Copyright (c) 2005, 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
    Lars Vogel  - Bug 448831
/*******************************************************************************
 * Copyright (c) 2005, 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
 *     Lars Vogel <Lars.Vogel@vogella.com> - Bug 448831
 *******************************************************************************/

package org.eclipse.core.commands.common;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

 A manager of HandleObject instances. This has some common behaviour which is shared between all such managers. 

Clients may extend.

Since:
3.2/**
 * <p>
 * A manager of {@link HandleObject} instances. This has some common behaviour
 * which is shared between all such managers.
 * </p>
 * <p>
 * Clients may extend.
 * </p>
 *
 * @since 3.2
 */
public abstract class HandleObjectManager extends EventManager {

	
The set of handle objects that are defined. This value may be empty, but
it is never null.
/**
	 * The set of handle objects that are defined. This value may be empty, but
	 * it is never <code>null</code>.
	 */
	@SuppressWarnings("rawtypes")
	protected final Set definedHandleObjects = new HashSet<>();

	
The map of identifiers (String) to handle objects (
HandleObject). This collection may be empty, but it is
never null.
/**
	 * The map of identifiers (<code>String</code>) to handle objects (
	 * <code>HandleObject</code>). This collection may be empty, but it is
	 * never <code>null</code>.
	 */
	@SuppressWarnings("rawtypes")
	protected final Map handleObjectsById = new HashMap<>();

	
Verifies that the identifier is valid. Exceptions will be thrown if the
identifier is invalid in some way.
Params:
id – 
           The identifier to validate; may be anything./**
	 * Verifies that the identifier is valid. Exceptions will be thrown if the
	 * identifier is invalid in some way.
	 *
	 * @param id
	 *            The identifier to validate; may be anything.
	 */
	protected final void checkId(final String id) {
		if (id == null) {
			throw new IllegalArgumentException("A handle object may not have a null identifier"); //$NON-NLS-1$
		}

		if (id.length() < 1) {
			throw new IllegalArgumentException("The handle object must not have a zero-length identifier"); //$NON-NLS-1$
		}
	}

	
Returns the set of identifiers for those handle objects that are defined.
Returns:
The set of defined handle object identifiers; this value may be
        empty, but it is never null./**
	 * Returns the set of identifiers for those handle objects that are defined.
	 *
	 * @return The set of defined handle object identifiers; this value may be
	 *         empty, but it is never <code>null</code>.
	 */
	@SuppressWarnings("rawtypes")
	protected final Set getDefinedHandleObjectIds() {
		final HashSet<String> definedHandleObjectIds = new HashSet<>(definedHandleObjects.size());
		final Iterator<NamedHandleObject> handleObjectItr = definedHandleObjects.iterator();
		while (handleObjectItr.hasNext()) {
			final HandleObject handleObject = handleObjectItr.next();
			final String id = handleObject.getId();
			definedHandleObjectIds.add(id);
		}
		return definedHandleObjectIds;
	}
}