src/compiler/cpp_plugin.cc

/*
 *
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 * modification, are permitted provided that the following conditions are
 * met:
 *
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 * 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.
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 * 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
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// Generates cpp gRPC service interface out of Protobuf IDL.
//

#include <memory>
#include <sstream>

#include "src/compiler/config.h"

#include "src/compiler/cpp_generator.h"
#include "src/compiler/cpp_generator_helpers.h"
#include "src/compiler/generator_helpers.h"

grpc::string GenerateComments(const std::vector<grpc::string> &in) {
  std::ostringstream oss;
  for (const grpc::string &elem : in) {
    if (elem.empty()) {
      oss << "//\n";
    } else if (elem[0] == ' ') {
      oss << "//" << elem << "\n";
    } else {
      oss << "// " << elem << "\n";
    }
  }
  return oss.str();
}

// Get leading or trailing comments in a string. Comment lines start with "// ".
// Leading detached comments are put in in front of leading comments.
template <typename DescriptorType>
grpc::string GetComments(const DescriptorType *desc, bool leading) {
  std::vector<grpc::string> out;
  if (leading) {
    grpc_generator::GetComment(
        desc, grpc_generator::COMMENTTYPE_LEADING_DETACHED, &out);
    std::vector<grpc::string> leading;
    grpc_generator::GetComment(desc, grpc_generator::COMMENTTYPE_LEADING,
                               &leading);
    out.insert(out.end(), leading.begin(), leading.end());
  } else {
    grpc_generator::GetComment(desc, grpc_generator::COMMENTTYPE_TRAILING,
                               &out);
  }
  return GenerateComments(out);
}

class ProtoBufMethod : public grpc_cpp_generator::Method {
 public:
  ProtoBufMethod(const grpc::protobuf::MethodDescriptor *method)
    : method_(method) {}

  grpc::string name() const { return method_->name(); }

  grpc::string input_type_name() const {
    return grpc_cpp_generator::ClassName(method_->input_type(), true);
  }
  grpc::string output_type_name() const {
    return grpc_cpp_generator::ClassName(method_->output_type(), true);
  }

  bool NoStreaming() const {
    return !method_->client_streaming() && !method_->server_streaming();
  }

  bool ClientOnlyStreaming() const {
    return method_->client_streaming() && !method_->server_streaming();
  }

  bool ServerOnlyStreaming() const {
    return !method_->client_streaming() && method_->server_streaming();
  }

  bool BidiStreaming() const {
    return method_->client_streaming() && method_->server_streaming();
  }

  grpc::string GetLeadingComments() const { return GetComments(method_, true); }

  grpc::string GetTrailingComments() const {
    return GetComments(method_, false);
  }

 private:
  const grpc::protobuf::MethodDescriptor *method_;
};

class ProtoBufService : public grpc_cpp_generator::Service {
 public:
  ProtoBufService(const grpc::protobuf::ServiceDescriptor *service)
    : service_(service) {}

  grpc::string name() const { return service_->name(); }

  int method_count() const { return service_->method_count(); };
  std::unique_ptr<const grpc_cpp_generator::Method> method(int i) const {
    return std::unique_ptr<const grpc_cpp_generator::Method>(
          new ProtoBufMethod(service_->method(i)));
  };

  grpc::string GetLeadingComments() const {
    return GetComments(service_, true);
  }

  grpc::string GetTrailingComments() const {
    return GetComments(service_, false);
  }

 private:
  const grpc::protobuf::ServiceDescriptor *service_;
};

class ProtoBufPrinter : public grpc_cpp_generator::Printer {
 public:
  ProtoBufPrinter(grpc::string *str)
    : output_stream_(str), printer_(&output_stream_, '$') {}

  void Print(const std::map<grpc::string, grpc::string> &vars,
             const char *string_template) {
    printer_.Print(vars, string_template);
  }

  void Print(const char *string) { printer_.Print(string); }
  void Indent() { printer_.Indent(); }
  void Outdent() { printer_.Outdent(); }

 private:
  grpc::protobuf::io::StringOutputStream output_stream_;
  grpc::protobuf::io::Printer printer_;
};

class ProtoBufFile : public grpc_cpp_generator::File {
 public:
  ProtoBufFile(const grpc::protobuf::FileDescriptor *file) : file_(file) {}

  grpc::string filename() const { return file_->name(); }
  grpc::string filename_without_ext() const {
    return grpc_generator::StripProto(filename());
  }

  grpc::string package() const { return file_->package(); }
  std::vector<grpc::string> package_parts() const {
    return grpc_generator::tokenize(package(), ".");
  }

