Revert https://codereview.chromium.org/1291903002 (protobuf roll).

third_party/protobuf/src/google/protobuf/compiler/java/java_message.cc

 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
-// https://developers.google.com/protocol-buffers/
+// 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
@@ skipping 16 matching lines @@
 
 // Author: kenton@google.com (Kenton Varda)
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
 #include <google/protobuf/compiler/java/java_message.h>
 
 #include <algorithm>
 #include <google/protobuf/stubs/hash.h>
 #include <map>
-#include <memory>
-#ifndef _SHARED_PTR_H
-#include <google/protobuf/stubs/shared_ptr.h>
-#endif
 #include <vector>
 
-#include <google/protobuf/compiler/java/java_context.h>
 #include <google/protobuf/compiler/java/java_doc_comment.h>
 #include <google/protobuf/compiler/java/java_enum.h>
 #include <google/protobuf/compiler/java/java_extension.h>
-#include <google/protobuf/compiler/java/java_generator_factory.h>
 #include <google/protobuf/compiler/java/java_helpers.h>
-#include <google/protobuf/compiler/java/java_message_builder.h>
-#include <google/protobuf/compiler/java/java_message_builder_lite.h>
-#include <google/protobuf/compiler/java/java_name_resolver.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/io/printer.h>
 #include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/wire_format.h>
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/stubs/substitute.h>
 
 namespace google {
 namespace protobuf {
 namespace compiler {
 namespace java {
 
 using internal::WireFormat;
 using internal::WireFormatLite;
 
 namespace {
-bool GenerateHasBits(const Descriptor* descriptor) {
-  return SupportFieldPresence(descriptor->file()) ||
-      HasRepeatedFields(descriptor);
-}
-
-string MapValueImmutableClassdName(const Descriptor* descriptor,
-                                   ClassNameResolver* name_resolver) {
-  const FieldDescriptor* value_field = descriptor->FindFieldByName("value");
-  GOOGLE_CHECK_EQ(FieldDescriptor::TYPE_MESSAGE, value_field->type());
-  return name_resolver->GetImmutableClassName(value_field->message_type());
-}
+
+void PrintFieldComment(io::Printer* printer, const FieldDescriptor* field) {
+  // Print the field's proto-syntax definition as a comment.  We don't want to
+  // print group bodies so we cut off after the first line.
+  string def = field->DebugString();
+  printer->Print("// $def$\n",
+    "def", def.substr(0, def.find_first_of('\n')));
+}
+
+struct FieldOrderingByNumber {
+  inline bool operator()(const FieldDescriptor* a,
+                         const FieldDescriptor* b) const {
+    return a->number() < b->number();
+  }
+};
+
+struct ExtensionRangeOrdering {
+  bool operator()(const Descriptor::ExtensionRange* a,
+                  const Descriptor::ExtensionRange* b) const {
+    return a->start < b->start;
+  }
+};
+
+// Sort the fields of the given Descriptor by number into a new[]'d array
+// and return it.
+const FieldDescriptor** SortFieldsByNumber(const Descriptor* descriptor) {
+  const FieldDescriptor** fields =
+    new const FieldDescriptor*[descriptor->field_count()];
+  for (int i = 0; i < descriptor->field_count(); i++) {
+    fields[i] = descriptor->field(i);
+  }
+  sort(fields, fields + descriptor->field_count(),
+       FieldOrderingByNumber());
+  return fields;
+}
+
+// Get an identifier that uniquely identifies this type within the file.
+// This is used to declare static variables related to this type at the
+// outermost file scope.
+string UniqueFileScopeIdentifier(const Descriptor* descriptor) {
+  return "static_" + StringReplace(descriptor->full_name(), ".", "_", true);
+}
+
+// Returns true if the message type has any required fields.  If it doesn't,
+// we can optimize out calls to its isInitialized() method.
+//
+// already_seen is used to avoid checking the same type multiple times
+// (and also to protect against recursion).
+static bool HasRequiredFields(
+    const Descriptor* type,
+    hash_set<const Descriptor*>* already_seen) {
+  if (already_seen->count(type) > 0) {
+    // The type is already in cache.  This means that either:
+    // a. The type has no required fields.
+    // b. We are in the midst of checking if the type has required fields,
+    //    somewhere up the stack.  In this case, we know that if the type
+    //    has any required fields, they'll be found when we return to it,
+    //    and the whole call to HasRequiredFields() will return true.
+    //    Therefore, we don't have to check if this type has required fields
+    //    here.
+    return false;
+  }
+  already_seen->insert(type);
+
+  // If the type has extensions, an extension with message type could contain
+  // required fields, so we have to be conservative and assume such an
+  // extension exists.
+  if (type->extension_range_count() > 0) return true;
+
+  for (int i = 0; i < type->field_count(); i++) {
+    const FieldDescriptor* field = type->field(i);
+    if (field->is_required()) {
+      return true;
+    }
+    if (GetJavaType(field) == JAVATYPE_MESSAGE) {
+      if (HasRequiredFields(field->message_type(), already_seen)) {
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
+static bool HasRequiredFields(const Descriptor* type) {
+  hash_set<const Descriptor*> already_seen;
+  return HasRequiredFields(type, &already_seen);
+}
+
 }  // namespace
 
 // ===================================================================
 
 MessageGenerator::MessageGenerator(const Descriptor* descriptor)
-  : descriptor_(descriptor) {}
+  : descriptor_(descriptor),
+    field_generators_(descriptor) {
+}
 
 MessageGenerator::~MessageGenerator() {}
 
-// ===================================================================
-// TODO(api): Move this class to a separate immutable_message.cc file.
-ImmutableMessageGenerator::ImmutableMessageGenerator(
-    const Descriptor* descriptor, Context* context)
-  : MessageGenerator(descriptor), context_(context),
-    name_resolver_(context->GetNameResolver()),
-    field_generators_(descriptor, context_) {
-  GOOGLE_CHECK_NE(
-      FileOptions::LITE_RUNTIME, descriptor->file()->options().optimize_for());
-}
-
-ImmutableMessageGenerator::~ImmutableMessageGenerator() {}
-
-void ImmutableMessageGenerator::GenerateStaticVariables(io::Printer* printer) {
-  // Because descriptor.proto (com.google.protobuf.DescriptorProtos) is
-  // used in the construction of descriptors, we have a tricky bootstrapping
-  // problem.  To help control static initialization order, we make sure all
-  // descriptors and other static data that depends on them are members of
-  // the outermost class in the file.  This way, they will be initialized in
-  // a deterministic order.
-
-  map<string, string> vars;
-  vars["identifier"] = UniqueFileScopeIdentifier(descriptor_);
-  vars["index"] = SimpleItoa(descriptor_->index());
-  vars["classname"] = name_resolver_->GetImmutableClassName(descriptor_);
-  if (descriptor_->containing_type() != NULL) {
-    vars["parent"] = UniqueFileScopeIdentifier(
-        descriptor_->containing_type());
-  }
-  if (MultipleJavaFiles(descriptor_->file(), /* immutable = */ true)) {
-    // We can only make these package-private since the classes that use them
-    // are in separate files.
-    vars["private"] = "";
-  } else {
-    vars["private"] = "private ";
-  }
-
-  // The descriptor for this type.
-  printer->Print(vars,
-    // TODO(teboring): final needs to be added back. The way to fix it is to
-    // generate methods that can construct the types, and then still declare the
-    // types, and then init them in clinit with the new method calls.
-    "$private$static com.google.protobuf.Descriptors.Descriptor\n"
-    "  internal_$identifier$_descriptor;\n");
-
-  // And the FieldAccessorTable.
-  GenerateFieldAccessorTable(printer);
+void MessageGenerator::GenerateStaticVariables(io::Printer* printer) {
+  if (HasDescriptorMethods(descriptor_)) {
+    // Because descriptor.proto (com.google.protobuf.DescriptorProtos) is
+    // used in the construction of descriptors, we have a tricky bootstrapping
+    // problem.  To help control static initialization order, we make sure all
+    // descriptors and other static data that depends on them are members of
+    // the outermost class in the file.  This way, they will be initialized in
+    // a deterministic order.
+
+    map<string, string> vars;
+    vars["identifier"] = UniqueFileScopeIdentifier(descriptor_);
+    vars["index"] = SimpleItoa(descriptor_->index());
+    vars["classname"] = ClassName(descriptor_);
+    if (descriptor_->containing_type() != NULL) {
+      vars["parent"] = UniqueFileScopeIdentifier(
+          descriptor_->containing_type());
+    }
+    if (descriptor_->file()->options().java_multiple_files()) {
+      // We can only make these package-private since the classes that use them
+      // are in separate files.
+      vars["private"] = "";
+    } else {
+      vars["private"] = "private ";
+    }
+
+    // The descriptor for this type.
+    printer->Print(vars,
+      "$private$static com.google.protobuf.Descriptors.Descriptor\n"
+      "  internal_$identifier$_descriptor;\n");
+
+    // And the FieldAccessorTable.
+    printer->Print(vars,
+      "$private$static\n"
+      "  com.google.protobuf.GeneratedMessage.FieldAccessorTable\n"
+      "    internal_$identifier$_fieldAccessorTable;\n");
+  }
 
   // Generate static members for all nested types.
   for (int i = 0; i < descriptor_->nested_type_count(); i++) {
     // TODO(kenton):  Reuse MessageGenerator objects?
-    ImmutableMessageGenerator(descriptor_->nested_type(i), context_)
+    MessageGenerator(descriptor_->nested_type(i))
       .GenerateStaticVariables(printer);
   }
 }
 
