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/**
* Copyright (C) 2015 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/exec/plan_stage.h"
namespace mongo {
/**
* Takes the output of its child and drops any results that are not in the sort order specified by
* 'pattern'. Thus, if the pattern is {a: -1} and the following documents are inputted:
* {a: 9}, {a: 6}, {a: 8}, {a, 1}
* The third document will be dropped so that the output is:
* {a: 9}, {a: 6}, {a, 1}
*/
class EnsureSortedStage final : public PlanStage {
public:
EnsureSortedStage(OperationContext* opCtx, BSONObj pattern, WorkingSet* ws, PlanStage* child);
bool isEOF() final;
StageState doWork(WorkingSetID* out) final;
StageType stageType() const final {
return STAGE_ENSURE_SORTED;
}
std::unique_ptr<PlanStageStats> getStats() final;
const SpecificStats* getSpecificStats() const final;
static const char* kStageType;
private:
/**
* Returns whether the result with the lhsSortKey should come before the result with the
* rhsSortKey in sort order.
*/
bool isInOrder(const BSONObj& lhsSortKey, const BSONObj& rhsSortKey) const;
WorkingSet* _ws;
// The pattern that we're sorting by.
BSONObj _pattern;
// The sort key of the previous result.
BSONObj _prevSortKey;
EnsureSortedStats _specificStats;
};
} // namespace mongo
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