text: ////////////////////////////////////////////////////////////////////////////////
  /// DISCLAIMER
  ///
  /// Copyright 2014-2017 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 Steemann
  ////////////////////////////////////////////////////////////////////////////////
  
  #ifndef ARANGOD_COLLECTION_EXPORT_H
  #define ARANGOD_COLLECTION_EXPORT_H 1
  
  #include "Basics/Common.h"
  
  namespace arangodb {
  
  struct CollectionExport {
   public:
    struct Restrictions {
      enum Type { RESTRICTION_NONE, RESTRICTION_INCLUDE, RESTRICTION_EXCLUDE };
  
      Restrictions() : fields(), type(RESTRICTION_NONE) {}
  
      std::unordered_set<std::string> fields;
      Type type;
    };
  
    static bool IncludeAttribute(
        CollectionExport::Restrictions::Type const restrictionType,
        std::unordered_set<std::string> const& fields, std::string const& key) {
      if (restrictionType ==
              CollectionExport::Restrictions::RESTRICTION_INCLUDE ||
          restrictionType ==
              CollectionExport::Restrictions::RESTRICTION_EXCLUDE) {
        bool const keyContainedInRestrictions = (fields.find(key) != fields.end());
        if ((restrictionType ==
                CollectionExport::Restrictions::RESTRICTION_INCLUDE &&
            !keyContainedInRestrictions) ||
            (restrictionType ==
                CollectionExport::Restrictions::RESTRICTION_EXCLUDE &&
            keyContainedInRestrictions)) {
          // exclude the field
          return false;
        }
        // include the field
        return true;
      } else {
        // no restrictions
        TRI_ASSERT(restrictionType ==
                  CollectionExport::Restrictions::RESTRICTION_NONE);
        return true;
      }
      return true;
    }
  
  };
  }
  
  #endif
  