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/**
* Copyright 2011 (c) 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/document_source.h"
#include <boost/optional.hpp>
#include <boost/smart_ptr/intrusive_ptr.hpp>
#include "mongo/db/pipeline/document.h"
#include "mongo/db/pipeline/expression.h"
#include "mongo/db/pipeline/parsed_aggregation_projection.h"
#include "mongo/db/pipeline/value.h"
#include "mongo/stdx/memory.h"
namespace mongo {
using boost::intrusive_ptr;
using parsed_aggregation_projection::ParsedAggregationProjection;
using parsed_aggregation_projection::ProjectionType;
DocumentSourceProject::DocumentSourceProject(
const intrusive_ptr<ExpressionContext>& expCtx,
std::unique_ptr<ParsedAggregationProjection> parsedProject)
: DocumentSource(expCtx), _parsedProject(std::move(parsedProject)) {}
REGISTER_DOCUMENT_SOURCE(project, DocumentSourceProject::createFromBson);
const char* DocumentSourceProject::getSourceName() const {
return "$project";
}
boost::optional<Document> DocumentSourceProject::getNext() {
pExpCtx->checkForInterrupt();
auto input = pSource->getNext();
if (!input) {
return boost::none;
}
return _parsedProject->applyProjection(*input);
}
intrusive_ptr<DocumentSource> DocumentSourceProject::optimize() {
_parsedProject->optimize();
return this;
}
Pipeline::SourceContainer::iterator DocumentSourceProject::optimizeAt(
Pipeline::SourceContainer::iterator itr, Pipeline::SourceContainer* container) {
invariant(*itr == this);
auto nextSkip = dynamic_cast<DocumentSourceSkip*>((*std::next(itr)).get());
auto nextLimit = dynamic_cast<DocumentSourceLimit*>((*std::next(itr)).get());
if (nextSkip || nextLimit) {
// Swap the $limit/$skip before ourselves, thus reducing the number of documents that
// pass through the $project.
std::swap(*itr, *std::next(itr));
return itr == container->begin() ? itr : std::prev(itr);
}
return std::next(itr);
}
void DocumentSourceProject::dispose() {
_parsedProject.reset();
}
Value DocumentSourceProject::serialize(bool explain) const {
return Value(Document{{getSourceName(), _parsedProject->serialize(explain)}});
}
intrusive_ptr<DocumentSource> DocumentSourceProject::createFromBson(
BSONElement elem, const intrusive_ptr<ExpressionContext>& expCtx) {
uassert(15969, "$project specification must be an object", elem.type() == Object);
return new DocumentSourceProject(expCtx, ParsedAggregationProjection::create(elem.Obj()));
}
DocumentSource::GetDepsReturn DocumentSourceProject::getDependencies(DepsTracker* deps) const {
// Add any fields referenced by the projection.
_parsedProject->addDependencies(deps);
if (_parsedProject->getType() == ProjectionType::kInclusion) {
// Stop looking for further dependencies later in the pipeline, since anything that is not
// explicitly included or added in this projection will not exist after this stage, so would
// be pointless to include in our dependencies.
return EXHAUSTIVE_FIELDS;
} else {
return SEE_NEXT;
}
}
void DocumentSourceProject::doInjectExpressionContext() {
_parsedProject->injectExpressionContext(pExpCtx);
}
} // namespace mongo
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