More work on debug_string

luprex/core/cpp/util.hpp

@@ -66,6 +66,17 @@ struct XYZ {
     std::string debug_string() const;
 };
 
+// These are formatting directives that can be sent to a std::ostream.
+class hex64 {};
+class hex32 {};
+class hex16 {};
+class hex8 {};
+
 } // namespace util
 
+std::ostream &operator<<(std::ostream &oss, const util::hex64 &v);
+std::ostream &operator<<(std::ostream &oss, const util::hex32 &v);
+std::ostream &operator<<(std::ostream &oss, const util::hex16 &v);
+std::ostream &operator<<(std::ostream &oss, const util::hex8 &v);
+
 #endif // UTIL_HPP