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/**
* Copyright (C) 2023-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/db/bson/dotted_path_support.h"
#include "mongo/db/hasher.h"
#include "mongo/db/matcher/expression_leaf.h"
namespace mongo {
/**
* An internal match expression node which represents a field path's hash being equal to the given
* NumberLong constant. This expression is not intended to be written directly by users, but rather
* generated by a rewrite of {$expr: {$eq: [{$toHashedIndexKey: '$fieldPath'}, NumberLong(123)]}}.
* The purpose of this is to allow us to generate index bounds on a hashed index to satisfy such a
* query.
*/
class InternalEqHashedKey : public ComparisonMatchExpressionBase {
public:
static constexpr StringData kName = "$_internalEqHash"_sd;
InternalEqHashedKey(boost::optional<StringData> path, long long hashVal)
: ComparisonMatchExpressionBase(MatchType::INTERNAL_EQ_HASHED_KEY,
path,
Value(hashVal),
// Match the agg expression semantics for traversals.
ElementPath::LeafArrayBehavior::kNoTraversal,
ElementPath::NonLeafArrayBehavior::kMatchSubpath) {}
InternalEqHashedKey(std::string path, long long hashVal)
: InternalEqHashedKey(boost::optional<StringData>(path), hashVal) {}
InternalEqHashedKey(boost::optional<StringData> path, BSONElement value)
// Checking the type should happen earlier during parsing.
: InternalEqHashedKey(path, value.numberLong()) {}
bool matchesSingleElement(const BSONElement& elem, MatchDetails* details) const final {
tassert(7281401, "hashed value must be a long", _rhs.type() == BSONType::NumberLong);
const auto hashVal = BSONElementHasher::hash64(elem, BSONElementHasher::DEFAULT_HASH_SEED);
return hashVal == _rhs.numberLong();
};
std::unique_ptr<MatchExpression> clone() const final {
auto clone = std::make_unique<InternalEqHashedKey>(path(), _rhs);
clone->setCollator(_collator);
if (getTag()) {
clone->setTag(getTag()->clone());
}
return clone;
}
bool matches(const MatchableDocument* doc, MatchDetails* details = nullptr) const override {
// Sadly, we need to match EOO elements to null index keys, as a special case.
if (!dotted_path_support::extractElementAtPath(doc->toBSON(), path())) {
return BSONElementHasher::hash64(BSON("" << BSONNULL).firstElement(),
BSONElementHasher::DEFAULT_HASH_SEED) ==
_rhs.numberLong();
}
// Otherwise, we let this traversal work for us.
return PathMatchExpression::matches(doc, details);
}
StringData name() const final {
return kName;
}
void acceptVisitor(MatchExpressionMutableVisitor* visitor) final {
visitor->visit(this);
}
void acceptVisitor(MatchExpressionConstVisitor* visitor) const final {
visitor->visit(this);
}
};
} // namespace mongo
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