-int ImmutableMessageGenerator::GenerateStaticVariableInitializers(
+void MessageGenerator::GenerateStaticVariableInitializers(
     io::Printer* printer) {
-  int bytecode_estimate = 0;
-  map<string, string> vars;
-  vars["identifier"] = UniqueFileScopeIdentifier(descriptor_);
-  vars["index"] = SimpleItoa(descriptor_->index());
-  vars["classname"] = name_resolver_->GetImmutableClassName(descriptor_);
-  if (descriptor_->containing_type() != NULL) {
-    vars["parent"] = UniqueFileScopeIdentifier(
-        descriptor_->containing_type());
-  }
-
-  // The descriptor for this type.
-  if (descriptor_->containing_type() == NULL) {
+  if (HasDescriptorMethods(descriptor_)) {
+    map<string, string> vars;
+    vars["identifier"] = UniqueFileScopeIdentifier(descriptor_);
+    vars["index"] = SimpleItoa(descriptor_->index());
+    vars["classname"] = ClassName(descriptor_);
+    if (descriptor_->containing_type() != NULL) {
+      vars["parent"] = UniqueFileScopeIdentifier(
+          descriptor_->containing_type());
+    }
+
+    // The descriptor for this type.
+    if (descriptor_->containing_type() == NULL) {
+      printer->Print(vars,
+        "internal_$identifier$_descriptor =\n"
+        "  getDescriptor().getMessageTypes().get($index$);\n");
+    } else {
+      printer->Print(vars,
+        "internal_$identifier$_descriptor =\n"
+        "  internal_$parent$_descriptor.getNestedTypes().get($index$);\n");
+    }
+
+    // And the FieldAccessorTable.
     printer->Print(vars,
-      "internal_$identifier$_descriptor =\n"
-      "  getDescriptor().getMessageTypes().get($index$);\n");
-    bytecode_estimate += 30;
-  } else {
-    printer->Print(vars,
-      "internal_$identifier$_descriptor =\n"
-      "  internal_$parent$_descriptor.getNestedTypes().get($index$);\n");
-    bytecode_estimate += 30;
-  }
-
-  // And the FieldAccessorTable.
-  bytecode_estimate += GenerateFieldAccessorTableInitializer(printer);
+      "internal_$identifier$_fieldAccessorTable = new\n"
+      "  com.google.protobuf.GeneratedMessage.FieldAccessorTable(\n"
+      "    internal_$identifier$_descriptor,\n"
+      "    new java.lang.String[] { ");
+    for (int i = 0; i < descriptor_->field_count(); i++) {
+      printer->Print(
+        "\"$field_name$\", ",
+        "field_name",
+          UnderscoresToCapitalizedCamelCase(descriptor_->field(i)));
+    }
+    printer->Print(
+        "});\n");
+  }
 
   // Generate static member initializers for all nested types.
   for (int i = 0; i < descriptor_->nested_type_count(); i++) {
     // TODO(kenton):  Reuse MessageGenerator objects?
-    bytecode_estimate +=
-        ImmutableMessageGenerator(descriptor_->nested_type(i), context_)
-            .GenerateStaticVariableInitializers(printer);
-  }
-  return bytecode_estimate;
-}
-
-void ImmutableMessageGenerator::
-GenerateFieldAccessorTable(io::Printer* printer) {
-  map<string, string> vars;
-  vars["identifier"] = UniqueFileScopeIdentifier(descriptor_);
-  if (MultipleJavaFiles(descriptor_->file(), /* immutable = */ true)) {
-    // We can only make these package-private since the classes that use them
-    // are in separate files.
-    vars["private"] = "";
+    MessageGenerator(descriptor_->nested_type(i))
+      .GenerateStaticVariableInitializers(printer);
+  }
+}
+
+// ===================================================================
+
+void MessageGenerator::GenerateInterface(io::Printer* printer) {
+  if (descriptor_->extension_range_count() > 0) {
+    if (HasDescriptorMethods(descriptor_)) {
+      printer->Print(
+        "public interface $classname$OrBuilder extends\n"
+        "    com.google.protobuf.GeneratedMessage.\n"
+        "        ExtendableMessageOrBuilder<$classname$> {\n",
+        "classname", descriptor_->name());
+    } else {
+      printer->Print(
+        "public interface $classname$OrBuilder extends \n"
+        "     com.google.protobuf.GeneratedMessageLite.\n"
+        "          ExtendableMessageOrBuilder<$classname$> {\n",
+        "classname", descriptor_->name());
+    }
   } else {
-    vars["private"] = "private ";
-  }
-  printer->Print(vars,
-    "$private$static\n"
-    "  com.google.protobuf.GeneratedMessage.FieldAccessorTable\n"
-    "    internal_$identifier$_fieldAccessorTable;\n");
-}
-
-int ImmutableMessageGenerator::
-GenerateFieldAccessorTableInitializer(io::Printer* printer) {
-  int bytecode_estimate = 10;
-  printer->Print(
-    "internal_$identifier$_fieldAccessorTable = new\n"
-    "  com.google.protobuf.GeneratedMessage.FieldAccessorTable(\n"
-    "    internal_$identifier$_descriptor,\n"
-    "    new java.lang.String[] { ",
-    "identifier",
-    UniqueFileScopeIdentifier(descriptor_));
-  for (int i = 0; i < descriptor_->field_count(); i++) {
-    const FieldDescriptor* field = descriptor_->field(i);
-    const FieldGeneratorInfo* info = context_->GetFieldGeneratorInfo(field);
-    bytecode_estimate += 6;
-    printer->Print(
-      "\"$field_name$\", ",
-      "field_name", info->capitalized_name);
-  }
-  for (int i = 0; i < descriptor_->oneof_decl_count(); i++) {
-    const OneofDescriptor* oneof = descriptor_->oneof_decl(i);
-    const OneofGeneratorInfo* info = context_->GetOneofGeneratorInfo(oneof);
-    bytecode_estimate += 6;
-    printer->Print(
-      "\"$oneof_name$\", ",
-      "oneof_name", info->capitalized_name);
-  }
-  printer->Print("});\n");
-  return bytecode_estimate;
-}
-
-// ===================================================================
-
-void ImmutableMessageGenerator::GenerateInterface(io::Printer* printer) {
-  if (descriptor_->extension_range_count() > 0) {
-    printer->Print(
-      "public interface $classname$OrBuilder extends\n"
-      "    $extra_interfaces$\n"
-      "    com.google.protobuf.GeneratedMessage.\n"
-      "        ExtendableMessageOrBuilder<$classname$> {\n",
-      "extra_interfaces", ExtraMessageOrBuilderInterfaces(descriptor_),
-      "classname", descriptor_->name());
-  } else {
-    printer->Print(
-      "public interface $classname$OrBuilder extends\n"
-      "    $extra_interfaces$\n"
-      "    com.google.protobuf.MessageOrBuilder {\n",
-      "extra_interfaces", ExtraMessageOrBuilderInterfaces(descriptor_),
-      "classname", descriptor_->name());
+    if (HasDescriptorMethods(descriptor_)) {
+      printer->Print(
+        "public interface $classname$OrBuilder\n"
+        "    extends com.google.protobuf.MessageOrBuilder {\n",
+        "classname", descriptor_->name());
+    } else {
+      printer->Print(
+        "public interface $classname$OrBuilder\n"
+        "    extends com.google.protobuf.MessageLiteOrBuilder {\n",
+        "classname", descriptor_->name());
+    }
   }
 
   printer->Indent();
     for (int i = 0; i < descriptor_->field_count(); i++) {
       printer->Print("\n");
+      PrintFieldComment(printer, descriptor_->field(i));
       field_generators_.get(descriptor_->field(i))
                        .GenerateInterfaceMembers(printer);
     }
   printer->Outdent();
 
   printer->Print("}\n");
 }
 
 // ===================================================================
 
-void ImmutableMessageGenerator::Generate(io::Printer* printer) {
+void MessageGenerator::Generate(io::Printer* printer) {
   bool is_own_file =
     descriptor_->containing_type() == NULL &&
-    MultipleJavaFiles(descriptor_->file(), /* immutable = */ true);
-
-  map<string, string> variables;
-  variables["static"] = is_own_file ? " " : " static ";
-  variables["classname"] = descriptor_->name();
-  variables["extra_interfaces"] = ExtraMessageInterfaces(descriptor_);
+    descriptor_->file()->options().java_multiple_files();
 
   WriteMessageDocComment(printer, descriptor_);
 
