advance

lib/include/intcode/Interpreter.hpp

@@ -2,6 +2,7 @@
 #define INTCODE_INTERPRETER_HPP_
 
 #include <variant>
+#include <concepts>
 
 #include <intcode/Machine.hpp>
 #include <Overload.hpp>
@@ -27,19 +28,22 @@ struct BadInstruction : public std::runtime_error {
   explicit BadInstruction(char const* what);
 };
 
-template <class Fin, class Fout>
+template <std::invocable<ValueType&> Fin, std::invocable<ValueType> Fout, std::invocable<> Fhalt>
+auto Advance(Machine & machine, Fin input, Fout output, Fhalt halt) {
+  return std::visit(overloaded{
+    [&](Halt) { return halt(); },
+    [&](Input i) { return input(i.pos); },
+    [&](Output o) { return output(o.val); },
+    }, Step(machine));
+}
+
+template <std::invocable<> Fin, std::invocable<ValueType> Fout>
 auto Run(Machine & machine, Fin input, Fout output) -> void {
-  while (std::visit(overloaded{
-    [](Halt) { return false; },
-    [&](Input arg) {
-      arg.pos = input();
-      return true;
-    },
-    [&](Output arg) {
-      output(arg.val);
-      return true;
-    }},
-    Step(machine)));
+  while (Advance(machine,
+    [&](ValueType &i) { i = input(); return true; },
+    [&](ValueType o) { output(o); return true; },
+    []() { return false; }
+    )) {}
 }
 
 } // namespace