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/*******************************************************************************
* Copyright (c) 2000, 2008 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
*******************************************************************************/
package org.eclipse.text.undo;
import java.util.HashMap;
import java.util.Map;
import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.text.IDocument;
/**
* This document undo manager registry provides access to a document's
* undo manager. In order to connect a document a document undo manager
* call <code>connect</code>. After that call has successfully completed
* undo manager can be obtained via <code>getDocumentUndoManager</code>.
* The undo manager is created on the first connect and disposed on the last
* disconnect, i.e. this registry keeps track of how often a undo manager is
* connected and returns the same undo manager to each client as long as the
* document is connected.
* <p>
* <em>The recoding of changes starts with the first {@link #connect(IDocument)}.</em></p>
*
* @since 3.2
* @noinstantiate This class is not intended to be instantiated by clients.
*/
public final class DocumentUndoManagerRegistry {
private static final class Record {
public Record(IDocument document) {
count= 0;
undoManager= new DocumentUndoManager(document);
}
private int count;
private IDocumentUndoManager undoManager;
}
private static Map fgFactory= new HashMap();
private DocumentUndoManagerRegistry() {
// Do not instantiate
}
/**
* Connects the file at the given location to this manager. After that call
* successfully completed it is guaranteed that each call to <code>getFileBuffer</code>
* returns the same file buffer until <code>disconnect</code> is called.
* <p>
* <em>The recoding of changes starts with the first {@link #connect(IDocument)}.</em></p>
*
* @param document the document to be connected
*/
public static synchronized void connect(IDocument document) {
Assert.isNotNull(document);
Record record= (Record)fgFactory.get(document);
if (record == null) {
record= new Record(document);
fgFactory.put(document, record);
}
record.count++;
}
/**
* Disconnects the given document from this registry.
*
* @param document the document to be disconnected
*/
public static synchronized void disconnect(IDocument document) {
Assert.isNotNull(document);
Record record= (Record)fgFactory.get(document);
record.count--;
if (record.count == 0)
fgFactory.remove(document);
}
/**
* Returns the file buffer managed for the given location or <code>null</code>
* if there is no such file buffer.
* <p>
* The provided location is either a full path of a workspace resource or
* an absolute path in the local file system. The file buffer manager does
* not resolve the location of workspace resources in the case of linked
* resources.
* </p>
*
* @param document the document for which to get its undo manager
* @return the document undo manager or <code>null</code>
*/
public static synchronized IDocumentUndoManager getDocumentUndoManager(IDocument document) {
Assert.isNotNull(document);
Record record= (Record)fgFactory.get(document);
if (record == null)
return null;
return record.undoManager;
}
}
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