/*
* Value.java
*
* Copyright (C) 2009-12 by RStudio, Inc.
*
* Unless you have received this program directly from RStudio pursuant
* to the terms of a commercial license agreement with RStudio, then
* this program is licensed to you under the terms of version 3 of the
* GNU Affero General Public License. This program is distributed WITHOUT
* ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING THOSE OF NON-INFRINGEMENT,
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Please refer to the
* AGPL (http://www.gnu.org/licenses/agpl-3.0.txt) for more details.
*
*/
package org.rstudio.studio.client.common;
import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.event.logical.shared.ValueChangeHandler;
import com.google.gwt.event.shared.GwtEvent;
import com.google.gwt.event.shared.HandlerManager;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.ui.HasValue;
public class Value<T> implements HasValue<T>, ReadOnlyValue<T>
{
public Value(T initialValue)
{
handlers_ = new HandlerManager(this);
value_ = initialValue;
}
public T getValue()
{
return value_;
}
public void setValue(T value)
{
setValue(value, false);
}
public void setValue(T value, boolean fireEvents)
{
if (!areEqual(value_, value))
{
value_ = value;
if (fireEvents)
ValueChangeEvent.fire(this, value);
}
}
public void fireChangeEvent()
{
ValueChangeEvent.fire(this, value_);
}
private boolean areEqual(T a, T b)
{
if (a == null ^ b == null)
return false;
if (a == null)
return true;
return a.equals(b);
}
public HandlerRegistration addValueChangeHandler(ValueChangeHandler<T> handler)
{
return handlers_.addHandler(ValueChangeEvent.getType(), handler);
}
public void fireEvent(GwtEvent<?> event)
{
handlers_.fireEvent(event);
}
private final HandlerManager handlers_;
private T value_;
}