Copyright (c) 2000, 2015 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2015 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * 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 connect. After that call has successfully completed
undo manager can be obtained via getDocumentUndoManager.
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.

The recoding of changes starts with the first connect(IDocument).
Since:
3.2
@noinstantiate
This class is not intended to be instantiated by clients./**
 * 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<IDocument, Record> 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 getFileBuffer
returns the same file buffer until disconnect is called.

The recoding of changes starts with the first connect(IDocument).
Params:
document – the document to be connected/**
	 * 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= fgFactory.get(document);
		if (record == null) {
			record= new Record(document);
			fgFactory.put(document, record);
		}
		record.count++;
	}

	
Disconnects the given document from this registry.
Params:
document – the document to be disconnected/**
	 * 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= fgFactory.get(document);
		record.count--;
		if (record.count == 0)
			fgFactory.remove(document);

	}

	
Returns the file buffer managed for the given location or null
if there is no such file buffer.

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.

Params:
document – the document for which to get its undo manager
Returns:
the document undo manager or null/**
	 * 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= fgFactory.get(document);
		if (record == null)
			return null;
		return record.undoManager;
	}

}