--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dwtx/core/commands/State.d	Wed Mar 26 00:57:19 2008 +0100
@@ -0,0 +1,141 @@
+/*******************************************************************************
+ * 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.State;
+
+import dwtx.core.commands.common.EventManager;
+import dwtx.core.internal.commands.util.Util;
+import dwtx.core.commands.IStateListener;
+
+import dwt.dwthelper.utils;
+
+/**
+ * <p>
+ * A piece of state information that can be shared between objects, and might be
+ * persisted between sessions. This can be used for commands that toggle between
+ * two states and wish to pass this state information between different
+ * handlers.
+ * </p>
+ * <p>
+ * This state object can either be used as a single state object shared between
+ * several commands, or one state object per command -- depending on the needs
+ * of the application.
+ * </p>
+ * <p>
+ * Clients may instantiate or extend this class.
+ * </p>
+ *
+ * @since 3.2
+ */
+public class State : EventManager {
+
+    /**
+     * The identifier of the state; may be <code>null</code> if it has not
+     * been initialized.
+     */
+    private String id;
+
+    /**
+     * The value held by this state; may be anything at all.
+     */
+    private Object value;
+
+    /**
+     * Adds a listener to changes for this state.
+     *
+     * @param listener
+     *            The listener to add; must not be <code>null</code>.
+     */
+    public void addListener(IStateListener listener) {
+        addListenerObject(cast(Object)listener);
+    }
+
+    /**
+     * Disposes of this state. This allows the state to unregister itself with
+     * any managers or as a listener.
+     */
+    public void dispose() {
+        // The default implementation does nothing.
+    }
+
+    /**
+     * Notifies listeners to this state that it has changed in some way.
+     *
+     * @param oldValue
+     *            The old value; may be anything.
+     */
+    protected final void fireStateChanged(Object oldValue) {
+        final Object[] listeners = getListeners();
+        for (int i = 0; i < listeners.length; i++) {
+            IStateListener listener = cast(IStateListener) listeners[i];
+            listener.handleStateChange(this, oldValue);
+        }
+    }
+
+    /**
+     * Returns the identifier for this state.
+     *
+     * @return The id; may be <code>null</code>.
+     */
+    public final String getId() {
+        return id;
+    }
+
+    /**
+     * The current value associated with this state. This can be any type of
+     * object, but implementations will usually restrict this value to a
+     * particular type.
+     *
+     * @return The current value; may be anything.
+     */
+
+    public Object getValue() {
+        return value;
+    }
+
+    /**
+     * Removes a listener to changes from this state.
+     *
+     * @param listener
+     *            The listener to remove; must not be <code>null</code>.
+     */
+
+    public void removeListener(IStateListener listener) {
+        removeListenerObject(cast(Object)listener);
+    }
+
+    /**
+     * Sets the identifier for this object.  This method should only be called
+     * by the command framework.  Clients should not call this method.
+     *
+     * @param id
+     *            The id; must not be <code>null</code>.
+     */
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    /**
+     * Sets the value for this state object.
+     *
+     * @param value
+     *            The value to set; may be anything.
+     */
+    public void setValue(Object value) {
+        if (!Util.equals(this.value, value)) {
+            final Object oldValue = this.value;
+            this.value = value;
+            fireStateChanged(oldValue);
+        }
+    }
+}