text: // Copyright 2021 Google LLC
  //
  // 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
  //
  //     https://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.
  
  #ifndef GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_COMMON_OPTIONS_H
  #define GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_COMMON_OPTIONS_H
  
  #include "google/cloud/options.h"
  #include "google/cloud/version.h"
  #include <set>
  #include <string>
  #include <vector>
  
  namespace google {
  namespace cloud {
  GOOGLE_CLOUD_CPP_INLINE_NAMESPACE_BEGIN
  
  /**
   * Change the endpoint.
   *
   * In almost all cases a suitable default will be chosen automatically.
   * Applications may need to be changed to (1) test against a fake or simulator,
   * or (2) use a beta or EAP version of the service.
   */
  struct EndpointOption {
    using Type = std::string;
  };
  
  /**
   * User-agent products to include with each request.
   *
   * Libraries or services that use Cloud C++ clients may want to set their own
   * user-agent product information. This can help them develop telemetry
   * information about number of users running particular versions of their
   * system or library.
   *
   * @see https://tools.ietf.org/html/rfc7231#section-5.5.3
   */
  struct UserAgentProductsOption {
    using Type = std::vector<std::string>;
  };
  
  /**
   * Return whether tracing is enabled for the given @p component.
   *
   * The C++ clients can log interesting events to help library and application
   * developers troubleshoot problems. To see log messages (maybe lots) you can
   * enable tracing for the component that interests you. Valid components are
   * currently:
   *
   * - rpc
   * - rpc-streams
   */
  struct TracingComponentsOption {
    using Type = std::set<std::string>;
  };
  
  /**
   * A list of all the common options.
   */
  using CommonOptionList = OptionList<EndpointOption, UserAgentProductsOption,
                                      TracingComponentsOption>;
  
  GOOGLE_CLOUD_CPP_INLINE_NAMESPACE_END
  }  // namespace cloud
  }  // namespace google
  
  #endif  // GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_COMMON_OPTIONS_H
  