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/**
* Copyright (C) 2017 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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/matcher/expression_leaf.h"
namespace mongo {
/**
* An InternalExprEqMatchExpression is an equality expression with similar semantics to the $eq
* expression. It differs from the regular equality match expression in the following ways:
*
* - The document will match if there is an array anywhere along the path. By always returning true
* in such cases, we match a superset of documents that the related aggregation expression would
* match. This sidesteps us having to implement field path expression evaluation as part of this
* match expression.
*
* - Equality to null matches literal nulls, but not documents in which the field path is missing or
* undefined.
*
* - Equality to an array is illegal. It is invalid usage to construct a
* InternalExprEqMatchExpression node which compares to an array.
*/
class InternalExprEqMatchExpression final : public ComparisonMatchExpressionBase {
public:
static constexpr StringData kName = "$_internalExprEq"_sd;
InternalExprEqMatchExpression(StringData path, BSONElement value)
: ComparisonMatchExpressionBase(MatchType::INTERNAL_EXPR_EQ,
path,
value,
ElementPath::LeafArrayBehavior::kNoTraversal,
ElementPath::NonLeafArrayBehavior::kMatchSubpath) {
invariant(_rhs.type() != BSONType::Undefined);
invariant(_rhs.type() != BSONType::Array);
}
StringData name() const final {
return kName;
}
bool matchesSingleElement(const BSONElement&, MatchDetails*) const final;
std::unique_ptr<MatchExpression> shallowClone() const final;
};
} // namespace mongo
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