  int service_count() const { return file_->service_count(); };
  std::unique_ptr<const grpc_cpp_generator::Service> service(int i) const {
    return std::unique_ptr<const grpc_cpp_generator::Service> (
          new ProtoBufService(file_->service(i)));
  }

  std::unique_ptr<grpc_cpp_generator::Printer> CreatePrinter(grpc::string *str) const {
    return std::unique_ptr<grpc_cpp_generator::Printer>(
          new ProtoBufPrinter(str));
  }

  grpc::string GetLeadingComments() const { return GetComments(file_, true); }

  grpc::string GetTrailingComments() const { return GetComments(file_, false); }

 private:
  const grpc::protobuf::FileDescriptor *file_;
};

class CppGrpcGenerator : public grpc::protobuf::compiler::CodeGenerator {
 public:
  CppGrpcGenerator() {}
  virtual ~CppGrpcGenerator() {}

  virtual bool Generate(const grpc::protobuf::FileDescriptor *file,
                        const grpc::string &parameter,
                        grpc::protobuf::compiler::GeneratorContext *context,
                        grpc::string *error) const {
    if (file->options().cc_generic_services()) {
      *error =
          "cpp grpc proto compiler plugin does not work with generic "
          "services. To generate cpp grpc APIs, please set \""
          "cc_generic_service = false\".";
      return false;
    }

    grpc_cpp_generator::Parameters generator_parameters;
    generator_parameters.use_system_headers = true;

    ProtoBufFile pbfile(file);

    if (!parameter.empty()) {
      std::vector<grpc::string> parameters_list =
        grpc_generator::tokenize(parameter, ",");
      for (auto parameter_string = parameters_list.begin();
           parameter_string != parameters_list.end();
           parameter_string++) {
        std::vector<grpc::string> param =
          grpc_generator::tokenize(*parameter_string, "=");
        if (param[0] == "services_namespace") {
          generator_parameters.services_namespace = param[1];
        } else if (param[0] == "use_system_headers") {
          if (param[1] == "true") {
            generator_parameters.use_system_headers = true;
          } else if (param[1] == "false") {
            generator_parameters.use_system_headers = false;
          } else {
            *error = grpc::string("Invalid parameter: ") + *parameter_string;
            return false;
          }
        } else if (param[0] == "grpc_search_path") {
          generator_parameters.grpc_search_path = param[1];
        } else {
          *error = grpc::string("Unknown parameter: ") + *parameter_string;
          return false;
        }
      }
    }

    grpc::string file_name = grpc_generator::StripProto(file->name());

    grpc::string header_code =
        grpc_cpp_generator::GetHeaderPrologue(&pbfile, generator_parameters) +
        grpc_cpp_generator::GetHeaderIncludes(&pbfile, generator_parameters) +
        grpc_cpp_generator::GetHeaderServices(&pbfile, generator_parameters) +
        grpc_cpp_generator::GetHeaderEpilogue(&pbfile, generator_parameters);
    std::unique_ptr<grpc::protobuf::io::ZeroCopyOutputStream> header_output(
        context->Open(file_name + ".grpc.pb.h"));
    grpc::protobuf::io::CodedOutputStream header_coded_out(
        header_output.get());
    header_coded_out.WriteRaw(header_code.data(), header_code.size());

    grpc::string source_code =
        grpc_cpp_generator::GetSourcePrologue(&pbfile, generator_parameters) +
        grpc_cpp_generator::GetSourceIncludes(&pbfile, generator_parameters) +
        grpc_cpp_generator::GetSourceServices(&pbfile, generator_parameters) +
        grpc_cpp_generator::GetSourceEpilogue(&pbfile, generator_parameters);
    std::unique_ptr<grpc::protobuf::io::ZeroCopyOutputStream> source_output(
        context->Open(file_name + ".grpc.pb.cc"));
    grpc::protobuf::io::CodedOutputStream source_coded_out(
        source_output.get());
    source_coded_out.WriteRaw(source_code.data(), source_code.size());

    return true;
  }

 private:
  // Insert the given code into the given file at the given insertion point.
  void Insert(grpc::protobuf::compiler::GeneratorContext *context,
              const grpc::string &filename, const grpc::string &insertion_point,
              const grpc::string &code) const {
    std::unique_ptr<grpc::protobuf::io::ZeroCopyOutputStream> output(
        context->OpenForInsert(filename, insertion_point));
    grpc::protobuf::io::CodedOutputStream coded_out(output.get());
    coded_out.WriteRaw(code.data(), code.size());
  }
};

int main(int argc, char *argv[]) {
  CppGrpcGenerator generator;
  return grpc::protobuf::compiler::PluginMain(argc, argv, &generator);
}