Check in protobuf java code and generate lite jar.

third_party/protobuf/java/src/main/java/com/google/protobuf/GeneratedMessage.java

Index: third_party/protobuf/java/src/main/java/com/google/protobuf/GeneratedMessage.java
diff --git a/third_party/protobuf/java/src/main/java/com/google/protobuf/GeneratedMessage.java b/third_party/protobuf/java/src/main/java/com/google/protobuf/GeneratedMessage.java
new file mode 100644
index 0000000000000000000000000000000000000000..b5eaded50097fe66552bf199f54cd5b3a5172b8b
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+++ b/third_party/protobuf/java/src/main/java/com/google/protobuf/GeneratedMessage.java
@@ -0,0 +1,1834 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import com.google.protobuf.Descriptors.Descriptor;
+import com.google.protobuf.Descriptors.EnumValueDescriptor;
+import com.google.protobuf.Descriptors.FieldDescriptor;
+
+import java.io.IOException;
+import java.io.ObjectStreamException;
+import java.io.Serializable;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+
+/**
+ * All generated protocol message classes extend this class.  This class
+ * implements most of the Message and Builder interfaces using Java reflection.
+ * Users can ignore this class and pretend that generated messages implement
+ * the Message interface directly.
+ *
+ * @author kenton@google.com Kenton Varda
+ */
+public abstract class GeneratedMessage extends AbstractMessage
+    implements Serializable {
+  private static final long serialVersionUID = 1L;
+
+  private final UnknownFieldSet unknownFields;
+
+  /**
+   * For testing. Allows a test to disable the optimization that avoids using
+   * field builders for nested messages until they are requested. By disabling
+   * this optimization, existing tests can be reused to test the field builders.
+   */
+  protected static boolean alwaysUseFieldBuilders = false;
+
+  protected GeneratedMessage() {
+    this.unknownFields = UnknownFieldSet.getDefaultInstance();
+  }
+
+  protected GeneratedMessage(Builder<?> builder) {
+    this.unknownFields = builder.getUnknownFields();
+  }
+
+ /**
+  * For testing. Allows a test to disable the optimization that avoids using
+  * field builders for nested messages until they are requested. By disabling
+  * this optimization, existing tests can be reused to test the field builders.
+  * See {@link RepeatedFieldBuilder} and {@link SingleFieldBuilder}.
+  */
+  static void enableAlwaysUseFieldBuildersForTesting() {
+    alwaysUseFieldBuilders = true;
+  }
+
+  /**
+   * Get the FieldAccessorTable for this type.  We can't have the message
+   * class pass this in to the constructor because of bootstrapping trouble
+   * with DescriptorProtos.
+   */
+  protected abstract FieldAccessorTable internalGetFieldAccessorTable();
+
+  //@Override (Java 1.6 override semantics, but we must support 1.5)
+  public Descriptor getDescriptorForType() {
+    return internalGetFieldAccessorTable().descriptor;
+  }
+
+  /** Internal helper which returns a mutable map. */
+  private Map<FieldDescriptor, Object> getAllFieldsMutable() {
+    final TreeMap<FieldDescriptor, Object> result =
+      new TreeMap<FieldDescriptor, Object>();
+    final Descriptor descriptor = internalGetFieldAccessorTable().descriptor;
+    for (final FieldDescriptor field : descriptor.getFields()) {
+      if (field.isRepeated()) {
+        final List<?> value = (List<?>) getField(field);
+        if (!value.isEmpty()) {
+          result.put(field, value);
+        }
+      } else {
+        if (hasField(field)) {
+          result.put(field, getField(field));
+        }
+      }
+    }
+    return result;
+  }
+
+  @Override
+  public boolean isInitialized() {
+    for (final FieldDescriptor field : getDescriptorForType().getFields()) {
+      // Check that all required fields are present.
+      if (field.isRequired()) {
+        if (!hasField(field)) {
+          return false;
+        }
+      }
+      // Check that embedded messages are initialized.
+      if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+        if (field.isRepeated()) {
+          @SuppressWarnings("unchecked") final
+          List<Message> messageList = (List<Message>) getField(field);
+          for (final Message element : messageList) {
+            if (!element.isInitialized()) {
+              return false;
+            }
+          }
+        } else {
+          if (hasField(field) && !((Message) getField(field)).isInitialized()) {
+            return false;
+          }
+        }
+      }
+    }
+
+    return true;
+  }
+
+  //@Override (Java 1.6 override semantics, but we must support 1.5)
+  public Map<FieldDescriptor, Object> getAllFields() {
+    return Collections.unmodifiableMap(getAllFieldsMutable());
+  }
+
+  //@Override (Java 1.6 override semantics, but we must support 1.5)
+  public boolean hasField(final FieldDescriptor field) {
+    return internalGetFieldAccessorTable().getField(field).has(this);
+  }
+
+  //@Override (Java 1.6 override semantics, but we must support 1.5)
+  public Object getField(final FieldDescriptor field) {
+    return internalGetFieldAccessorTable().getField(field).get(this);
+  }
+
+  //@Override (Java 1.6 override semantics, but we must support 1.5)
+  public int getRepeatedFieldCount(final FieldDescriptor field) {
+    return internalGetFieldAccessorTable().getField(field)
+      .getRepeatedCount(this);
+  }
+
+  //@Override (Java 1.6 override semantics, but we must support 1.5)
+  public Object getRepeatedField(final FieldDescriptor field, final int index) {
+    return internalGetFieldAccessorTable().getField(field)
+      .getRepeated(this, index);
+  }
+
+  //@Override (Java 1.6 override semantics, but we must support 1.5)
+  public final UnknownFieldSet getUnknownFields() {
+    return unknownFields;
+  }
+
+  protected abstract Message.Builder newBuilderForType(BuilderParent parent);
+
+  /**
+   * Interface for the parent of a Builder that allows the builder to
+   * communicate invalidations back to the parent for use when using nested
+   * builders.
+   */
+  protected interface BuilderParent {
+
+    /**
+     * A builder becomes dirty whenever a field is modified -- including fields
+     * in nested builders -- and becomes clean when build() is called.  Thus,
+     * when a builder becomes dirty, all its parents become dirty as well, and
+     * when it becomes clean, all its children become clean.  The dirtiness
+     * state is used to invalidate certain cached values.
+     * <br>
+     * To this end, a builder calls markAsDirty() on its parent whenever it
+     * transitions from clean to dirty.  The parent must propagate this call to
+     * its own parent, unless it was already dirty, in which case the
+     * grandparent must necessarily already be dirty as well.  The parent can
+     * only transition back to "clean" after calling build() on all children.
+     */
+    void markDirty();
+  }
+
+  @SuppressWarnings("unchecked")
+  public abstract static class Builder <BuilderType extends Builder>
+      extends AbstractMessage.Builder<BuilderType> {
+
+    private BuilderParent builderParent;
+
+    private BuilderParentImpl meAsParent;
+
+    // Indicates that we've built a message and so we are now obligated
+    // to dispatch dirty invalidations. See GeneratedMessage.BuilderListener.
+    private boolean isClean;
+
+    private UnknownFieldSet unknownFields =
+        UnknownFieldSet.getDefaultInstance();
+
+    protected Builder() {
+      this(null);
+    }
+
+    protected Builder(BuilderParent builderParent) {
+      this.builderParent = builderParent;
+    }
+
+    void dispose() {
+      builderParent = null;
+    }
+
+    /**
+     * Called by the subclass when a message is built.
