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/**
* Copyright 2016 (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_replace_root.h"
#include <boost/smart_ptr/intrusive_ptr.hpp>
#include "mongo/db/jsobj.h"
#include "mongo/db/pipeline/document.h"
#include "mongo/db/pipeline/expression.h"
#include "mongo/db/pipeline/lite_parsed_document_source.h"
#include "mongo/db/pipeline/value.h"
namespace mongo {
using boost::intrusive_ptr;
/**
* This class implements the transformation logic for the $replaceRoot stage.
*/
class ReplaceRootTransformation final
: public DocumentSourceSingleDocumentTransformation::TransformerInterface {
public:
ReplaceRootTransformation(const boost::intrusive_ptr<ExpressionContext>& expCtx)
: _expCtx(expCtx) {}
Document applyTransformation(const Document& input) final {
// Extract subdocument in the form of a Value.
Value newRoot = _newRoot->evaluate(input);
// The newRoot expression, if it exists, must evaluate to an object.
uassert(40228,
str::stream()
<< "'newRoot' expression must evaluate to an object, but resulting value was: "
<< newRoot.toString()
<< ". Type of resulting value: '"
<< typeName(newRoot.getType())
<< "'. Input document: "
<< input.toString(),
newRoot.getType() == Object);
// Turn the value into a document.
return newRoot.getDocument();
}
// Optimize the newRoot expression.
void optimize() final {
_newRoot->optimize();
}
Document serialize(boost::optional<ExplainOptions::Verbosity> explain) const final {
return Document{{"newRoot", _newRoot->serialize(static_cast<bool>(explain))}};
}
DocumentSource::GetDepsReturn addDependencies(DepsTracker* deps) const final {
_newRoot->addDependencies(deps);
// This stage will replace the entire document with a new document, so any existing fields
// will be replaced and cannot be required as dependencies.
return DocumentSource::EXHAUSTIVE_FIELDS;
}
DocumentSource::GetModPathsReturn getModifiedPaths() const final {
// Replaces the entire root, so all paths are modified.
return {DocumentSource::GetModPathsReturn::Type::kAllPaths, std::set<std::string>{}, {}};
}
// Create the replaceRoot transformer. Uasserts on invalid input.
static std::unique_ptr<ReplaceRootTransformation> create(
const boost::intrusive_ptr<ExpressionContext>& expCtx, const BSONElement& spec) {
// Confirm that the stage was called with an object.
uassert(40229,
str::stream() << "expected an object as specification for $replaceRoot stage, got "
<< typeName(spec.type()),
spec.type() == Object);
// Create the pointer, parse the stage, and return.
std::unique_ptr<ReplaceRootTransformation> parsedReplaceRoot =
stdx::make_unique<ReplaceRootTransformation>(expCtx);
parsedReplaceRoot->parse(expCtx, spec);
return parsedReplaceRoot;
}
// Check for valid replaceRoot options, and populate internal state variables.
void parse(const boost::intrusive_ptr<ExpressionContext>& expCtx, const BSONElement& spec) {
// We need a VariablesParseState in order to parse the 'newRoot' expression.
VariablesParseState vps = expCtx->variablesParseState;
// Get the options from this stage. Currently the only option is newRoot.
for (auto&& argument : spec.Obj()) {
const StringData argName = argument.fieldNameStringData();
if (argName == "newRoot") {
// Allows for field path, object, and other expressions.
_newRoot = Expression::parseOperand(expCtx, argument, vps);
} else {
uasserted(40230,
str::stream() << "unrecognized option to $replaceRoot stage: " << argName
<< ", only valid option is 'newRoot'.");
}
}
// Check that there was a new root specified.
uassert(40231, "no newRoot specified for the $replaceRoot stage", _newRoot);
}
private:
boost::intrusive_ptr<Expression> _newRoot;
const boost::intrusive_ptr<ExpressionContext> _expCtx;
};
REGISTER_DOCUMENT_SOURCE(replaceRoot,
LiteParsedDocumentSourceDefault::parse,
DocumentSourceReplaceRoot::createFromBson);
intrusive_ptr<DocumentSource> DocumentSourceReplaceRoot::createFromBson(
BSONElement elem, const intrusive_ptr<ExpressionContext>& pExpCtx) {
return new DocumentSourceSingleDocumentTransformation(
pExpCtx, ReplaceRootTransformation::create(pExpCtx, elem), "$replaceRoot");
}
} // namespace mongo
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