⚡ Bolt: escapeHtml 최적화 (불필요한 문자열 할당 제거)

.jules/bolt.md

@@ -5,3 +5,7 @@
 ## 2024-05-24 - Loop Allocation Hot Paths
 **Learning:** Rendering directory entries with repeated string concatenation and list-based exclusion lookups creates avoidable allocation and lookup cost in large directories.
 **Action:** Use `StringBuilder` for entry rendering and a `Set` for excluded file names.
+
+## 2024-08-01 - Chained String Replace
+**Learning:** Using chained `.replace()` calls on a String for frequent operations (like HTML escaping) is inefficient due to multiple intermediate allocations.
+**Action:** Use a single-pass loop with a lazily-initialized `StringBuilder` for string manipulation functions called frequently on hot paths to minimize allocations and improve performance.

src/main/kotlin/html4tree/main.kt

@@ -49,12 +49,31 @@ fun go(topDir: String, maxLevel: Int)  {
 }
 
 fun String.escapeHtml(): String {
-    return this.replace("&", "&")
-               .replace("<", "&lt;")
-               .replace(">", "&gt;")
-               .replace("\"", "&quot;")
-               .replace("'", "&#x27;")
-               .replace("`", "&#x60;")
+    // ⚡ Bolt: Use a single-pass loop with a lazily-initialized StringBuilder
+    // to avoid intermediate string allocations from chained replace calls.
+    var sb: java.lang.StringBuilder? = null
+    for (i in this.indices) {
+        val c = this[i]
+        val replacement = when (c) {
+            '&' -> "&amp;"
+            '<' -> "&lt;"
+            '>' -> "&gt;"
+            '"' -> "&quot;"
+            '\'' -> "&#x27;"
+            '`' -> "&#x60;"
+            else -> null
+        }
+        if (replacement != null) {
+            if (sb == null) {
+                sb = java.lang.StringBuilder(this.length + 16)
+                sb.append(this, 0, i)
+            }
+            sb.append(replacement)
+        } else {
+            sb?.append(c)
+        }
+    }
+    return sb?.toString() ?: this
 }
 
 fun String.urlEncodePath(): String {