[482528] Consider null as a valid evaluation result

It is perfectly legitimate for an expression to return null, but we
considered this as a failure which disabled a lot of behavior which
depends on IEvaluationResult.success().

Note that AQL raises a WARNING in its own EvaluationResult class when
a *service* returns null (instead of Nothing). It is debatable if this
is a good idea (see #487006), but for now this means we have to consider
diagnostics with a WARNING severity to represent successful evaluations.

Bug: 482528
Change-Id: Id7be86b5c330fd4e1d5dee5948f32a4aae32dd70
Signed-off-by: Pierre-Charles David <pierre-charles.david@obeo.fr>

1 files changed, 2 insertions, 2 deletions

diff --git a/incubation/org.eclipse.sirius.common.interpreter/src/org/eclipse/sirius/common/interpreter/api/EvaluationResult.java b/incubation/org.eclipse.sirius.common.interpreter/src/org/eclipse/sirius/common/interpreter/api/EvaluationResult.java
index 8b59e38bbf..c194cfbfc2 100644
--- a/incubation/org.eclipse.sirius.common.interpreter/src/org/eclipse/sirius/common/interpreter/api/EvaluationResult.java
+++ b/incubation/org.eclipse.sirius.common.interpreter/src/org/eclipse/sirius/common/interpreter/api/EvaluationResult.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2015 Obeo.
+ * Copyright (c) 2015, 2016 Obeo.
  * 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
@@ -74,7 +74,7 @@ public class EvaluationResult implements IEvaluationResult {
 
     @Override
     public boolean success() {
-        return Diagnostic.OK == status.getSeverity() && rawValue != null;
+        return Diagnostic.ERROR != status.getSeverity();
     }
 
     @Override