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// string_map.h
/**
* 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 <third_party/murmurhash3/MurmurHash3.h>
#include "mongo/base/string_data.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/unordered_fast_key_table.h"
namespace mongo {
struct StringMapTraits {
static uint32_t hash(StringData a) {
uint32_t hash;
MurmurHash3_x86_32(a.rawData(), a.size(), 0, &hash);
return hash;
}
static bool equals(StringData a, StringData b) {
return a == b;
}
static std::string toStorage(StringData s) {
return s.toString();
}
static StringData toLookup(const std::string& s) {
return StringData(s);
}
class HashedKey {
public:
explicit HashedKey(StringData key = "") : _key(key), _hash(StringMapTraits::hash(_key)) {}
HashedKey(StringData key, uint32_t hash) : _key(key), _hash(hash) {
// If you claim to know the hash, it better be correct.
dassert(_hash == StringMapTraits::hash(_key));
}
const StringData& key() const {
return _key;
}
uint32_t hash() const {
return _hash;
}
private:
StringData _key;
uint32_t _hash;
};
};
template <typename V>
using StringMap = UnorderedFastKeyTable<StringData, // K_L
std::string, // K_S
V,
StringMapTraits>;
} // namespace mongo
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