Install exception handler for command stack showing errors to user

Issue-Ref: 4169
Issue-Url: af3#4169



Signed-off-by: Simon Barner <barner@fortiss.org>

org.fortiss.tooling.kernel/src/org/fortiss/tooling/kernel/internal/storage/eclipse/.ratings

 AutoUndoCommandStack.java fc326adf66c6cea2354884cdc240da5f2f82689a GREEN
 EMFTransactionalCommand.java ba4b5bead9768b6ce6c955b9238cd96cb722533c GREEN
 EclipseResourceStorageService.java 5e60ef7628ea2ad4113cfebde939341e1b1f6cf2 GREEN
-ModelContext.java 76eeaef7f56da5f0e288cf96792850be606b7757 GREEN
+ModelContext.java 484298fe527a4b83a6dceaef5dd459f874f8b737 YELLOW
 NonDirtyingEMFTransactionalCommand.java d288ebe35d22442c603496b0c917fb99a8febeea GREEN

org.fortiss.tooling.kernel/src/org/fortiss/tooling/kernel/internal/storage/eclipse/ModelContext.java

@@ -20,6 +20,7 @@ import static org.eclipse.core.resources.IResource.DEPTH_ZERO;
 import static org.eclipse.emf.common.util.URI.createPlatformResourceURI;
 import static org.fortiss.tooling.kernel.utils.EMFResourceUtils.buildOptionsMap;
 import static org.fortiss.tooling.kernel.utils.LoggingUtils.error;
+import static org.fortiss.tooling.kernel.utils.LoggingUtils.showError;
 import static org.fortiss.tooling.kernel.utils.LoggingUtils.warning;
 import static org.fortiss.tooling.kernel.utils.UniqueIDUtils.generateMissingIDs;
 
@@ -55,6 +56,8 @@ import org.eclipse.emf.ecore.util.Diagnostician;
 import org.eclipse.emf.ecore.util.EContentAdapter;
 import org.eclipse.emf.ecore.xmi.XMIResource;
 import org.eclipse.emf.ecore.xml.type.AnyType;
+import org.eclipse.emf.transaction.ExceptionHandler;
+import org.eclipse.emf.transaction.RollbackException;
 import org.eclipse.emf.transaction.TransactionalEditingDomain;
 import org.fortiss.tooling.kernel.ToolingKernelActivator;
 import org.fortiss.tooling.kernel.extension.data.ITopLevelElement;
@@ -123,6 +126,18 @@ class ModelContext implements ITopLevelElement, CommandStackListener {
 
 		transactionalCommandStack = new AutoUndoCommandStack(editingDomain);
 		transactionalCommandStack.addCommandStackListener(this);
+		transactionalCommandStack.setExceptionHandler(new ExceptionHandler() {
+
+			@Override
+			public void handleException(Exception e) {
+				// Each original exception results into a RollbackException that undoes the changes
+				// of the failed command
+				if(!(e instanceof RollbackException)) {
+					showError(e.getMessage());
+					error(ToolingKernelActivator.getDefault(), e.getMessage(), e);
+				}
+			}
+		});
 
 		// Install adapter to maintain XMI IDs
 		resource.eAdapters().add(new EContentAdapter() {