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

lib/tinyfsm/examples/api/debugging_switch.cpp

@@ -0,0 +1,122 @@
+#include <tinyfsm.hpp>
+#include <iostream>
+#include <cassert>
+
+struct Off; // forward declaration
+
+
+// ----------------------------------------------------------------------------
+// Event Declarations
+//
+struct Toggle : tinyfsm::Event { }; // Event Declarations
+
+
+// ----------------------------------------------------------------------------
+// State Machine Declaration
+//
+struct Switch
+: tinyfsm::Fsm<Switch>
+{
+  static void reset(void);
+
+  // NOTE: on reset: "tinyfsm::StateList<Off, On>::reset()", copy
+  // constructor is used by default, so "this" points to neither
+  // "Off" nor "On" (see operator=() below).
+  Switch() : counter(0) {
+    std::cout << "* Switch()" << std::endl
+              << "  this          = " << this << std::endl;
+  }
+
+  ~Switch() {
+    std::cout << "* ~Switch()" << std::endl
+              << "  this          = " << this << std::endl;
+  }
+
+  Switch & operator=(const Switch & other) {
+    std::cout << "* operator=()" << std::endl
+              << "  this          = " << this << std::endl
+              << "  other         = " << &other << std::endl;
+    counter = other.counter;
+    return *this;
+  }
+
+  virtual void react(Toggle const &) { };
+  void entry(void);
+  void exit(void);
+
+  int counter;
+};
+
+struct On : Switch {
+  void react(Toggle const &) override { transit<Off>(); };
+};
+
+struct Off : Switch {
+  void react(Toggle const &) override { transit<On>(); };
+};
+
+FSM_INITIAL_STATE(Switch, Off)
+
+
+// ----------------------------------------------------------------------------
+// State Machine Definitions
+//
+void Switch::reset() {
+  tinyfsm::StateList<Off, On>::reset();
+}
+
+void Switch::entry() {
+  counter++;
+
+  // debugging only. properly designed state machines don't need this:
+  if(is_in_state<On>())       { std::cout << "* On::entry()"  << std::endl; }
+  else if(is_in_state<Off>()) { std::cout << "* Off::entry()" << std::endl; }
+  else assert(true);
+
+  assert(current_state_ptr == this);
+  std::cout << "  this (cur)    = " << this << std::endl
+            << "  state<On>     = " << &state<On>()  << std::endl
+            << "  state<Off>    = " << &state<Off>() << std::endl;
+}
+
+void Switch::exit() {
+  assert(current_state_ptr == this);
+  std::cout << "* exit()" << std::endl
+            << "  this (cur)    = " << this << std::endl
+            << "  state<On>     = " << &state<On>()  << std::endl
+            << "  state<Off>    = " << &state<Off>() << std::endl;
+}
+
+
+// ----------------------------------------------------------------------------
+// Main
+//
+int main()
+{
+  Switch::start();
+
+  while(1)
+  {
+    char c;
+    std::cout << "* main()" << std::endl
+              << "  cur_counter   = " << Switch::current_state_ptr->counter  << std::endl
+              << "  on_counter    = " << Switch::state<On>().counter  << std::endl
+              << "  off_counter   = " << Switch::state<Off>().counter << std::endl;
+
+    std::cout << std::endl << "t=Toggle, r=Restart, q=Quit ? ";
+    std::cin >> c;
+    switch(c) {
+    case 't':
+      Switch::dispatch(Toggle());
+      break;
+    case 'r':
+      Switch::reset();
+      Switch::start();
+      break;
+    case 'q':
+      return 0;
+    default:
+      std::cout << "> Invalid input" << std::endl;
+    };
+  }
+}