+     */
+    protected void onBuilt() {
+      if (builderParent != null) {
+        markClean();
+      }
+    }
+
+    /**
+     * Called by the subclass or a builder to notify us that a message was
+     * built and may be cached and therefore invalidations are needed.
+     */
+    protected void markClean() {
+      this.isClean = true;
+    }
+
+    /**
+     * Gets whether invalidations are needed
+     *
+     * @return whether invalidations are needed
+     */
+    protected boolean isClean() {
+      return isClean;
+    }
+
+    // This is implemented here only to work around an apparent bug in the
+    // Java compiler and/or build system.  See bug #1898463.  The mere presence
+    // of this dummy clone() implementation makes it go away.
+    @Override
+    public BuilderType clone() {
+      throw new UnsupportedOperationException(
+          "This is supposed to be overridden by subclasses.");
+    }
+
+    /**
+     * Called by the initialization and clear code paths to allow subclasses to
+     * reset any of their builtin fields back to the initial values.
+     */
+    public BuilderType clear() {
+      unknownFields = UnknownFieldSet.getDefaultInstance();
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    /**
+     * Get the FieldAccessorTable for this type.  We can't have the message
+     * class pass this in to the constructor because of bootstrapping trouble
+     * with DescriptorProtos.
+     */
+    protected abstract FieldAccessorTable internalGetFieldAccessorTable();
+
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public Descriptor getDescriptorForType() {
+      return internalGetFieldAccessorTable().descriptor;
+    }
+
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public Map<FieldDescriptor, Object> getAllFields() {
+      return Collections.unmodifiableMap(getAllFieldsMutable());
+    }
+
+    /** Internal helper which returns a mutable map. */
+    private Map<FieldDescriptor, Object> getAllFieldsMutable() {
+      final TreeMap<FieldDescriptor, Object> result =
+        new TreeMap<FieldDescriptor, Object>();
+      final Descriptor descriptor = internalGetFieldAccessorTable().descriptor;
+      for (final FieldDescriptor field : descriptor.getFields()) {
+        if (field.isRepeated()) {
+          final List value = (List) getField(field);
+          if (!value.isEmpty()) {
+            result.put(field, value);
+          }
+        } else {
+          if (hasField(field)) {
+            result.put(field, getField(field));
+          }
+        }
+      }
+      return result;
+    }
+
+    public Message.Builder newBuilderForField(
+        final FieldDescriptor field) {
+      return internalGetFieldAccessorTable().getField(field).newBuilder();
+    }
+
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public boolean hasField(final FieldDescriptor field) {
+      return internalGetFieldAccessorTable().getField(field).has(this);
+    }
+
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public Object getField(final FieldDescriptor field) {
+      Object object = internalGetFieldAccessorTable().getField(field).get(this);
+      if (field.isRepeated()) {
+        // The underlying list object is still modifiable at this point.
+        // Make sure not to expose the modifiable list to the caller.
+        return Collections.unmodifiableList((List) object);
+      } else {
+        return object;
+      }
+    }
+
+    public BuilderType setField(final FieldDescriptor field,
+                                final Object value) {
+      internalGetFieldAccessorTable().getField(field).set(this, value);
+      return (BuilderType) this;
+    }
+
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public BuilderType clearField(final FieldDescriptor field) {
+      internalGetFieldAccessorTable().getField(field).clear(this);
+      return (BuilderType) this;
+    }
+
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public int getRepeatedFieldCount(final FieldDescriptor field) {
+      return internalGetFieldAccessorTable().getField(field)
+          .getRepeatedCount(this);
+    }
+
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public Object getRepeatedField(final FieldDescriptor field,
+                                   final int index) {
+      return internalGetFieldAccessorTable().getField(field)
+          .getRepeated(this, index);
+    }
+
+    public BuilderType setRepeatedField(final FieldDescriptor field,
+                                        final int index, final Object value) {
+      internalGetFieldAccessorTable().getField(field)
+        .setRepeated(this, index, value);
+      return (BuilderType) this;
+    }
+
+    public BuilderType addRepeatedField(final FieldDescriptor field,
+                                        final Object value) {
+      internalGetFieldAccessorTable().getField(field).addRepeated(this, value);
+      return (BuilderType) this;
+    }
+
+    public final BuilderType setUnknownFields(
+        final UnknownFieldSet unknownFields) {
+      this.unknownFields = unknownFields;
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    @Override
+    public final BuilderType mergeUnknownFields(
+        final UnknownFieldSet unknownFields) {
+      this.unknownFields =
+        UnknownFieldSet.newBuilder(this.unknownFields)
+                       .mergeFrom(unknownFields)
+                       .build();
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public boolean isInitialized() {
+      for (final FieldDescriptor field : getDescriptorForType().getFields()) {
+        // Check that all required fields are present.
+        if (field.isRequired()) {
+          if (!hasField(field)) {
+            return false;
+          }
+        }
+        // Check that embedded messages are initialized.
+        if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+          if (field.isRepeated()) {
+            @SuppressWarnings("unchecked") final
+            List<Message> messageList = (List<Message>) getField(field);
+            for (final Message element : messageList) {
+              if (!element.isInitialized()) {
+                return false;
+              }
+            }
+          } else {
+            if (hasField(field) &&
+                !((Message) getField(field)).isInitialized()) {
+              return false;
+            }
+          }
+        }
+      }
+      return true;
+    }
+
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public final UnknownFieldSet getUnknownFields() {
+      return unknownFields;
+    }
+
+    /**
+     * Called by subclasses to parse an unknown field.
+     * @return {@code true} unless the tag is an end-group tag.
+     */
+    protected boolean parseUnknownField(
+        final CodedInputStream input,
+        final UnknownFieldSet.Builder unknownFields,
+        final ExtensionRegistryLite extensionRegistry,
+        final int tag) throws IOException {
+      return unknownFields.mergeFieldFrom(tag, input);
+    }
+
+    /**
+     * Implementation of {@link BuilderParent} for giving to our children. This
+     * small inner class makes it so we don't publicly expose the BuilderParent
+     * methods.
+     */
+    private class BuilderParentImpl implements BuilderParent {
+
+      //@Override (Java 1.6 override semantics, but we must support 1.5)
+      public void markDirty() {
+        onChanged();
+      }
+    }
+
+    /**
+     * Gets the {@link BuilderParent} for giving to our children.
+     * @return The builder parent for our children.
+     */
+    protected BuilderParent getParentForChildren() {
+      if (meAsParent == null) {
+        meAsParent = new BuilderParentImpl();
+      }
+      return meAsParent;
+    }
+
+    /**
+     * Called when a the builder or one of its nested children has changed
+     * and any parent should be notified of its invalidation.
+     */
+    protected final void onChanged() {
+      if (isClean && builderParent != null) {
+        builderParent.markDirty();
+
+        // Don't keep dispatching invalidations until build is called again.
+        isClean = false;
+      }
+    }
+  }
+
+  // =================================================================
+  // Extensions-related stuff
+
+  public interface ExtendableMessageOrBuilder<
+      MessageType extends ExtendableMessage> extends MessageOrBuilder {
+
+    /** Check if a singular extension is present. */
+    <Type> boolean hasExtension(
+        GeneratedExtension<MessageType, Type> extension);
+
+    /** Get the number of elements in a repeated extension. */
+    <Type> int getExtensionCount(
+        GeneratedExtension<MessageType, List<Type>> extension);
+
+    /** Get the value of an extension. */
+    <Type> Type getExtension(GeneratedExtension<MessageType, Type> extension);
+
+    /** Get one element of a repeated extension. */
+    <Type> Type getExtension(
+        GeneratedExtension<MessageType, List<Type>> extension,
+        int index);
+  }
+
+  /**
+   * Generated message classes for message types that contain extension ranges
+   * subclass this.
