src/google/protobuf/compiler/java/java_file.cc

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.
// http://code.google.com/p/protobuf/
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// 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_file.h>
#include <google/protobuf/compiler/java/java_enum.h>
#include <google/protobuf/compiler/java/java_service.h>
#include <google/protobuf/compiler/java/java_extension.h>
#include <google/protobuf/compiler/java/java_helpers.h>
#include <google/protobuf/compiler/java/java_message.h>
#include <google/protobuf/compiler/code_generator.h>
#include <google/protobuf/io/printer.h>
#include <google/protobuf/io/zero_copy_stream.h>
#include <google/protobuf/descriptor.pb.h>
#include <google/protobuf/stubs/strutil.h>

namespace google {
namespace protobuf {
namespace compiler {
namespace java {

FileGenerator::FileGenerator(const FileDescriptor* file)
  : file_(file),
    java_package_(FileJavaPackage(file)),
    classname_(FileClassName(file)) {}

FileGenerator::~FileGenerator() {}

bool FileGenerator::Validate(string* error) {
  // Check that no class name matches the file's class name.  This is a common
  // problem that leads to Java compile errors that can be hard to understand.
  // It's especially bad when using the java_multiple_files, since we would
  // end up overwriting the outer class with one of the inner ones.

  bool found_conflict = false;
  for (int i = 0; i < file_->enum_type_count() && !found_conflict; i++) {
    if (file_->enum_type(i)->name() == classname_) {
      found_conflict = true;
    }
  }
  for (int i = 0; i < file_->message_type_count() && !found_conflict; i++) {
    if (file_->message_type(i)->name() == classname_) {
      found_conflict = true;
    }
  }
  for (int i = 0; i < file_->service_count() && !found_conflict; i++) {
    if (file_->service(i)->name() == classname_) {
      found_conflict = true;
    }
  }

  if (found_conflict) {
    error->assign(file_->name());
    error->append(
      ": Cannot generate Java output because the file's outer class name, \"");
    error->append(classname_);
    error->append(
      "\", matches the name of one of the types declared inside it.  "
      "Please either rename the type or use the java_outer_classname "
      "option to specify a different outer class name for the .proto file.");
    return false;
  }

  return true;
}

void FileGenerator::Generate(io::Printer* printer) {
  // We don't import anything because we refer to all classes by their
  // fully-qualified names in the generated source.
  printer->Print(
    "// Generated by the protocol buffer compiler.  DO NOT EDIT!\n"
    "\n");
  if (!java_package_.empty()) {
    printer->Print(
      "package $package$;\n"
      "\n",
      "package", java_package_);
  }
  printer->Print(
    "public final class $classname$ {\n"
    "  private $classname$() {}\n",
    "classname", classname_);
  printer->Indent();

  // -----------------------------------------------------------------

  // Embed the descriptor.  We simply serialize the entire FileDescriptorProto
  // and embed it as a string literal, which is parsed and built into real
  // descriptors at initialization time.  We unfortunately have to put it in
  // a string literal, not a byte array, because apparently using a literal
  // byte array causes the Java compiler to generate *instructions* to
  // initialize each and every byte of the array, e.g. as if you typed:
  //   b[0] = 123; b[1] = 456; b[2] = 789;
  // This makes huge bytecode files and can easily hit the compiler's internal
  // code size limits (error "code to large").  String literals are apparently
  // embedded raw, which is what we want.
  FileDescriptorProto file_proto;
  file_->CopyTo(&file_proto);
  string file_data;
  file_proto.SerializeToString(&file_data);

  printer->Print(
    "public static com.google.protobuf.Descriptors.FileDescriptor\n"
    "    getDescriptor() {\n"
    "  return descriptor;\n"
    "}\n"
    "private static final com.google.protobuf.Descriptors.FileDescriptor\n"
    "    descriptor = buildDescriptor();\n"
    "private static\n"
    "    com.google.protobuf.Descriptors.FileDescriptor\n"
    "    buildDescriptor() {\n"
    "  java.lang.String descriptorData =\n");
  printer->Indent();
  printer->Indent();

