From 0387da02f243c29e7b5e2810b9e556cde0c75a85 Mon Sep 17 00:00:00 2001
From: Julian Meyers <Julian@MeyersWorld.com>
Date: Mon, 22 May 2023 18:14:34 -0500
Subject: [PATCH] Adds handling information about events added to the
 process_queue

---
 example/defer_and_process.cpp       |  9 +++++----
 include/boost/sml.hpp               | 11 ++++++-----
 test/ft/actions_process.cpp         | 26 +++++++++++++-------------
 test/ft/actions_process_n_defer.cpp | 12 ++++++------
 4 files changed, 30 insertions(+), 28 deletions(-)

diff --git a/example/defer_and_process.cpp b/example/defer_and_process.cpp
index fe35dd2c..65b54b2f 100644
--- a/example/defer_and_process.cpp
+++ b/example/defer_and_process.cpp
@@ -25,7 +25,7 @@ struct defer_and_process {
     return make_transition_table(
        *"idle"_s + event<e1> / defer
       , "idle"_s + event<e2> = "s1"_s
-      , "s1"_s   + event<e1> = "s2"_s
+      , "s1"_s   + event<e1> / process(e2{}) = "s2"_s
       , "s2"_s   + event<e3> / process(e4{})
       , "s2"_s   + event<e4> = X
     );
@@ -40,12 +40,13 @@ int main() {
       sm;  /// defer_queue policy to enable deferred events using std::queue
   assert(sm.is("idle"_s));
 
-  sm.process_event(e1{});
+  assert(sm.process_event(e1{}));
   assert(sm.is("idle"_s));
 
-  sm.process_event(e2{});  /// triggers idle -> s1 and s1 -> s2 (via deferred e1)
+  assert(!sm.process_event(e2{}));  /// triggers idle -> s1 and s1 -> s2 (via deferred e1)
+                                    /// additionally triggers e2 again which is unhandled so it returns false
   assert(sm.is("s2"_s));
 
-  sm.process_event(e3{});  /// triggers s2.process(e4) -> X (via processed e4)
+  assert(sm.process_event(e3{}));  /// triggers s2.process(e4) -> X (via processed e4)
   assert(sm.is(sml::X));
 }
diff --git a/include/boost/sml.hpp b/include/boost/sml.hpp
index ca00ff43..11838947 100644
--- a/include/boost/sml.hpp
+++ b/include/boost/sml.hpp
@@ -1426,13 +1426,14 @@ struct sm_impl : aux::conditional_t<aux::is_empty<typename TSM::sm>::value, aux:
     const auto lock = thread_safety_.create_lock();
     (void)lock;
     bool handled = process_internal_events(event, deps, subs);
+    bool queued_handled = true;
     do {
       do {
         while (process_internal_events(anonymous{}, deps, subs)) {
         }
       } while (process_defer_events(deps, subs, handled, aux::type<defer_queue_t<TEvent>>{}, events_t{}));
-    } while (process_queued_events(deps, subs, aux::type<process_queue_t<TEvent>>{}, events_t{}));
-    return handled;
+    } while (process_queued_events(deps, subs, queued_handled, aux::type<process_queue_t<TEvent>>{}, events_t{}));
+    return handled && queued_handled;
   }
   constexpr void initialize(const aux::type_list<> &) {}
   template <class TState>
@@ -1639,7 +1640,7 @@ struct sm_impl : aux::conditional_t<aux::is_empty<typename TSM::sm>::value, aux:
     return processed_events;
   }
   template <class TDeps, class TSubs, class... TEvents>
-  constexpr bool process_queued_events(TDeps &, TSubs &, const aux::type<no_policy> &, const aux::type_list<TEvents...> &) {
+  constexpr bool process_queued_events(TDeps &, TSubs &,  bool &, const aux::type<no_policy> &, const aux::type_list<TEvents...> &) {
     return false;
   }
   template <class TDeps, class TSubs, class TEvent>
@@ -1654,13 +1655,13 @@ struct sm_impl : aux::conditional_t<aux::is_empty<typename TSM::sm>::value, aux:
 #endif
   }
   template <class TDeps, class TSubs, class TDeferQueue, class... TEvents>
-  bool process_queued_events(TDeps &deps, TSubs &subs, const aux::type<TDeferQueue> &, const aux::type_list<TEvents...> &) {
+  bool process_queued_events(TDeps &deps, TSubs &subs, bool &queued_handled, const aux::type<TDeferQueue> &, const aux::type_list<TEvents...> &) {
     using dispatch_table_t = bool (sm_impl::*)(TDeps &, TSubs &, const void *);
     const static dispatch_table_t dispatch_table[__BOOST_SML_ZERO_SIZE_ARRAY_CREATE(sizeof...(TEvents))] = {
         &sm_impl::process_event_no_queue<TDeps, TSubs, TEvents>...};
     bool wasnt_empty = !process_.empty();
     while (!process_.empty()) {
-      (this->*dispatch_table[process_.front().id])(deps, subs, process_.front().data);
+      queued_handled &= (this->*dispatch_table[process_.front().id])(deps, subs, process_.front().data);
       process_.pop();
     }
     return wasnt_empty;
diff --git a/test/ft/actions_process.cpp b/test/ft/actions_process.cpp
index 90f9dd2f..31d9c642 100644
--- a/test/ft/actions_process.cpp
+++ b/test/ft/actions_process.cpp
@@ -85,26 +85,26 @@ test process_event_from_substate = [] {
   expect(sm.is(idle));
   expect(sm.is<decltype(sml::state<sub>)>(s1));
 