+   *
+   * <p>This class implements type-safe accessors for extensions.  They
+   * implement all the same operations that you can do with normal fields --
+   * e.g. "has", "get", and "getCount" -- but for extensions.  The extensions
+   * are identified using instances of the class {@link GeneratedExtension};
+   * the protocol compiler generates a static instance of this class for every
+   * extension in its input.  Through the magic of generics, all is made
+   * type-safe.
+   *
+   * <p>For example, imagine you have the {@code .proto} file:
+   *
+   * <pre>
+   * option java_class = "MyProto";
+   *
+   * message Foo {
+   *   extensions 1000 to max;
+   * }
+   *
+   * extend Foo {
+   *   optional int32 bar;
+   * }
+   * </pre>
+   *
+   * <p>Then you might write code like:
+   *
+   * <pre>
+   * MyProto.Foo foo = getFoo();
+   * int i = foo.getExtension(MyProto.bar);
+   * </pre>
+   *
+   * <p>See also {@link ExtendableBuilder}.
+   */
+  public abstract static class ExtendableMessage<
+        MessageType extends ExtendableMessage>
+      extends GeneratedMessage
+      implements ExtendableMessageOrBuilder<MessageType> {
+
+    private final FieldSet<FieldDescriptor> extensions;
+
+    protected ExtendableMessage() {
+      this.extensions = FieldSet.newFieldSet();
+    }
+
+    protected ExtendableMessage(
+        ExtendableBuilder<MessageType, ?> builder) {
+      super(builder);
+      this.extensions = builder.buildExtensions();
+    }
+
+    private void verifyExtensionContainingType(
+        final GeneratedExtension<MessageType, ?> extension) {
+      if (extension.getDescriptor().getContainingType() !=
+          getDescriptorForType()) {
+        // This can only happen if someone uses unchecked operations.
+        throw new IllegalArgumentException(
+          "Extension is for type \"" +
+          extension.getDescriptor().getContainingType().getFullName() +
+          "\" which does not match message type \"" +
+          getDescriptorForType().getFullName() + "\".");
+      }
+    }
+
+    /** Check if a singular extension is present. */
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public final <Type> boolean hasExtension(
+        final GeneratedExtension<MessageType, Type> extension) {
+      verifyExtensionContainingType(extension);
+      return extensions.hasField(extension.getDescriptor());
+    }
+
+    /** Get the number of elements in a repeated extension. */
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public final <Type> int getExtensionCount(
+        final GeneratedExtension<MessageType, List<Type>> extension) {
+      verifyExtensionContainingType(extension);
+      final FieldDescriptor descriptor = extension.getDescriptor();
+      return extensions.getRepeatedFieldCount(descriptor);
+    }
+
+    /** Get the value of an extension. */
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    @SuppressWarnings("unchecked")
+    public final <Type> Type getExtension(
+        final GeneratedExtension<MessageType, Type> extension) {
+      verifyExtensionContainingType(extension);
+      FieldDescriptor descriptor = extension.getDescriptor();
+      final Object value = extensions.getField(descriptor);
+      if (value == null) {
+        if (descriptor.isRepeated()) {
+          return (Type) Collections.emptyList();
+        } else if (descriptor.getJavaType() ==
+                   FieldDescriptor.JavaType.MESSAGE) {
+          return (Type) extension.getMessageDefaultInstance();
+        } else {
+          return (Type) extension.fromReflectionType(
+              descriptor.getDefaultValue());
+        }
+      } else {
+        return (Type) extension.fromReflectionType(value);
+      }
+    }
+
+    /** Get one element of a repeated extension. */
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    @SuppressWarnings("unchecked")
+    public final <Type> Type getExtension(
+        final GeneratedExtension<MessageType, List<Type>> extension,
+        final int index) {
+      verifyExtensionContainingType(extension);
+      FieldDescriptor descriptor = extension.getDescriptor();
+      return (Type) extension.singularFromReflectionType(
+          extensions.getRepeatedField(descriptor, index));
+    }
+
+    /** Called by subclasses to check if all extensions are initialized. */
+    protected boolean extensionsAreInitialized() {
+      return extensions.isInitialized();
+    }
+
+    @Override
+    public boolean isInitialized() {
+      return super.isInitialized() && extensionsAreInitialized();
+    }
+
+    /**
+     * Used by subclasses to serialize extensions.  Extension ranges may be
+     * interleaved with field numbers, but we must write them in canonical
+     * (sorted by field number) order.  ExtensionWriter helps us write
+     * individual ranges of extensions at once.
+     */
+    protected class ExtensionWriter {
+      // Imagine how much simpler this code would be if Java iterators had
+      // a way to get the next element without advancing the iterator.
+
+      private final Iterator<Map.Entry<FieldDescriptor, Object>> iter =
+        extensions.iterator();
+      private Map.Entry<FieldDescriptor, Object> next;
+      private final boolean messageSetWireFormat;
+
+      private ExtensionWriter(final boolean messageSetWireFormat) {
+        if (iter.hasNext()) {
+          next = iter.next();
+        }
+        this.messageSetWireFormat = messageSetWireFormat;
+      }
+
+      public void writeUntil(final int end, final CodedOutputStream output)
+                             throws IOException {
+        while (next != null && next.getKey().getNumber() < end) {
+          FieldDescriptor descriptor = next.getKey();
+          if (messageSetWireFormat && descriptor.getLiteJavaType() ==
+                  WireFormat.JavaType.MESSAGE &&
+              !descriptor.isRepeated()) {
+            output.writeMessageSetExtension(descriptor.getNumber(),
+                                            (Message) next.getValue());
+          } else {
+            FieldSet.writeField(descriptor, next.getValue(), output);
+          }
+          if (iter.hasNext()) {
+            next = iter.next();
+          } else {
+            next = null;
+          }
+        }
+      }
+    }
+
+    protected ExtensionWriter newExtensionWriter() {
+      return new ExtensionWriter(false);
+    }
+    protected ExtensionWriter newMessageSetExtensionWriter() {
+      return new ExtensionWriter(true);
+    }
+
+    /** Called by subclasses to compute the size of extensions. */
+    protected int extensionsSerializedSize() {
+      return extensions.getSerializedSize();
+    }
+    protected int extensionsSerializedSizeAsMessageSet() {
+      return extensions.getMessageSetSerializedSize();
+    }
+
+    // ---------------------------------------------------------------
+    // Reflection
+
+    protected Map<FieldDescriptor, Object> getExtensionFields() {
+      return extensions.getAllFields();
+    }
+
+    @Override
+    public Map<FieldDescriptor, Object> getAllFields() {
+      final Map<FieldDescriptor, Object> result = super.getAllFieldsMutable();
+      result.putAll(getExtensionFields());
+      return Collections.unmodifiableMap(result);
+    }
+
+    @Override
+    public boolean hasField(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        return extensions.hasField(field);
+      } else {
+        return super.hasField(field);
+      }
+    }
+
+    @Override
+    public Object getField(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        final Object value = extensions.getField(field);
+        if (value == null) {
+          if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+            // Lacking an ExtensionRegistry, we have no way to determine the
+            // extension's real type, so we return a DynamicMessage.
