Added state machine for the server.

src/rosjava_actionlib/rosjava_actionlib/src/main/java/com/github/ekumen/rosjava_actionlib/ServerStateMachine.java

+/**
+ * Copyright (c) 2015, Ernesto Corbellini, Ekumen
+ *
+ * Pending license.
+ *
+ */
+
+
+package com.github.ekumen.rosjava_actionlib;
+
+import java.lang.Exception;
+import actionlib_msgs.GoalStatus;
+
+/*
+ * Class to manage the server state machine transitions.
+ * @author Ernesto Corbellini
+ */
+public class ServerStateMachine {
+  public static class Events {
+    public final static int CANCEL_REQUEST = 1;
+    public final static int CANCEL = 2;
+    public final static int REJECT = 3;
+    public final static int ACCEPT = 4;
+    public final static int SUCCEED = 5;
+    public final static int ABORT = 6;
+  }
+
+  private int state;
+
+  ServerStateMachine() {
+    // Initial state
+    state = GoalStatus.PENDING;
+  }
+
+  public synchronized int getState() {
+    return state;
+  }
+
+  public synchronized void setState(int s) {
+    state = s;
+  }
+
+  public synchronized int transition(int event) throws Exception {
+    int nextState = state;
+
+    switch (state) {
+      case GoalStatus.PENDING:
+        switch (event) {
+          case Events.REJECT:
+            nextState = GoalStatus.REJECTED;
+            break;
+          case Events.CANCEL_REQUEST:
+            nextState = GoalStatus.RECALLING;
+            break;
+          case Events.ACCEPT:
+            nextState = GoalStatus.ACTIVE;
+            break;
+          default:
+            throw new Exception("Actionlib server exception: Invalid transition event!");
+        }
+        break;
+      case GoalStatus.RECALLING:
+        switch (event) {
+          case Events.REJECT:
+            nextState = GoalStatus.REJECTED;
+            break;
+          case Events.CANCEL:
+            nextState = GoalStatus.RECALLED;
+            break;
+          case Events.ACCEPT:
+            nextState = GoalStatus.PREEMPTING;
+            break;
+          default:
+            throw new Exception("Actionlib server exception: Invalid transition event!");
+        }
+        break;
+      case GoalStatus.ACTIVE:
+        switch (event) {
+          case Events.SUCCEED:
+            nextState = GoalStatus.SUCCEEDED;
+            break;
+          case Events.CANCEL_REQUEST:
+            nextState = GoalStatus.PREEMPTING;
+            break;
+          case Events.ABORT:
+            nextState = GoalStatus.ABORTED;
+            break;
+          default:
+            throw new Exception("Actionlib server exception: Invalid transition event!");
+        }
+        break;
+      case GoalStatus.PREEMPTING:
+        switch (event) {
+          case Events.SUCCEED:
+            nextState = GoalStatus.SUCCEEDED;
+            break;
+          case Events.CANCEL:
+            nextState = GoalStatus.PREEMPTED;
+            break;
+          case Events.ABORT:
+            nextState = GoalStatus.ABORTED;
+            break;
+          default:
+            throw new Exception("Actionlib server exception: Invalid transition event!");
+        }
+        break;
+      case GoalStatus.REJECTED:
+        break;
+      case GoalStatus.RECALLED:
+        break;
+      case GoalStatus.PREEMPTED:
+        break;
+      case GoalStatus.SUCCEEDED:
+        break;
+      case GoalStatus.ABORTED:
+        break;
+      default:
+        throw new Exception("Actionlib server exception: Invalid state!");
+    }
+    // transition to the next state
+    state = nextState;
+    return nextState;
+  }
+}