text: ////////////////////////////////////////////////////////////////////////////////
  /// DISCLAIMER
  ///
  /// Copyright 2014-2021 ArangoDB GmbH, Cologne, Germany
  /// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
  ///
  /// 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.
  ///
  /// Copyright holder is ArangoDB GmbH, Cologne, Germany
  ///
  /// @author Jan Christoph Uhde
  ////////////////////////////////////////////////////////////////////////////////
  
  #ifndef ARANGODB_META_UTILITY_H
  #define ARANGODB_META_UTILITY_H 1
  
  #include <memory>
  
  namespace arangodb {
  namespace meta {
  
  ////////////////////////////////////////////////////////////////////////////////
  /// @brief adjusts constness of 'Out' according to 'In'
  ////////////////////////////////////////////////////////////////////////////////
  template <typename In, typename Out>
  struct adjustConst {
    typedef Out value_type;
    typedef Out& reference;
    typedef Out* pointer;
  };
  
  template <typename In, typename Out>
  struct adjustConst<const In, Out> {
    typedef const Out value_type;
    typedef const Out& reference;
    typedef const Out* pointer;
  };
  
  template <class T, class U = T>
  T exchange(T& obj, U&& new_value) {
    T old_value = std::move(obj);
    obj = std::forward<U>(new_value);
    return old_value;
  }
  
  }  // namespace meta
  }  // namespace arangodb
  #endif
  