Made ObjectNavigator a reusable object. We now use just one instance of ObjectNavigator instead of creating one for each field/object.

gson/src/main/java/com/google/gson/JsonDeserializationContextDefault.java

@@ -60,8 +60,8 @@ final class JsonDeserializationContextDefault implements JsonDeserializationCont
       JsonDeserializationContext context) throws JsonParseException {
     JsonArrayDeserializationVisitor<T> visitor = new JsonArrayDeserializationVisitor<T>(
         jsonArray, arrayType, navigatorFactory, objectConstructor, deserializers, context);
-    ObjectNavigator on = navigatorFactory.create(new ObjectTypePair(null, arrayType, true));
+    ObjectNavigator on = navigatorFactory.create();
-    on.accept(visitor);
+    on.accept(new ObjectTypePair(null, arrayType, true), visitor);
     return visitor.getTarget();
   }
 
@@ -69,8 +69,8 @@ final class JsonDeserializationContextDefault implements JsonDeserializationCont
       JsonDeserializationContext context) throws JsonParseException {
     JsonObjectDeserializationVisitor<T> visitor = new JsonObjectDeserializationVisitor<T>(
         jsonObject, typeOfT, navigatorFactory, objectConstructor, deserializers, context);
-    ObjectNavigator on = navigatorFactory.create(new ObjectTypePair(null, typeOfT, true));
+    ObjectNavigator on = navigatorFactory.create();
-    on.accept(visitor);
+    on.accept(new ObjectTypePair(null, typeOfT, true), visitor);
     return visitor.getTarget();
   }
 
@@ -79,9 +79,8 @@ final class JsonDeserializationContextDefault implements JsonDeserializationCont
       JsonDeserializationContext context) throws JsonParseException {
     JsonObjectDeserializationVisitor<T> visitor = new JsonObjectDeserializationVisitor<T>(
         json, typeOfT, navigatorFactory, objectConstructor, deserializers, context);
-    ObjectNavigator on = 
+    ObjectNavigator on = navigatorFactory.create();
-      navigatorFactory.create(new ObjectTypePair(json.getAsObject(), typeOfT, true));
+    on.accept(new ObjectTypePair(json.getAsObject(), typeOfT, true), visitor);
-    on.accept(visitor);
     Object target = visitor.getTarget();
     return (T) target;
   }

gson/src/main/java/com/google/gson/JsonDeserializationVisitor.java

@@ -105,8 +105,8 @@ abstract class JsonDeserializationVisitor<T> implements ObjectNavigator.Visitor
   }
 
   private Object visitChild(Type type, JsonDeserializationVisitor<?> childVisitor) {
-    ObjectNavigator on = factory.create(new ObjectTypePair(null, type, false));
+    ObjectNavigator on = factory.create();
-    on.accept(childVisitor);
+    on.accept(new ObjectTypePair(null, type, false), childVisitor);
     // the underlying object may have changed during the construction phase
     // This happens primarily because of custom deserializers
     return childVisitor.getTarget();

gson/src/main/java/com/google/gson/JsonSerializationContextDefault.java

@@ -54,10 +54,10 @@ final class JsonSerializationContextDefault implements JsonSerializationContext
   }
 
   JsonElement serialize(Object src, Type typeOfSrc, boolean preserveType) {
-    ObjectNavigator on = factory.create(new ObjectTypePair(src, typeOfSrc, preserveType));
+    ObjectNavigator on = factory.create();
     JsonSerializationVisitor visitor =
         new JsonSerializationVisitor(factory, serializeNulls, serializers, this, ancestors);
-    on.accept(visitor);
+    on.accept(new ObjectTypePair(src, typeOfSrc, preserveType), visitor);
     return visitor.getJsonElement();
   }
 }

gson/src/main/java/com/google/gson/JsonSerializationVisitor.java

@@ -142,10 +142,10 @@ final class JsonSerializationVisitor implements ObjectNavigator.Visitor {
   }
 
