Persistence state classes doesn't have to implement "equals" anymore

If you don’t implement “equals” in your sub state class, XmlSerializer cannot check it for defaults.

TextDiffSettingsHolder.State.SHARED_SETTINGS = new SharedSettings();
The problem — “new SharedSettings()” is not equals to “new SharedSettings()”.
As result, user gets

<option name="SHARED_SETTINGS">
  <SharedSettings />
</option>
even if SkipDefaultValuesSerializationFilters is used.

While I dream about Kotlin, I can’t fight anymore against Java-developers. XmlSerializer can throw warning in this case, but to simplify developer life, it will compare objects by serializable fields, but not by reference (if equals is not implemented).

java/compiler/impl/src/com/intellij/compiler/CompilerConfigurationImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2015 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -142,11 +142,11 @@ public class CompilerConfigurationImpl extends CompilerConfiguration implements
     Element state = new Element("state");
     XmlSerializer.serializeInto(myState, state, new SkipDefaultValuesSerializationFilters() {
       @Override
-      protected boolean accepts(@NotNull Accessor accessor, @NotNull Object bean, @Nullable Object beanValue) {
+      public boolean accepts(@NotNull Accessor accessor, @NotNull Object bean) {
         if (myState.compilerWasSpecified && "DEFAULT_COMPILER".equals(accessor.getName())) {
           return true;
         }
-        return super.accepts(accessor, bean, beanValue);
+        return super.accepts(accessor, bean);
       }
     });
 

platform/editor-ui-api/src/com/intellij/ide/ui/UISettings.java

@@ -184,7 +184,7 @@ public class UISettings extends SimpleModificationTracker implements PersistentS
 
   public static class FontFilter implements SerializationFilter {
     @Override
-    public boolean accepts(@NotNull Accessor accessor, Object bean) {
+    public boolean accepts(@NotNull Accessor accessor, @NotNull Object bean) {
       UISettings settings = (UISettings)bean;
       return !hasDefaultFontSetting(settings);
     }

platform/lang-impl/src/com/intellij/psi/impl/source/codeStyle/PersistableCodeStyleSchemes.java

@@ -49,9 +49,9 @@ class PersistableCodeStyleSchemes extends CodeStyleSchemesImpl implements Persis
   public Element getState() {
     return XmlSerializer.serialize(this, new SerializationFilter() {
       @Override
-      public boolean accepts(@NotNull Accessor accessor, Object bean) {
+      public boolean accepts(@NotNull Accessor accessor, @NotNull Object bean) {
         if ("CURRENT_SCHEME_NAME".equals(accessor.getName())) {
-          return bean != null && !DEFAULT_SCHEME_NAME.equals(accessor.read(bean));
+          return !DEFAULT_SCHEME_NAME.equals(accessor.read(bean));
         }
         else {
           return accessor.getValueClass().equals(String.class);

platform/platform-impl/src/com/intellij/openapi/components/impl/stores/SaveSessionBase.java

@@ -19,14 +19,14 @@ import com.intellij.openapi.components.StateStorage;
 import com.intellij.openapi.components.Storage;
 import com.intellij.openapi.util.JDOMExternalizable;
 import com.intellij.openapi.util.WriteExternalException;
-import com.intellij.util.xmlb.SkipDefaultValuesSerializationFilters;
+import com.intellij.util.xmlb.SkipDefaultsSerializationFilter;
 import com.intellij.util.xmlb.XmlSerializer;
 import org.jdom.Element;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 abstract class SaveSessionBase implements StateStorage.SaveSession, StateStorage.ExternalizationSession {
-  private SkipDefaultValuesSerializationFilters serializationFilter;
+  private SkipDefaultsSerializationFilter serializationFilter;
 
