diff --git a/src/SysYFormatter.cpp b/src/SysYFormatter.cpp
deleted file mode 100644
index 145b4e8..0000000
--- a/src/SysYFormatter.cpp
+++ /dev/null
@@ -1,28 +0,0 @@
-#include <algorithm>
-#include <iostream>
-using namespace std;
-#include "SysYParser.h"
-#include "SysYFormatter.h"
-
-// any ASTPrinter::visitNumber(SysYParser::NumberContext *ctx) {
-//   cout << ctx->IntConst()->getText();
-//   return nullptr;
-// }
-
-// any ASTPrinter::visitString(SysYParser::StringContext *ctx) {
-//   cout << ctx->String()->getText();
-//   return nullptr;
-// }
-
-// any ASTPrinter::visitFuncRParams(SysYParser::FuncRParamsContext *ctx) {
-//   if (ctx->funcRParam().empty())
-//     return nullptr;
-//   auto numParams = ctx->funcRParam().size();
-//   ctx->funcRParam(0)->accept(this);
-//   for (int i = 1; i < numParams; ++i) {
-//     cout << ", ";
-//     ctx->funcRParam(i)->accept(this);
-//   }
-//   cout << '\n';
-//   return nullptr;
-// }
diff --git a/src/SysYFormatter.h b/src/SysYFormatter.h
index ac6192b..fdaf615 100644
--- a/src/SysYFormatter.h
+++ b/src/SysYFormatter.h
@@ -4,6 +4,8 @@
 #include "SysYParser.h"
 #include <ostream>
 
+namespace sysy {
+
 class SysYFormatter : public SysYBaseVisitor {
 protected:
   std::ostream &os;
@@ -331,4 +333,6 @@ public:
     interleave(ctx->exp(), ", ");
     return 0;
   }
-};
\ No newline at end of file
+};
+
+} // namespace sysy