Add copying utility methods to Arena

benchmarks/bench_parser_comparison.cpp

@@ -76,13 +76,6 @@ private:
   Precondition current_precondition;
   Operation current_operation;
 
-  // Helper to store string in arena and return string_view
-  std::string_view store_string(const char *str, size_t length) {
-    char *stored = arena.allocate<char>(length);
-    std::memcpy(stored, str, length);
-    return std::string_view(stored, length);
-  }
-
 public:
   explicit CommitRequestArenaHandler()
       : preconditions(ArenaStlAllocator<Precondition>(&arena)),
@@ -109,7 +102,7 @@ public:
   bool RawNumber(const char *, rapidjson::SizeType, bool) { abort(); }
 
   bool String(const char *str, rapidjson::SizeType length, bool) {
-    std::string_view value = store_string(str, length);
+    std::string_view value = arena.copy_string({str, length});
 
     if (state == State::Root) {
       if (current_key == "request_id") {