   // The builder_type stores the super type name of the nested Builder class.
   string builder_type;
   if (descriptor_->extension_range_count() > 0) {
-    printer->Print(variables,
-      "public $static$final class $classname$ extends\n"
-      "    com.google.protobuf.GeneratedMessage.ExtendableMessage<\n"
-      "      $classname$> implements\n"
-      "    $extra_interfaces$\n"
-      "    $classname$OrBuilder {\n");
-    builder_type = strings::Substitute(
-             "com.google.protobuf.GeneratedMessage.ExtendableBuilder<$0, ?>",
-             name_resolver_->GetImmutableClassName(descriptor_));
+    if (HasDescriptorMethods(descriptor_)) {
+      printer->Print(
+        "public $static$ final class $classname$ extends\n"
+        "    com.google.protobuf.GeneratedMessage.ExtendableMessage<\n"
+        "      $classname$> implements $classname$OrBuilder {\n",
+        "static", is_own_file ? "" : "static",
+        "classname", descriptor_->name());
+      builder_type = strings::Substitute(
+          "com.google.protobuf.GeneratedMessage.ExtendableBuilder<$0, ?>",
+          ClassName(descriptor_));
+    } else {
+      printer->Print(
+        "public $static$ final class $classname$ extends\n"
+        "    com.google.protobuf.GeneratedMessageLite.ExtendableMessage<\n"
+        "      $classname$> implements $classname$OrBuilder {\n",
+        "static", is_own_file ? "" : "static",
+        "classname", descriptor_->name());
+      builder_type = strings::Substitute(
+          "com.google.protobuf.GeneratedMessageLite.ExtendableBuilder<$0, ?>",
+          ClassName(descriptor_));
+    }
   } else {
-    printer->Print(variables,
-      "public $static$final class $classname$ extends\n"
-      "    com.google.protobuf.GeneratedMessage implements\n"
-      "    $extra_interfaces$\n"
-      "    $classname$OrBuilder {\n");
-
-    builder_type = "com.google.protobuf.GeneratedMessage.Builder";
+    if (HasDescriptorMethods(descriptor_)) {
+      printer->Print(
+        "public $static$ final class $classname$ extends\n"
+        "    com.google.protobuf.GeneratedMessage\n"
+        "    implements $classname$OrBuilder {\n",
+        "static", is_own_file ? "" : "static",
+        "classname", descriptor_->name());
+      builder_type = "com.google.protobuf.GeneratedMessage.Builder<?>";
+    } else {
+      printer->Print(
+        "public $static$ final class $classname$ extends\n"
+        "    com.google.protobuf.GeneratedMessageLite\n"
+        "    implements $classname$OrBuilder {\n",
+        "static", is_own_file ? "" : "static",
+        "classname", descriptor_->name());
+      builder_type = "com.google.protobuf.GeneratedMessageLite.Builder";
+    }
   }
   printer->Indent();
   // Using builder_type, instead of Builder, prevents the Builder class from
   // being loaded into PermGen space when the default instance is created.
   // This optimizes the PermGen space usage for clients that do not modify
   // messages.
   printer->Print(
     "// Use $classname$.newBuilder() to construct.\n"
     "private $classname$($buildertype$ builder) {\n"
     "  super(builder);\n"
+    "$set_unknown_fields$\n"
     "}\n",
     "classname", descriptor_->name(),
-    "buildertype", builder_type);
+    "buildertype", builder_type,
+    "set_unknown_fields", HasUnknownFields(descriptor_)
+        ? "  this.unknownFields = builder.getUnknownFields();" : "");
   printer->Print(
-    "private $classname$() {\n",
-    "classname", descriptor_->name());
-  printer->Indent();
-  GenerateInitializers(printer);
-  printer->Outdent();
-  printer->Print(
+    // Used when constructing the default instance, which cannot be initialized
+    // immediately because it may cyclically refer to other default instances.
+    "private $classname$(boolean noInit) {$set_default_unknown_fields$}\n"
+    "\n"
+    "private static final $classname$ defaultInstance;\n"
+    "public static $classname$ getDefaultInstance() {\n"
+    "  return defaultInstance;\n"
     "}\n"
-    "\n");
+    "\n"
+    "public $classname$ getDefaultInstanceForType() {\n"
+    "  return defaultInstance;\n"
+    "}\n"
+    "\n",
+    "classname", descriptor_->name(),
+    "set_default_unknown_fields", HasUnknownFields(descriptor_)
+        ? " this.unknownFields ="
+          " com.google.protobuf.UnknownFieldSet.getDefaultInstance(); " : "");
 
-  printer->Print(
-    "@java.lang.Override\n"
-    "public final com.google.protobuf.UnknownFieldSet\n"
-    "getUnknownFields() {\n");
-  if (PreserveUnknownFields(descriptor_)) {
+  if (HasUnknownFields(descriptor_)) {
     printer->Print(
-      "  return this.unknownFields;\n");
-  } else {
-    printer->Print(
-      "  return com.google.protobuf.UnknownFieldSet.getDefaultInstance();\n");
+        "private final com.google.protobuf.UnknownFieldSet unknownFields;\n"
+        ""
+        "@java.lang.Override\n"
+        "public final com.google.protobuf.UnknownFieldSet\n"
+        "    getUnknownFields() {\n"
+        "  return this.unknownFields;\n"
+        "}\n");
   }
-  printer->Print(
-    "}\n");
 
   if (HasGeneratedMethods(descriptor_)) {
     GenerateParsingConstructor(printer);
   }
 
   GenerateDescriptorMethods(printer);
+  GenerateParser(printer);
 
   // Nested types
   for (int i = 0; i < descriptor_->enum_type_count(); i++) {
-    EnumGenerator(descriptor_->enum_type(i), true, context_)
-        .Generate(printer);
+    EnumGenerator(descriptor_->enum_type(i)).Generate(printer);
   }
 
   for (int i = 0; i < descriptor_->nested_type_count(); i++) {
-    // Don't generate Java classes for map entry messages.
-    if (IsMapEntry(descriptor_->nested_type(i))) continue;
-    ImmutableMessageGenerator messageGenerator(
-        descriptor_->nested_type(i), context_);
+    MessageGenerator messageGenerator(descriptor_->nested_type(i));
     messageGenerator.GenerateInterface(printer);
     messageGenerator.Generate(printer);
   }
 
-  if (GenerateHasBits(descriptor_)) {
-    // Integers for bit fields.
-    int totalBits = 0;
-    for (int i = 0; i < descriptor_->field_count(); i++) {
-      totalBits += field_generators_.get(descriptor_->field(i))
-          .GetNumBitsForMessage();
-    }
-    int totalInts = (totalBits + 31) / 32;
-    for (int i = 0; i < totalInts; i++) {
-      printer->Print("private int $bit_field_name$;\n",
-        "bit_field_name", GetBitFieldName(i));
-    }
+  // Integers for bit fields.
+  int totalBits = 0;
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    totalBits += field_generators_.get(descriptor_->field(i))
+        .GetNumBitsForMessage();
   }
-
-  // oneof
-  map<string, string> vars;
-  for (int i = 0; i < descriptor_->oneof_decl_count(); i++) {
-    vars["oneof_name"] = context_->GetOneofGeneratorInfo(
-        descriptor_->oneof_decl(i))->name;
-    vars["oneof_capitalized_name"] = context_->GetOneofGeneratorInfo(
-        descriptor_->oneof_decl(i))->capitalized_name;
-    vars["oneof_index"] = SimpleItoa(descriptor_->oneof_decl(i)->index());
-    // oneofCase_ and oneof_
-    printer->Print(vars,
-      "private int $oneof_name$Case_ = 0;\n"
-      "private java.lang.Object $oneof_name$_;\n");
-    // OneofCase enum
-    printer->Print(vars,
-      "public enum $oneof_capitalized_name$Case\n"
-      "    implements com.google.protobuf.Internal.EnumLite {\n");
-    printer->Indent();
-    for (int j = 0; j < descriptor_->oneof_decl(i)->field_count(); j++) {
-      const FieldDescriptor* field = descriptor_->oneof_decl(i)->field(j);
-      printer->Print(
-        "$field_name$($field_number$),\n",
-        "field_name",
-        ToUpper(field->name()),
-        "field_number",
-        SimpleItoa(field->number()));
-    }
-    printer->Print(
-      "$cap_oneof_name$_NOT_SET(0);\n",
-      "cap_oneof_name",
-      ToUpper(vars["oneof_name"]));
-    printer->Print(vars,
-      "private int value = 0;\n"
-      "private $oneof_capitalized_name$Case(int value) {\n"
-      "  this.value = value;\n"
-      "}\n");
-    printer->Print(vars,
-      "public static $oneof_capitalized_name$Case valueOf(int value) {\n"
-      "  switch (value) {\n");
-    for (int j = 0; j < descriptor_->oneof_decl(i)->field_count(); j++) {
-      const FieldDescriptor* field = descriptor_->oneof_decl(i)->field(j);
-      printer->Print(
-        "    case $field_number$: return $field_name$;\n",
-        "field_number",
-        SimpleItoa(field->number()),
-        "field_name",
-        ToUpper(field->name()));
-    }
-    printer->Print(
-      "    case 0: return $cap_oneof_name$_NOT_SET;\n"
-      "    default: throw new java.lang.IllegalArgumentException(\n"
-      "      \"Value is undefined for this oneof enum.\");\n"
-      "  }\n"
-      "}\n"
-      "public int getNumber() {\n"
-      "  return this.value;\n"
-      "}\n",
-      "cap_oneof_name", ToUpper(vars["oneof_name"]));
-    printer->Outdent();
-    printer->Print("};\n\n");
-    // oneofCase()
-    printer->Print(vars,
-      "public $oneof_capitalized_name$Case\n"
-      "get$oneof_capitalized_name$Case() {\n"
-      "  return $oneof_capitalized_name$Case.valueOf(\n"
-      "      $oneof_name$Case_);\n"
-      "}\n"
-      "\n");
+  int totalInts = (totalBits + 31) / 32;
+  for (int i = 0; i < totalInts; i++) {
+    printer->Print("private int $bit_field_name$;\n",
+      "bit_field_name", GetBitFieldName(i));
   }
 
   // Fields
   for (int i = 0; i < descriptor_->field_count(); i++) {
+    PrintFieldComment(printer, descriptor_->field(i));
     printer->Print("public static final int $constant_name$ = $number$;\n",
       "constant_name", FieldConstantName(descriptor_->field(i)),
       "number", SimpleItoa(descriptor_->field(i)->number()));
     field_generators_.get(descriptor_->field(i)).GenerateMembers(printer);
     printer->Print("\n");
   }
 
