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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.
*/
#pragma once
#include <memory>
#include "mongo/base/string_data.h"
#include "mongo/db/update/modifier_node.h"
namespace mongo {
class PopNode final : public ModifierNode {
public:
Status init(BSONElement modExpr, const boost::intrusive_ptr<ExpressionContext>& expCtx) final;
ModifyResult updateExistingElement(mutablebson::Element* element,
std::shared_ptr<FieldRef> elementPath) const final;
void validateUpdate(mutablebson::ConstElement updatedElement,
mutablebson::ConstElement leftSibling,
mutablebson::ConstElement rightSibling,
std::uint32_t recursionLevel,
ModifyResult modifyResult) const final;
std::unique_ptr<UpdateNode> clone() const final {
return std::make_unique<PopNode>(*this);
}
void setCollator(const CollatorInterface* collator) final {}
/**
* Returns true if this node is popping the first element off the front of the array. Returns
* false if this node is popping the last element off the back of the array.
*/
bool popFromFront() const {
return _popFromFront;
}
void acceptVisitor(UpdateNodeVisitor* visitor) final {
visitor->visit(this);
}
private:
StringData operatorName() const final {
return "$pop";
}
BSONObj operatorValue() const final {
return _popFromFront ? BSON("" << -1) : BSON("" << 1);
}
bool _popFromFront = true;
};
} // namespace mongo
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