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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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/document_source_replace_root_gen.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 and $replaceWith stages.
*/
class ReplaceRootTransformation final : public TransformerInterface {
public:
ReplaceRootTransformation(const boost::intrusive_ptr<ExpressionContext>& expCtx,
boost::intrusive_ptr<Expression> newRootExpression)
: _expCtx(expCtx), _newRoot(std::move(newRootExpression)) {}
TransformerType getType() const final {
return TransformerType::kReplaceRoot;
}
Document applyTransformation(const Document& input) final {
// Extract subdocument in the form of a Value.
Value newRoot = _newRoot->evaluate(input, &_expCtx->variables);
// 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() == BSONType::Object);
// Turn the value into a document.
MutableDocument newDoc(newRoot.getDocument());
newDoc.copyMetaDataFrom(input);
return newDoc.freeze();
}
// Optimize the newRoot expression.
void optimize() final {
_newRoot->optimize();
}
Document serializeTransformation(
boost::optional<ExplainOptions::Verbosity> explain) const final {
return Document{{"newRoot", _newRoot->serialize(static_cast<bool>(explain))}};
}
DepsTracker::State 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 DepsTracker::State::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>{}, {}};
}
private:
const boost::intrusive_ptr<ExpressionContext> _expCtx;
boost::intrusive_ptr<Expression> _newRoot;
};
REGISTER_DOCUMENT_SOURCE(replaceRoot,
LiteParsedDocumentSourceDefault::parse,
DocumentSourceReplaceRoot::createFromBson);
REGISTER_DOCUMENT_SOURCE(replaceWith,
LiteParsedDocumentSourceDefault::parse,
DocumentSourceReplaceRoot::createFromBson);
intrusive_ptr<DocumentSource> DocumentSourceReplaceRoot::createFromBson(
BSONElement elem, const intrusive_ptr<ExpressionContext>& expCtx) {
const auto stageName = elem.fieldNameStringData();
auto newRootExpression = [&]() {
if (stageName == kAliasNameReplaceWith) {
return Expression::parseOperand(expCtx, elem, expCtx->variablesParseState);
}
invariant(
stageName == kStageName,
str::stream() << "Unexpected stage registered with DocumentSourceReplaceRoot parser: "
<< stageName);
uassert(40229,
str::stream() << "expected an object as specification for " << kStageName
<< " stage, got "
<< typeName(elem.type()),
elem.type() == Object);
auto spec =
ReplaceRootSpec::parse(IDLParserErrorContext(kStageName), elem.embeddedObject());
// The IDL doesn't give us back the type we need to feed into the expression parser, and
// the expression parser needs the extra state in 'vps' and 'expCtx', so for now we have
// to adapt the two.
BSONObj parsingBson = BSON("newRoot" << spec.getNewRoot());
return Expression::parseOperand(
expCtx, parsingBson.firstElement(), expCtx->variablesParseState);
}();
// Whether this was specified as $replaceWith or $replaceRoot, always use the name $replaceRoot
// to simplify the serialization process.
const bool isIndependentOfAnyCollection = false;
return new DocumentSourceSingleDocumentTransformation(
expCtx,
std::make_unique<ReplaceRootTransformation>(expCtx, newRootExpression),
kStageName.toString(),
isIndependentOfAnyCollection);
}
} // namespace mongo
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