Update csv_writer.hpp

Author: vincentlaucsb

include/internal/csv_writer.hpp

@@ -275,11 +275,17 @@ namespace internals {
         }
 
         /** Configure whether each write operation flushes the underlying stream. */
-        DelimWriter& set_auto_flush(bool value) noexcept {
+        DelimWriter& set_auto_flush(bool value) & noexcept {
             this->auto_flush_ = value;
             return *this;
         }
 
+        /** Configure whether each write operation flushes the underlying stream. */
+        DelimWriter&& set_auto_flush(bool value) && noexcept {
+            this->auto_flush_ = value;
+            return std::move(*this);
+        }
+
         /** Return whether each write operation flushes the underlying stream. */
         bool get_auto_flush() const noexcept {
             return this->auto_flush_;
@@ -583,8 +589,7 @@ namespace internals {
                 return;
             }
 
-            if (batch_buffer_.size() >= batch_flush_threshold_)
-                flush_batch();
+            flush_batch_if_needed();
         }
 
         void flush_batch() {
@@ -594,6 +599,11 @@ namespace internals {
             batch_buffer_.clear();
         }
 
+        void flush_batch_if_needed() {
+            if (batch_buffer_.size() >= batch_flush_threshold_)
+                flush_batch();
+        }
+
         /**
          * An owned output stream, if the writer owns it.
          * May be null if the writer does not own its output stream, i.e.