cleanup

lib/include/aocpp/Parsing.hpp

@@ -46,9 +46,10 @@ auto ParseGrammar_(G const& grammar, std::istream & in) -> typename G::start_typ
   return result;
 }
 
-template <typename P, typename R>
-auto ParseSimple(std::istream& in, P p, R & result) -> void
+template <typename R>
+auto ParseSimple(std::istream& in, auto p) -> R
 {
+  R result;
   namespace qi = boost::spirit::qi;
   auto const content = std::string{std::istreambuf_iterator{in}, {}};
   qi::rule<std::string::const_iterator, R()> r { std::move(p) };
@@ -58,6 +59,7 @@ auto ParseSimple(std::istream& in, P p, R & result) -> void
   if (!success || it != end) {
       throw std::runtime_error("Parsing failed or input was not fully consumed.");
   }
+  return result;
 }
 
 }