+            return DynamicMessage.getDefaultInstance(field.getMessageType());
+          } else {
+            return field.getDefaultValue();
+          }
+        } else {
+          return value;
+        }
+      } else {
+        return super.getField(field);
+      }
+    }
+
+    @Override
+    public int getRepeatedFieldCount(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        return extensions.getRepeatedFieldCount(field);
+      } else {
+        return super.getRepeatedFieldCount(field);
+      }
+    }
+
+    @Override
+    public Object getRepeatedField(final FieldDescriptor field,
+                                   final int index) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        return extensions.getRepeatedField(field, index);
+      } else {
+        return super.getRepeatedField(field, index);
+      }
+    }
+
+    private void verifyContainingType(final FieldDescriptor field) {
+      if (field.getContainingType() != getDescriptorForType()) {
+        throw new IllegalArgumentException(
+          "FieldDescriptor does not match message type.");
+      }
+    }
+  }
+
+  /**
+   * Generated message builders for message types that contain extension ranges
+   * subclass this.
+   *
+   * <p>This class implements type-safe accessors for extensions.  They
+   * implement all the same operations that you can do with normal fields --
+   * e.g. "get", "set", and "add" -- but for extensions.  The extensions are
+   * identified using instances of the class {@link GeneratedExtension}; the
+   * protocol compiler generates a static instance of this class for every
+   * extension in its input.  Through the magic of generics, all is made
+   * type-safe.
+   *
+   * <p>For example, imagine you have the {@code .proto} file:
+   *
+   * <pre>
+   * option java_class = "MyProto";
+   *
+   * message Foo {
+   *   extensions 1000 to max;
+   * }
+   *
+   * extend Foo {
+   *   optional int32 bar;
+   * }
+   * </pre>
+   *
+   * <p>Then you might write code like:
+   *
+   * <pre>
+   * MyProto.Foo foo =
+   *   MyProto.Foo.newBuilder()
+   *     .setExtension(MyProto.bar, 123)
+   *     .build();
+   * </pre>
+   *
+   * <p>See also {@link ExtendableMessage}.
+   */
+  @SuppressWarnings("unchecked")
+  public abstract static class ExtendableBuilder<
+        MessageType extends ExtendableMessage,
+        BuilderType extends ExtendableBuilder>
+      extends Builder<BuilderType>
+      implements ExtendableMessageOrBuilder<MessageType> {
+
+    private FieldSet<FieldDescriptor> extensions = FieldSet.emptySet();
+
+    protected ExtendableBuilder() {}
+
+    protected ExtendableBuilder(
+        BuilderParent parent) {
+      super(parent);
+    }
+
+    @Override
+    public BuilderType clear() {
+      extensions = FieldSet.emptySet();
+      return super.clear();
+    }
+
+    // This is implemented here only to work around an apparent bug in the
+    // Java compiler and/or build system.  See bug #1898463.  The mere presence
+    // of this dummy clone() implementation makes it go away.
+    @Override
+    public BuilderType clone() {
+      throw new UnsupportedOperationException(
+          "This is supposed to be overridden by subclasses.");
+    }
+
+    private void ensureExtensionsIsMutable() {
+      if (extensions.isImmutable()) {
+        extensions = extensions.clone();
+      }
+    }
+
+    private void verifyExtensionContainingType(
+        final GeneratedExtension<MessageType, ?> extension) {
+      if (extension.getDescriptor().getContainingType() !=
+          getDescriptorForType()) {
+        // This can only happen if someone uses unchecked operations.
+        throw new IllegalArgumentException(
+          "Extension is for type \"" +
+          extension.getDescriptor().getContainingType().getFullName() +
+          "\" which does not match message type \"" +
+          getDescriptorForType().getFullName() + "\".");
+      }
+    }
+
+    /** Check if a singular extension is present. */
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public final <Type> boolean hasExtension(
+        final GeneratedExtension<MessageType, Type> extension) {
+      verifyExtensionContainingType(extension);
+      return extensions.hasField(extension.getDescriptor());
+    }
+
+    /** Get the number of elements in a repeated extension. */
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public final <Type> int getExtensionCount(
+        final GeneratedExtension<MessageType, List<Type>> extension) {
+      verifyExtensionContainingType(extension);
+      final FieldDescriptor descriptor = extension.getDescriptor();
+      return extensions.getRepeatedFieldCount(descriptor);
+    }
+
+    /** Get the value of an extension. */
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public final <Type> Type getExtension(
+        final GeneratedExtension<MessageType, Type> extension) {
+      verifyExtensionContainingType(extension);
+      FieldDescriptor descriptor = extension.getDescriptor();
+      final Object value = extensions.getField(descriptor);
+      if (value == null) {
+        if (descriptor.isRepeated()) {
+          return (Type) Collections.emptyList();
+        } else if (descriptor.getJavaType() ==
+                   FieldDescriptor.JavaType.MESSAGE) {
+          return (Type) extension.getMessageDefaultInstance();
+        } else {
+          return (Type) extension.fromReflectionType(
+              descriptor.getDefaultValue());
+        }
+      } else {
+        return (Type) extension.fromReflectionType(value);
+      }
+    }
+
+    /** Get one element of a repeated extension. */
+    //@Override (Java 1.6 override semantics, but we must support 1.5)
+    public final <Type> Type getExtension(
+        final GeneratedExtension<MessageType, List<Type>> extension,
+        final int index) {
+      verifyExtensionContainingType(extension);
+      FieldDescriptor descriptor = extension.getDescriptor();
+      return (Type) extension.singularFromReflectionType(
+          extensions.getRepeatedField(descriptor, index));
+    }
+
+    /** Set the value of an extension. */
+    public final <Type> BuilderType setExtension(
+        final GeneratedExtension<MessageType, Type> extension,
+        final Type value) {
+      verifyExtensionContainingType(extension);
+      ensureExtensionsIsMutable();
+      final FieldDescriptor descriptor = extension.getDescriptor();
+      extensions.setField(descriptor, extension.toReflectionType(value));
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    /** Set the value of one element of a repeated extension. */
+    public final <Type> BuilderType setExtension(
+        final GeneratedExtension<MessageType, List<Type>> extension,
+        final int index, final Type value) {
+      verifyExtensionContainingType(extension);
+      ensureExtensionsIsMutable();
+      final FieldDescriptor descriptor = extension.getDescriptor();
+      extensions.setRepeatedField(
+        descriptor, index,
+        extension.singularToReflectionType(value));
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    /** Append a value to a repeated extension. */
+    public final <Type> BuilderType addExtension(
+        final GeneratedExtension<MessageType, List<Type>> extension,
+        final Type value) {
+      verifyExtensionContainingType(extension);
+      ensureExtensionsIsMutable();
+      final FieldDescriptor descriptor = extension.getDescriptor();
+      extensions.addRepeatedField(
+          descriptor, extension.singularToReflectionType(value));
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    /** Clear an extension. */
+    public final <Type> BuilderType clearExtension(
+        final GeneratedExtension<MessageType, ?> extension) {
+      verifyExtensionContainingType(extension);
+      ensureExtensionsIsMutable();
+      extensions.clearField(extension.getDescriptor());
+      onChanged();
+      return (BuilderType) this;
+    }
+
+    /** Called by subclasses to check if all extensions are initialized. */
+    protected boolean extensionsAreInitialized() {
+      return extensions.isInitialized();
+    }
+
+    /**
+     * Called by the build code path to create a copy of the extensions for
+     * building the message.
+     */
+    private FieldSet<FieldDescriptor> buildExtensions() {
+      extensions.makeImmutable();
+      return extensions;
+    }
+
+    @Override
+    public boolean isInitialized() {
+      return super.isInitialized() && extensionsAreInitialized();
+    }
+
+    /**
+     * Called by subclasses to parse an unknown field or an extension.