  // Only write 40 bytes per line.
  static const int kBytesPerLine = 40;
  for (int i = 0; i < file_data.size(); i += kBytesPerLine) {
    if (i > 0) printer->Print(" +\n");
    printer->Print("\"$data$\"",
      "data", CEscape(file_data.substr(i, kBytesPerLine)));
  }
  printer->Print(";\n");

  printer->Outdent();
  printer->Print(
    "try {\n"
    "  return com.google.protobuf.Descriptors.FileDescriptor\n"
    "    .internalBuildGeneratedFileFrom(descriptorData,\n"
    "      new com.google.protobuf.Descriptors.FileDescriptor[] {\n");

  for (int i = 0; i < file_->dependency_count(); i++) {
    printer->Print(
      "        $dependency$.getDescriptor(),\n",
      "dependency", ClassName(file_->dependency(i)));
  }

  printer->Print(
    "      });\n"
    "} catch (Exception e) {\n"
    "  throw new RuntimeException(\n"
    "    \"Failed to parse protocol buffer descriptor for \" +\n"
    "    \"\\\"$filename$\\\".\", e);\n"
    "}\n",
    "filename", file_->name());

  printer->Outdent();
  printer->Print(
    "}\n"
    "\n");

  // -----------------------------------------------------------------

  if (!file_->options().java_multiple_files()) {
    for (int i = 0; i < file_->enum_type_count(); i++) {
      EnumGenerator(file_->enum_type(i)).Generate(printer);
    }
    for (int i = 0; i < file_->message_type_count(); i++) {
      MessageGenerator(file_->message_type(i)).Generate(printer);
    }
    for (int i = 0; i < file_->service_count(); i++) {
      ServiceGenerator(file_->service(i)).Generate(printer);
    }
  }

  // Extensions must be generated in the outer class since they are values,
  // not classes.
  for (int i = 0; i < file_->extension_count(); i++) {
    ExtensionGenerator(file_->extension(i)).Generate(printer);
  }

  // Static variables.
  for (int i = 0; i < file_->message_type_count(); i++) {
    // TODO(kenton):  Reuse MessageGenerator objects?
    MessageGenerator(file_->message_type(i)).GenerateStaticVariables(printer);
  }

  printer->Outdent();
  printer->Print("}\n");
}

template<typename GeneratorClass, typename DescriptorClass>
static void GenerateSibling(const string& package_dir,
                            const string& java_package,
                            const DescriptorClass* descriptor,
                            OutputDirectory* output_directory,
                            vector<string>* file_list) {
  string filename = package_dir + descriptor->name() + ".java";
  file_list->push_back(filename);

  scoped_ptr<io::ZeroCopyOutputStream> output(
    output_directory->Open(filename));
  io::Printer printer(output.get(), '$');

  printer.Print(
    "// Generated by the protocol buffer compiler.  DO NOT EDIT!\n"
    "\n");
  if (!java_package.empty()) {
    printer.Print(
      "package $package$;\n"
      "\n",
      "package", java_package);
  }

  GeneratorClass(descriptor).Generate(&printer);
}

void FileGenerator::GenerateSiblings(const string& package_dir,
                                     OutputDirectory* output_directory,
                                     vector<string>* file_list) {
  if (file_->options().java_multiple_files()) {
    for (int i = 0; i < file_->enum_type_count(); i++) {
      GenerateSibling<EnumGenerator>(package_dir, java_package_,
                                     file_->enum_type(i),
                                     output_directory, file_list);
    }
    for (int i = 0; i < file_->message_type_count(); i++) {
      GenerateSibling<MessageGenerator>(package_dir, java_package_,
                                        file_->message_type(i),
                                        output_directory, file_list);
    }
    for (int i = 0; i < file_->service_count(); i++) {
      GenerateSibling<ServiceGenerator>(package_dir, java_package_,
                                        file_->service(i),
                                        output_directory, file_list);
    }
  }
}

}  // namespace java
}  // namespace compiler
}  // namespace protobuf
}  // namespace google