text: // Copyright 2018-present MongoDB Inc.
  //
  // 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.
  
  #pragma once
  
  #include <mongocxx/config/prelude.hpp>
  
  #include <bsoncxx/oid.hpp>
  #include <mongocxx/events/topology_description.hpp>
  
  namespace mongocxx {
  MONGOCXX_INLINE_NAMESPACE_BEGIN
  
  namespace events {
  
  ///
  /// An event notification sent when the driver observes a change in any of the servers it is
  /// connected to or a change in the overall server topology.
  ///
  /// @see "TopologyDescriptionChangedEvent" in
  /// https://github.com/mongodb/specifications/blob/master/source/server-discovery-and-monitoring/server-discovery-and-monitoring-monitoring.rst
  ///
  class MONGOCXX_API topology_changed_event {
     public:
      MONGOCXX_PRIVATE explicit topology_changed_event(const void* event);
  
      ///
      /// Destroys a topology_changed_event.
      ///
      ~topology_changed_event();
  
      ///
      /// An opaque id, unique to this topology for this mongocxx::client or mongocxx::pool.
      ///
      /// @return The id.
      ///
      bsoncxx::oid topology_id() const;
  
      ///
      /// The server's description before it changed.
      ///
      /// @return The topology_description.
      ///
      topology_description previous_description() const;
  
      ///
      /// The server's description after it changed.
      ///
      /// @return The topology_description.
      ///
      topology_description new_description() const;
  
     private:
      const void* _event;
  };
  
  }  // namespace events
  MONGOCXX_INLINE_NAMESPACE_END
  }  // namespace mongocxx
  
  #include <mongocxx/config/postlude.hpp>
  