From a9cfe764844d5df432d7b74c5242517280a9d6d0 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Wed, 1 Jul 2026 22:03:42 +0000
Subject: [PATCH] bolt: optimize string concatenation in casing.rs

Co-authored-by: cloudesize67-cmd <237356855+cloudesize67-cmd@users.noreply.github.com>
---
 .jules/bolt.md        |  3 +++
 xdk-lib/src/casing.rs | 10 ++++------
 2 files changed, 7 insertions(+), 6 deletions(-)
 create mode 100644 .jules/bolt.md

diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 00000000..2e40d55d
--- /dev/null
+++ b/.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()`.
diff --git a/xdk-lib/src/casing.rs b/xdk-lib/src/casing.rs
index 6463487e..5772196d 100644
--- a/xdk-lib/src/casing.rs
+++ b/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(),
     }
 }