01 - Avoid intermediate Vec allocations for string concatenation
+**Learning:** In Rust, when mapping an iterator of strings and joining them, using `.collect::<String>()` directly is more efficient than `.collect::<Vec<_>>().join("")` because it avoids an intermediate heap allocation for the vector. Additionally, for `char::to_lowercase()`, chaining `.to_string()` is preferred over `.collect::<String>()` because it leverages the `Display` implementation and avoids unnecessary iterator collection overhead.
+**Action:** When performing string concatenations on iterators, prefer `.collect::<String>()` to aggregate into a single string directly. When converting a `char` to lower/upper case string, use `.to_string()`.

xdk-lib/src/casing.rs

@@ -29,11 +29,8 @@ impl Casing {
                     result
                 }
             }
-            Casing::Pascal => words
-                .iter()
-                .map(|w| pascal_case(w))
-                .collect::<Vec<_>>()
-                .join(""),
+            // Avoid intermediate Vec allocation by collecting directly to String
+            Casing::Pascal => words.iter().map(|w| pascal_case(w)).collect::<String>(),
             Casing::Kebab => words.join("-").to_lowercase(),
             Casing::ScreamingSnake => words.join("_").to_uppercase(),
         }
@@ -118,6 +115,7 @@ pub fn camel_case(value: &str) -> String {
     let mut chars = pascal.chars();
     match chars.next() {
         None => String::new(),
-        Some(first) => first.to_lowercase().collect::<String>() + chars.as_str(),
+        // Use .to_string() instead of .collect::<String>() for `Display` usage
+        Some(first) => first.to_lowercase().to_string() + chars.as_str(),
     }
 }