org.conqat.lib.commons.collections.IdManagerBase Maven / Gradle / Ivy

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Provides common utility functions

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/*
 * Copyright (c) CQSE GmbH
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.conqat.lib.commons.collections;

import java.util.Map;

/**
 * Base class for id managers.
 *
 *
 * @author Florian Deissenboeck
 */
public class IdManagerBase implements IIdProvider {

	/** Maps from object to ids. */
	private final Map ids;

	/** the next id to bes used */
	private int currentId = 0;

	/**
	 * Create new id manager
	 *
	 * @param map
	 *            maps from object to ids
	 */
	protected IdManagerBase(Map map) {
		this.ids = map;
	}

	/**
	 * Obtain a unique id for an object. Note that obtaining a id for an object prevents it from being
	 * garbage collected.
	 */
	@Override
	public Integer obtainId(K k) {
		// is already stored
		if (ids.containsKey(k)) {
			return ids.get(k);
		}

		ids.put(k, currentId);

		// return id and increase it afterwards
		return currentId++;
	}

	/**
	 * Clear the manager. Adding an object to the manager, clearing the manager and re-adding the object
	 * will not result in the same ids.
	 */
	public void clear() {
		ids.clear();
		currentId = 0;
	}
}