text: /**
   *    Copyright (C) 2018-present MongoDB, Inc.
   *
   *    This program is free software: you can redistribute it and/or modify
   *    it under the terms of the Server Side Public License, version 1,
   *    as published by MongoDB, Inc.
   *
   *    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
   *    Server Side Public License for more details.
   *
   *    You should have received a copy of the Server Side Public License
   *    along with this program. If not, see
   *    <http://www.mongodb.com/licensing/server-side-public-license>.
   *
   *    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 Server Side 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.
   */
  
  #pragma once
  
  #include "mongo/platform/basic.h"
  
  #include "mongo/bson/bsontypes.h"
  
  namespace mongo {
  
  /**
   * When evaluating the $type operator, it's handy to be able to represent a set of BSONTypes as a
   * bitmask, where each bit in the bitmask represents a different BSONType. Specifically, we use
   * bit 0 to represent the MinKey type, bit 31 to represent the MaxKey type, and for all other
   * BSONTypes we use bit N to represent (BSONType)(N). Because in practice aren't any real values
   * of type EOO, there is no bit assigned to represent the EOO type.
   *
   * getBSONTypeMask(t) returns a mask where the bit representing BSONType t is 1 and all the other
   * bits are 0. For EOO, getBSONTypeMask() returns 0.
   *
   * To build a bitmask representing a set containing multiple BSONTypes t1,t2,..,tN, the bitwise-or
   * operator can be used to combine results of getBSONTypeMask() like so:
   *   getBSONTypeMask(t1) | getBSONTypeMask(t2) | .. | getBSONTypeMask(tN)
   *
   * To test whether a bitmask representing a set of BSONTypes `mask` contains a given BSONType t,
   * the bitwise-and operator can be used like so:
   *   (mask & getBSONTypeMask(t)) != 0
   */
  inline uint32_t getBSONTypeMask(BSONType t) noexcept {
      switch (t) {
          case BSONType::EOO:
              return 0;
          case BSONType::MinKey:
              return uint32_t{1} << 0;
          case BSONType::MaxKey:
              return uint32_t{1} << 31;
          default:
              return uint32_t{1} << static_cast<uint8_t>(t);
      }
  }
  
  }  // namespace mongo
  