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/**
* Copyright (c) 2011 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 "mongo/pch.h"
#include <boost/unordered_set.hpp>
#include "mongo/bson/bsontypes.h"
#include "mongo/db/pipeline/value.h"
namespace mongo {
class Accumulator : public RefCountable {
public:
/** Process input and update internal state.
* merging should be true when processing outputs from getValue(true).
*/
void process(const Value& input, bool merging) {
processInternal(input, merging);
}
/** Marks the end of the evaluate() phase and return accumulated result.
* toBeMerged should be true when the outputs will be merged by process().
*/
virtual Value getValue(bool toBeMerged) const = 0;
/// The name of the op as used in a serialization of the pipeline.
virtual const char* getOpName() const = 0;
int memUsageForSorter() const {
dassert(_memUsageBytes != 0); // This would mean subclass didn't set it
return _memUsageBytes;
}
/// Reset this accumulator to a fresh state ready to receive input.
virtual void reset() = 0;
protected:
Accumulator() : _memUsageBytes(0) {}
/// Update subclass's internal state based on input
virtual void processInternal(const Value& input, bool merging) = 0;
/// subclasses are expected to update this as necessary
int _memUsageBytes;
};
class AccumulatorAddToSet : public Accumulator {
public:
virtual void processInternal(const Value& input, bool merging);
virtual Value getValue(bool toBeMerged) const;
virtual const char* getOpName() const;
virtual void reset();
static intrusive_ptr<Accumulator> create();
private:
AccumulatorAddToSet();
typedef boost::unordered_set<Value, Value::Hash> SetType;
SetType set;
};
class AccumulatorFirst : public Accumulator {
public:
virtual void processInternal(const Value& input, bool merging);
virtual Value getValue(bool toBeMerged) const;
virtual const char* getOpName() const;
virtual void reset();
static intrusive_ptr<Accumulator> create();
private:
AccumulatorFirst();
bool _haveFirst;
Value _first;
};
class AccumulatorLast : public Accumulator {
public:
virtual void processInternal(const Value& input, bool merging);
virtual Value getValue(bool toBeMerged) const;
virtual const char* getOpName() const;
virtual void reset();
static intrusive_ptr<Accumulator> create();
private:
AccumulatorLast();
Value _last;
};
class AccumulatorSum : public Accumulator {
public:
virtual void processInternal(const Value& input, bool merging);
virtual Value getValue(bool toBeMerged) const;
virtual const char* getOpName() const;
virtual void reset();
static intrusive_ptr<Accumulator> create();
private:
AccumulatorSum();
BSONType totalType;
long long longTotal;
double doubleTotal;
};
class AccumulatorMinMax : public Accumulator {
public:
virtual void processInternal(const Value& input, bool merging);
virtual Value getValue(bool toBeMerged) const;
virtual const char* getOpName() const;
virtual void reset();
static intrusive_ptr<Accumulator> createMin();
static intrusive_ptr<Accumulator> createMax();
private:
AccumulatorMinMax(int theSense);
Value _val;
const int _sense; /* 1 for min, -1 for max; used to "scale" comparison */
};
class AccumulatorPush : public Accumulator {
public:
virtual void processInternal(const Value& input, bool merging);
virtual Value getValue(bool toBeMerged) const;
virtual const char* getOpName() const;
virtual void reset();
static intrusive_ptr<Accumulator> create();
private:
AccumulatorPush();
std::vector<Value> vpValue;
};
class AccumulatorAvg : public Accumulator {
public:
virtual void processInternal(const Value& input, bool merging);
virtual Value getValue(bool toBeMerged) const;
virtual const char* getOpName() const;
virtual void reset();
static intrusive_ptr<Accumulator> create();
private:
AccumulatorAvg();
double _total;
long long _count;
};
}
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