+     * @return {@code true} unless the tag is an end-group tag.
+     */
+    @Override
+    protected boolean parseUnknownField(
+        final CodedInputStream input,
+        final UnknownFieldSet.Builder unknownFields,
+        final ExtensionRegistryLite extensionRegistry,
+        final int tag) throws IOException {
+      return AbstractMessage.Builder.mergeFieldFrom(
+        input, unknownFields, extensionRegistry, this, tag);
+    }
+
+    // ---------------------------------------------------------------
+    // Reflection
+
+    @Override
+    public Map<FieldDescriptor, Object> getAllFields() {
+      final Map<FieldDescriptor, Object> result = super.getAllFieldsMutable();
+      result.putAll(extensions.getAllFields());
+      return Collections.unmodifiableMap(result);
+    }
+
+    @Override
+    public Object getField(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        final Object value = extensions.getField(field);
+        if (value == null) {
+          if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+            // Lacking an ExtensionRegistry, we have no way to determine the
+            // extension's real type, so we return a DynamicMessage.
+            return DynamicMessage.getDefaultInstance(field.getMessageType());
+          } else {
+            return field.getDefaultValue();
+          }
+        } else {
+          return value;
+        }
+      } else {
+        return super.getField(field);
+      }
+    }
+
+    @Override
+    public int getRepeatedFieldCount(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        return extensions.getRepeatedFieldCount(field);
+      } else {
+        return super.getRepeatedFieldCount(field);
+      }
+    }
+
+    @Override
+    public Object getRepeatedField(final FieldDescriptor field,
+                                   final int index) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        return extensions.getRepeatedField(field, index);
+      } else {
+        return super.getRepeatedField(field, index);
+      }
+    }
+
+    @Override
+    public boolean hasField(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        return extensions.hasField(field);
+      } else {
+        return super.hasField(field);
+      }
+    }
+
+    @Override
+    public BuilderType setField(final FieldDescriptor field,
+                                final Object value) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        ensureExtensionsIsMutable();
+        extensions.setField(field, value);
+        onChanged();
+        return (BuilderType) this;
+      } else {
+        return super.setField(field, value);
+      }
+    }
+
+    @Override
+    public BuilderType clearField(final FieldDescriptor field) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        ensureExtensionsIsMutable();
+        extensions.clearField(field);
+        onChanged();
+        return (BuilderType) this;
+      } else {
+        return super.clearField(field);
+      }
+    }
+
+    @Override
+    public BuilderType setRepeatedField(final FieldDescriptor field,
+                                        final int index, final Object value) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        ensureExtensionsIsMutable();
+        extensions.setRepeatedField(field, index, value);
+        onChanged();
+        return (BuilderType) this;
+      } else {
+        return super.setRepeatedField(field, index, value);
+      }
+    }
+
+    @Override
+    public BuilderType addRepeatedField(final FieldDescriptor field,
+                                        final Object value) {
+      if (field.isExtension()) {
+        verifyContainingType(field);
+        ensureExtensionsIsMutable();
+        extensions.addRepeatedField(field, value);
+        onChanged();
+        return (BuilderType) this;
+      } else {
+        return super.addRepeatedField(field, value);
+      }
+    }
+
+    protected final void mergeExtensionFields(final ExtendableMessage other) {
+      ensureExtensionsIsMutable();
+      extensions.mergeFrom(other.extensions);
+      onChanged();
+    }
+
+    private void verifyContainingType(final FieldDescriptor field) {
+      if (field.getContainingType() != getDescriptorForType()) {
+        throw new IllegalArgumentException(
+          "FieldDescriptor does not match message type.");
+      }
+    }
+  }
+
+  // -----------------------------------------------------------------
+
+  /**
+   * Gets the descriptor for an extension. The implementation depends on whether
+   * the extension is scoped in the top level of a file or scoped in a Message.
+   */
+  private static interface ExtensionDescriptorRetriever {
+    FieldDescriptor getDescriptor();
+  }
+
+  /** For use by generated code only. */
+  public static <ContainingType extends Message, Type>
+      GeneratedExtension<ContainingType, Type>
+      newMessageScopedGeneratedExtension(final Message scope,
+                                         final int descriptorIndex,
+                                         final Class singularType,
+                                         final Message defaultInstance) {
+    // For extensions scoped within a Message, we use the Message to resolve
+    // the outer class's descriptor, from which the extension descriptor is
+    // obtained.
+    return new GeneratedExtension<ContainingType, Type>(
+        new ExtensionDescriptorRetriever() {
+          //@Override (Java 1.6 override semantics, but we must support 1.5)
+          public FieldDescriptor getDescriptor() {
+            return scope.getDescriptorForType().getExtensions()
+                .get(descriptorIndex);
+          }
+        },
+        singularType,
+        defaultInstance);
+  }
+
+  /** For use by generated code only. */
+  public static <ContainingType extends Message, Type>
+     GeneratedExtension<ContainingType, Type>
+     newFileScopedGeneratedExtension(final Class singularType,
+                                     final Message defaultInstance) {
+    // For extensions scoped within a file, we rely on the outer class's
+    // static initializer to call internalInit() on the extension when the
+    // descriptor is available.
+    return new GeneratedExtension<ContainingType, Type>(
+        null,  // ExtensionDescriptorRetriever is initialized in internalInit();
+        singularType,
+        defaultInstance);
+  }
+
+  /**
+   * Type used to represent generated extensions.  The protocol compiler
+   * generates a static singleton instance of this class for each extension.
+   *
+   * <p>For example, imagine you have the {@code .proto} file:
+   *
+   * <pre>
+   * option java_class = "MyProto";
+   *
+   * message Foo {
+   *   extensions 1000 to max;
+   * }
+   *
+   * extend Foo {
+   *   optional int32 bar;
+   * }
+   * </pre>
+   *
+   * <p>Then, {@code MyProto.Foo.bar} has type
+   * {@code GeneratedExtension<MyProto.Foo, Integer>}.
+   *
+   * <p>In general, users should ignore the details of this type, and simply use
+   * these static singletons as parameters to the extension accessors defined
+   * in {@link ExtendableMessage} and {@link ExtendableBuilder}.
+   */
+  public static final class GeneratedExtension<
+      ContainingType extends Message, Type> {
+    // TODO(kenton):  Find ways to avoid using Java reflection within this
+    //   class.  Also try to avoid suppressing unchecked warnings.
+
+    // We can't always initialize the descriptor of a GeneratedExtension when
+    // we first construct it due to initialization order difficulties (namely,
+    // the descriptor may not have been constructed yet, since it is often
+    // constructed by the initializer of a separate module).
+    //
+    // In the case of nested extensions, we initialize the
+    // ExtensionDescriptorRetriever with an instance that uses the scoping
+    // Message's default instance to retrieve the extension's descriptor.
+    //
+    // In the case of non-nested extensions, we initialize the
+    // ExtensionDescriptorRetriever to null and rely on the outer class's static
+    // initializer to call internalInit() after the descriptor has been parsed.
