⚡ Bolt: [performance improvement] Optimize string and iterator allocations

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2024-05-20 - String and Iterator Micro-Optimizations
+**Learning:** In hot or frequently executed string manipulations, intermediate `Vec` allocations from `collect()` can be surprisingly costly in Rust. `collect::<String>()` handles direct string concatenation more efficiently. Similarly, `split` on strings vs characters (`"\n"` vs `'\n'`) carries measurable overhead, and chaining iterators directly avoids temporary vector allocations.
+**Action:** Always prefer `collect::<String>()` for aggregating strings instead of `.collect::<Vec<_>>().join("")`. Prefer `char`-based over string-slice-based splits, and extract elements via pattern-matching on the iterator's `.next()` to avoid intermediate `.collect::<Vec<_>>()` calls.

xdk-build/src/python.rs

@@ -159,16 +159,12 @@ fn run_formatter(output_dir: &Path, venv_python_path: &Path, script_path: &Path)
     let stdout = String::from_utf8_lossy(&output.stdout);
     if !stdout.trim().is_empty() {
         println!();
-        stdout
-            .split("\n")
-            .collect::<Vec<&str>>()
-            .into_iter()
-            .for_each(|line| {
-                let parts = line.split(" ").collect::<Vec<&str>>();
-                if parts.len() == 2 {
-                    log_info!("{} {}", parts[0], parts[1].magenta());
-                }
-            });
+        stdout.split('\n').for_each(|line| {
+            let mut parts = line.split(' ');
+            if let (Some(p1), Some(p2), None) = (parts.next(), parts.next(), parts.next()) {
+                log_info!("{} {}", p1, p2.magenta());
+            }
+        });
         println!();
     }
 

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(),
         }