move operator<< into separate header <variant_io.hpp>

test/binary_visitor_test.cpp

@@ -9,6 +9,7 @@
 #include <boost/variant.hpp>
 #include <boost/timer/timer.hpp>
 #include "variant.hpp"
+#include "variant_io.hpp"
 
 using namespace mapbox;
 

test/unit.cpp

@@ -2,7 +2,7 @@
 #include "catch.hpp"
 
 #include "variant.hpp"
-
+#include "variant_io.hpp"
 #include <algorithm>
 #include <cstdint>
 #include <iterator>

variant.hpp

@@ -497,24 +497,6 @@ class comparer
     Variant const& lhs_;
 };
 
-// operator<< helper
-template <typename Out>
-class printer
-{
-public:
-    explicit printer(Out & out)
-        : out_(out) {}
-    printer& operator=(printer const&) = delete;
-
-// visitor
-    template <typename T>
-    void operator()(T const& operand) const
-    {
-        out_ << operand;
-    }
-private:
-    Out & out_;
-};
 
 } // namespace detail
 
@@ -768,16 +750,6 @@ ResultType const&  get(T const& var)
 }
 
 
-// operator<<
-template <typename charT, typename traits, typename... Types>
-VARIANT_INLINE std::basic_ostream<charT, traits>&
-operator<< (std::basic_ostream<charT, traits>& out, variant<Types...> const& rhs)
-{
-    detail::printer<std::basic_ostream<charT, traits>> visitor(out);
-    apply_visitor(visitor, rhs);
-    return out;
-}
-
 }}
 
 #endif  // MAPBOX_UTIL_VARIANT_HPP

variant_io.hpp

@@ -0,0 +1,39 @@
+#ifndef MAPBOX_UTIL_VARIANT_IO_HPP
+#define MAPBOX_UTIL_VARIANT_IO_HPP
+
+namespace mapbox { namespace util {
+
+namespace detail {
+// operator<< helper
+template <typename Out>
+class printer
+{
+public:
+    explicit printer(Out & out)
+        : out_(out) {}
+    printer& operator=(printer const&) = delete;
+
+// visitor
+    template <typename T>
+    void operator()(T const& operand) const
+    {
+        out_ << operand;
+    }
+private:
+    Out & out_;
+};
+}
+
+// operator<<
+template <typename charT, typename traits, typename... Types>
+VARIANT_INLINE std::basic_ostream<charT, traits>&
+operator<< (std::basic_ostream<charT, traits>& out, variant<Types...> const& rhs)
+{
+    detail::printer<std::basic_ostream<charT, traits>> visitor(out);
+    apply_visitor(visitor, rhs);
+    return out;
+}
+
+}}
+
+#endif //MAPBOX_UTIL_VARIANT_IO_HPP