-  sm.process_event(e1{});
+  expect(sm.process_event(e1{}));
   expect(sm.is(sml::state<sub>));
   expect(sm.is<decltype(sml::state<sub>)>(s1));
   expect(!c_.a_called);
 
-  sm.process_event(e1{});
+  expect(sm.process_event(e1{}));
   expect(sm.is(sml::state<sub>));
   expect(sm.is<decltype(sml::state<sub>)>(s2));
   expect(!c_.a_called);
 
-  sm.process_event(e2{});  // + process(e3{})
+  expect(!sm.process_event(e2{}));  // + process(e3{}) + process(e2{})
   expect(sm.is(sml::state<sub>));
   expect(sm.is<decltype(sml::state<sub>)>(s3));
   expect(!c_.a_called);
 
-  sm.process_event(e3{});
+  expect(sm.process_event(e3{}));
   expect(sm.is(sml::state<sub>));
   expect(sm.is<decltype(sml::state<sub>)>(sml::X));
 
-  sm.process_event(e4{});
+  expect(sm.process_event(e4{}));
   expect(1 == c_.a_called);
 };
 
@@ -148,7 +148,7 @@ test queue_and_internal_process_events = [] {
       return make_transition_table(
         * idle + on_entry<sml::initial> / process(e1())
         , s1 <= idle + event<e1>
-        , s2 <= s1
+        , s2 <= s1 / process(e1())  // This process is unhandled, but the state machine still transitions to s2
         , s2 + on_entry<_> / process(e2())
         , s3 <= s2 + event<e2>
         , X <= s3
@@ -186,7 +186,7 @@ test queue_process_reaction = [] {
 
   sml::sm<c, sml::process_queue<std::queue>> sm{};
 
-  sm.process_event(e1());
+  expect(!sm.process_event(e1()));  // e3 was unexpected so it returns false
   expect(sm.is(sml::X));
 
   const c& c_ = sm;
@@ -209,7 +209,7 @@ test mix_process_and_internal = [] {
 
   sml::sm<c, sml::process_queue<std::queue>> sm{};
 
-  sm.process_event(e1{});
+  expect(sm.process_event(e1{}));
   expect(sm.is(sml::X));
 };
 
@@ -242,11 +242,11 @@ test process_event_sent_from_substate = [] {
   expect(sm.is(idle, s2));
   expect(sm.is<decltype(sml::state<sub>)>(s1));
 
-  sm.process_event(e1{});
+  expect(sm.process_event(e1{}));
   expect(sm.is(sml::state<sub>, s2));
   expect(sm.is<decltype(sml::state<sub>)>(s1));
 
-  sm.process_event(e1{});  // + process(e2{})
+  expect(sm.process_event(e1{}));  // + process(e2{})
   expect(sm.is(sml::X, sml::X));
   expect(sm.is<decltype(sml::state<sub>)>(sml::X));
 };
@@ -279,10 +279,10 @@ test process_event_of_substate = [] {
   expect(sm.is(idle));
   expect(sm.is<decltype(sml::state<sub>)>(s1));
 
-  sm.process_event(e1{});
+  expect(sm.process_event(e1{}));
   expect(sm.is(sml::state<sub>));
 
-  sm.process_event(e2{});  // + process(e2{})
+  expect(sm.process_event(e2{}));  // + process(e2{})
   expect(sm.is(sml::state<sub>));
   expect(sm.is<decltype(sml::state<sub>)>(sml::X));
 };
@@ -327,7 +327,7 @@ test process_between_substates = [] {
   expect(sm.is<decltype(sml::state<sub1>)>(s1));
   expect(sm.is<decltype(sml::state<sub2>)>(s2));
 
-  sm.process_event(e1{});
+  expect(sm.process_event(e1{}));
   expect(sm.is(sml::X, sml::X));
   expect(sm.is<decltype(sml::state<sub1>)>(sml::X));
   expect(sm.is<decltype(sml::state<sub2>)>(sml::X));
diff --git a/test/ft/actions_process_n_defer.cpp b/test/ft/actions_process_n_defer.cpp
index f5df2a05..387fcb65 100644
--- a/test/ft/actions_process_n_defer.cpp
+++ b/test/ft/actions_process_n_defer.cpp
@@ -62,7 +62,7 @@ test mix_process_n_defer = [] {
         , s3 + event<e2> / defer = s4
         , s4 + event<e2> = s5
         , s5 = s6
-        , s6 + on_entry<_> / process(e3{})
+        , s6 + on_entry<_> / (process(e1{}), process(e3{}))  // e1 is not handled
         , s6 + event<e3> = s7
         , s7 = X
       );
@@ -70,7 +70,7 @@ test mix_process_n_defer = [] {
     }
   };  // internal, defer, process, defer, internal, process, internal
   sml::sm<c, sml::process_queue<std::queue>, sml::defer_queue<std::deque>> sm{};
-  sm.process_event(e1{});
+  expect(!sm.process_event(e1{}));
   expect(sm.is(sml::X));
 };
 
@@ -105,10 +105,10 @@ test process_n_defer_again = [] {
 
   std::string calls;
   sml::sm<c, sml::process_queue<std::queue>, sml::defer_queue<std::deque>> sm{calls};
-  sm.process_event(e1{});
-  sm.process_event(e1{});
-  sm.process_event(e1{});
-  sm.process_event(e3{});
+  expect(sm.process_event(e1{}));
+  expect(sm.process_event(e1{}));
+  expect(sm.process_event(e1{}));
+  expect(sm.process_event(e3{}));
   expect(calls == "");
   sm.process_event(e2{});
   std::cout << calls << "\n";