⚡ Bolt: [performance improvement] Optimize string concatenation in casing conversions

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2024-06-26 - String Concatenation Optimization
+**Learning:** In Rust, `.collect::<Vec<_>>().join("")` allocates an intermediate vector on the heap just to hold strings before joining them. Similarly, chaining `.collect::<String>()` when converting cases (like `.to_lowercase().collect::<String>()`) creates an intermediate string buffer.
+**Action:** When joining strings without a separator, directly collect into a String using `.collect::<String>()`. When converting the casing of a single character, leverage its Display implementation directly with `.to_lowercase().to_string()` to avoid unnecessary intermediate heap allocations.

xdk-lib/src/casing.rs

@@ -29,11 +29,7 @@ impl Casing {
                     result
                 }
             }
-            Casing::Pascal => words
-                .iter()
-                .map(|w| pascal_case(w))
-                .collect::<Vec<_>>()
-                .join(""),
+            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 +114,6 @@ 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(),
+        Some(first) => first.to_lowercase().to_string() + chars.as_str(),
     }
 }