Trying out an FSM for controlling the main loop.

fsm.hpp

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <fmt/core.h>
+
+#ifndef FSM_DEBUG
+#define FSM_STATE(C, S, E, ...) case C::S: S(E, ##__VA_ARGS__); break
+#else
+#define FSM_STATE(C, S, E, ...) case C::S: fmt::println(">> " #C " " #S " event={}, state={}", int(E), int($state)); S(E, ##__VA_ARGS__); fmt::println("<< " #C " state={}", int($state)); break
+#endif
+
+template<typename S, typename E>
+class DeadSimpleFSM {
+protected:
+  // BUG: don't put this in your class because state() won't work
+ S $state = S::START;
+
+public:
+  template<typename... Types>
+  void event(E event, Types... args);
+
+  void state(S next_state) {
+    $state = next_state;
+  }
+
+  bool in_state(S state) {
+    return $state == state;
+  }
+};