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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/bson/bson_comparator_interface_base.h"
#include <boost/functional/hash.hpp>
#include "mongo/base/simple_string_data_comparator.h"
#include "mongo/bson/bsonelement.h"
#include "mongo/bson/bsonobj.h"
#include "mongo/bson/simple_bsonobj_comparator.h"
namespace mongo {
template <typename T>
void BSONComparatorInterfaceBase<T>::hashCombineBSONObj(
size_t& seed,
const BSONObj& objToHash,
ComparisonRulesSet rules,
const StringData::ComparatorInterface* stringComparator) {
if (rules & ComparisonRules::kIgnoreFieldOrder) {
BSONObjIteratorSorted iter(objToHash);
while (iter.more()) {
hashCombineBSONElement(seed, iter.next(), rules, stringComparator);
}
} else {
for (auto elem : objToHash) {
hashCombineBSONElement(seed, elem, rules, stringComparator);
}
}
}
template <typename T>
void BSONComparatorInterfaceBase<T>::hashCombineBSONElement(
size_t& hash,
BSONElement elemToHash,
ComparisonRulesSet rules,
const StringData::ComparatorInterface* stringComparator) {
boost::hash_combine(hash, elemToHash.canonicalType());
const StringData fieldName = elemToHash.fieldNameStringData();
if ((rules & ComparisonRules::kConsiderFieldName) && !fieldName.empty()) {
SimpleStringDataComparator::kInstance.hash_combine(hash, fieldName);
}
switch (elemToHash.type()) {
case mongo::EOO:
case mongo::Undefined:
case mongo::jstNULL:
case mongo::MaxKey:
case mongo::MinKey:
// These are valueless types
break;
case mongo::Bool:
boost::hash_combine(hash, elemToHash.boolean());
break;
case mongo::bsonTimestamp:
boost::hash_combine(hash, elemToHash.timestamp().asULL());
break;
case mongo::Date:
boost::hash_combine(hash, elemToHash.date().asInt64());
break;
case mongo::NumberDecimal: {
const Decimal128 dcml = elemToHash.numberDecimal();
if (dcml.toAbs().isGreater(Decimal128(std::numeric_limits<double>::max(),
Decimal128::kRoundTo34Digits,
Decimal128::kRoundTowardZero)) &&
!dcml.isInfinite() && !dcml.isNaN()) {
// Normalize our decimal to force equivalent decimals
// in the same cohort to hash to the same value
Decimal128 dcmlNorm(dcml.normalize());
boost::hash_combine(hash, dcmlNorm.getValue().low64);
boost::hash_combine(hash, dcmlNorm.getValue().high64);
break;
}
// Else, fall through and convert the decimal to a double and hash.
// At this point the decimal fits into the range of doubles, is infinity, or is NaN,
// which doubles have a cheaper representation for.
[[fallthrough]];
}
case mongo::NumberDouble:
case mongo::NumberLong:
case mongo::NumberInt: {
// This converts all numbers to doubles, which ignores the low-order bits of
// NumberLongs > 2**53 and precise decimal numbers without double representations,
// but that is ok since the hash will still be the same for equal numbers and is
// still likely to be different for different numbers. (Note: this issue only
// applies for decimals when they are outside of the valid double range. See
// the above case.)
// SERVER-16851
const double dbl = elemToHash.numberDouble();
if (std::isnan(dbl)) {
boost::hash_combine(hash, std::numeric_limits<double>::quiet_NaN());
} else {
boost::hash_combine(hash, dbl);
}
break;
}
case mongo::jstOID:
elemToHash.__oid().hash_combine(hash);
break;
case mongo::String: {
if (stringComparator) {
stringComparator->hash_combine(hash, elemToHash.valueStringData());
} else {
SimpleStringDataComparator::kInstance.hash_combine(hash,
elemToHash.valueStringData());
}
break;
}
case mongo::Code:
case mongo::Symbol:
SimpleStringDataComparator::kInstance.hash_combine(hash, elemToHash.valueStringData());
break;
case mongo::Object:
case mongo::Array:
hashCombineBSONObj(hash,
elemToHash.embeddedObject(),
rules | ComparisonRules::kConsiderFieldName,
stringComparator);
break;
case mongo::DBRef:
case mongo::BinData:
// All bytes of the value are required to be identical.
SimpleStringDataComparator::kInstance.hash_combine(
hash, StringData(elemToHash.value(), elemToHash.valuesize()));
break;
case mongo::RegEx:
SimpleStringDataComparator::kInstance.hash_combine(hash, elemToHash.regex());
SimpleStringDataComparator::kInstance.hash_combine(hash, elemToHash.regexFlags());
break;
case mongo::CodeWScope: {
SimpleStringDataComparator::kInstance.hash_combine(
hash, StringData(elemToHash.codeWScopeCode(), elemToHash.codeWScopeCodeLen()));
hashCombineBSONObj(hash,
elemToHash.codeWScopeObject(),
rules | ComparisonRules::kConsiderFieldName,
&SimpleStringDataComparator::kInstance);
break;
}
}
}
template class BSONComparatorInterfaceBase<BSONObj>;
template class BSONComparatorInterfaceBase<BSONElement>;
} // namespace mongo
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