   @SuppressWarnings("deprecation")
   @Override
@@ -42,7 +42,7 @@ abstract class SaveSessionBase implements StateStorage.SaveSession, StateStorage
       }
       else {
         if (serializationFilter == null) {
-          serializationFilter = new SkipDefaultValuesSerializationFilters();
+          serializationFilter = new SkipDefaultsSerializationFilter();
         }
         element = XmlSerializer.serializeIfNotDefault(state, serializationFilter);
       }

platform/util/src/com/intellij/util/xmlb/BeanBinding.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2015 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,7 +39,7 @@ import java.util.*;
 import java.util.List;
 
 class BeanBinding extends Binding {
-  private static final Logger LOG = Logger.getInstance(BeanBinding.class);
+  static final Logger LOG = Logger.getInstance(BeanBinding.class);
 
   private static final Map<Class, List<Accessor>> ourAccessorCache = ContainerUtil.createConcurrentSoftValueMap();
 
@@ -47,7 +47,7 @@ class BeanBinding extends Binding {
   @SuppressWarnings("FieldAccessedSynchronizedAndUnsynchronized")
   private Binding[] myBindings;
 
-  private final Class<?> myBeanClass;
+  final Class<?> myBeanClass;
 
   public BeanBinding(@NotNull Class<?> beanClass, @Nullable Accessor accessor) {
     super(accessor);
@@ -86,7 +86,13 @@ class BeanBinding extends Binding {
   public Element serializeInto(@NotNull Object o, @Nullable Element element, @NotNull SerializationFilter filter) {
     for (Binding binding : myBindings) {
       Accessor accessor = binding.getAccessor();
-      if (!filter.accepts(accessor, o)) {
+
+      if (filter instanceof SkipDefaultsSerializationFilter) {
+        if (((SkipDefaultsSerializationFilter)filter).equal(binding, o)) {
+          continue;
+        }
+      }
+      else if (!filter.accepts(accessor, o)) {
         continue;
       }
 
@@ -121,6 +127,16 @@ class BeanBinding extends Binding {
     return instance;
   }
 
+  boolean equalByFields(@NotNull Object currentValue, @NotNull Object defaultValue, @NotNull SkipDefaultsSerializationFilter filter) {
+    for (Binding binding : myBindings) {
+      Accessor accessor = binding.getAccessor();
+      if (!filter.equal(binding, accessor.read(currentValue), accessor.read(defaultValue))) {
+        return false;
+      }
+    }
+    return true;
+  }
+
   @NotNull
   public TObjectFloatHashMap<String> computeBindingWeights(@NotNull LinkedHashSet<String> accessorNameTracker) {
     TObjectFloatHashMap<String> weights = new TObjectFloatHashMap<String>(accessorNameTracker.size());

platform/util/src/com/intellij/util/xmlb/FieldAccessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2015 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,7 +13,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 package com.intellij.util.xmlb;
 
 import org.jetbrains.annotations.NonNls;
@@ -39,7 +38,7 @@ class FieldAccessor implements Accessor {
       return myField.get(o);
     }
     catch (IllegalAccessException e) {
-      throw new XmlSerializationException("Reading "+myField, e);
+      throw new XmlSerializationException("Reading " + myField, e);
     }
   }
 
@@ -52,7 +51,7 @@ class FieldAccessor implements Accessor {
       myField.set(o, XmlSerializerImpl.convert(value, type));
     }
     catch (IllegalAccessException e) {
-      throw new XmlSerializationException("Writing "+myField,e);
+      throw new XmlSerializationException("Writing " + myField, e);
     }
   }
 

platform/util/src/com/intellij/util/xmlb/SerializationFilter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2015 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,5 +18,5 @@ package com.intellij.util.xmlb;
 import org.jetbrains.annotations.NotNull;
 
 public interface SerializationFilter {
-  boolean accepts(@NotNull Accessor accessor, Object bean);
+  boolean accepts(@NotNull Accessor accessor, @NotNull Object bean);
 }

platform/util/src/com/intellij/util/xmlb/SerializationFilterBase.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2015 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,10 +20,7 @@ import org.jetbrains.annotations.Nullable;
 
 public abstract class SerializationFilterBase implements SerializationFilter {
   @Override
-  public final boolean accepts(@NotNull Accessor accessor, Object bean) {
-    if (bean == null) {
-      return true;
-    }
+  public boolean accepts(@NotNull Accessor accessor, @NotNull Object bean) {
     return accepts(accessor, bean, accessor.read(bean));
   }
 

platform/util/src/com/intellij/util/xmlb/SkipDefaultValuesSerializationFilters.java

