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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.
*/
#include "mongo/platform/basic.h"
#include "mongo/base/simple_string_data_comparator.h"
#include <third_party/murmurhash3/MurmurHash3.h>
#include "mongo/base/data_type_endian.h"
#include "mongo/base/data_view.h"
namespace mongo {
namespace {
template <int SizeofSizeT>
size_t murmur3(StringData str, size_t seed);
template <>
size_t murmur3<4>(StringData str, size_t seed) {
char hash[4];
MurmurHash3_x86_32(str.rawData(), str.size(), seed, &hash);
return ConstDataView(hash).read<LittleEndian<std::uint32_t>>();
}
template <>
size_t murmur3<8>(StringData str, size_t seed) {
char hash[16];
MurmurHash3_x64_128(str.rawData(), str.size(), seed, hash);
return static_cast<size_t>(ConstDataView(hash).read<LittleEndian<std::uint64_t>>());
}
} // namespace
const SimpleStringDataComparator SimpleStringDataComparator::kInstance{};
int SimpleStringDataComparator::compare(StringData left, StringData right) const {
return left.compare(right);
}
void SimpleStringDataComparator::hash_combine(size_t& seed, StringData stringToHash) const {
seed = murmur3<sizeof(size_t)>(stringToHash, seed);
}
} // namespace mongo
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