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/**
* Copyright (C) 2019-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.
*/
#pragma once
#include "mongo/db/query/projection_ast.h"
#include "mongo/util/str.h"
namespace mongo {
namespace projection_ast {
/**
* Summary of the dependency analysis done on the projection AST.
*/
struct ProjectionDependencies {
// Whether MatchDetails of the query's filter are required.
bool requiresMatchDetails = false;
// Whether the entire document is required to do the projection.
bool requiresDocument = false;
// Which fields are necessary to perform the projection, or boost::none if all are required.
boost::optional<std::vector<std::string>> requiredFields;
bool needsGeoDistance = false;
bool needsGeoPoint = false;
bool needsSortKey = false;
bool needsTextScore = false;
bool hasDottedPath = false;
};
/**
* Used to represent a projection for dependency analysis and query planning.
*/
enum class ProjectType { kInclusion, kExclusion };
class Projection {
public:
Projection(ProjectionPathASTNode root, ProjectType type, const BSONObj& bson);
ProjectionPathASTNode* root() {
return &_root;
}
ProjectType type() const {
return _type;
}
/**
* Returns true if the projection requires match details from the query,
* and false otherwise.
*/
bool requiresMatchDetails() const {
return _deps.requiresMatchDetails;
}
/**
* Returns whether the full document is required to compute this projection.
*/
bool requiresDocument() const {
return _deps.requiresDocument;
}
/**
* Return which fields are required to compute the projection, assuming the entire document is
* not needed.
*/
const std::vector<std::string>& getRequiredFields() const {
invariant(_type == ProjectType::kInclusion);
return *_deps.requiredFields;
}
/**
* Does the projection want geoNear metadata? If so any geoNear stage should include them.
*/
bool wantGeoNearDistance() const {
return _deps.needsGeoDistance;
}
bool wantGeoNearPoint() const {
return _deps.needsGeoPoint;
}
bool wantSortKey() const {
return _deps.needsSortKey;
}
bool wantTextScore() const {
return _deps.needsTextScore;
}
/**
* Returns true if the element at 'path' is preserved entirely after this projection is applied,
* and false otherwise. For example, the projection {a: 1} will preserve the element located at
* 'a.b', and the projection {'a.b': 0} will not preserve the element located at 'a'.
*/
bool isFieldRetainedExactly(StringData path);
/**
* TODO SERVER-42423: Delete this method and _bson.
*
* This method is deprecated and new call sites should not be added.
*/
BSONObj getProjObj() const {
return _bson;
}
/**
* A projection is considered "simple" if it doesn't require the full document, operates only
* on top-level fields, has no positional projection, and doesn't require the sort key.
*/
bool isSimple() const {
return !_deps.hasDottedPath && !_deps.requiresMatchDetails && !_deps.needsSortKey &&
!_deps.requiresDocument;
}
private:
ProjectionPathASTNode _root;
ProjectType _type;
ProjectionDependencies _deps;
// Do NOT add new usages of this.
BSONObj _bson;
};
} // namespace projection_ast
} // namespace mongo
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