1 files changed, 149 insertions, 0 deletions
diff --git a/plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/util/fsm/StateMachine.java b/plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/util/fsm/StateMachine.java
new file mode 100644
index 0000000000..2f5e991122
--- /dev/null
+++ b/plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/util/fsm/StateMachine.java
@@ -0,0 +1,149 @@
+package org.eclipse.net4j.util.fsm;
+
+
+import org.apache.log4j.Logger;
+
+
+public abstract class StateMachine<SUBJECT> implements IStateMachine<SUBJECT>
+{
+  private static final Logger logger = Logger.getLogger(StateMachine.class.getName());
+
+  private String[] stateNames;
+
+  private String[] eventNames;
+
+  private ITransition<SUBJECT>[][] matrix;
+
+  public StateMachine(String[] stateNames, String[] eventNames,
+      ITransition<SUBJECT> defaultTransition)
+  {
+    this.stateNames = stateNames;
+    this.eventNames = eventNames;
+
+    matrix = new ITransition[stateNames.length][eventNames.length];
+
+    if (defaultTransition != null)
+    {
+      for (int state = 0; state < stateNames.length; state++)
+      {
+        for (int event = 0; event < eventNames.length; event++)
+        {
+          handle(state, event, defaultTransition);
+        }
+      }
+    }
+  }
+
+  public StateMachine(String[] stateNames, String[] eventNames)
+  {
+    this(stateNames, eventNames, null);
+  }
+
+  public int getStateCount()
+  {
+    return stateNames.length;
+  }
+
+  public int getEventCount()
+  {
+    return eventNames.length;
+  }
+
+  public String getStateName(int state)
+  {
+    return stateNames[state];
+  }
+
+  public String getEventName(int event)
+  {
+    return eventNames[event];
+  }
+
+  public ITransition<SUBJECT> getIdentityTransition()
+  {
+    return new ITransition<SUBJECT>()
+    {
+      public void process(SUBJECT subject, int event, Object data) throws Exception
+      {
+        if (getLogger().isDebugEnabled())
+        {
+          int state = getState(subject);
+          getLogger().debug("Ignoring   " + makeLabel(subject, state, event));
+        }
+      }
+    };
+  }
+
+  public void handle(int state, int event, ITransition<SUBJECT> transition)
+  {
+    matrix[state][event] = transition;
+  }
+
+  public void handle(int state, int event, final int newState)
+  {
+    handle(state, event, new ITransition<SUBJECT>()
+    {
+      public void process(SUBJECT subject, int event, Object data) throws Exception
+      {
+        setState(subject, newState);
+      }
+    });
+  }
+
+  public void ignore(int state, int event)
+  {
+    handle(state, event, getIdentityTransition());
+  }
+
+  public void cancel(int state, int event)
+  {
+    handle(state, event, null);
+  }
+
+  public void process(SUBJECT subject, int event, Object data) throws Exception
+  {
+    int state = getState(subject);
+    ITransition<SUBJECT> transition = matrix[state][event];
+
+    if (transition == null)
+    {
+      if (getLogger().isDebugEnabled())
+      {
+        getLogger().warn("Ignoring   " + makeLabel(subject, state, event));
+      }
+
+      return;
+    }
+
+    if (getLogger().isDebugEnabled())
+    {
+      getLogger().debug("Processing " + makeLabel(subject, state, event));
+    }
+
+    transition.process(subject, event, data);
+
+    if (getLogger().isDebugEnabled())
+    {
+      int newState = getState(subject);
+      getLogger()
+          .debug(
+              "Finished   " + makeLabel(subject, state, event) + ", newState="
+                  + getStateName(newState));
+    }
+  }
+
+  protected Logger getLogger()
+  {
+    return logger;
+  }
+
+  protected String makeLabel(SUBJECT subject, int state, int event)
+  {
+    return "event " + eventNames[event] + " in state " + stateNames[state] + " for subject "
+        + subject;
+  }
+
+  protected abstract int getState(SUBJECT subject);
+
+  protected abstract void setState(SUBJECT subject, int state);
+}
+\ No newline at end of file