[392956] [Legacy] Support partial/conditional persistence of features

https://bugs.eclipse.org/bugs/show_bug.cgi?id=392956

3 files changed, 189 insertions, 1 deletions

diff --git a/plugins/org.eclipse.emf.cdo.common/src/org/eclipse/emf/cdo/internal/common/model/CDOClassInfoImpl.java b/plugins/org.eclipse.emf.cdo.common/src/org/eclipse/emf/cdo/internal/common/model/CDOClassInfoImpl.java
index 69a40cd8fb..dd833a77a6 100644
--- a/plugins/org.eclipse.emf.cdo.common/src/org/eclipse/emf/cdo/internal/common/model/CDOClassInfoImpl.java
+++ b/plugins/org.eclipse.emf.cdo.common/src/org/eclipse/emf/cdo/internal/common/model/CDOClassInfoImpl.java
@@ -7,18 +7,22 @@
  *
  * Contributors:
  *    Eike Stepper - initial API and implementation
+ *    Christian W. Damus (CEA) - support partially persistent features
  */
 package org.eclipse.emf.cdo.internal.common.model;
 
 import org.eclipse.emf.cdo.common.model.CDOClassInfo;
 import org.eclipse.emf.cdo.common.model.CDOModelUtil;
 import org.eclipse.emf.cdo.common.model.EMFUtil;
+import org.eclipse.emf.cdo.internal.common.bundle.OM;
+import org.eclipse.emf.cdo.spi.common.model.InternalCDOClassInfo;
 
 import org.eclipse.emf.common.notify.Notifier;
 import org.eclipse.emf.common.notify.impl.AdapterImpl;
 import org.eclipse.emf.common.util.EList;
 import org.eclipse.emf.ecore.EClass;
 import org.eclipse.emf.ecore.EStructuralFeature;
+import org.eclipse.emf.ecore.util.EcoreUtil;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -27,12 +31,16 @@ import java.util.List;
 /**
  * @author Eike Stepper
  */
-public class CDOClassInfoImpl extends AdapterImpl implements CDOClassInfo
+public class CDOClassInfoImpl extends AdapterImpl implements InternalCDOClassInfo
 {
   private static final int NOT_MAPPED = -1;
 
+  private static final PersistenceFilter[] NO_FILTERS = {};
+
   private EStructuralFeature[] allPersistentFeatures;
 
+  private PersistenceFilter[] persistenceFilters = NO_FILTERS;
+
   private int[] featureIDMappings;
 
   public CDOClassInfoImpl()
@@ -94,6 +102,17 @@ public class CDOClassInfoImpl extends AdapterImpl implements CDOClassInfo
     return index;
   }
 
+  public PersistenceFilter getPersistenceFilter(EStructuralFeature feature)
+  {
+    if (persistenceFilters == NO_FILTERS)
+    {
+      return null;
+    }
+
+    int featureID = getEClass().getFeatureID(feature);
+    return persistenceFilters[featureID];
+  }
+
   private void init(EClass eClass)
   {
     List<EStructuralFeature> persistentFeatures = new ArrayList<EStructuralFeature>();
@@ -115,7 +134,39 @@ public class CDOClassInfoImpl extends AdapterImpl implements CDOClassInfo
       EStructuralFeature feature = allPersistentFeatures[i];
       int featureID = eClass.getFeatureID(feature);
       featureIDMappings[featureID] = i;
+
+      PersistenceFilter persistenceFilter = initPersistenceFilter(feature);
+      if (persistenceFilter != null)
+      {
+        if (persistenceFilters == NO_FILTERS)
+        {
+          persistenceFilters = new PersistenceFilter[allFeatures.size()];
+        }
+
+        persistenceFilters[featureID] = persistenceFilter;
+      }
+    }
+  }
+
+  private PersistenceFilter initPersistenceFilter(EStructuralFeature feature)
+  {
+    CDOPersistenceFilterImpl result = null;
+    String filter = EcoreUtil.getAnnotation(feature, EMFUtil.CDO_ANNOTATION_SOURCE, "filter");
+
+    if (filter != null)
+    {
+      EStructuralFeature dependency = feature.getEContainingClass().getEStructuralFeature(filter);
+      if (dependency != null)
+      {
+        result = new CDOPersistenceFilterImpl(dependency);
+      }
+      else
+      {
+        OM.LOG.warn("Persistence filter '" + filter + "' not found for " + feature);
+      }
     }
+
+    return result;
   }
 
