Reuse: Remove only external references when adding to library

When removing references before adding elements to a library, only
references that leave the elements containment (sub-)tree are removed.

Issue-ref: 4346
Issue-URL: af3#4346



Signed-off-by: Andreas Bayha <bayha@fortiss.org>

org.fortiss.tooling.ext.reuse/src/org/fortiss/tooling/ext/reuse/service/.ratings

 IReuseProvider.java 18d293f7f1f072883188f16fb6eeb52c8d6042cf GREEN
 IReuseProviderService.java bcc70de0bb8d39c330e3a25d884abc7092dc1b7e GREEN
 LayoutedReuseProviderBase.java b0e4ce3cda818b0723ec37b925a4c4c3d0c41909 GREEN
-ReuseProviderBase.java c956ba13df1b7b5c8dbd7cd1a9205a06b5cebba1 YELLOW
+ReuseProviderBase.java d7b615677c9b147f93943a8b87c631c26f6e5b4d YELLOW
 ReuseProviderService.java c4ef33283002d6dac6167f9c6c8f71d2c2ce39d1 GREEN

org.fortiss.tooling.ext.reuse/src/org/fortiss/tooling/ext/reuse/service/ReuseProviderBase.java

@@ -17,11 +17,14 @@ package org.fortiss.tooling.ext.reuse.service;
 
 import static org.eclipse.emf.ecore.util.EcoreUtil.replace;
 import static org.fortiss.tooling.ext.variability.util.VariabilityUtils.getOptVarPointSpecification;
+import static org.fortiss.tooling.kernel.utils.EcoreUtils.getChildrenWithType;
 import static org.fortiss.tooling.kernel.utils.EcoreUtils.replaceEObjectReferences;
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 import org.eclipse.emf.ecore.EObject;
 import org.eclipse.emf.ecore.EReference;
@@ -137,8 +140,19 @@ public class ReuseProviderBase<T extends EObject> implements IReuseProvider<T> {
 	 * @param eObj
 	 *            The {@link EObject} for which all reference targets shall be removed.
 	 */
-	@SuppressWarnings("unchecked")
 	private void removeExternalReferences(EObject eObj) {
+		// whitelist all contained elements as reference targets.
+		Set<EObject> whitelist = new HashSet<EObject>(getChildrenWithType(eObj, EObject.class));
+
+		removeReferences(eObj, whitelist);
+	}
+
+	/**
+	 * Recursively removes all reference targets from this and all contained {@link EObject}s which
+	 * are not contained in the given whitelist.
+	 */
+	@SuppressWarnings("unchecked")
+	private void removeReferences(EObject eObj, Set<EObject> whitelist) {
 		for(EReference ref : eObj.eClass().getEReferences()) {
 			Object refTarget = eObj.eGet(ref);
 
@@ -146,17 +160,29 @@ public class ReuseProviderBase<T extends EObject> implements IReuseProvider<T> {
 				continue;
 			}
 
-			if(ref.isContainment()) {
-				// Containment relations must not be removed. Yet, references of childs need to be
-				// removed recursively.
-				if(refTarget instanceof Collection<?>) {
-					((Collection<EObject>)refTarget).stream()
-							.forEach(t -> removeExternalReferences(t));
+			if(refTarget instanceof Collection<?>) {
+				Collection<EObject> refTargetCollection = (Collection<EObject>)refTarget;
+
+				if(ref.isContainment()) {
+					// Containment relations must not be removed. Yet, references of childs need to
+					// be removed recursively.
+					refTargetCollection.stream().forEach(t -> removeReferences(t, whitelist));
 				} else {
-					removeExternalReferences((EObject)refTarget);
+					for(EObject t : refTargetCollection) {
+						if(!whitelist.contains(t)) {
+							refTargetCollection.remove(t);
+						}
+					}
 				}
 			} else {
-				eObj.eSet(ref, null);
+				if(ref.isContainment()) {
+					// Keep reference target and make recursive call.
+					removeReferences((EObject)refTarget, whitelist);
+				} else {
+					if(!whitelist.contains(refTarget)) {
+						eObj.eSet(ref, null);
+					}
+				}
 			}
 		}
 	}