+    private GeneratedExtension(ExtensionDescriptorRetriever descriptorRetriever,
+                               Class singularType,
+                               Message messageDefaultInstance) {
+      if (Message.class.isAssignableFrom(singularType) &&
+          !singularType.isInstance(messageDefaultInstance)) {
+        throw new IllegalArgumentException(
+            "Bad messageDefaultInstance for " + singularType.getName());
+      }
+      this.descriptorRetriever = descriptorRetriever;
+      this.singularType = singularType;
+      this.messageDefaultInstance = messageDefaultInstance;
+
+      if (ProtocolMessageEnum.class.isAssignableFrom(singularType)) {
+        this.enumValueOf = getMethodOrDie(singularType, "valueOf",
+                                          EnumValueDescriptor.class);
+        this.enumGetValueDescriptor =
+            getMethodOrDie(singularType, "getValueDescriptor");
+      } else {
+        this.enumValueOf = null;
+        this.enumGetValueDescriptor = null;
+      }
+    }
+
+    /** For use by generated code only. */
+    public void internalInit(final FieldDescriptor descriptor) {
+      if (descriptorRetriever != null) {
+        throw new IllegalStateException("Already initialized.");
+      }
+      descriptorRetriever = new ExtensionDescriptorRetriever() {
+          //@Override (Java 1.6 override semantics, but we must support 1.5)
+          public FieldDescriptor getDescriptor() {
+            return descriptor;
+          }
+        };
+    }
+
+    private ExtensionDescriptorRetriever descriptorRetriever;
+    private final Class singularType;
+    private final Message messageDefaultInstance;
+    private final Method enumValueOf;
+    private final Method enumGetValueDescriptor;
+
+    public FieldDescriptor getDescriptor() {
+      if (descriptorRetriever == null) {
+        throw new IllegalStateException(
+            "getDescriptor() called before internalInit()");
+      }
+      return descriptorRetriever.getDescriptor();
+    }
+
+    /**
+     * If the extension is an embedded message or group, returns the default
+     * instance of the message.
+     */
+    public Message getMessageDefaultInstance() {
+      return messageDefaultInstance;
+    }
+
+    /**
+     * Convert from the type used by the reflection accessors to the type used
+     * by native accessors.  E.g., for enums, the reflection accessors use
+     * EnumValueDescriptors but the native accessors use the generated enum
+     * type.
+     */
+    @SuppressWarnings("unchecked")
+    private Object fromReflectionType(final Object value) {
+      FieldDescriptor descriptor = getDescriptor();
+      if (descriptor.isRepeated()) {
+        if (descriptor.getJavaType() == FieldDescriptor.JavaType.MESSAGE ||
+            descriptor.getJavaType() == FieldDescriptor.JavaType.ENUM) {
+          // Must convert the whole list.
+          final List result = new ArrayList();
+          for (final Object element : (List) value) {
+            result.add(singularFromReflectionType(element));
+          }
+          return result;
+        } else {
+          return value;
+        }
+      } else {
+        return singularFromReflectionType(value);
+      }
+    }
+
+    /**
+     * Like {@link #fromReflectionType(Object)}, but if the type is a repeated
+     * type, this converts a single element.
+     */
+    private Object singularFromReflectionType(final Object value) {
+      FieldDescriptor descriptor = getDescriptor();
+      switch (descriptor.getJavaType()) {
+        case MESSAGE:
+          if (singularType.isInstance(value)) {
+            return value;
+          } else {
+            // It seems the copy of the embedded message stored inside the
+            // extended message is not of the exact type the user was
+            // expecting.  This can happen if a user defines a
+            // GeneratedExtension manually and gives it a different type.
+            // This should not happen in normal use.  But, to be nice, we'll
+            // copy the message to whatever type the caller was expecting.
+            return messageDefaultInstance.newBuilderForType()
+                           .mergeFrom((Message) value).build();
+          }
+        case ENUM:
+          return invokeOrDie(enumValueOf, null, (EnumValueDescriptor) value);
+        default:
+          return value;
+      }
+    }
+
+    /**
+     * Convert from the type used by the native accessors to the type used
+     * by reflection accessors.  E.g., for enums, the reflection accessors use
+     * EnumValueDescriptors but the native accessors use the generated enum
+     * type.
+     */
+    @SuppressWarnings("unchecked")
+    private Object toReflectionType(final Object value) {
+      FieldDescriptor descriptor = getDescriptor();
+      if (descriptor.isRepeated()) {
+        if (descriptor.getJavaType() == FieldDescriptor.JavaType.ENUM) {
+          // Must convert the whole list.
+          final List result = new ArrayList();
+          for (final Object element : (List) value) {
+            result.add(singularToReflectionType(element));
+          }
+          return result;
+        } else {
+          return value;
+        }
+      } else {
+        return singularToReflectionType(value);
+      }
+    }
+
+    /**
+     * Like {@link #toReflectionType(Object)}, but if the type is a repeated
+     * type, this converts a single element.
+     */
+    private Object singularToReflectionType(final Object value) {
+      FieldDescriptor descriptor = getDescriptor();
+      switch (descriptor.getJavaType()) {
+        case ENUM:
+          return invokeOrDie(enumGetValueDescriptor, value);
+        default:
+          return value;
+      }
+    }
+  }
+
+  // =================================================================
+
+  /** Calls Class.getMethod and throws a RuntimeException if it fails. */
+  @SuppressWarnings("unchecked")
+  private static Method getMethodOrDie(
+      final Class clazz, final String name, final Class... params) {
+    try {
+      return clazz.getMethod(name, params);
+    } catch (NoSuchMethodException e) {
+      throw new RuntimeException(
+        "Generated message class \"" + clazz.getName() +
+        "\" missing method \"" + name + "\".", e);
+    }
+  }
+
+  /** Calls invoke and throws a RuntimeException if it fails. */
+  private static Object invokeOrDie(
+      final Method method, final Object object, final Object... params) {
+    try {
+      return method.invoke(object, params);
+    } catch (IllegalAccessException e) {
+      throw new RuntimeException(
+        "Couldn't use Java reflection to implement protocol message " +
+        "reflection.", e);
+    } catch (InvocationTargetException e) {
+      final Throwable cause = e.getCause();
+      if (cause instanceof RuntimeException) {
+        throw (RuntimeException) cause;
+      } else if (cause instanceof Error) {
+        throw (Error) cause;
+      } else {
+        throw new RuntimeException(
+          "Unexpected exception thrown by generated accessor method.", cause);
+      }
+    }
+  }
+
+  /**
+   * Users should ignore this class.  This class provides the implementation
+   * with access to the fields of a message object using Java reflection.
+   */
+  public static final class FieldAccessorTable {
+
+    /**
+     * Construct a FieldAccessorTable for a particular message class.  Only
+     * one FieldAccessorTable should ever be constructed per class.
+     *
+     * @param descriptor     The type's descriptor.
+     * @param camelCaseNames The camelcase names of all fields in the message.
+     *                       These are used to derive the accessor method names.
+     * @param messageClass   The message type.
+     * @param builderClass   The builder type.
+     */
+    public FieldAccessorTable(
+        final Descriptor descriptor,
+        final String[] camelCaseNames,
+        final Class<? extends GeneratedMessage> messageClass,
+        final Class<? extends Builder> builderClass) {
+      this.descriptor = descriptor;
+      fields = new FieldAccessor[descriptor.getFields().size()];
+
+      for (int i = 0; i < fields.length; i++) {
+        final FieldDescriptor field = descriptor.getFields().get(i);
+        if (field.isRepeated()) {
+          if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+            fields[i] = new RepeatedMessageFieldAccessor(
+              field, camelCaseNames[i], messageClass, builderClass);
+          } else if (field.getJavaType() == FieldDescriptor.JavaType.ENUM) {
+            fields[i] = new RepeatedEnumFieldAccessor(
+              field, camelCaseNames[i], messageClass, builderClass);
+          } else {
+            fields[i] = new RepeatedFieldAccessor(
+              field, camelCaseNames[i], messageClass, builderClass);
+          }
+        } else {
+          if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+            fields[i] = new SingularMessageFieldAccessor(
+              field, camelCaseNames[i], messageClass, builderClass);
+          } else if (field.getJavaType() == FieldDescriptor.JavaType.ENUM) {
+            fields[i] = new SingularEnumFieldAccessor(
+              field, camelCaseNames[i], messageClass, builderClass);
+          } else {
+            fields[i] = new SingularFieldAccessor(
+              field, camelCaseNames[i], messageClass, builderClass);
+          }
+        }
+      }
+    }
+
+    private final Descriptor descriptor;
+    private final FieldAccessor[] fields;
+
+    /** Get the FieldAccessor for a particular field. */
+    private FieldAccessor getField(final FieldDescriptor field) {
+      if (field.getContainingType() != descriptor) {
+        throw new IllegalArgumentException(
+          "FieldDescriptor does not match message type.");
+      } else if (field.isExtension()) {
+        // If this type had extensions, it would subclass ExtendableMessage,
+        // which overrides the reflection interface to handle extensions.
