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/**
* Copyright (C) 2013 10gen 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 <boost/scoped_ptr.hpp>
#include <string>
#include "mongo/base/status.h"
#include "mongo/db/query/runner.h"
namespace mongo {
class BSONObj;
class CanonicalQuery;
class DiskLoc;
class TypeExplain;
struct PlanInfo;
/**
* EOFRunner is EOF immediately and doesn't do anything except return EOF and possibly die
* during a yield.
*/
class EOFRunner : public Runner {
public:
/* Takes ownership */
EOFRunner(CanonicalQuery* cq, const std::string& ns);
virtual ~EOFRunner();
virtual Runner::RunnerState getNext(BSONObj* objOut, DiskLoc* dlOut);
virtual bool isEOF();
virtual void saveState();
virtual bool restoreState(OperationContext* opCtx);
virtual void invalidate(const DiskLoc& dl, InvalidationType type);
virtual const std::string& ns();
virtual void kill();
// this can return NULL since we never yield or anything over it
virtual const Collection* collection() { return NULL; }
/**
* Always returns OK, allocating and filling in '*explain' with a fake ("zeroed")
* collection scan plan. Fills in '*planInfo' with information indicating an
* EOF runner. Caller owns '*explain', though.
*/
virtual Status getInfo(TypeExplain** explain,
PlanInfo** planInfo) const;
private:
boost::scoped_ptr<CanonicalQuery> _cq;
std::string _ns;
};
} // namespace mongo
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