+  // Called by the constructor, except in the case of the default instance,
+  // in which case this is called by static init code later on.
+  printer->Print("private void initFields() {\n");
+  printer->Indent();
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    field_generators_.get(descriptor_->field(i))
+                     .GenerateInitializationCode(printer);
+  }
+  printer->Outdent();
+  printer->Print("}\n");
+
   if (HasGeneratedMethods(descriptor_)) {
-    GenerateIsInitialized(printer);
+    GenerateIsInitialized(printer, MEMOIZE);
     GenerateMessageSerializationMethods(printer);
   }
 
   if (HasEqualsAndHashCode(descriptor_)) {
     GenerateEqualsAndHashCode(printer);
   }
 
-
   GenerateParseFromMethods(printer);
   GenerateBuilder(printer);
 
-  printer->Print(
-    "\n"
-    "// @@protoc_insertion_point(class_scope:$full_name$)\n",
-    "full_name", descriptor_->full_name());
-
-
   // Carefully initialize the default instance in such a way that it doesn't
   // conflict with other initialization.
   printer->Print(
-    "private static final $classname$ DEFAULT_INSTANCE;\n",
-    "classname", name_resolver_->GetImmutableClassName(descriptor_));
-  printer->Print(
+    "\n"
     "static {\n"
-    "  DEFAULT_INSTANCE = new $classname$();\n"
+    "  defaultInstance = new $classname$(true);\n"
+    "  defaultInstance.initFields();\n"
     "}\n"
-    "\n",
-    "classname", name_resolver_->GetImmutableClassName(descriptor_));
+    "\n"
+    "// @@protoc_insertion_point(class_scope:$full_name$)\n",
+    "classname", descriptor_->name(),
+    "full_name", descriptor_->full_name());
 
-  printer->Print(
-      "public static $classname$ getDefaultInstance() {\n"
-      "  return DEFAULT_INSTANCE;\n"
-      "}\n"
-      "\n",
-      "classname", name_resolver_->GetImmutableClassName(descriptor_));
-
-  GenerateParser(printer);
-
-  printer->Print(
-    "public $classname$ getDefaultInstanceForType() {\n"
-    "  return DEFAULT_INSTANCE;\n"
-    "}\n"
-    "\n",
-    "classname", name_resolver_->GetImmutableClassName(descriptor_));
-
-  // Extensions must be declared after the DEFAULT_INSTANCE is initialized
-  // because the DEFAULT_INSTANCE is used by the extension to lazily retrieve
+  // Extensions must be declared after the defaultInstance is initialized
+  // because the defaultInstance is used by the extension to lazily retrieve
   // the outer class's FileDescriptor.
   for (int i = 0; i < descriptor_->extension_count(); i++) {
-    ImmutableExtensionGenerator(descriptor_->extension(i), context_)
-        .Generate(printer);
+    ExtensionGenerator(descriptor_->extension(i)).Generate(printer);
   }
 
   printer->Outdent();
   printer->Print("}\n\n");
 }
 
 
 // ===================================================================
 
-void ImmutableMessageGenerator::
+void MessageGenerator::
 GenerateMessageSerializationMethods(io::Printer* printer) {
-  google::protobuf::scoped_array<const FieldDescriptor * > sorted_fields(
-      SortFieldsByNumber(descriptor_));
+  scoped_array<const FieldDescriptor*> sorted_fields(
+    SortFieldsByNumber(descriptor_));
 
   vector<const Descriptor::ExtensionRange*> sorted_extensions;
   for (int i = 0; i < descriptor_->extension_range_count(); ++i) {
     sorted_extensions.push_back(descriptor_->extension_range(i));
   }
-  std::sort(sorted_extensions.begin(), sorted_extensions.end(),
-            ExtensionRangeOrdering());
+  sort(sorted_extensions.begin(), sorted_extensions.end(),
+       ExtensionRangeOrdering());
 
   printer->Print(
     "public void writeTo(com.google.protobuf.CodedOutputStream output)\n"
     "                    throws java.io.IOException {\n");
   printer->Indent();
-  if (HasPackedFields(descriptor_)) {
-    // writeTo(CodedOutputStream output) might be invoked without
-    // getSerializedSize() ever being called, but we need the memoized
-    // sizes in case this message has packed fields. Rather than emit checks for
-    // each packed field, just call getSerializedSize() up front.
-    // In most cases, getSerializedSize() will have already been called anyway
-    // by one of the wrapper writeTo() methods, making this call cheap.
-    printer->Print(
-      "getSerializedSize();\n");
-  }
+  // writeTo(CodedOutputStream output) might be invoked without
+  // getSerializedSize() ever being called, but we need the memoized
+  // sizes in case this message has packed fields. Rather than emit checks for
+  // each packed field, just call getSerializedSize() up front for all messages.
+  // In most cases, getSerializedSize() will have already been called anyway by
+  // one of the wrapper writeTo() methods, making this call cheap.
+  printer->Print(
+    "getSerializedSize();\n");
 
   if (descriptor_->extension_range_count() > 0) {
     if (descriptor_->options().message_set_wire_format()) {
       printer->Print(
-        "com.google.protobuf.GeneratedMessage\n"
-        "  .ExtendableMessage<$classname$>.ExtensionWriter\n"
-        "    extensionWriter = newMessageSetExtensionWriter();\n",
-        "classname", name_resolver_->GetImmutableClassName(descriptor_));
+        "com.google.protobuf.GeneratedMessage$lite$\n"
+        "  .ExtendableMessage<$classname$>.ExtensionWriter extensionWriter =\n"
+        "    newMessageSetExtensionWriter();\n",
+        "lite", HasDescriptorMethods(descriptor_) ? "" : "Lite",
+        "classname", ClassName(descriptor_));
     } else {
       printer->Print(
-        "com.google.protobuf.GeneratedMessage\n"
-        "  .ExtendableMessage<$classname$>.ExtensionWriter\n"
-        "    extensionWriter = newExtensionWriter();\n",
-        "classname", name_resolver_->GetImmutableClassName(descriptor_));
+        "com.google.protobuf.GeneratedMessage$lite$\n"
+        "  .ExtendableMessage<$classname$>.ExtensionWriter extensionWriter =\n"
+        "    newExtensionWriter();\n",
+        "lite", HasDescriptorMethods(descriptor_) ? "" : "Lite",
+        "classname", ClassName(descriptor_));
     }
   }
 
   // Merge the fields and the extension ranges, both sorted by field number.
   for (int i = 0, j = 0;
        i < descriptor_->field_count() || j < sorted_extensions.size();
        ) {
     if (i == descriptor_->field_count()) {
       GenerateSerializeOneExtensionRange(printer, sorted_extensions[j++]);
     } else if (j == sorted_extensions.size()) {
       GenerateSerializeOneField(printer, sorted_fields[i++]);
     } else if (sorted_fields[i]->number() < sorted_extensions[j]->start) {
       GenerateSerializeOneField(printer, sorted_fields[i++]);
     } else {
       GenerateSerializeOneExtensionRange(printer, sorted_extensions[j++]);
     }
   }
 
-  if (PreserveUnknownFields(descriptor_)) {
+  if (HasUnknownFields(descriptor_)) {
     if (descriptor_->options().message_set_wire_format()) {
       printer->Print(
-        "unknownFields.writeAsMessageSetTo(output);\n");
+        "getUnknownFields().writeAsMessageSetTo(output);\n");
     } else {
       printer->Print(
-        "unknownFields.writeTo(output);\n");
+        "getUnknownFields().writeTo(output);\n");
     }
   }
 
   printer->Outdent();
   printer->Print(
     "}\n"
     "\n"
     "private int memoizedSerializedSize = -1;\n"
     "public int getSerializedSize() {\n"
     "  int size = memoizedSerializedSize;\n"
     "  if (size != -1) return size;\n"
     "\n"
     "  size = 0;\n");
   printer->Indent();
 
   for (int i = 0; i < descriptor_->field_count(); i++) {
     field_generators_.get(sorted_fields[i]).GenerateSerializedSizeCode(printer);
   }
 
   if (descriptor_->extension_range_count() > 0) {
     if (descriptor_->options().message_set_wire_format()) {
       printer->Print(
         "size += extensionsSerializedSizeAsMessageSet();\n");
     } else {
       printer->Print(
         "size += extensionsSerializedSize();\n");
     }
   }
 
-  if (PreserveUnknownFields(descriptor_)) {
+  if (HasUnknownFields(descriptor_)) {
     if (descriptor_->options().message_set_wire_format()) {
       printer->Print(
-        "size += unknownFields.getSerializedSizeAsMessageSet();\n");
+        "size += getUnknownFields().getSerializedSizeAsMessageSet();\n");
     } else {
       printer->Print(
-        "size += unknownFields.getSerializedSize();\n");
+        "size += getUnknownFields().getSerializedSize();\n");
     }
   }
 
   printer->Outdent();
   printer->Print(
     "  memoizedSerializedSize = size;\n"
     "  return size;\n"
     "}\n"
     "\n");
 
   printer->Print(
-    "private static final long serialVersionUID = 0L;\n");
+    "private static final long serialVersionUID = 0L;\n"
+    "@java.lang.Override\n"
+    "protected java.lang.Object writeReplace()\n"
+    "    throws java.io.ObjectStreamException {\n"
+    "  return super.writeReplace();\n"
+    "}\n"
+    "\n");
 }
 
-void ImmutableMessageGenerator::
+void MessageGenerator::
 GenerateParseFromMethods(io::Printer* printer) {
   // Note:  These are separate from GenerateMessageSerializationMethods()
   //   because they need to be generated even for messages that are optimized
   //   for code size.
   printer->Print(
     "public static $classname$ parseFrom(\n"
     "    com.google.protobuf.ByteString data)\n"
     "    throws com.google.protobuf.InvalidProtocolBufferException {\n"
     "  return PARSER.parseFrom(data);\n"
     "}\n"
@@ skipping 38 matching lines @@
     "    throws java.io.IOException {\n"
     "  return PARSER.parseFrom(input);\n"
     "}\n"
     "public static $classname$ parseFrom(\n"
     "    com.google.protobuf.CodedInputStream input,\n"
     "    com.google.protobuf.ExtensionRegistryLite extensionRegistry)\n"
     "    throws java.io.IOException {\n"
     "  return PARSER.parseFrom(input, extensionRegistry);\n"
     "}\n"
     "\n",
-    "classname", name_resolver_->GetImmutableClassName(descriptor_));
+    "classname", ClassName(descriptor_));
 }
 
