bundles/org.eclipse.emf.emfstore.common/src/org/eclipse/emf/emfstore/internal/common/APIUtil.java

/*******************************************************************************
 * Copyright (c) 2012-2013 EclipseSource Muenchen GmbH 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:
 * Otto von Wesendonk, Edgar Mueller - initial API and implementation
 ******************************************************************************/
package org.eclipse.emf.emfstore.internal.common;

import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;

import org.eclipse.emf.emfstore.internal.common.api.APIDelegate;
import org.eclipse.emf.emfstore.internal.common.api.InternalAPIDelegator;

/**
 * Convenience class for mapping internal and external types contained in lists onto each other.
 *
 * @author ovonwesen
 * @author emueller
 * @author eneufeld
 */
public final class APIUtil {

	private APIUtil() {
	}

	/**
	 * Copies the given list.
	 *
	 * @param toCopy
	 *            the list to be copied
	 * @return the copied list
	 *
	 * @param <T> the type of the instances the list is holding
	 */
	public static <T> List<T> copy(List<T> toCopy) {

		if (toCopy == null) {
			return null;
		}

		final ArrayList<T> result = new ArrayList<T>(toCopy.size());

		for (final T element : toCopy) {
			result.add(element);
		}

		return result;
	}

	/**
	 * Maps a list of a given API type to its internal API counterpart by copying and mapping the entities.
	 *
	 * @param toCopy
	 *            the list to be copied and mapped to the internal API type
	 * @return the copied list with its elements mapped to their internal API type
	 *
	 * @param <INT> the internal API mapping to an API implementation class
	 * @param <API> the type of the API interface
	 * @param <IMPL> the type of the API implementation class
	 */
	public static <IMPL extends InternalAPIDelegator<API, INT>, INT extends APIDelegate<API>, API>
		List<INT> toInternal(List<API> toCopy) {

		if (toCopy == null) {
			return null;
		}

		final ArrayList<INT> result = new ArrayList<INT>(toCopy.size());

		for (final API element : toCopy) {
			@SuppressWarnings("unchecked")
			final IMPL i = (IMPL) element;
			result.add(i.toInternalAPI());
		}

		return result;
	}

	/**
	 * Maps a list of a given internal API type to its external API counterpart by copying and mapping the entities.
	 *
	 * @param cls
	 *            the desired internal API type
	 * @param toCopy
	 *            the list to be copied and mapped to the external API type
	 * @return the copied list with its elements mapped to their external API type
	 *
	 * @param <DESIRED> the internal API type
	 * @param <INT> the internal API mapping to an API implementation class
	 * @param <API> the type of the API interface
	 * @param <IMPL> the type of the API implementation class
	 */
	public static <IMPL extends InternalAPIDelegator<API, INT>, INT extends APIDelegate<API>, API, DESIRED>
		List<INT> toInternal(Class<DESIRED> cls, List<API> toCopy) {

		if (toCopy == null) {
			return null;
		}

		final ArrayList<INT> result = new ArrayList<INT>(toCopy.size());

		for (final API element : toCopy) {
			@SuppressWarnings("unchecked")
			final IMPL i = (IMPL) element;
			result.add(i.toInternalAPI());
		}

		return result;
	}

	/**
	 * Maps a list of a given internal API type to its external API counterpart by copying and mapping the entities.
	 *
	 * @param toCopy
	 *            the list to be copied and mapped to the external API type
	 * @return the copied list with its elements mapped to their external API type
	 *
	 * @param <INT> the internal API mapping to an API implementation class
	 * @param <API> the type of the API interface
	 * @param <IMPL> the type of the API implementation class
	 */
	public static <IMPL extends InternalAPIDelegator<API, INT>, INT extends APIDelegate<API>, API>
		List<API> toExternal(List<INT> toCopy) {

		if (toCopy == null) {
			return null;
		}

		final ArrayList<API> result = new ArrayList<API>(toCopy.size());

