--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dwtx/core/commands/AbstractHandlerWithState.d	Wed Mar 26 00:57:19 2008 +0100
@@ -0,0 +1,131 @@
+/*******************************************************************************
+ * Copyright (c) 2005, 2006 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ * Port to the D programming language:
+ *     Frank Benoit <benoit@tionex.de>
+ *******************************************************************************/
+
+module dwtx.core.commands.AbstractHandlerWithState;
+
+import dwtx.core.commands.AbstractHandler;
+import dwtx.core.commands.IObjectWithState;
+import dwtx.core.commands.IStateListener;
+import dwtx.core.commands.State;
+
+import dwt.dwthelper.utils;
+
+import tango.util.collection.HashMap;
+import tango.util.collection.model.Map;
+import tango.util.collection.model.Set;
+
+/**
+ * <p>
+ * An abstract implementation of {@link IObjectWithState}. This provides basic
+ * handling for adding and remove state. When state is added, the handler
+ * attaches itself as a listener and fire a handleStateChange event to notify
+ * this handler. When state is removed, the handler removes itself as a
+ * listener.
+ * </p>
+ * <p>
+ * Clients may extend this class.
+ * </p>
+ *
+ * @since 3.2
+ */
+public abstract class AbstractHandlerWithState : AbstractHandler,
+        IObjectWithState, IStateListener {
+
+    /**
+     * The map of states currently held by this handler. If this handler has no
+     * state (generally, when inactive), then this will be <code>null</code>.
+     */
+    private Map!(String,State) states = null;
+
+    /**
+     * <p>
+     * Adds a state to this handler. This will add this handler as a listener to
+     * the state, and then fire a handleStateChange so that the handler can
+     * respond to the incoming state.
+     * </p>
+     * <p>
+     * Clients may extend this method, but they should call this super method
+     * first before doing anything else.
+     * </p>
+     *
+     * @param stateId
+     *            The identifier indicating the type of state being added; must
+     *            not be <code>null</code>.
+     * @param state
+     *            The state to add; must not be <code>null</code>.
+     */
+    public void addState(String stateId, State state) {
+        if (state is null) {
+            throw new NullPointerException("Cannot add a null state"); //$NON-NLS-1$
+        }
+
+        if (states is null) {
+            states = new HashMap!(String,State)(/+3+/);
+        }
+        states.add(stateId, state);
+        state.addListener(this);
+        handleStateChange(state, null);
+    }
+
+    public final State getState(String stateId) {
+        if ((states is null) || (states.drained())) {
+            return null;
+        }
+
+        return cast(State) states.get(stateId);
+    }
+
+    public final String[] getStateIds() {
+        if ((states is null) || (states.drained())) {
+            return null;
+        }
+
+        String[] res;
+        foreach( k, v; states.keys() ){
+            res ~= k;
+        }
+        return res;
+    }
+
+    /**
+     * <p>
+     * Removes a state from this handler. This will remove this handler as a
+     * listener to the state. No event is fired to notify the handler of this
+     * change.
+     * </p>
+     * <p>
+     * Clients may extend this method, but they should call this super method
+     * first before doing anything else.
+     * </p>
+     *
+     * @param stateId
+     *            The identifier of the state to remove; must not be
+     *            <code>null</code>.
+     */
+    public void removeState(String stateId) {
+        if (stateId is null) {
+            throw new NullPointerException("Cannot remove a null state"); //$NON-NLS-1$
+        }
+
+        State state = cast(State) states.get(stateId);
+        if (state !is null) {
+            state.removeListener(this);
+            if (states !is null) {
+                states.remove(state);
+                if (states.drained()) {
+                    states = null;
+                }
+            }
+        }
+    }
+}