-void ImmutableMessageGenerator::GenerateSerializeOneField(
+void MessageGenerator::GenerateSerializeOneField(
     io::Printer* printer, const FieldDescriptor* field) {
   field_generators_.get(field).GenerateSerializationCode(printer);
 }
 
-void ImmutableMessageGenerator::GenerateSerializeOneExtensionRange(
+void MessageGenerator::GenerateSerializeOneExtensionRange(
     io::Printer* printer, const Descriptor::ExtensionRange* range) {
   printer->Print(
     "extensionWriter.writeUntil($end$, output);\n",
     "end", SimpleItoa(range->end));
 }
 
 // ===================================================================
 
-void ImmutableMessageGenerator::GenerateBuilder(io::Printer* printer) {
-  // LITE_RUNTIME implements this at the GeneratedMessageLite level.
-  printer->Print(
-    "public Builder newBuilderForType() { return newBuilder(); }\n");
-
-  printer->Print(
-    "public static Builder newBuilder() {\n"
-    "  return DEFAULT_INSTANCE.toBuilder();\n"
-    "}\n"
+void MessageGenerator::GenerateBuilder(io::Printer* printer) {
+  printer->Print(
+    "public static Builder newBuilder() { return Builder.create(); }\n"
+    "public Builder newBuilderForType() { return newBuilder(); }\n"
     "public static Builder newBuilder($classname$ prototype) {\n"
-    "  return DEFAULT_INSTANCE.toBuilder().mergeFrom(prototype);\n"
-    "}\n"
-    "public Builder toBuilder() {\n"
-    "  return this == DEFAULT_INSTANCE\n"
-    "      ? new Builder() : new Builder().mergeFrom(this);\n"
-    "}\n"
+    "  return newBuilder().mergeFrom(prototype);\n"
+    "}\n"
+    "public Builder toBuilder() { return newBuilder(this); }\n"
     "\n",
-    "classname", name_resolver_->GetImmutableClassName(descriptor_));
-
-  printer->Print(
-    "@java.lang.Override\n"
-    "protected Builder newBuilderForType(\n"
-    "    com.google.protobuf.GeneratedMessage.BuilderParent parent) {\n"
-    "  Builder builder = new Builder(parent);\n"
-    "  return builder;\n"
-    "}\n");
-
-  MessageBuilderGenerator builderGenerator(descriptor_, context_);
-  builderGenerator.Generate(printer);
+    "classname", ClassName(descriptor_));
+
+  if (HasNestedBuilders(descriptor_)) {
+     printer->Print(
+      "@java.lang.Override\n"
+      "protected Builder newBuilderForType(\n"
+      "    com.google.protobuf.GeneratedMessage.BuilderParent parent) {\n"
+      "  Builder builder = new Builder(parent);\n"
+      "  return builder;\n"
+      "}\n");
+  }
+
+  WriteMessageDocComment(printer, descriptor_);
+
+  if (descriptor_->extension_range_count() > 0) {
+    if (HasDescriptorMethods(descriptor_)) {
+      printer->Print(
+        "public static final class Builder extends\n"
+        "    com.google.protobuf.GeneratedMessage.ExtendableBuilder<\n"
+        "      $classname$, Builder> implements $classname$OrBuilder {\n",
+        "classname", ClassName(descriptor_));
+    } else {
+      printer->Print(
+        "public static final class Builder extends\n"
+        "    com.google.protobuf.GeneratedMessageLite.ExtendableBuilder<\n"
+        "      $classname$, Builder> implements $classname$OrBuilder {\n",
+        "classname", ClassName(descriptor_));
+    }
+  } else {
+    if (HasDescriptorMethods(descriptor_)) {
+      printer->Print(
+        "public static final class Builder extends\n"
+        "    com.google.protobuf.GeneratedMessage.Builder<Builder>\n"
+         "   implements $classname$OrBuilder {\n",
+        "classname", ClassName(descriptor_));
+    } else {
+      printer->Print(
+        "public static final class Builder extends\n"
+        "    com.google.protobuf.GeneratedMessageLite.Builder<\n"
+        "      $classname$, Builder>\n"
+        "    implements $classname$OrBuilder {\n",
+        "classname", ClassName(descriptor_));
+    }
+  }
+  printer->Indent();
+
+  GenerateDescriptorMethods(printer);
+  GenerateCommonBuilderMethods(printer);
+
+  if (HasGeneratedMethods(descriptor_)) {
+    GenerateIsInitialized(printer, DONT_MEMOIZE);
+    GenerateBuilderParsingMethods(printer);
+  }
+
+  // Integers for bit fields.
+  int totalBits = 0;
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    totalBits += field_generators_.get(descriptor_->field(i))
+        .GetNumBitsForBuilder();
+  }
+  int totalInts = (totalBits + 31) / 32;
+  for (int i = 0; i < totalInts; i++) {
+    printer->Print("private int $bit_field_name$;\n",
+      "bit_field_name", GetBitFieldName(i));
+  }
+
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    printer->Print("\n");
+    PrintFieldComment(printer, descriptor_->field(i));
+    field_generators_.get(descriptor_->field(i))
+                     .GenerateBuilderMembers(printer);
+  }
+
+  printer->Print(
+    "\n"
+    "// @@protoc_insertion_point(builder_scope:$full_name$)\n",
+    "full_name", descriptor_->full_name());
+
+  printer->Outdent();
+  printer->Print("}\n");
 }
 
