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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.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/pipeline/accumulator.h"
#include "mongo/db/pipeline/accumulation_statement.h"
#include "mongo/db/pipeline/value.h"
namespace mongo {
using boost::intrusive_ptr;
REGISTER_ACCUMULATOR(first, AccumulatorFirst::create);
const char* AccumulatorFirst::getOpName() const {
return "$first";
}
void AccumulatorFirst::processInternal(const Value& input, bool merging) {
/* only remember the first value seen */
if (!_haveFirst) {
// can't use pValue.missing() since we want the first value even if missing
_haveFirst = true;
_first = input;
_memUsageBytes = sizeof(*this) + input.getApproximateSize() - sizeof(Value);
}
}
Value AccumulatorFirst::getValue(bool toBeMerged) {
return _first;
}
AccumulatorFirst::AccumulatorFirst(const boost::intrusive_ptr<ExpressionContext>& expCtx)
: Accumulator(expCtx), _haveFirst(false) {
_memUsageBytes = sizeof(*this);
}
void AccumulatorFirst::reset() {
_haveFirst = false;
_first = Value();
_memUsageBytes = sizeof(*this);
}
intrusive_ptr<Accumulator> AccumulatorFirst::create(
const boost::intrusive_ptr<ExpressionContext>& expCtx) {
return new AccumulatorFirst(expCtx);
}
}
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