plugins/org.eclipse.ocl.ecore/src/org/eclipse/ocl/ecore/opposites/EcoreEnvironmentFactoryWithHiddenOpposites.java

/*******************************************************************************
 * Copyright (c) 2011 SAP AG 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:
 *     SAP AG - initial API and implementation
 ******************************************************************************/
package org.eclipse.ocl.ecore.opposites;

import org.eclipse.emf.ecore.EPackage;
import org.eclipse.emf.ecore.EPackage.Registry;
import org.eclipse.ocl.ecore.EcoreEnvironmentFactory;


/**
 * An environment factory which can be used to provide a non-<code>null</code>
 * {@link OppositeEndFinder} to the OCL environment. This enables lookup and
 * evaluation of so-called "hidden opposites" which are represented by
 * annotations with key "Property#oppositeRoleName" on the forward reference
 * and which allow for querying the opposite direction by simple dotted syntax
 * and by cleanly providing a scope for the opposite lookup.<p>
 * 
 * If no {@link OppositeEndFinder} is provided to a constructor, a
 * {@link DefaultOppositeEndFinder} is used that is either specific to the
 * {@link Registry registry} provided or that is aligned with the
 * default {@link Registry#INSTANCE package registry}.
 * 
 * @author Axel Uhl (auhl)
 * @since 3.1
 */
public class EcoreEnvironmentFactoryWithHiddenOpposites
		extends EcoreEnvironmentFactory {
	
	/**
	 * A default instance that works with the default {@link Registry#INSTANCE package registry}.
	 */
	public static final EcoreEnvironmentFactoryWithHiddenOpposites INSTANCE = new EcoreEnvironmentFactoryWithHiddenOpposites();

    private final OppositeEndFinder oppositeEndFinder;
    
    /**
     * Initializes me. Environments that I create will use the global package registry to look up packages.
     * Uses the result of {@link DefaultOppositeEndFinder#getInstance()} as opposite end finder.
     */
    public EcoreEnvironmentFactoryWithHiddenOpposites() {
        this(EPackage.Registry.INSTANCE);
    }

    /**
     * Initializes me with an <code>EPackage.Registry</code> that the environments I create will use to look up
     * packages. A new {@link DefaultOppositeEndFinder} object is created for the specific package registry
     * provided as <code>reg</code>.
     * 
     * @param reg
     *            my package registry (must not be <code>null</code>)
     */
    public EcoreEnvironmentFactoryWithHiddenOpposites(EPackage.Registry reg) {
        this(reg, DefaultOppositeEndFinder.getInstance(reg));
    }
    
    /**
     * Configures both, a specific package registry as well as a dedicated opposite end finder to be used
     * by the OCL environment created by this factory.
     */
    public EcoreEnvironmentFactoryWithHiddenOpposites(EPackage.Registry reg, OppositeEndFinder oppositeEndFinder) {
        super(reg);
        this.oppositeEndFinder = oppositeEndFinder;
    }

    @Override
    protected OppositeEndFinder createOppositeEndFinder(Registry registry) {
        return oppositeEndFinder;
    }

}