+        throw new IllegalArgumentException(
+          "This type does not have extensions.");
+      }
+      return fields[field.getIndex()];
+    }
+
+    /**
+     * Abstract interface that provides access to a single field.  This is
+     * implemented differently depending on the field type and cardinality.
+     */
+    private interface FieldAccessor {
+      Object get(GeneratedMessage message);
+      Object get(GeneratedMessage.Builder builder);
+      void set(Builder builder, Object value);
+      Object getRepeated(GeneratedMessage message, int index);
+      Object getRepeated(GeneratedMessage.Builder builder, int index);
+      void setRepeated(Builder builder,
+                       int index, Object value);
+      void addRepeated(Builder builder, Object value);
+      boolean has(GeneratedMessage message);
+      boolean has(GeneratedMessage.Builder builder);
+      int getRepeatedCount(GeneratedMessage message);
+      int getRepeatedCount(GeneratedMessage.Builder builder);
+      void clear(Builder builder);
+      Message.Builder newBuilder();
+    }
+
+    // ---------------------------------------------------------------
+
+    private static class SingularFieldAccessor implements FieldAccessor {
+      SingularFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessage> messageClass,
+          final Class<? extends Builder> builderClass) {
+        getMethod = getMethodOrDie(messageClass, "get" + camelCaseName);
+        getMethodBuilder = getMethodOrDie(builderClass, "get" + camelCaseName);
+        type = getMethod.getReturnType();
+        setMethod = getMethodOrDie(builderClass, "set" + camelCaseName, type);
+        hasMethod =
+            getMethodOrDie(messageClass, "has" + camelCaseName);
+        hasMethodBuilder =
+            getMethodOrDie(builderClass, "has" + camelCaseName);
+        clearMethod = getMethodOrDie(builderClass, "clear" + camelCaseName);
+      }
+
+      // Note:  We use Java reflection to call public methods rather than
+      //   access private fields directly as this avoids runtime security
+      //   checks.
+      protected final Class<?> type;
+      protected final Method getMethod;
+      protected final Method getMethodBuilder;
+      protected final Method setMethod;
+      protected final Method hasMethod;
+      protected final Method hasMethodBuilder;
+      protected final Method clearMethod;
+
+      public Object get(final GeneratedMessage message) {
+        return invokeOrDie(getMethod, message);
+      }
+      public Object get(GeneratedMessage.Builder builder) {
+        return invokeOrDie(getMethodBuilder, builder);
+      }
+      public void set(final Builder builder, final Object value) {
+        invokeOrDie(setMethod, builder, value);
+      }
+      public Object getRepeated(final GeneratedMessage message,
+                                final int index) {
+        throw new UnsupportedOperationException(
+          "getRepeatedField() called on a singular field.");
+      }
+      public Object getRepeated(GeneratedMessage.Builder builder, int index) {
+        throw new UnsupportedOperationException(
+          "getRepeatedField() called on a singular field.");
+      }
+      public void setRepeated(final Builder builder,
+                              final int index, final Object value) {
+        throw new UnsupportedOperationException(
+          "setRepeatedField() called on a singular field.");
+      }
+      public void addRepeated(final Builder builder, final Object value) {
+        throw new UnsupportedOperationException(
+          "addRepeatedField() called on a singular field.");
+      }
+      public boolean has(final GeneratedMessage message) {
+        return (Boolean) invokeOrDie(hasMethod, message);
+      }
+      public boolean has(GeneratedMessage.Builder builder) {
+        return (Boolean) invokeOrDie(hasMethodBuilder, builder);
+      }
+      public int getRepeatedCount(final GeneratedMessage message) {
+        throw new UnsupportedOperationException(
+          "getRepeatedFieldSize() called on a singular field.");
+      }
+      public int getRepeatedCount(GeneratedMessage.Builder builder) {
+        throw new UnsupportedOperationException(
+          "getRepeatedFieldSize() called on a singular field.");
+      }
+      public void clear(final Builder builder) {
+        invokeOrDie(clearMethod, builder);
+      }
+      public Message.Builder newBuilder() {
+        throw new UnsupportedOperationException(
+          "newBuilderForField() called on a non-Message type.");
+      }
+    }
+
+    private static class RepeatedFieldAccessor implements FieldAccessor {
+      protected final Class type;
+      protected final Method getMethod;
+      protected final Method getMethodBuilder;
+      protected final Method getRepeatedMethod;
+      protected final Method getRepeatedMethodBuilder;
+      protected final Method setRepeatedMethod;
+      protected final Method addRepeatedMethod;
+      protected final Method getCountMethod;
+      protected final Method getCountMethodBuilder;
+      protected final Method clearMethod;
+
+      RepeatedFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessage> messageClass,
+          final Class<? extends Builder> builderClass) {
+        getMethod = getMethodOrDie(messageClass,
+                                   "get" + camelCaseName + "List");
+        getMethodBuilder = getMethodOrDie(builderClass,
+                                   "get" + camelCaseName + "List");
+
+
+        getRepeatedMethod =
+            getMethodOrDie(messageClass, "get" + camelCaseName, Integer.TYPE);
+        getRepeatedMethodBuilder =
+            getMethodOrDie(builderClass, "get" + camelCaseName, Integer.TYPE);
+        type = getRepeatedMethod.getReturnType();
+        setRepeatedMethod =
+            getMethodOrDie(builderClass, "set" + camelCaseName,
+                           Integer.TYPE, type);
+        addRepeatedMethod =
+            getMethodOrDie(builderClass, "add" + camelCaseName, type);
+        getCountMethod =
+            getMethodOrDie(messageClass, "get" + camelCaseName + "Count");
+        getCountMethodBuilder =
+            getMethodOrDie(builderClass, "get" + camelCaseName + "Count");
+
+        clearMethod = getMethodOrDie(builderClass, "clear" + camelCaseName);
+      }
+
+      public Object get(final GeneratedMessage message) {
+        return invokeOrDie(getMethod, message);
+      }
+      public Object get(GeneratedMessage.Builder builder) {
+        return invokeOrDie(getMethodBuilder, builder);
+      }
+      public void set(final Builder builder, final Object value) {
+        // Add all the elements individually.  This serves two purposes:
+        // 1) Verifies that each element has the correct type.
+        // 2) Insures that the caller cannot modify the list later on and
+        //    have the modifications be reflected in the message.