@@ -39,7 +39,8 @@ public class SkipDefaultValuesSerializationFilters extends SerializationFilterBa
     }
   }
 
-  private Object getDefaultBean(@NotNull Object bean) {
+  @NotNull
+  Object getDefaultBean(@NotNull Object bean) {
     Class<?> c = bean.getClass();
     Object o = myDefaultBeans.get(c);
     if (o == null) {

platform/util/src/com/intellij/util/xmlb/SkipDefaultsSerializationFilter.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2000-2015 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.util.xmlb;
+
+import com.intellij.openapi.util.Comparing;
+import com.intellij.openapi.util.JDOMUtil;
+import com.intellij.util.ThreeState;
+import gnu.trove.THashMap;
+import org.jdom.Element;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Map;
+
+public final class SkipDefaultsSerializationFilter extends SkipDefaultValuesSerializationFilters {
+  private Map<Class<?>, ThreeState> hasEqualMethod;
+
+  boolean equal(@NotNull Binding binding, @NotNull Object bean) {
+    Accessor accessor = binding.getAccessor();
+    return equal(binding, accessor.read(bean), accessor.read(getDefaultBean(bean)));
+  }
+
+  boolean equal(@Nullable Binding binding, @Nullable Object currentValue, @Nullable Object defaultValue) {
+    if (defaultValue instanceof Element && currentValue instanceof Element) {
+      return JDOMUtil.areElementsEqual((Element)currentValue, (Element)defaultValue);
+    }
+    else {
+      if (currentValue == defaultValue) {
+        return true;
+      }
+      if (currentValue == null || defaultValue == null) {
+        return false;
+      }
+
+      if (binding instanceof BasePrimitiveBinding) {
+        Binding referencedBinding = ((BasePrimitiveBinding)binding).myBinding;
+        if (referencedBinding instanceof BeanBinding) {
+          Class<?> referencedBeanClass = ((BeanBinding)referencedBinding).myBeanClass;
+          ThreeState compareByFields;
+          if (hasEqualMethod == null) {
+            compareByFields = null;
+            hasEqualMethod = new THashMap<Class<?>, ThreeState>();
+          }
+          else {
+            compareByFields = hasEqualMethod.get(referencedBeanClass);
+          }
+
+          if (compareByFields == null) {
+            try {
+              referencedBeanClass.getDeclaredMethod("equals", Object.class);
+              compareByFields = ThreeState.NO;
+              hasEqualMethod.put(referencedBeanClass, compareByFields);
+            }
+            catch (NoSuchMethodException ignored) {
+              compareByFields = ThreeState.YES;
+              hasEqualMethod.put(referencedBeanClass, compareByFields);
+            }
+            catch (Exception e) {
+              BeanBinding.LOG.warn(e);
+            }
+          }
+
+          if (compareByFields == ThreeState.YES) {
+            return ((BeanBinding)referencedBinding).equalByFields(currentValue, defaultValue, this);
+          }
+        }
+      }
+
+      return Comparing.equal(currentValue, defaultValue);
+    }
+  }
+}

platform/util/src/com/intellij/util/xmlb/SmartSerializer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2015 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,7 +19,6 @@ import com.intellij.util.ThreeState;
 import gnu.trove.TObjectFloatHashMap;
 import org.jdom.Element;
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 import java.util.LinkedHashSet;
 
