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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/>.
*/
#include "mongo/pch.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/pipeline/document.h"
#include "mongo/db/pipeline/document_source.h"
#include "mongo/db/pipeline/expression.h"
#include "mongo/db/pipeline/value.h"
namespace mongo {
const char DocumentSourceProject::projectName[] = "$project";
DocumentSourceProject::DocumentSourceProject(const intrusive_ptr<ExpressionContext>& pExpCtx,
const intrusive_ptr<ExpressionObject>& exprObj)
: DocumentSource(pExpCtx)
, pEO(exprObj)
{ }
const char *DocumentSourceProject::getSourceName() const {
return projectName;
}
boost::optional<Document> DocumentSourceProject::getNext() {
pExpCtx->checkForInterrupt();
boost::optional<Document> input = pSource->getNext();
if (!input)
return boost::none;
/* create the result document */
const size_t sizeHint = pEO->getSizeHint();
MutableDocument out (sizeHint);
/*
Use the ExpressionObject to create the base result.
If we're excluding fields at the top level, leave out the _id if
it is found, because we took care of it above.
*/
pEO->addToDocument(out, *input, Variables(*input));
#if defined(_DEBUG)
if (!_simpleProjection.getSpec().isEmpty()) {
// Make sure we return the same results as Projection class
BSONObj inputBson = input->toBson();
BSONObj outputBson = out.peek().toBson();
BSONObj projected = _simpleProjection.transform(inputBson);
if (projected != outputBson) {
log() << "$project applied incorrectly: " << getRaw() << endl;
log() << "input: " << inputBson << endl;
log() << "out: " << outputBson << endl;
log() << "projected: " << projected << endl;
verify(false); // exits in _DEBUG builds
}
}
#endif
return out.freeze();
}
void DocumentSourceProject::optimize() {
intrusive_ptr<Expression> pE(pEO->optimize());
pEO = dynamic_pointer_cast<ExpressionObject>(pE);
}
Value DocumentSourceProject::serialize(bool explain) const {
return Value(DOC(getSourceName() << pEO->serialize()));
}
intrusive_ptr<DocumentSource> DocumentSourceProject::createFromBson(
BSONElement *pBsonElement,
const intrusive_ptr<ExpressionContext> &pExpCtx) {
/* validate */
uassert(15969, str::stream() << projectName <<
" specification must be an object",
pBsonElement->type() == Object);
Expression::ObjectCtx objectCtx(
Expression::ObjectCtx::DOCUMENT_OK
| Expression::ObjectCtx::TOP_LEVEL
| Expression::ObjectCtx::INCLUSION_OK
);
intrusive_ptr<Expression> parsed = Expression::parseObject(pBsonElement, &objectCtx);
ExpressionObject* exprObj = dynamic_cast<ExpressionObject*>(parsed.get());
massert(16402, "parseObject() returned wrong type of Expression", exprObj);
uassert(16403, "$projection requires at least one output field", exprObj->getFieldCount());
intrusive_ptr<DocumentSourceProject> pProject(new DocumentSourceProject(pExpCtx, exprObj));
BSONObj projectObj = pBsonElement->Obj();
pProject->_raw = projectObj.getOwned(); // probably not necessary, but better to be safe
#if defined(_DEBUG)
if (exprObj->isSimple()) {
set<string> deps;
vector<string> path;
exprObj->addDependencies(deps, &path);
pProject->_simpleProjection.init(depsToProjection(deps));
}
#endif
return pProject;
}
DocumentSource::GetDepsReturn DocumentSourceProject::getDependencies(set<string>& deps) const {
vector<string> path; // empty == top-level
pEO->addDependencies(deps, &path);
return EXHAUSTIVE;
}
}
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