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

lib/tinyfsm/examples/api/simple_switch.cpp

@@ -0,0 +1,85 @@
+#include <tinyfsm.hpp>
+#include <iostream>
+
+struct Off; // forward declaration
+
+
+// ----------------------------------------------------------------------------
+// 1. Event Declarations
+//
+struct Toggle : tinyfsm::Event { };
+
+
+// ----------------------------------------------------------------------------
+// 2. State Machine Base Class Declaration
+//
+struct Switch : tinyfsm::Fsm<Switch>
+{
+  virtual void react(Toggle const &) { };
+
+  // alternative: enforce handling of Toggle in all states (pure virtual)
+  //virtual void react(Toggle const &) = 0;
+
+  virtual void entry(void) { };  /* entry actions in some states */
+  void         exit(void)  { };  /* no exit actions */
+
+  // alternative: enforce entry actions in all states (pure virtual)
+  //virtual void entry(void) = 0;
+};
+
+
+// ----------------------------------------------------------------------------
+// 3. State Declarations
+//
+struct On : Switch
+{
+  void entry() override { std::cout << "* Switch is ON" << std::endl; };
+  void react(Toggle const &) override { transit<Off>(); };
+};
+
+struct Off : Switch
+{
+  void entry() override { std::cout << "* Switch is OFF" << std::endl; };
+  void react(Toggle const &) override { transit<On>(); };
+};
+
+FSM_INITIAL_STATE(Switch, Off)
+
+
+// ----------------------------------------------------------------------------
+// 4. State Machine List Declaration (dispatches events to multiple FSM's)
+//
+// In this example, we only have a single state machine, no need to use FsmList<>:
+//using fsm_handle = tinyfsm::FsmList< Switch >;
+using fsm_handle = Switch;
+
+
+// ----------------------------------------------------------------------------
+// Main
+//
+int main()
+{
+  // instantiate events
+  Toggle toggle;
+
+  fsm_handle::start();
+
+  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;
+      fsm_handle::dispatch(toggle);
+      // alternative: instantiating causes no overhead (empty declaration)
+      //fsm_handle::dispatch(Toggle());
+      break;
+    case 'q':
+      return 0;
+    default:
+      std::cout << "> Invalid input" << std::endl;
+    };
+  }
+}