org.rstudio.studio.client.common.Value.java Source code

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Here is the source code for org.rstudio.studio.client.common.Value.java

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/*
 * 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_;
}