Add tinyfsm, start converting core functions to an FSM-based event loop

lib/tinyfsm/examples/api/mealy_machine.cpp

@@ -0,0 +1,70 @@
+#include <tinyfsm.hpp>
+#include <iostream>
+
+// ----------------------------------------------------------------------------
+// 1. Event Declarations
+//
+struct Toggle : tinyfsm::Event { };
+
+
+// ----------------------------------------------------------------------------
+// 2. State Machine Base Class Declaration
+//
+struct Switch : tinyfsm::MealyMachine<Switch>
+{
+  /* pure virtual reaction (override required in all states) */
+  virtual void react(Toggle const &) = 0;
+
+  /* transition actions */
+  static void OpenCircuit() {
+    std::cout << "* Opening ciruit (light goes OFF)" << std::endl;
+  }
+  static void CloseCircuit()  {
+    std::cout << "* Closing ciruit (light goes ON)"  << std::endl;
+  }
+};
+
+
+// ----------------------------------------------------------------------------
+// 3. State Declarations
+//
+struct Off; // forward declaration
+
+struct On : Switch
+{
+  void react(Toggle const &) override { transit<Off>(OpenCircuit); };
+};
+
+struct Off : Switch
+{
+  void react(Toggle const &) override { transit<On>(CloseCircuit); };
+};
+
+FSM_INITIAL_STATE(Switch, Off)
+
+
+// ----------------------------------------------------------------------------
+// Main
+//
+int main()
+{
+  Switch::start();
+
+  std::cout << "> You are facing a light switch..." << std::endl;
+  while(1)
+  {
+    char c;
+    std::cout << std::endl << "t=Toggle, q=Quit ? ";
+    std::cin >> c;
+    switch(c) {
+    case 't':
+      std::cout << "> Toggling switch..." << std::endl;
+      Switch::dispatch(Toggle());
+      break;
+    case 'q':
+      return 0;
+    default:
+      std::cout << "> Invalid input" << std::endl;
+    };
+  }
+}