Add support for junction states

- Adding junction state construction and
  guard resolving.
- Relates to #262

spring-statemachine-data/jpa/src/test/java/org/springframework/statemachine/data/jpa/JpaRepositoryTests.java

@@ -357,6 +357,74 @@ public class JpaRepositoryTests extends AbstractJpaRepositoryTests {
 		plan.test();
 	}
 
+	@SuppressWarnings("unchecked")
+	@Test
+	public void testMachine8First() throws Exception {
+		context.register(Config8.class, FactoryConfig.class);
+		context.refresh();
+		StateMachineFactory<String, String> stateMachineFactory = context.getBean(StateMachineFactory.class);
+		StateMachine<String, String> stateMachine = stateMachineFactory.getStateMachine();
+
+		StateMachineTestPlan<String, String> plan =
+				StateMachineTestPlanBuilder.<String, String>builder()
+					.stateMachine(stateMachine)
+					.step().expectStates("SI").and()
+					.step().sendEvent(MessageBuilder.withPayload("E1").setHeader("junction", "s30").build()).expectStates("S30").and()
+					.build();
+		plan.test();
+	}
+
+	@SuppressWarnings("unchecked")
+	@Test
+	public void testMachine8Then1() throws Exception {
+		context.register(Config8.class, FactoryConfig.class);
+		context.refresh();
+		StateMachineFactory<String, String> stateMachineFactory = context.getBean(StateMachineFactory.class);
+		StateMachine<String, String> stateMachine = stateMachineFactory.getStateMachine();
+
+		StateMachineTestPlan<String, String> plan =
+				StateMachineTestPlanBuilder.<String, String>builder()
+					.stateMachine(stateMachine)
+					.step().expectStates("SI").and()
+					.step().sendEvent(MessageBuilder.withPayload("E1").setHeader("junction", "s31").build()).expectStates("S31").and()
+					.build();
+		plan.test();
+	}
+
+	@SuppressWarnings("unchecked")
+	@Test
+	public void testMachine8Then2() throws Exception {
+		context.register(Config8.class, FactoryConfig.class);
+		context.refresh();
+		StateMachineFactory<String, String> stateMachineFactory = context.getBean(StateMachineFactory.class);
+		StateMachine<String, String> stateMachine = stateMachineFactory.getStateMachine();
+
+		StateMachineTestPlan<String, String> plan =
+				StateMachineTestPlanBuilder.<String, String>builder()
+					.stateMachine(stateMachine)
+					.step().expectStates("SI").and()
+					.step().sendEvent(MessageBuilder.withPayload("E1").setHeader("junction", "s32").build()).expectStates("S32").and()
+					.build();
+		plan.test();
+	}
+
+	@SuppressWarnings("unchecked")
+	@Test
+	public void testMachine8Last() throws Exception {
+		context.register(Config8.class, FactoryConfig.class);
+		context.refresh();
+		StateMachineFactory<String, String> stateMachineFactory = context.getBean(StateMachineFactory.class);
+		StateMachine<String, String> stateMachine = stateMachineFactory.getStateMachine();
+
+		StateMachineTestPlan<String, String> plan =
+				StateMachineTestPlanBuilder.<String, String>builder()
+					.stateMachine(stateMachine)
+					.step().expectStates("SI").and()
+					.step().sendEvent(MessageBuilder.withPayload("E1").build()).expectStates("S33").and()
+					.build();
+		plan.test();
+	}
+
 	@Test
 	public void testPopulate1() {
 		context.register(Config2.class);
@@ -500,6 +568,33 @@ public class JpaRepositoryTests extends AbstractJpaRepositoryTests {
 		}
 	}
 
+	@EnableAutoConfiguration
+	static class Config8 {
+
+		@Bean
+		public StateMachineJackson2RepositoryPopulatorFactoryBean jackson2RepositoryPopulatorFactoryBean() {
+			StateMachineJackson2RepositoryPopulatorFactoryBean factoryBean = new StateMachineJackson2RepositoryPopulatorFactoryBean();
+			factoryBean.setResources(new Resource[]{new ClassPathResource("data8.json")});
+			return factoryBean;
+		}
+
+		@Bean
+		public Guard<String, String> s30Guard() {
+			return new JunctionGuard("s30");
+		}
+
+		@Bean
+		public Guard<String, String> s31Guard() {
+			return new JunctionGuard("s31");
+		}
+
+		@Bean
+		public Guard<String, String> s32Guard() {
+			return new JunctionGuard("s32");
+		}
+
+	}
+
 	@Configuration
 	@EnableStateMachineFactory
 	public static class FactoryConfig extends StateMachineConfigurerAdapter<String, String> {
@@ -537,4 +632,17 @@ public class JpaRepositoryTests extends AbstractJpaRepositoryTests {
 		}
 	}
 