-void ImmutableMessageGenerator::
-GenerateDescriptorMethods(io::Printer* printer) {
-  if (!descriptor_->options().no_standard_descriptor_accessor()) {
-    printer->Print(
-      "public static final com.google.protobuf.Descriptors.Descriptor\n"
-      "    getDescriptor() {\n"
+void MessageGenerator::GenerateDescriptorMethods(io::Printer* printer) {
+  if (HasDescriptorMethods(descriptor_)) {
+    if (!descriptor_->options().no_standard_descriptor_accessor()) {
+      printer->Print(
+        "public static final com.google.protobuf.Descriptors.Descriptor\n"
+        "    getDescriptor() {\n"
+        "  return $fileclass$.internal_$identifier$_descriptor;\n"
+        "}\n"
+        "\n",
+        "fileclass", ClassName(descriptor_->file()),
+        "identifier", UniqueFileScopeIdentifier(descriptor_));
+    }
+    printer->Print(
+      "protected com.google.protobuf.GeneratedMessage.FieldAccessorTable\n"
+      "    internalGetFieldAccessorTable() {\n"
+      "  return $fileclass$.internal_$identifier$_fieldAccessorTable\n"
+      "      .ensureFieldAccessorsInitialized(\n"
+      "          $classname$.class, $classname$.Builder.class);\n"
+      "}\n"
+      "\n",
+      "classname", ClassName(descriptor_),
+      "fileclass", ClassName(descriptor_->file()),
+      "identifier", UniqueFileScopeIdentifier(descriptor_));
+  }
+}
+
+// ===================================================================
+
+void MessageGenerator::GenerateCommonBuilderMethods(io::Printer* printer) {
+  printer->Print(
+    "// Construct using $classname$.newBuilder()\n"
+    "private Builder() {\n"
+    "  maybeForceBuilderInitialization();\n"
+    "}\n"
+    "\n",
+    "classname", ClassName(descriptor_));
+
+  if (HasDescriptorMethods(descriptor_)) {
+    printer->Print(
+      "private Builder(\n"
+      "    com.google.protobuf.GeneratedMessage.BuilderParent parent) {\n"
+      "  super(parent);\n"
+      "  maybeForceBuilderInitialization();\n"
+      "}\n",
+      "classname", ClassName(descriptor_));
+  }
+
+
+  if (HasNestedBuilders(descriptor_)) {
+    printer->Print(
+      "private void maybeForceBuilderInitialization() {\n"
+      "  if (com.google.protobuf.GeneratedMessage.alwaysUseFieldBuilders) {\n");
+
+    printer->Indent();
+    printer->Indent();
+    for (int i = 0; i < descriptor_->field_count(); i++) {
+      field_generators_.get(descriptor_->field(i))
+          .GenerateFieldBuilderInitializationCode(printer);
+    }
+    printer->Outdent();
+    printer->Outdent();
+
+    printer->Print(
+      "  }\n"
+      "}\n");
+  } else {
+    printer->Print(
+      "private void maybeForceBuilderInitialization() {\n"
+      "}\n");
+  }
+
+  printer->Print(
+    "private static Builder create() {\n"
+    "  return new Builder();\n"
+    "}\n"
+    "\n"
+    "public Builder clear() {\n"
+    "  super.clear();\n",
+    "classname", ClassName(descriptor_));
+
+  printer->Indent();
+
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    field_generators_.get(descriptor_->field(i))
+        .GenerateBuilderClearCode(printer);
+  }
+
+  printer->Outdent();
+
+  printer->Print(
+    "  return this;\n"
+    "}\n"
+    "\n"
+    "public Builder clone() {\n"
+    "  return create().mergeFrom(buildPartial());\n"
+    "}\n"
+    "\n",
+    "classname", ClassName(descriptor_));
+  if (HasDescriptorMethods(descriptor_)) {
+    printer->Print(
+      "public com.google.protobuf.Descriptors.Descriptor\n"
+      "    getDescriptorForType() {\n"
       "  return $fileclass$.internal_$identifier$_descriptor;\n"
       "}\n"
       "\n",
-      "fileclass", name_resolver_->GetImmutableClassName(descriptor_->file()),
+      "fileclass", ClassName(descriptor_->file()),
       "identifier", UniqueFileScopeIdentifier(descriptor_));
   }
-  vector<const FieldDescriptor*> map_fields;
-  for (int i = 0; i < descriptor_->field_count(); i++) {
-    const FieldDescriptor* field = descriptor_->field(i);
-    if (GetJavaType(field) == JAVATYPE_MESSAGE &&
-        IsMapEntry(field->message_type())) {
-      map_fields.push_back(field);
-    }
-  }
-  if (!map_fields.empty()) {
-    printer->Print(
-      "@SuppressWarnings({\"rawtypes\"})\n"
-      "protected com.google.protobuf.MapField internalGetMapField(\n"
-      "    int number) {\n"
-      "  switch (number) {\n");
+  printer->Print(
+    "public $classname$ getDefaultInstanceForType() {\n"
+    "  return $classname$.getDefaultInstance();\n"
+    "}\n"
+    "\n",
+    "classname", ClassName(descriptor_));
+
+  // -----------------------------------------------------------------
+
+  printer->Print(
+    "public $classname$ build() {\n"
+    "  $classname$ result = buildPartial();\n"
+    "  if (!result.isInitialized()) {\n"
+    "    throw newUninitializedMessageException(result);\n"
+    "  }\n"
+    "  return result;\n"
+    "}\n"
+    "\n"
+    "public $classname$ buildPartial() {\n"
+    "  $classname$ result = new $classname$(this);\n",
+    "classname", ClassName(descriptor_));
+
+  printer->Indent();
+
+  // Local vars for from and to bit fields to avoid accessing the builder and
+  // message over and over for these fields. Seems to provide a slight
+  // perforamance improvement in micro benchmark and this is also what proto1
+  // code does.
+  int totalBuilderBits = 0;
+  int totalMessageBits = 0;
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    const FieldGenerator& field = field_generators_.get(descriptor_->field(i));
+    totalBuilderBits += field.GetNumBitsForBuilder();
+    totalMessageBits += field.GetNumBitsForMessage();
+  }
+  int totalBuilderInts = (totalBuilderBits + 31) / 32;
+  int totalMessageInts = (totalMessageBits + 31) / 32;
+  for (int i = 0; i < totalBuilderInts; i++) {
+    printer->Print("int from_$bit_field_name$ = $bit_field_name$;\n",
+      "bit_field_name", GetBitFieldName(i));
+  }
+  for (int i = 0; i < totalMessageInts; i++) {
+    printer->Print("int to_$bit_field_name$ = 0;\n",
+      "bit_field_name", GetBitFieldName(i));
+  }
+
+  // Output generation code for each field.
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    field_generators_.get(descriptor_->field(i)).GenerateBuildingCode(printer);
+  }
+
+  // Copy the bit field results to the generated message
+  for (int i = 0; i < totalMessageInts; i++) {
+    printer->Print("result.$bit_field_name$ = to_$bit_field_name$;\n",
+      "bit_field_name", GetBitFieldName(i));
+  }
+
+  printer->Outdent();
+
+  if (HasDescriptorMethods(descriptor_)) {
+    printer->Print(
+    "  onBuilt();\n");
+  }
+
+  printer->Print(
+    "  return result;\n"
+    "}\n"
+    "\n",
+    "classname", ClassName(descriptor_));
+
+  // -----------------------------------------------------------------
+
+  if (HasGeneratedMethods(descriptor_)) {
+    // MergeFrom(Message other) requires the ability to distinguish the other
+    // messages type by its descriptor.
+    if (HasDescriptorMethods(descriptor_)) {
+      printer->Print(
+        "public Builder mergeFrom(com.google.protobuf.Message other) {\n"
+        "  if (other instanceof $classname$) {\n"
+        "    return mergeFrom(($classname$)other);\n"
+        "  } else {\n"
+        "    super.mergeFrom(other);\n"
+        "    return this;\n"
+        "  }\n"
+        "}\n"
+        "\n",
+        "classname", ClassName(descriptor_));
+    }
+
+    printer->Print(
+      "public Builder mergeFrom($classname$ other) {\n"
+      // Optimization:  If other is the default instance, we know none of its
+      //   fields are set so we can skip the merge.
+      "  if (other == $classname$.getDefaultInstance()) return this;\n",
+      "classname", ClassName(descriptor_));
     printer->Indent();
-    printer->Indent();
-    for (int i = 0; i < map_fields.size(); ++i) {
-      const FieldDescriptor* field = map_fields[i];
-      const FieldGeneratorInfo* info = context_->GetFieldGeneratorInfo(field);
-      printer->Print(
-        "case $number$:\n"
-        "  return internalGet$capitalized_name$();\n",
-        "number", SimpleItoa(field->number()),
-        "capitalized_name", info->capitalized_name);
-    }
-    printer->Print(
-        "default:\n"
-        "  throw new RuntimeException(\n"
-        "      \"Invalid map field number: \" + number);\n");
+
+    for (int i = 0; i < descriptor_->field_count(); i++) {
+      field_generators_.get(descriptor_->field(i)).GenerateMergingCode(printer);
+    }
+
     printer->Outdent();
-    printer->Outdent();
-    printer->Print(
-        "  }\n"
-        "}\n");
-  }
-  printer->Print(
-    "protected com.google.protobuf.GeneratedMessage.FieldAccessorTable\n"
-    "    internalGetFieldAccessorTable() {\n"
-    "  return $fileclass$.internal_$identifier$_fieldAccessorTable\n"
-    "      .ensureFieldAccessorsInitialized(\n"
-    "          $classname$.class, $classname$.Builder.class);\n"
-    "}\n"
-    "\n",
-    "classname", name_resolver_->GetImmutableClassName(descriptor_),
-    "fileclass", name_resolver_->GetImmutableClassName(descriptor_->file()),
-    "identifier", UniqueFileScopeIdentifier(descriptor_));
+
+    // if message type has extensions
+    if (descriptor_->extension_range_count() > 0) {
+      printer->Print(
+        "  this.mergeExtensionFields(other);\n");
+    }
+
+    if (HasUnknownFields(descriptor_)) {
+      printer->Print(
+        "  this.mergeUnknownFields(other.getUnknownFields());\n");
+    }
+
+    printer->Print(
+      "  return this;\n"
+      "}\n"
+      "\n");
+  }
 }
 
 // ===================================================================
 
-void ImmutableMessageGenerator::GenerateIsInitialized(
-    io::Printer* printer) {
-  // Memoizes whether the protocol buffer is fully initialized (has all
-  // required fields). -1 means not yet computed. 0 means false and 1 means
-  // true.
-  printer->Print(
-    "private byte memoizedIsInitialized = -1;\n");
+void MessageGenerator::GenerateBuilderParsingMethods(io::Printer* printer) {
+  printer->Print(
+    "public Builder mergeFrom(\n"
+    "    com.google.protobuf.CodedInputStream input,\n"
+    "    com.google.protobuf.ExtensionRegistryLite extensionRegistry)\n"
+    "    throws java.io.IOException {\n"
+    "  $classname$ parsedMessage = null;\n"
+    "  try {\n"
+    "    parsedMessage = PARSER.parsePartialFrom(input, extensionRegistry);\n"
+    "  } catch (com.google.protobuf.InvalidProtocolBufferException e) {\n"
+    "    parsedMessage = ($classname$) e.getUnfinishedMessage();\n"
+    "    throw e;\n"
+    "  } finally {\n"
+    "    if (parsedMessage != null) {\n"
+    "      mergeFrom(parsedMessage);\n"
+    "    }\n"
+    "  }\n"
+    "  return this;\n"
+    "}\n",
+    "classname", ClassName(descriptor_));
+}
+
+// ===================================================================
+
+void MessageGenerator::GenerateIsInitialized(
+    io::Printer* printer, UseMemoization useMemoization) {
+  bool memoization = useMemoization == MEMOIZE;
+  if (memoization) {
+    // Memoizes whether the protocol buffer is fully initialized (has all
+    // required fields). -1 means not yet computed. 0 means false and 1 means
+    // true.
+    printer->Print(
+      "private byte memoizedIsInitialized = -1;\n");
+  }
   printer->Print(
     "public final boolean isInitialized() {\n");
   printer->Indent();
 
-  // Don't directly compare to -1 to avoid an Android x86 JIT bug.
-  printer->Print(
-    "byte isInitialized = memoizedIsInitialized;\n"
-    "if (isInitialized == 1) return true;\n"
-    "if (isInitialized == 0) return false;\n"
-    "\n");
+  if (memoization) {
+    printer->Print(
+      "byte isInitialized = memoizedIsInitialized;\n"
+      "if (isInitialized != -1) return isInitialized == 1;\n"
+      "\n");
+  }
 
   // Check that all required fields in this message are set.
   // TODO(kenton):  We can optimize this when we switch to putting all the
   //   "has" fields into a single bitfield.
   for (int i = 0; i < descriptor_->field_count(); i++) {
     const FieldDescriptor* field = descriptor_->field(i);
-    const FieldGeneratorInfo* info = context_->GetFieldGeneratorInfo(field);
 
     if (field->is_required()) {
       printer->Print(
         "if (!has$name$()) {\n"
-        "  memoizedIsInitialized = 0;\n"
+        "  $memoize$\n"
         "  return false;\n"
         "}\n",
-        "name", info->capitalized_name);
+        "name", UnderscoresToCapitalizedCamelCase(field),
+        "memoize", memoization ? "memoizedIsInitialized = 0;" : "");
     }
   }
 
