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/*
 * Copyright (c) 2011, 2015, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
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 */

package com.sun.javafx.binding;

import java.lang.ref.WeakReference;

import javafx.beans.InvalidationListener;
import javafx.beans.Observable;
import javafx.beans.WeakListener;
import javafx.beans.binding.Binding;

public class BindingHelperObserver implements InvalidationListener, WeakListener {

    private final WeakReference> ref;

    public BindingHelperObserver(Binding binding) {
        if (binding == null) {
            throw new NullPointerException("Binding has to be specified.");
        }
        ref = new WeakReference>(binding);
    }

    @Override
    public void invalidated(Observable observable) {
        final Binding binding = ref.get();
        if (binding == null) {
            observable.removeListener(this);
        } else {
            binding.invalidate();
        }
    }

    @Override
    public boolean wasGarbageCollected() {
        return ref.get() == null;
    }
}