reintroduced optional enter/exit methods for each state

lib/include/srslte/common/choice_type.h

@@ -310,11 +310,16 @@ template <typename... Args>
 class choice_t : private choice_details::tagged_union_t<Args...>
 {
   using base_t = choice_details::tagged_union_t<Args...>;
+
+public:
+  //! Useful metafunction
   template <typename T>
   using enable_if_can_hold =
       typename std::enable_if<base_t::template can_hold_type<typename std::decay<T>::type>()>::type;
+  template <typename T>
+  using disable_if_can_hold =
+      typename std::enable_if<not base_t::template can_hold_type<typename std::decay<T>::type>()>::type;
 
-public:
   using base_t::can_hold_type;
   using base_t::get;
   using base_t::get_if;
@@ -408,6 +413,12 @@ const T* get_if(const choice_t<Args...>& c)
   return c.template get_if<T>();
 }
 
+template <typename T, typename... Args>
+T& get(choice_t<Args...>& c)
+{
+  return c.template get<T>();
+}
+
 template <std::size_t I, typename... Args>
 auto get(const choice_t<Args...>& c) -> decltype(c.template get<I>())
 {

lib/include/srslte/common/fsm.h

@@ -57,13 +57,25 @@ struct variant_convert {
   {
     static_assert(not std::is_same<typename std::decay<State>::type, typename std::decay<PrevState>::type>::value,
                   "State cannot transition to itself.\n");
+    if (p != nullptr) {
+      srslte::get<PrevState>(*v).exit();
+    }
     *v = std::move(s);
+    srslte::get<State>(*v).enter();
   }
   TargetVariant* v;
   PrevState*     p;
 };
 
 struct fsm_helper {
+  //! Metafunction to determine if FSM can hold given State type
+  template <typename FSM>
+  using get_fsm_state_list = decltype(std::declval<typename FSM::derived_view>().states);
+  template <typename FSM, typename State>
+  using enable_if_fsm_state = typename get_fsm_state_list<FSM>::template enable_if_can_hold<State>;
+  template <typename FSM, typename State>
+  using disable_if_fsm_state = typename get_fsm_state_list<FSM>::template disable_if_can_hold<State>;
+
   //! Stayed in same state
   template <typename FSM, typename PrevState>
   static void handle_state_change(FSM* f, same_state* s, PrevState* p)
@@ -79,17 +91,25 @@ struct fsm_helper {
   }
   //! Simple state transition in FSM
   template <typename FSM, typename State, typename PrevState>
-  static auto handle_state_change(FSM* f, State* s, PrevState* p) -> decltype(f->states = std::move(*s), void())
+  static enable_if_fsm_state<FSM, State> handle_state_change(FSM* f, State* s, PrevState* p)
   {
     static_assert(not std::is_same<State, PrevState>::value, "State cannot transition to itself.\n");
+    if (p != nullptr) {
+      srslte::get<PrevState>(f->states).exit();
+    }
     f->states = std::move(*s);
+    srslte::get<State>(f->states).enter();
   }
   //! State not present in current FSM. Attempt state transition in parent FSM in the case of NestedFSM
-  template <typename FSM, typename... Args>
-  static void handle_state_change(FSM* f, Args&&... args)
+  template <typename FSM, typename State, typename PrevState>
+  static disable_if_fsm_state<FSM, State> handle_state_change(FSM* f, State* s, PrevState* p)
   {
     static_assert(FSM::is_nested, "State is not present in the FSM list of valid states");
-    handle_state_change(f->parent_fsm()->derived(), args...);
+    if (p != nullptr) {
+      srslte::get<PrevState>(f->states).exit();
+      p = nullptr;
+    }
+    handle_state_change(f->parent_fsm()->derived(), s, p);
   }
 
   //! Trigger Event, that will result in a state transition
@@ -140,10 +160,12 @@ class state_t
 public:
   state_t()                        = default;
   virtual const char* name() const = 0;
+  virtual void        enter() {}
+  virtual void        exit() {}
 };
 
 template <typename Derived>
-class fsm_t
+class fsm_t : public state_t
 {
 public:
   // get access to derived protected members from the base
@@ -155,8 +177,6 @@ public:
   };
   static const bool is_nested = false;
 
-  virtual const char* name() const = 0;
-
   // Push Events to FSM
   template <typename Ev>
   void trigger(Ev&& e)

lib/test/common/choice_type_test.cc

@@ -77,6 +77,10 @@ static_assert(std::is_same<tagged_union_t<char, int, double>::default_type, char
 static_assert(tagged_union_t<char, int, double>::can_hold_type<int>(), "Can hold type implementation is incorrect\n");
 static_assert(not tagged_union_t<char, int, double>::can_hold_type<uint8_t>(),
               "Can hold type implementation is incorrect\n");
+static_assert(std::is_same<choice_t<char, int, double>::enable_if_can_hold<char>, void>::value,
+              "Metafunction enable if not working\n");
+static_assert(std::is_same<choice_t<char, int, double>::disable_if_can_hold<float>, void>::value,
+              "Metafunction enable if not working\n");
 
 } // namespace choice_details
 } // namespace srslte

lib/test/common/fsm_test.cc

@@ -38,18 +38,13 @@ public:
   uint32_t idle_enter_counter = 0, state1_enter_counter = 0;
   uint32_t foo_counter = 0;
 
-  fsm1() : states(idle_st{this}) {}
-
   const char* name() const override { return "fsm1"; }
 
   // idle state
-  struct idle_st : srslte::state_t {
-    idle_st(fsm1* f)
-    {
-      test_log->info("fsm1::%s::enter called\n", name());
-      f->idle_enter_counter++;
-    }
-    ~idle_st() { test_log->info("fsm1::%s::exit called\n", name()); }
+  struct idle_st : public srslte::state_t {
+    idle_st(fsm1* f) { f->idle_enter_counter++; }
+    void        enter() final { test_log->info("fsm1::%s::enter called\n", name()); }
+    void        exit() final { test_log->info("fsm1::%s::exit called\n", name()); }
     const char* name() const final { return "idle"; }
   };
 
@@ -72,7 +67,7 @@ public:
     struct state_inner : public srslte::state_t {
       const char* name() const final { return "state_inner"; }
       state_inner() { test_log->info("fsm2::%s::enter called\n", name()); }
-      ~state_inner() { test_log->info("fsm2::%s::exit called\n", name()); }
+      void exit() final { test_log->info("fsm2::%s::exit called\n", name()); }
     };
 
     fsm2(fsm1* f_) : nested_fsm_t(f_) { test_log->info("%s::enter called\n", name()); }
@@ -130,6 +125,24 @@ auto fsm1::react(state1& s, ev2 e) -> srslte::state_list<idle_st, fsm2>
   return idle_st{this};
 }
 
+// Static Checks
+
+namespace srslte {
+namespace fsm_details {
+
+static_assert(std::is_same<fsm_helper::get_fsm_state_list<fsm1>,
+                           srslte::state_list<fsm1::idle_st, fsm1::state1, fsm1::fsm2> >::value,
+              "get state list failed\n");
+static_assert(std::is_same<fsm_helper::enable_if_fsm_state<fsm1, fsm1::idle_st>, void>::value,
+              "get state list failed\n");
+static_assert(std::is_same<fsm_helper::disable_if_fsm_state<fsm1, fsm1::fsm2::state_inner>, void>::value,
+              "get state list failed\n");
+
+} // namespace fsm_details
+} // namespace srslte
+
+// Runtime checks
+
 int test_hsm()
 {
   test_log->set_level(srslte::LOG_LEVEL_INFO);