   // Now check that all embedded messages are initialized.
   for (int i = 0; i < descriptor_->field_count(); i++) {
     const FieldDescriptor* field = descriptor_->field(i);
-    const FieldGeneratorInfo* info = context_->GetFieldGeneratorInfo(field);
     if (GetJavaType(field) == JAVATYPE_MESSAGE &&
         HasRequiredFields(field->message_type())) {
       switch (field->label()) {
         case FieldDescriptor::LABEL_REQUIRED:
           printer->Print(
             "if (!get$name$().isInitialized()) {\n"
-             "  memoizedIsInitialized = 0;\n"
+             "  $memoize$\n"
              "  return false;\n"
              "}\n",
-            "type", name_resolver_->GetImmutableClassName(
-                field->message_type()),
-            "name", info->capitalized_name);
+            "type", ClassName(field->message_type()),
+            "name", UnderscoresToCapitalizedCamelCase(field),
+            "memoize", memoization ? "memoizedIsInitialized = 0;" : "");
           break;
         case FieldDescriptor::LABEL_OPTIONAL:
-          if (!SupportFieldPresence(descriptor_->file()) &&
-              field->containing_oneof() != NULL) {
-            const OneofDescriptor* oneof = field->containing_oneof();
-            const OneofGeneratorInfo* oneof_info =
-                context_->GetOneofGeneratorInfo(oneof);
-            printer->Print(
-              "if ($oneof_name$Case_ == $field_number$) {\n",
-              "oneof_name", oneof_info->name,
-              "field_number", SimpleItoa(field->number()));
-          } else {
-            printer->Print(
-              "if (has$name$()) {\n",
-              "name", info->capitalized_name);
-          }
           printer->Print(
+            "if (has$name$()) {\n"
             "  if (!get$name$().isInitialized()) {\n"
-            "    memoizedIsInitialized = 0;\n"
+            "    $memoize$\n"
             "    return false;\n"
             "  }\n"
             "}\n",
-            "name", info->capitalized_name);
+            "type", ClassName(field->message_type()),
+            "name", UnderscoresToCapitalizedCamelCase(field),
+            "memoize", memoization ? "memoizedIsInitialized = 0;" : "");
           break;
         case FieldDescriptor::LABEL_REPEATED:
-          if (IsMapEntry(field->message_type())) {
-            printer->Print(
-              "for ($type$ item : get$name$().values()) {\n"
-              "  if (!item.isInitialized()) {\n"
-              "    memoizedIsInitialized = 0;\n"
-              "    return false;\n"
-              "  }\n"
-              "}\n",
-              "type", MapValueImmutableClassdName(field->message_type(),
-                                                  name_resolver_),
-              "name", info->capitalized_name);
-          } else {
-            printer->Print(
-              "for (int i = 0; i < get$name$Count(); i++) {\n"
-              "  if (!get$name$(i).isInitialized()) {\n"
-              "    memoizedIsInitialized = 0;\n"
-              "    return false;\n"
-              "  }\n"
-              "}\n",
-              "type", name_resolver_->GetImmutableClassName(
-                  field->message_type()),
-              "name", info->capitalized_name);
-          }
+          printer->Print(
+            "for (int i = 0; i < get$name$Count(); i++) {\n"
+            "  if (!get$name$(i).isInitialized()) {\n"
+            "    $memoize$\n"
+            "    return false;\n"
+            "  }\n"
+            "}\n",
+            "type", ClassName(field->message_type()),
+            "name", UnderscoresToCapitalizedCamelCase(field),
+            "memoize", memoization ? "memoizedIsInitialized = 0;" : "");
           break;
       }
     }
   }
 
   if (descriptor_->extension_range_count() > 0) {
     printer->Print(
       "if (!extensionsAreInitialized()) {\n"
-      "  memoizedIsInitialized = 0;\n"
+      "  $memoize$\n"
       "  return false;\n"
-      "}\n");
+      "}\n",
+      "memoize", memoization ? "memoizedIsInitialized = 0;" : "");
   }
 
   printer->Outdent();
 
-  printer->Print(
-    "  memoizedIsInitialized = 1;\n");
+  if (memoization) {
+    printer->Print(
+      "  memoizedIsInitialized = 1;\n");
+  }
 
   printer->Print(
     "  return true;\n"
     "}\n"
     "\n");
 }
 
 // ===================================================================
 
-namespace {
-bool CheckHasBitsForEqualsAndHashCode(const FieldDescriptor* field) {
-  if (field->is_repeated()) {
-    return false;
-  }
-  if (SupportFieldPresence(field->file())) {
-    return true;
-  }
-  return GetJavaType(field) == JAVATYPE_MESSAGE &&
-      field->containing_oneof() == NULL;
-}
-}  // namespace
-
-void ImmutableMessageGenerator::
-GenerateEqualsAndHashCode(io::Printer* printer) {
+void MessageGenerator::GenerateEqualsAndHashCode(io::Printer* printer) {
   printer->Print(
     "@java.lang.Override\n"
     "public boolean equals(final java.lang.Object obj) {\n");
   printer->Indent();
   printer->Print(
     "if (obj == this) {\n"
     " return true;\n"
     "}\n"
     "if (!(obj instanceof $classname$)) {\n"
     "  return super.equals(obj);\n"
     "}\n"
     "$classname$ other = ($classname$) obj;\n"
     "\n",
-    "classname", name_resolver_->GetImmutableClassName(descriptor_));
+    "classname", ClassName(descriptor_));
 
   printer->Print("boolean result = true;\n");
   for (int i = 0; i < descriptor_->field_count(); i++) {
     const FieldDescriptor* field = descriptor_->field(i);
-    const FieldGeneratorInfo* info = context_->GetFieldGeneratorInfo(field);
-    bool check_has_bits = CheckHasBitsForEqualsAndHashCode(field);
-    if (check_has_bits) {
+    if (!field->is_repeated()) {
       printer->Print(
         "result = result && (has$name$() == other.has$name$());\n"
         "if (has$name$()) {\n",
-        "name", info->capitalized_name);
+        "name", UnderscoresToCapitalizedCamelCase(field));
       printer->Indent();
     }
     field_generators_.get(field).GenerateEqualsCode(printer);
-    if (check_has_bits) {
+    if (!field->is_repeated()) {
       printer->Outdent();
       printer->Print(
         "}\n");
     }
   }
-  if (PreserveUnknownFields(descriptor_)) {
-    // Always consider unknown fields for equality. This will sometimes return
-    // false for non-canonical ordering when running in LITE_RUNTIME but it's
-    // the best we can do.
-    printer->Print(
-      "result = result && unknownFields.equals(other.unknownFields);\n");
-  }
-  if (descriptor_->extension_range_count() > 0) {
+  if (HasDescriptorMethods(descriptor_)) {
     printer->Print(
       "result = result &&\n"
-      "    getExtensionFields().equals(other.getExtensionFields());\n");
+      "    getUnknownFields().equals(other.getUnknownFields());\n");
+    if (descriptor_->extension_range_count() > 0) {
+      printer->Print(
+        "result = result &&\n"
+        "    getExtensionFields().equals(other.getExtensionFields());\n");
+    }
   }
   printer->Print(
     "return result;\n");
   printer->Outdent();
   printer->Print(
     "}\n"
     "\n");
 
   printer->Print(
+    "private int memoizedHashCode = 0;\n");
+  printer->Print(
     "@java.lang.Override\n"
     "public int hashCode() {\n");
   printer->Indent();
   printer->Print(
     "if (memoizedHashCode != 0) {\n");
   printer->Indent();
   printer->Print(
     "return memoizedHashCode;\n");
   printer->Outdent();
   printer->Print(
     "}\n"
-    "int hash = 41;\n");
-
-  printer->Print("hash = (19 * hash) + getDescriptorForType().hashCode();\n");
-
+    "int hash = 41;\n"
+    "hash = (19 * hash) + getDescriptorForType().hashCode();\n");
   for (int i = 0; i < descriptor_->field_count(); i++) {
     const FieldDescriptor* field = descriptor_->field(i);
-    const FieldGeneratorInfo* info = context_->GetFieldGeneratorInfo(field);
-    bool check_has_bits = CheckHasBitsForEqualsAndHashCode(field);
-    if (check_has_bits) {
+    if (!field->is_repeated()) {
       printer->Print(
         "if (has$name$()) {\n",
-        "name", info->capitalized_name);
+        "name", UnderscoresToCapitalizedCamelCase(field));
       printer->Indent();
     }
     field_generators_.get(field).GenerateHashCode(printer);
-    if (check_has_bits) {
+    if (!field->is_repeated()) {
       printer->Outdent();
       printer->Print("}\n");
     }
   }
-  if (descriptor_->extension_range_count() > 0) {
-    printer->Print(
-      "hash = hashFields(hash, getExtensionFields());\n");
+  if (HasDescriptorMethods(descriptor_)) {
+    if (descriptor_->extension_range_count() > 0) {
+      printer->Print(
+        "hash = hashFields(hash, getExtensionFields());\n");
+    }
   }
-
   printer->Print(
-    "hash = (29 * hash) + unknownFields.hashCode();\n");
-  printer->Print(
+    "hash = (29 * hash) + getUnknownFields().hashCode();\n"
     "memoizedHashCode = hash;\n"
     "return hash;\n");
   printer->Outdent();
   printer->Print(
     "}\n"
     "\n");
 }
 