+        clear(builder);
+        for (final Object element : (List<?>) value) {
+          addRepeated(builder, element);
+        }
+      }
+      public Object getRepeated(final GeneratedMessage message,
+                                final int index) {
+        return invokeOrDie(getRepeatedMethod, message, index);
+      }
+      public Object getRepeated(GeneratedMessage.Builder builder, int index) {
+        return invokeOrDie(getRepeatedMethodBuilder, builder, index);
+      }
+      public void setRepeated(final Builder builder,
+                              final int index, final Object value) {
+        invokeOrDie(setRepeatedMethod, builder, index, value);
+      }
+      public void addRepeated(final Builder builder, final Object value) {
+        invokeOrDie(addRepeatedMethod, builder, value);
+      }
+      public boolean has(final GeneratedMessage message) {
+        throw new UnsupportedOperationException(
+          "hasField() called on a singular field.");
+      }
+      public boolean has(GeneratedMessage.Builder builder) {
+        throw new UnsupportedOperationException(
+          "hasField() called on a singular field.");
+      }
+      public int getRepeatedCount(final GeneratedMessage message) {
+        return (Integer) invokeOrDie(getCountMethod, message);
+      }
+      public int getRepeatedCount(GeneratedMessage.Builder builder) {
+        return (Integer) invokeOrDie(getCountMethodBuilder, builder);
+      }
+      public void clear(final Builder builder) {
+        invokeOrDie(clearMethod, builder);
+      }
+      public Message.Builder newBuilder() {
+        throw new UnsupportedOperationException(
+          "newBuilderForField() called on a non-Message type.");
+      }
+    }
+
+    // ---------------------------------------------------------------
+
+    private static final class SingularEnumFieldAccessor
+        extends SingularFieldAccessor {
+      SingularEnumFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessage> messageClass,
+          final Class<? extends Builder> builderClass) {
+        super(descriptor, camelCaseName, messageClass, builderClass);
+
+        valueOfMethod = getMethodOrDie(type, "valueOf",
+                                       EnumValueDescriptor.class);
+        getValueDescriptorMethod =
+          getMethodOrDie(type, "getValueDescriptor");
+      }
+
+      private Method valueOfMethod;
+      private Method getValueDescriptorMethod;
+
+      @Override
+      public Object get(final GeneratedMessage message) {
+        return invokeOrDie(getValueDescriptorMethod, super.get(message));
+      }
+
+      @Override
+      public Object get(final GeneratedMessage.Builder builder) {
+        return invokeOrDie(getValueDescriptorMethod, super.get(builder));
+      }
+
+      @Override
+      public void set(final Builder builder, final Object value) {
+        super.set(builder, invokeOrDie(valueOfMethod, null, value));
+      }
+    }
+
+    private static final class RepeatedEnumFieldAccessor
+        extends RepeatedFieldAccessor {
+      RepeatedEnumFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessage> messageClass,
+          final Class<? extends Builder> builderClass) {
+        super(descriptor, camelCaseName, messageClass, builderClass);
+
+        valueOfMethod = getMethodOrDie(type, "valueOf",
+                                       EnumValueDescriptor.class);
+        getValueDescriptorMethod =
+          getMethodOrDie(type, "getValueDescriptor");
+      }
+
+      private final Method valueOfMethod;
+      private final Method getValueDescriptorMethod;
+
+      @Override
+      @SuppressWarnings("unchecked")
+      public Object get(final GeneratedMessage message) {
+        final List newList = new ArrayList();
+        for (final Object element : (List) super.get(message)) {
+          newList.add(invokeOrDie(getValueDescriptorMethod, element));
+        }
+        return Collections.unmodifiableList(newList);
+      }
+
+      @Override
+      @SuppressWarnings("unchecked")
+      public Object get(final GeneratedMessage.Builder builder) {
+        final List newList = new ArrayList();
+        for (final Object element : (List) super.get(builder)) {
+          newList.add(invokeOrDie(getValueDescriptorMethod, element));
+        }
+        return Collections.unmodifiableList(newList);
+      }
+
+      @Override
+      public Object getRepeated(final GeneratedMessage message,
+                                final int index) {
+        return invokeOrDie(getValueDescriptorMethod,
+          super.getRepeated(message, index));
+      }
+      @Override
+      public Object getRepeated(final GeneratedMessage.Builder builder,
+                                final int index) {
+        return invokeOrDie(getValueDescriptorMethod,
+          super.getRepeated(builder, index));
+      }
+      @Override
+      public void setRepeated(final Builder builder,
+                              final int index, final Object value) {
+        super.setRepeated(builder, index, invokeOrDie(valueOfMethod, null,
+                          value));
+      }
+      @Override
+      public void addRepeated(final Builder builder, final Object value) {
+        super.addRepeated(builder, invokeOrDie(valueOfMethod, null, value));
+      }
+    }
+
+    // ---------------------------------------------------------------
+
+    private static final class SingularMessageFieldAccessor
+        extends SingularFieldAccessor {
+      SingularMessageFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessage> messageClass,
+          final Class<? extends Builder> builderClass) {
+        super(descriptor, camelCaseName, messageClass, builderClass);
+
+        newBuilderMethod = getMethodOrDie(type, "newBuilder");
+      }
+
+      private final Method newBuilderMethod;
+
+      private Object coerceType(final Object value) {
+        if (type.isInstance(value)) {
+          return value;
+        } else {
+          // The value is not the exact right message type.  However, if it
+          // is an alternative implementation of the same type -- e.g. a
+          // DynamicMessage -- we should accept it.  In this case we can make
+          // a copy of the message.
+          return ((Message.Builder) invokeOrDie(newBuilderMethod, null))
+                  .mergeFrom((Message) value).build();
+        }
+      }
+
+      @Override
+      public void set(final Builder builder, final Object value) {
+        super.set(builder, coerceType(value));
+      }
+      @Override
+      public Message.Builder newBuilder() {
+        return (Message.Builder) invokeOrDie(newBuilderMethod, null);
+      }
+    }
+
+    private static final class RepeatedMessageFieldAccessor
+        extends RepeatedFieldAccessor {
+      RepeatedMessageFieldAccessor(
+          final FieldDescriptor descriptor, final String camelCaseName,
+          final Class<? extends GeneratedMessage> messageClass,
+          final Class<? extends Builder> builderClass) {
+        super(descriptor, camelCaseName, messageClass, builderClass);
+
+        newBuilderMethod = getMethodOrDie(type, "newBuilder");
+      }
+
+      private final Method newBuilderMethod;
+
+      private Object coerceType(final Object value) {
+        if (type.isInstance(value)) {
+          return value;
+        } else {
+          // The value is not the exact right message type.  However, if it
+          // is an alternative implementation of the same type -- e.g. a
+          // DynamicMessage -- we should accept it.  In this case we can make
+          // a copy of the message.
+          return ((Message.Builder) invokeOrDie(newBuilderMethod, null))
+                  .mergeFrom((Message) value).build();
+        }
+      }
+
+      @Override
+      public void setRepeated(final Builder builder,
+                              final int index, final Object value) {
+        super.setRepeated(builder, index, coerceType(value));
+      }
+      @Override
+      public void addRepeated(final Builder builder, final Object value) {
+        super.addRepeated(builder, coerceType(value));
+      }
+      @Override
+      public Message.Builder newBuilder() {
+        return (Message.Builder) invokeOrDie(newBuilderMethod, null);
+      }
+    }
+  }
+
+  /**
+   * Replaces this object in the output stream with a serialized form.
+   * Part of Java's serialization magic.  Generated sub-classes must override
+   * this method by calling <code>return super.writeReplace();</code>
+   * @return a SerializedForm of this message
+   */
+  protected Object writeReplace() throws ObjectStreamException {
+    return new GeneratedMessageLite.SerializedForm(this);
+  }
+}