⚡ Bolt: [performance improvement] optimize string allocations in Casing module

.jules/bolt.md

@@ -0,0 +1,7 @@
+## 2024-05-24 - Avoid `.collect::<Vec<_>>().join("")` for string concatenation in Rust
+**Learning:** Found a pattern where multiple strings are aggregated using `.collect::<Vec<_>>().join("")`, which introduces intermediate `Vec` allocations.
+**Action:** Use `.collect::<String>()` directly on an iterator of strings or string slices instead, which avoids the intermediate vector allocation when joining with an empty string.
+
+## 2024-05-24 - Use `to_lowercase().to_string()` over `to_lowercase().collect::<String>()`
+**Learning:** `char::to_lowercase()` returns an iterator (since a char can map to multiple chars), and using `.collect::<String>()` on it has collection overhead.
+**Action:** `char::to_lowercase()` implements `Display`, so prefer `.to_string()` over `.collect::<String>()` to leverage its Display implementation directly for string conversion.

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(),
     }
 }