 // ===================================================================
 
-void ImmutableMessageGenerator::
-GenerateExtensionRegistrationCode(io::Printer* printer) {
+void MessageGenerator::GenerateExtensionRegistrationCode(io::Printer* printer) {
   for (int i = 0; i < descriptor_->extension_count(); i++) {
-    ImmutableExtensionGenerator(descriptor_->extension(i), context_)
+    ExtensionGenerator(descriptor_->extension(i))
       .GenerateRegistrationCode(printer);
   }
 
   for (int i = 0; i < descriptor_->nested_type_count(); i++) {
-    ImmutableMessageGenerator(descriptor_->nested_type(i), context_)
+    MessageGenerator(descriptor_->nested_type(i))
       .GenerateExtensionRegistrationCode(printer);
   }
 }
 
 // ===================================================================
-void ImmutableMessageGenerator::
-GenerateParsingConstructor(io::Printer* printer) {
-  google::protobuf::scoped_array<const FieldDescriptor * > sorted_fields(
+void MessageGenerator::GenerateParsingConstructor(io::Printer* printer) {
+  scoped_array<const FieldDescriptor*> sorted_fields(
       SortFieldsByNumber(descriptor_));
 
   printer->Print(
       "private $classname$(\n"
       "    com.google.protobuf.CodedInputStream input,\n"
-      "    com.google.protobuf.ExtensionRegistryLite extensionRegistry) {\n",
+      "    com.google.protobuf.ExtensionRegistryLite extensionRegistry)\n"
+      "    throws com.google.protobuf.InvalidProtocolBufferException {\n",
       "classname", descriptor_->name());
   printer->Indent();
 
   // Initialize all fields to default.
   printer->Print(
-      "this();\n");
+      "initFields();\n");
 
   // Use builder bits to track mutable repeated fields.
   int totalBuilderBits = 0;
   for (int i = 0; i < descriptor_->field_count(); i++) {
-    const ImmutableFieldGenerator& field =
-        field_generators_.get(descriptor_->field(i));
+    const FieldGenerator& field = field_generators_.get(descriptor_->field(i));
     totalBuilderBits += field.GetNumBitsForBuilder();
   }
   int totalBuilderInts = (totalBuilderBits + 31) / 32;
   for (int i = 0; i < totalBuilderInts; i++) {
     printer->Print("int mutable_$bit_field_name$ = 0;\n",
       "bit_field_name", GetBitFieldName(i));
   }
 
-  if (PreserveUnknownFields(descriptor_)) {
+  if (HasUnknownFields(descriptor_)) {
     printer->Print(
       "com.google.protobuf.UnknownFieldSet.Builder unknownFields =\n"
       "    com.google.protobuf.UnknownFieldSet.newBuilder();\n");
   }
 
   printer->Print(
       "try {\n");
   printer->Indent();
 
   printer->Print(
     "boolean done = false;\n"
     "while (!done) {\n");
   printer->Indent();
 
   printer->Print(
     "int tag = input.readTag();\n"
     "switch (tag) {\n");
   printer->Indent();
 
   printer->Print(
     "case 0:\n"          // zero signals EOF / limit reached
     "  done = true;\n"
-    "  break;\n");
-
-  if (PreserveUnknownFields(descriptor_)) {
-    printer->Print(
-      "default: {\n"
-      "  if (!parseUnknownField(input, unknownFields,\n"
-      "                         extensionRegistry, tag)) {\n"
-      "    done = true;\n"  // it's an endgroup tag
-      "  }\n"
-      "  break;\n"
-      "}\n");
-  } else {
-    printer->Print(
-      "default: {\n"
-      "  if (!input.skipField(tag)) {\n"
-      "    done = true;\n"  // it's an endgroup tag
-      "  }\n"
-      "  break;\n"
-      "}\n");
-  }
+    "  break;\n"
+    "default: {\n"
+    "  if (!parseUnknownField(input,$unknown_fields$\n"
+    "                         extensionRegistry, tag)) {\n"
+    "    done = true;\n"  // it's an endgroup tag
+    "  }\n"
+    "  break;\n"
+    "}\n",
+    "unknown_fields", HasUnknownFields(descriptor_)
+        ? " unknownFields," : "");
 
   for (int i = 0; i < descriptor_->field_count(); i++) {
     const FieldDescriptor* field = sorted_fields[i];
     uint32 tag = WireFormatLite::MakeTag(field->number(),
       WireFormat::WireTypeForFieldType(field->type()));
 
     printer->Print(
       "case $tag$: {\n",
       "tag", SimpleItoa(tag));
     printer->Indent();
@@ skipping 26 matching lines @@
 
   printer->Outdent();
   printer->Outdent();
   printer->Print(
       "  }\n"     // switch (tag)
       "}\n");     // while (!done)
 
   printer->Outdent();
   printer->Print(
       "} catch (com.google.protobuf.InvalidProtocolBufferException e) {\n"
-      "  throw new RuntimeException(e.setUnfinishedMessage(this));\n"
+      "  throw e.setUnfinishedMessage(this);\n"
       "} catch (java.io.IOException e) {\n"
-      "  throw new RuntimeException(\n"
-      "      new com.google.protobuf.InvalidProtocolBufferException(\n"
-      "          e.getMessage()).setUnfinishedMessage(this));\n"
+      "  throw new com.google.protobuf.InvalidProtocolBufferException(\n"
+      "      e.getMessage()).setUnfinishedMessage(this);\n"
       "} finally {\n");
   printer->Indent();
 
   // Make repeated field list immutable.
   for (int i = 0; i < descriptor_->field_count(); i++) {
     const FieldDescriptor* field = sorted_fields[i];
     field_generators_.get(field).GenerateParsingDoneCode(printer);
   }
 
-  if (PreserveUnknownFields(descriptor_)) {
-    // Make unknown fields immutable.
-    printer->Print("this.unknownFields = unknownFields.build();\n");
+  // Make unknown fields immutable.
+  if (HasUnknownFields(descriptor_)) {
+    printer->Print(
+        "this.unknownFields = unknownFields.build();\n");
   }
 
   // Make extensions immutable.
   printer->Print(
       "makeExtensionsImmutable();\n");
 
   printer->Outdent();
   printer->Outdent();
   printer->Print(
       "  }\n"     // finally
       "}\n");
 }
 
 // ===================================================================
-void ImmutableMessageGenerator::GenerateParser(io::Printer* printer) {
+void MessageGenerator::GenerateParser(io::Printer* printer) {
   printer->Print(
-      "public static final com.google.protobuf.Parser<$classname$> PARSER =\n"
+      "public static com.google.protobuf.Parser<$classname$> PARSER =\n"
       "    new com.google.protobuf.AbstractParser<$classname$>() {\n",
       "classname", descriptor_->name());
   printer->Indent();
   printer->Print(
       "public $classname$ parsePartialFrom(\n"
       "    com.google.protobuf.CodedInputStream input,\n"
       "    com.google.protobuf.ExtensionRegistryLite extensionRegistry)\n"
       "    throws com.google.protobuf.InvalidProtocolBufferException {\n",
       "classname", descriptor_->name());
   if (HasGeneratedMethods(descriptor_)) {
-    // The parsing constructor throws an InvalidProtocolBufferException via a
-    // RuntimeException to aid in method pruning. We unwrap it here.
     printer->Print(
-        "  try {\n"
-        "    return new $classname$(input, extensionRegistry);\n"
-        "  } catch (RuntimeException e) {\n"
-        "    if (e.getCause() instanceof\n"
-        "        com.google.protobuf.InvalidProtocolBufferException) {\n"
-        "      throw (com.google.protobuf.InvalidProtocolBufferException)\n"
-        "          e.getCause();\n"
-        "    }\n"
-        "    throw e;\n"
-        "  }\n",
+        "  return new $classname$(input, extensionRegistry);\n",
         "classname", descriptor_->name());
   } else {
-    // When parsing constructor isn't generated, use builder to parse
-    // messages. Note, will fallback to use reflection based mergeFieldFrom()
-    // in AbstractMessage.Builder.
+    // When parsing constructor isn't generated, use builder to parse messages.
+    // Note, will fallback to use reflection based mergeFieldFrom() in
+    // AbstractMessage.Builder.
     printer->Indent();
     printer->Print(
         "Builder builder = newBuilder();\n"
         "try {\n"
         "  builder.mergeFrom(input, extensionRegistry);\n"
         "} catch (com.google.protobuf.InvalidProtocolBufferException e) {\n"
         "  throw e.setUnfinishedMessage(builder.buildPartial());\n"
         "} catch (java.io.IOException e) {\n"
         "  throw new com.google.protobuf.InvalidProtocolBufferException(\n"
-        "      e.getMessage()).setUnfinishedMessage(\n"
-        "          builder.buildPartial());\n"
+        "      e.getMessage()).setUnfinishedMessage(builder.buildPartial());\n"
         "}\n"
         "return builder.buildPartial();\n");
     printer->Outdent();
   }
   printer->Print(
         "}\n");
   printer->Outdent();
   printer->Print(
       "};\n"
       "\n");
 
   printer->Print(
       "@java.lang.Override\n"
       "public com.google.protobuf.Parser<$classname$> getParserForType() {\n"
       "  return PARSER;\n"
       "}\n"
       "\n",
       "classname", descriptor_->name());
 }
 
-// ===================================================================
-void ImmutableMessageGenerator::GenerateInitializers(io::Printer* printer) {
-  for (int i = 0; i < descriptor_->field_count(); i++) {
-    if (!descriptor_->field(i)->containing_oneof()) {
-      field_generators_.get(descriptor_->field(i))
-          .GenerateInitializationCode(printer);
-    }
-  }
-}
-
-
 }  // namespace java
 }  // namespace compiler
 }  // namespace protobuf
 }  // namespace google