@@ -40,11 +39,11 @@ public final class SmartSerializer {
                             } :
                             new SkipDefaultValuesSerializationFilters() {
                               @Override
-                              protected boolean accepts(@NotNull Accessor accessor, @NotNull Object bean, @Nullable Object beanValue) {
+                              public boolean accepts(@NotNull Accessor accessor, @NotNull Object bean) {
                                 if (mySerializedAccessorNameTracker != null && mySerializedAccessorNameTracker.contains(accessor.getName())) {
                                   return true;
                                 }
-                                return super.accepts(accessor, bean, beanValue);
+                                return super.accepts(accessor, bean);
                               }
                             };
   }

platform/util/src/com/intellij/util/xmlb/XmlSerializer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2009 JetBrains s.r.o.
+ * Copyright 2000-2015 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,7 +31,7 @@ import java.util.Set;
 public class XmlSerializer {
   private static final SerializationFilter TRUE_FILTER = new SerializationFilter() {
     @Override
-    public boolean accepts(@NotNull Accessor accessor, Object bean) {
+    public boolean accepts(@NotNull Accessor accessor, @NotNull Object bean) {
       return true;
     }
   };

platform/util/testSrc/com/intellij/util/xmlb/XmlSerializerTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2015 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -158,6 +158,13 @@ public class XmlSerializerTest extends TestCase {
       bean);
   }
 
+  public void testSubBeanSerializationAndSkipDefaults() {
+    BeanWithSubBean bean = new BeanWithSubBean();
+    doSerializerTest(
+      "<BeanWithSubBean />",
+      bean, new SkipDefaultsSerializationFilter());
+  }
+
   public void testNullFieldValue() {
     BeanWithPublicFields bean1 = new BeanWithPublicFields();
 
@@ -538,7 +545,7 @@ public class XmlSerializerTest extends TestCase {
                      "</BeanWithPublicFields>",
                      new SerializationFilter() {
       @Override
-      public boolean accepts(@NotNull Accessor accessor, Object bean) {
+      public boolean accepts(@NotNull Accessor accessor, @NotNull Object bean) {
         return accessor.getName().startsWith("I");
       }
     });
@@ -851,7 +858,7 @@ public class XmlSerializerTest extends TestCase {
   }
   public static class PropertyFilterTest implements SerializationFilter {
     @Override
-    public boolean accepts(@NotNull Accessor accessor, Object bean) {
+    public boolean accepts(@NotNull Accessor accessor, @NotNull Object bean) {
       return !accessor.read(bean).equals("skip");
     }
   }

plugins/tasks/tasks-core/src/com/intellij/tasks/context/XDebuggerBreakpointsContextProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2013 JetBrains s.r.o.
+ * Copyright 2000-2015 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -56,7 +56,7 @@ public class XDebuggerBreakpointsContextProvider extends WorkingContextProvider
     XBreakpointManagerImpl.BreakpointManagerState state = myBreakpointManager.getState();
     Element serialize = XmlSerializer.serialize(state, new SerializationFilter() {
       @Override
-      public boolean accepts(@NotNull Accessor accessor, Object bean) {
+      public boolean accepts(@NotNull Accessor accessor, @NotNull Object bean) {
         return accessor.read(bean) != null;
       }
     });

plugins/tasks/tasks-core/src/com/intellij/tasks/context/XDebuggerWatchesProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2015 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -54,7 +54,7 @@ public class XDebuggerWatchesProvider extends WorkingContextProvider {
     XDebuggerWatchesManager.WatchesManagerState state = myWatchesManager.getState();
     Element serialize = XmlSerializer.serialize(state, new SerializationFilter() {
       @Override
-      public boolean accepts(@NotNull Accessor accessor, Object bean) {
+      public boolean accepts(@NotNull Accessor accessor, @NotNull Object bean) {
         return accessor.read(bean) != null;
       }
     });