1 files changed, 41 insertions, 0 deletions
diff --git a/include/mbgl/util/variant_io.hpp b/include/mbgl/util/variant_io.hpp
new file mode 100644
index 0000000000..224732d97c
--- /dev/null
+++ b/include/mbgl/util/variant_io.hpp
@@ -0,0 +1,41 @@
+#ifndef MAPBOX_UTIL_VARIANT_IO_HPP
+#define MAPBOX_UTIL_VARIANT_IO_HPP
+
+#include "variant.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