src/mongo/db/pipeline/accumulator_push.cpp


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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/>.
 */

#include "mongo/pch.h"

#include "mongo/db/pipeline/accumulator.h"
#include "mongo/db/pipeline/expression_context.h"
#include "mongo/db/pipeline/value.h"

namespace mongo {
    void AccumulatorPush::processInternal(const Value& input, bool merging) {
        if (!merging) {
            if (!input.missing()) {
                vpValue.push_back(input);
                _memUsageBytes += input.getApproximateSize();
            }
        }
        else {
            // If we're merging, we need to take apart the arrays we
            // receive and put their elements into the array we are collecting.
            // If we didn't, then we'd get an array of arrays, with one array
            // from each merge source.
            verify(input.getType() == Array);
            
            const vector<Value>& vec = input.getArray();
            vpValue.insert(vpValue.end(), vec.begin(), vec.end());

            for (size_t i=0; i < vec.size(); i++) {
                _memUsageBytes += vec[i].getApproximateSize();
            }
        }
    }

    Value AccumulatorPush::getValue(bool toBeMerged) const {
        return Value(vpValue);
    }

    AccumulatorPush::AccumulatorPush() {
        _memUsageBytes = sizeof(*this);
    }

    void AccumulatorPush::reset() {
        vector<Value>().swap(vpValue);
        _memUsageBytes = sizeof(*this);
    }

    intrusive_ptr<Accumulator> AccumulatorPush::create() {
        return new AccumulatorPush();
    }

    const char *AccumulatorPush::getOpName() const {
        return "$push";
    }
}