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/**
* 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
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