Refined the FSM to allow easily passing in data to the even handler and state functions.

tests/fsm.cpp

@@ -0,0 +1,67 @@
+#include <catch2/catch_test_macros.hpp>
+#include <fmt/core.h>
+#include <string>
+#include "../fsm.hpp"
+
+using namespace fmt;
+using std::string;
+
+enum class MyState {
+  START, RUNNING, END
+};
+
+enum class MyEvent {
+  STARTED, PUSH, QUIT
+};
+
+class MyFSM : public DeadSimpleFSM<MyState, MyEvent> {
+public:
+  void event(MyEvent ev, string data="") {
+    switch(_state) {
+      FSM_STATE(MyState, START, START, ev);
+      FSM_STATE(MyState, RUNNING, RUNNING, ev, data);
+      FSM_STATE(MyState, END, END, ev);
+    }
+  }
+
+  void START(MyEvent ev) {
+    println("<<< START");
+    state(MyState::RUNNING);
+  }
+
+  void RUNNING(MyEvent ev, string &data) {
+    if(ev == MyEvent::QUIT) {
+      println("<<< QUITTING {}", data);
+      state(MyState::END);
+    } else {
+      println("<<< RUN: {}", data);
+      state(MyState::RUNNING);
+    }
+  }
+
+  void END(MyEvent ev) {
+    println("<<< STOP");
+    state(MyState::END);
+  }
+};
+
+TEST_CASE("confirm fsm works with optional data", "[utils]") {
+  MyFSM fsm;
+
+  REQUIRE(fsm.in_state(MyState::START));
+
+  fsm.event(MyEvent::STARTED);
+  REQUIRE(fsm.in_state(MyState::RUNNING));
+
+  fsm.event(MyEvent::PUSH);
+  REQUIRE(fsm.in_state(MyState::RUNNING));
+
+  fsm.event(MyEvent::PUSH);
+  REQUIRE(fsm.in_state(MyState::RUNNING));
+
+  fsm.event(MyEvent::PUSH);
+  REQUIRE(fsm.in_state(MyState::RUNNING));
+
+  fsm.event(MyEvent::QUIT, "DONE!");
+  REQUIRE(fsm.in_state(MyState::END));
+}