		for (final INT element : toCopy) {
			result.add(element.toAPI());
		}

		return result;
	}

	/**
	 * Maps a set of a given internal API type to its external API counterpart by copying and mapping the entities.
	 *
	 * @param toCopy
	 *            the set to be copied and mapped to the external API type
	 * @return the copied set with its elements mapped to their external API type
	 *
	 * @param <INT> the internal API mapping to an API implementation class
	 * @param <API> the type of the API interface
	 * @param <IMPL> the type of the API implementation class
	 */
	public static <IMPL extends InternalAPIDelegator<API, INT>, INT extends APIDelegate<API>, API>
		Set<API> toExternal(Set<INT> toCopy) {

		if (toCopy == null) {
			return null;
		}

		final LinkedHashSet<API> result = new LinkedHashSet<API>(toCopy.size());

		for (final INT element : toCopy) {
			result.add(element.toAPI());
		}

		return result;
	}

	/**
	 * Maps a list of a given internal type to its corresponding API type by copying it.
	 *
	 * @param apiClass
	 *            the desired API type
	 * @param toCopy
	 *            the list to be copied
	 * @return the copied list with its elements mapped to their API type
	 *
	 * @param <T> the internal API mapping to an API implementation class
	 * @param <V> the type of the API interface
	 * @param <U> the type of the API implementation class
	 */
	// e.g.
	// T = Usersession
	// U = ESUsersessionImpl
	// V = ESUsersession
	public static <T extends APIDelegate<U>, V, U extends V> List<V> mapToAPI(Class<V> apiClass, List<T> toCopy) {

		if (toCopy == null) {
			return null;
		}

		final ArrayList<V> result = new ArrayList<V>(toCopy.size());

		for (final T element : toCopy) {
			result.add(element.toAPI());
		}

		return result;
	}

	/**
	 * Maps a list of a given external API type to its corresponding internal type by copying it.
	 *
	 * @param apiClass
	 *            the desired API type
	 * @param toCopy
	 *            the list to be copied
	 * @return the copied list with its elements mapped to their API type
	 *
	 * @param <T> the internal API mapping to an API implementation class
	 * @param <V> the type of the API interface
	 * @param <U> the type of the API implementation class
	 */
	// e.g.
	// T = Usersession
	// U = ESUsersessionImpl
	// V = ESUsersession
	@SuppressWarnings("unchecked")
	public static <V, U extends InternalAPIDelegator<U, T>, T extends APIDelegate<U>> List<T> mapToInternalAPI(
		Class<T> apiClass, List<V> toCopy) {

		if (toCopy == null) {
			return null;
		}

		final ArrayList<T> result = new ArrayList<T>(toCopy.size());

		for (final V element : toCopy) {
			result.add(((U) element).toInternalAPI());
		}

		return result;
	}

	/**
	 * Maps a set of a given API type to its internal API counterpart by copying and mapping the entities.
	 *
	 * @param toCopy
	 *            the set to be copied and mapped to the internal API type
	 * @return the copied set with its elements mapped to their internal API type
	 *
	 * @param <INT> the internal API mapping to an API implementation class
	 * @param <API> the type of the API interface
	 * @param <IMPL> the type of the API implementation class
	 */
	public static <IMPL extends InternalAPIDelegator<API, INT>, INT extends APIDelegate<API>, API>
		Set<INT> toInternal(Set<API> toCopy) {

		if (toCopy == null) {
			return null;
		}

		final Set<INT> result = new LinkedHashSet<INT>(toCopy.size());

		for (final API element : toCopy) {
			@SuppressWarnings("unchecked")
			final IMPL i = (IMPL) element;
			result.add(i.toInternalAPI());
		}

		return result;
	}

	/**
	 * Maps an given API type to its internal API counterpart.
	 *
	 * @param apiClass
	 *            the desired API type
	 * @param element
	 *            the type to be mapped
	 * @return the internal API type
	 *
	 * @param <T> the internal API mapping to an API implementation class
	 * @param <V> the type of the API interface
	 * @param <U> the type of the API implementation class
	 */
	@SuppressWarnings("unchecked")
	public static <V, U extends InternalAPIDelegator<U, T>, T extends APIDelegate<U>> T toInternal(
		Class<T> apiClass, V element) {

		if (element == null) {
			return null;
		}

		return ((U) element).toInternalAPI();
	}
}