   private JsonElement getJsonElementForChild(ObjectTypePair fieldValueTypePair) {
-    ObjectNavigator on = factory.create(fieldValueTypePair);
+    ObjectNavigator on = factory.create();
     JsonSerializationVisitor childVisitor =
         new JsonSerializationVisitor(factory, serializeNulls, serializers, context, ancestors);
-    on.accept(childVisitor);
+    on.accept(fieldValueTypePair, childVisitor);
     return childVisitor.getJsonElement();
   }
 

gson/src/main/java/com/google/gson/ObjectNavigator.java

@@ -80,8 +80,7 @@ final class ObjectNavigator {
   }
 
   private final ExclusionStrategy exclusionStrategy;
-  private final ObjectTypePair objTypePair;
+  private final ReflectingFieldNavigator reflectingFieldNavigator;
-  private ReflectingFieldNavigator reflectingFieldNavigator;
 
   /**
    * @param objTypePair
@@ -90,9 +89,8 @@ final class ObjectNavigator {
    *          the concrete strategy object to be used to filter out fields of an
    *          object.
    */
-  ObjectNavigator(ObjectTypePair objTypePair, ExclusionStrategy exclusionStrategy) {
+  ObjectNavigator(ExclusionStrategy exclusionStrategy) {
     reflectingFieldNavigator = new ReflectingFieldNavigator(exclusionStrategy);
-    this.objTypePair = objTypePair;
     this.exclusionStrategy = Preconditions.checkNotNull(exclusionStrategy);
   }
 
@@ -100,7 +98,7 @@ final class ObjectNavigator {
    * Navigate all the fields of the specified object. If a field is null, it
    * does not get visited.
    */
-  public void accept(Visitor visitor) {
+  public void accept(ObjectTypePair objTypePair, Visitor visitor) {
     if (exclusionStrategy.shouldSkipClass(Types.getRawType(objTypePair.type))) {
       return;
     }

gson/src/main/java/com/google/gson/ObjectNavigatorFactory.java

@@ -26,8 +26,8 @@ import com.google.gson.internal.Preconditions;
  * @author Joel Leitch
  */
 final class ObjectNavigatorFactory {
-  private final ExclusionStrategy strategy;
   private final FieldNamingStrategy2 fieldNamingPolicy;
+  private final ObjectNavigator objectNavigator;
 
   /**
    * Creates a factory object that will be able to create new
@@ -39,8 +39,9 @@ final class ObjectNavigatorFactory {
    *        names
    */
   public ObjectNavigatorFactory(ExclusionStrategy strategy, FieldNamingStrategy2 fieldNamingPolicy) {
-    this.strategy = (strategy == null ? new NullExclusionStrategy() : strategy);
     this.fieldNamingPolicy = Preconditions.checkNotNull(fieldNamingPolicy);
+    this.objectNavigator = new ObjectNavigator(
+        strategy == null ? new NullExclusionStrategy() : strategy);
   }
 
   /**
@@ -52,8 +53,8 @@ final class ObjectNavigatorFactory {
    *         {@code srcObject} while taking into consideration the
    *         {@code type}.
    */
-  public ObjectNavigator create(ObjectTypePair objTypePair) {
+  public ObjectNavigator create() {
-    return new ObjectNavigator(objTypePair, strategy);
+    return objectNavigator;
   }
 
   FieldNamingStrategy2 getFieldNamingPolicy() {

gson/src/test/java/com/google/gson/functional/UncategorizedTest.java

@@ -69,6 +69,13 @@ public class UncategorizedTest extends TestCase {
     assertFalse(gson.toJson(target).contains("DEFAULT_VALUE"));
   }
 
+  public void testGsonInstanceReusableForSerializationAndDeserialization() {
+    BagOfPrimitives bag = new BagOfPrimitives();
+    String json = gson.toJson(bag);
+    BagOfPrimitives deserialized = gson.fromJson(json, BagOfPrimitives.class);
+    assertEquals(bag, deserialized);
+  }
+
   /**
    * This test ensures that a custom deserializer is able to return a derived class instance for a
    * base class object. For a motivation for this test, see Issue 37 and