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/**
* Copyright (C) 2016 MongoDB, 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.
*/
#pragma once
#include "mongo/platform/basic.h"
#include <boost/intrusive_ptr.hpp>
#include <memory>
#include "mongo/bson/bsonelement.h"
#include "mongo/db/pipeline/document_source_single_document_transformation.h"
#include "mongo/db/pipeline/field_path.h"
namespace mongo {
class BSONObj;
class Document;
class ExpressionContext;
namespace parsed_aggregation_projection {
enum class ProjectionType { kExclusion, kInclusion, kComputed };
/**
* This class ensures that the specification was valid: that none of the paths specified conflict
* with one another, that there is at least one field, etc. Here "projection" includes both
* $project specifications and $addFields specifications.
*/
class ProjectionSpecValidator {
public:
/**
* Returns a Status: either a Status::OK() if the specification is valid for a projection, or a
* non-OK Status, error number, and message with why not.
*/
static Status validate(const BSONObj& spec);
private:
ProjectionSpecValidator(const BSONObj& spec) : _rawObj(spec) {}
/**
* Uses '_seenPaths' to see if 'path' conflicts with any paths that have already been specified.
*
* For example, a user is not allowed to specify {'a': 1, 'a.b': 1}, or some similar conflicting
* paths.
*/
Status ensurePathDoesNotConflictOrThrow(StringData path);
/**
* Returns the relevant error if an invalid projection specification is detected.
*/
Status validate();
/**
* Parses a single BSONElement. 'pathToElem' should include the field name of 'elem'.
*
* Delegates to parseSubObject() if 'elem' is an object. Otherwise adds the full path to 'elem'
* to '_seenPaths'.
*
* Calls ensurePathDoesNotConflictOrThrow with the path to this element, which sets the _status
* appropriately for conflicting path specifications.
*/
Status parseElement(const BSONElement& elem, const FieldPath& pathToElem);
/**
* Traverses 'thisLevelSpec', parsing each element in turn.
*
* Sets _status appropriately if any paths conflict with each other or existing paths,
* 'thisLevelSpec' contains a dotted path, or if 'thisLevelSpec' represents an invalid
* expression.
*/
Status parseNestedObject(const BSONObj& thisLevelSpec, const FieldPath& prefix);
// The original object. Used to generate more helpful error messages.
const BSONObj& _rawObj;
// Tracks which paths we've seen to ensure no two paths conflict with each other.
// Can be a vector since we iterate through it.
std::vector<std::string> _seenPaths;
};
/**
* A ParsedAggregationProjection is responsible for parsing and executing a $project. It
* represents either an inclusion or exclusion projection. This is the common interface between the
* two types of projections.
*/
class ParsedAggregationProjection
: public DocumentSourceSingleDocumentTransformation::TransformerInterface {
public:
/**
* Main entry point for a ParsedAggregationProjection.
*
* Throws a UserException if 'spec' is an invalid projection specification.
*/
static std::unique_ptr<ParsedAggregationProjection> create(
const boost::intrusive_ptr<ExpressionContext>& expCtx, const BSONObj& spec);
virtual ~ParsedAggregationProjection() = default;
/**
* Returns the type of projection represented by this ParsedAggregationProjection.
*/
virtual ProjectionType getType() const = 0;
/**
* Parse the user-specified BSON object 'spec'. By the time this is called, 'spec' has already
* been verified to not have any conflicting path specifications, and not to mix and match
* inclusions and exclusions. 'variablesParseState' is used by any contained expressions to
* track which variables are defined so that they can later be referenced at execution time.
*/
virtual void parse(const BSONObj& spec) = 0;
/**
* Optimize any expressions contained within this projection.
*/
virtual void optimize() {}
/**
* Add any dependencies needed by this projection or any sub-expressions to 'deps'.
*/
virtual DocumentSource::GetDepsReturn addDependencies(DepsTracker* deps) const {
return DocumentSource::NOT_SUPPORTED;
}
/**
* Apply the projection transformation.
*/
Document applyTransformation(Document input) {
return applyProjection(input);
}
protected:
ParsedAggregationProjection(const boost::intrusive_ptr<ExpressionContext>& expCtx)
: _expCtx(expCtx){};
/**
* Apply the projection to 'input'.
*/
virtual Document applyProjection(Document input) const = 0;
boost::intrusive_ptr<ExpressionContext> _expCtx;
};
} // namespace parsed_aggregation_projection
} // namespace mongo
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