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/*******************************************************************************
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* Copyright (c) 2006 IBM Corporation and others.
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Public License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/legal/epl-v10.html
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*
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* Contributors:
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* IBM Corporation - initial API and implementation
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******************************************************************************/
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package org.eclipse.ui.internal.navigator.dnd;
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import java.lang.ref.WeakReference;
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import java.util.HashSet;
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import java.util.Iterator;
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import java.util.Set;
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import org.eclipse.ui.navigator.INavigatorContentService;
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/**
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* Caches instances of {@link INavigatorContentService} to facilitate the
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* handling of drop operations in other viewers.
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*
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* @since 3.2
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*
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*/
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public class NavigatorContentServiceTransfer {
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private static final NavigatorContentServiceTransfer instance = new NavigatorContentServiceTransfer();
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/**
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*
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* @return The singleton instance of the transfer service.
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*/
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public static NavigatorContentServiceTransfer getInstance() {
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return instance;
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}
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private final Set registeredContentServices = new HashSet();
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/**
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*
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* @param aContentService The Content Service to register.
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*/
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public synchronized void registerContentService(INavigatorContentService aContentService) {
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if(findService(aContentService.getViewerId()) == null) {
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registeredContentServices.add(new WeakReference(aContentService));
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}
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}
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/**
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*
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* @param aContentService The Content Service to unregister.
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*/
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public synchronized void unregisterContentService(INavigatorContentService aContentService) {
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for (Iterator iter = registeredContentServices.iterator(); iter.hasNext();) {
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WeakReference ref = (WeakReference) iter.next();
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if(ref.get() == null) {
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iter.remove();
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} else {
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if(ref.get() == aContentService) {
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iter.remove();
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return;
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}
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}
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}
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}
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/**
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*
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* @param aViewerId A viewer id that should have previously been registered with the service.
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* @return The registered content service for the given viewer id.
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*/
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public synchronized INavigatorContentService findService(String aViewerId) {
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if(aViewerId == null || aViewerId.length() == 0) {
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return null;
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}
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INavigatorContentService contentService;
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for (Iterator iter = registeredContentServices.iterator(); iter.hasNext();) {
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WeakReference ref = (WeakReference) iter.next();
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if(ref.get() == null) {
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iter.remove();
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} else {
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contentService = (INavigatorContentService)ref.get();
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if(aViewerId.equals(contentService.getViewerId())) {
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return contentService;
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}
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}
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}
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return null;
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}
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}
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