text: /**
   *    Copyright (C) 2018 MongoDB Inc.
   *
   *    This program is free software: you can redistribute it and/or  modify
   *    it under the terms of the GNU Affero General Public License, version 3,
   *    as published by the Free Software Foundation.
   *
   *    This program is distributed in the hope that it will be useful,
   *    but WITHOUT ANY WARRANTY; without even the implied warranty of
   *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *    GNU Affero General Public License for more details.
   *
   *    You should have received a copy of the GNU Affero General Public License
   *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   *    As a special exception, the copyright holders give permission to link the
   *    code of portions of this program with the OpenSSL library under certain
   *    conditions as described in each individual source file and distribute
   *    linked combinations including the program with the OpenSSL library. You
   *    must comply with the GNU Affero General Public License in all respects for
   *    all of the code used other than as permitted herein. If you modify file(s)
   *    with this exception, you may extend this exception to your version of the
   *    file(s), but you are not obligated to do so. If you do not wish to do so,
   *    delete this exception statement from your version. If you delete this
   *    exception statement from all source files in the program, then also delete
   *    it in the license file.
   */
  
  #include "mongo/platform/basic.h"
  
  #include "mongo/db/command_generic_argument.h"
  
  #include <algorithm>
  #include <array>
  #include <cstdlib>
  #include <iterator>
  
  namespace mongo {
  
  namespace {
  
  struct SpecialArgRecord {
      StringData name;
      bool isGeneric : 1;
      bool stripFromRequest : 1;
      bool stripFromReply : 1;
  };
  
  // Not including "help" since we don't pass help requests through to the command parser.
  // If that changes, it should be added. When you add to this list, consider whether you
  // should also change the filterCommandRequestForPassthrough() function.
  // clang-format off
  static constexpr std::array<SpecialArgRecord, 25> specials{{
      //                                       /-isGeneric
      //                                       |  /-stripFromRequest
      //                                       |  |  /-stripFromReply
      {"$audit"_sd,                            1, 1, 0},
      {"$client"_sd,                           1, 1, 0},
      {"$configServerState"_sd,                1, 1, 1},
      {"$db"_sd,                               1, 1, 0},
      {"allowImplicitCollectionCreation"_sd,   1, 1, 0},
      {"$oplogQueryData"_sd,                   1, 1, 1},
      {"$queryOptions"_sd,                     1, 0, 0},
      {"$readPreference"_sd,                   1, 1, 0},
      {"$replData"_sd,                         1, 1, 1},
      {"$clusterTime"_sd,                      1, 1, 1},
      {"maxTimeMS"_sd,                         1, 0, 0},
      {"readConcern"_sd,                       1, 0, 0},
      {"databaseVersion"_sd,                   1, 1, 0},
      {"shardVersion"_sd,                      1, 1, 0},
      {"tracking_info"_sd,                     1, 1, 0},
      {"writeConcern"_sd,                      1, 0, 0},
      {"lsid"_sd,                              1, 0, 0},
      {"txnNumber"_sd,                         1, 0, 0},
      {"autocommit"_sd,                        1, 0, 0},
      {"startTransaction"_sd,                  1, 0, 0},
      {"stmtId"_sd,                            1, 0, 0},
      {"$gleStats"_sd,                         0, 0, 1},
      {"customerCmd"_sd,                       1, 0, 1},
      {"operationTime"_sd,                     0, 0, 1},
      {"lastCommittedOpTime"_sd,               0, 0, 1}}};
  // clang-format on
  
  const SpecialArgRecord* findSpecialArg(StringData arg) {
      for (const auto& e : specials)
          if (e.name == arg)
              return &e;
      return nullptr;
  }
  
  }  // namespace
  
  bool isGenericArgument(StringData arg) {
      auto p = findSpecialArg(arg);
      return p && p->isGeneric;
  }
  
  bool isRequestStripArgument(StringData arg) {
      auto p = findSpecialArg(arg);
      return p && p->stripFromRequest;
  }
  
  bool isReplyStripArgument(StringData arg) {
      auto p = findSpecialArg(arg);
      return p && p->stripFromReply;
  }
  
  }  // namespace mongo
  