+	private static class JunctionGuard implements Guard<String, String> {
+
+		private final String match;
+
+		public JunctionGuard(String match) {
+			this.match = match;
+		}
+
+		@Override
+		public boolean evaluate(StateContext<String, String> context) {
+			return ObjectUtils.nullSafeEquals(match, context.getMessageHeaders().get("junction", String.class));
+		}
+	}
 }

spring-statemachine-data/jpa/src/test/resources/data8.json

@@ -0,0 +1,84 @@
+[
+	{
+		"@id": "1",
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryState",
+		"initial": true,
+		"state": "SI"
+	},
+	{
+		"@id": "2",
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryState",
+		"initial": false,
+		"state": "S3",
+		"kind": "JUNCTION"
+	},
+	{
+		"@id": "3",
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryState",
+		"initial": false,
+		"state": "S30"
+	},
+	{
+		"@id": "4",
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryState",
+		"initial": false,
+		"state": "S31"
+	},
+	{
+		"@id": "5",
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryState",
+		"initial": false,
+		"state": "S32"
+	},
+	{
+		"@id": "6",
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryState",
+		"initial": false,
+		"state": "S33"
+	},
+	{
+		"@id": "7",
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryGuard",
+		"name": "s30Guard"
+	},
+	{
+		"@id": "8",
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryGuard",
+		"name": "s31Guard"
+	},
+	{
+		"@id": "9",
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryGuard",
+		"name": "s32Guard"
+	},
+	{
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryTransition",
+		"source": "1",
+		"target": "2",
+		"event": "E1",
+		"kind": "EXTERNAL"
+	},
+	{
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryTransition",
+		"source": "2",
+		"target": "3",
+		"guard": "7"
+	},
+	{
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryTransition",
+		"source": "2",
+		"target": "4",
+		"guard": "8"
+	},
+	{
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryTransition",
+		"source": "2",
+		"target": "5",
+		"guard": "9"
+	},
+	{
+		"_class": "org.springframework.statemachine.data.jpa.JpaRepositoryTransition",
+		"source": "2",
+		"target": "6"
+	}
+]

spring-statemachine-data/src/main/java/org/springframework/statemachine/data/RepositoryStateMachineModelFactory.java

@@ -33,6 +33,7 @@ import org.springframework.statemachine.config.model.ChoiceData;
 import org.springframework.statemachine.config.model.ConfigurationData;
 import org.springframework.statemachine.config.model.DefaultStateMachineModel;
 import org.springframework.statemachine.config.model.HistoryData;
+import org.springframework.statemachine.config.model.JunctionData;
 import org.springframework.statemachine.config.model.StateData;
 import org.springframework.statemachine.config.model.StateMachineModel;
 import org.springframework.statemachine.config.model.StateMachineModelFactory;
@@ -155,6 +156,7 @@ public class RepositoryStateMachineModelFactory extends AbstractStateMachineMode
 		Collection<TransitionData<String, String>> transitionData = new ArrayList<>();
 		Collection<HistoryData<String, String>> historys = new ArrayList<HistoryData<String, String>>();
 		Map<String, LinkedList<ChoiceData<String, String>>> choices = new HashMap<String, LinkedList<ChoiceData<String,String>>>();
+		Map<String, LinkedList<JunctionData<String, String>>> junctions = new HashMap<String, LinkedList<JunctionData<String,String>>>();
 		for (RepositoryTransition t : transitionRepository.findByMachineId(machineId)) {
 
 			Collection<Action<String, String>> actions = new ArrayList<Action<String, String>>();
@@ -194,7 +196,19 @@ public class RepositoryStateMachineModelFactory extends AbstractStateMachineMode
 				} else {
 					list.addFirst(new ChoiceData<String, String>(t.getSource().getState(), t.getTarget().getState(), guard));
 				}
-
+			} else if (t.getSource().getKind() == PseudoStateKind.JUNCTION) {
+				LinkedList<JunctionData<String, String>> list = junctions.get(t.getSource().getState());
+				if (list == null) {
+					list = new LinkedList<JunctionData<String, String>>();
+					junctions.put(t.getSource().getState(), list);
+				}
+				guard = resolveGuard(t);
+				// we want null guards to be at the end
+				if (guard == null) {
+					list.addLast(new JunctionData<String, String>(t.getSource().getState(), t.getTarget().getState(), guard));
+				} else {
+					list.addFirst(new JunctionData<String, String>(t.getSource().getState(), t.getTarget().getState(), guard));
+				}
 			} else if (t.getSource().getKind() == PseudoStateKind.HISTORY_SHALLOW) {
 				historys.add(new HistoryData<String, String>(t.getSource().getState(), t.getTarget().getState()));
 			} else if (t.getSource().getKind() == PseudoStateKind.HISTORY_DEEP) {
@@ -204,8 +218,10 @@ public class RepositoryStateMachineModelFactory extends AbstractStateMachineMode
 
 		HashMap<String, List<ChoiceData<String, String>>> choicesCopy = new HashMap<String, List<ChoiceData<String, String>>>();
 		choicesCopy.putAll(choices);
+		HashMap<String, List<JunctionData<String, String>>> junctionsCopy = new HashMap<String, List<JunctionData<String, String>>>();
+		junctionsCopy.putAll(junctions);
 
-		TransitionsData<String, String> transitionsData = new TransitionsData<>(transitionData, choicesCopy, null, null, null, null, null, historys);
+		TransitionsData<String, String> transitionsData = new TransitionsData<>(transitionData, choicesCopy, junctionsCopy, null, null, null, null, historys);
 
 		StateMachineModel<String, String> stateMachineModel = new DefaultStateMachineModel<>(configurationData, statesData, transitionsData);
 		return stateMachineModel;