   @Override
diff --git a/plugins/org.eclipse.emf.cdo.common/src/org/eclipse/emf/cdo/internal/common/model/CDOPersistenceFilterImpl.java b/plugins/org.eclipse.emf.cdo.common/src/org/eclipse/emf/cdo/internal/common/model/CDOPersistenceFilterImpl.java
new file mode 100644
index 0000000000..6282fee24c
--- /dev/null
+++ b/plugins/org.eclipse.emf.cdo.common/src/org/eclipse/emf/cdo/internal/common/model/CDOPersistenceFilterImpl.java
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2004 - 2012 Eike Stepper (Berlin, Germany) 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:
+ *    Christian W. Damus (CEA) - initial API and implementation
+ */
+package org.eclipse.emf.cdo.internal.common.model;
+
+import org.eclipse.emf.cdo.spi.common.model.InternalCDOClassInfo.PersistenceFilter;
+
+import org.eclipse.emf.common.util.BasicEList;
+import org.eclipse.emf.ecore.EObject;
+import org.eclipse.emf.ecore.EStructuralFeature;
+
+import java.util.Collection;
+import java.util.Collections;
+
+/**
+ * Encapsulation of a rule for filtering the persistent values
+ * of a {@linkplain EStructuralFeature feature} in some model element.
+ * <p>
+ * Some models (such as UML's Activity metaclass) require partial persistence
+ * of features, persisting a subset of the values in a feature that are also
+ * in some other feature (the filtering feature).  Other models may apply other
+ * transformations to features that require partial or otherwise custom
+ * persistence rules.
+ *
+ * @since 4.2
+ */
+public class CDOPersistenceFilterImpl implements PersistenceFilter
+{
+  private final EStructuralFeature dependency;
+
+  public CDOPersistenceFilterImpl(EStructuralFeature dependency)
+  {
+    this.dependency = dependency;
+  }
+
+  public Object getPersistableValue(EObject owner, Object value)
+  {
+    if (value instanceof Collection<?>)
+    {
+      Collection<?> collection = (Collection<?>)value;
+      return filter(collection, asCollection(owner.eGet(dependency)));
+    }
+
+    if (asCollection(owner.eGet(dependency)).contains(value))
+    {
+      return value;
+    }
+
+    return null;
+  }
+
+  private Collection<?> asCollection(Object value)
+  {
+    if (value instanceof Collection<?>)
+    {
+      return (Collection<?>)value;
+    }
+
+    if (value == null)
+    {
+      return Collections.emptyList();
+    }
+
+    return Collections.singletonList(value);
+  }
+
+  private Collection<?> filter(Collection<?> elements, Collection<?> filter)
+  {
+    Collection<?> result = new BasicEList<Object>(elements);
+    result.retainAll(filter);
+    return result;
+  }
+}
diff --git a/plugins/org.eclipse.emf.cdo.common/src/org/eclipse/emf/cdo/spi/common/model/InternalCDOClassInfo.java b/plugins/org.eclipse.emf.cdo.common/src/org/eclipse/emf/cdo/spi/common/model/InternalCDOClassInfo.java
new file mode 100644
index 0000000000..2526cb8890
--- /dev/null
+++ b/plugins/org.eclipse.emf.cdo.common/src/org/eclipse/emf/cdo/spi/common/model/InternalCDOClassInfo.java
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2004 - 2012 Eike Stepper (Berlin, Germany) 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:
+ *    Christian W. Damus (CEA) - initial API and implementation
+ */
+package org.eclipse.emf.cdo.spi.common.model;
+
+import org.eclipse.emf.cdo.common.model.CDOClassInfo;
+
+import org.eclipse.emf.ecore.EObject;
+import org.eclipse.emf.ecore.EStructuralFeature;
+
+/**
+ * @since 4.2
+ */
+public interface InternalCDOClassInfo extends CDOClassInfo
+{
+  /**
+   * Obtains a rule that filters/transforms the persist values of the given
+   * {@code feature}.
+   *
+   * @param feature a feature to be persisted
+   * @return a persistence filter rule for the {@code feature}, or {@code null}
+   *    if it has no filter but just follows the default persistence rules
+   */
+  public PersistenceFilter getPersistenceFilter(EStructuralFeature feature);
+
+  /**
+   * Encapsulation of a rule for filtering the persistent values
+   * of a {@linkplain EStructuralFeature feature} in some model element.
+   * Some models (such as UML's Activity metaclass) require partial persistence
+   * of features, persisting a subset of the values in a feature that are also
+   * in some other feature (the filtering feature). Other models may apply other
+   * transformations to features that require partial or otherwise custom
+   * persistence rules.
+   */
+  public interface PersistenceFilter
+  {
+    /**
+     * Get a subset or other transformation of the specified {@code value} of
+     * a persistable feature, based on its dependencies.
+     *
+     * @param owner an object this filter is to be applied to.
+     * @param value the value (which may be a collection) of the {@code owner}'s feature.
+     *
+     * @return the transformed value to persist. It should be a collection (possibly empty)
+     * if the {@code value} is a collection, or a scalar (possibly {@code null}) if the
+     * {@code value} is a scalar
+     */
+    public Object getPersistableValue(EObject owner, Object value);
+  }
+}