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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.
*/
#pragma once
#include "mongo/db/jsobj.h"
#include "mongo/db/matcher/expression_parser.h"
#include "mongo/util/mongoutils/str.h"
namespace mongo {
class ParsedProjection {
public:
// TODO: this is duplicated in here and in the proj exec code. When we have
// ProjectionExpression we can remove dups.
enum ArrayOpType { ARRAY_OP_NORMAL = 0, ARRAY_OP_ELEM_MATCH, ARRAY_OP_POSITIONAL };
/**
* Parses the projection 'spec' and checks its validity with respect to the query 'query'.
* Puts covering information into 'out'.
*
* Returns Status::OK() if it's a valid spec.
* Returns a Status indicating how it's invalid otherwise.
*/
static Status make(OperationContext* opCtx,
const BSONObj& spec,
const MatchExpression* const query,
ParsedProjection** out);
/**
* Returns true if the projection requires match details from the query,
* and false otherwise.
*/
bool requiresMatchDetails() const {
return _requiresMatchDetails;
}
/**
* Is the full document required to compute this projection?
*/
bool requiresDocument() const {
return _requiresDocument;
}
/**
* If requiresDocument() == false, what fields are required to compute
* the projection?
*
* Returned StringDatas are owned by, and have the lifetime of, the ParsedProjection.
*/
const std::vector<StringData>& getRequiredFields() const {
return _requiredFields;
}
/**
* Get the raw BSONObj proj spec obj
*/
const BSONObj& getProjObj() const {
return _source;
}
bool wantTextScore() const {
return _wantTextScore;
}
/**
* Does the projection want geoNear metadata? If so any geoNear stage should include them.
*/
bool wantGeoNearDistance() const {
return _wantGeoNearDistance;
}
bool wantGeoNearPoint() const {
return _wantGeoNearPoint;
}
bool wantIndexKey() const {
return _returnKey;
}
bool wantSortKey() const {
return _wantSortKey;
}
/**
* 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) const;
/**
* Returns true if the project contains any paths with multiple path pieces (e.g. returns true
* for {_id: 0, "a.b": 1} and returns false for {_id: 0, a: 1, b: 1}).
*/
bool hasDottedFieldPath() const {
return _hasDottedFieldPath;
}
private:
/**
* Must go through ::make
*/
ParsedProjection() = default;
/**
* Returns true if field name refers to a positional projection.
*/
static bool _isPositionalOperator(const char* fieldName);
/**
* Returns true if the MatchExpression 'query' queries against
* the field named by 'matchfield'. This deeply traverses logical
* nodes in the matchfield and returns true if any of the children
* have the field (so if 'query' is {$and: [{a: 1}, {b: 1}]} and
* 'matchfield' is "b", the return value is true).
*
* Does not take ownership of 'query'.
*/
static bool _hasPositionalOperatorMatch(const MatchExpression* const query,
const std::string& matchfield);
// Track fields needed by the projection so that the query planner can perform projection
// analysis and possibly give us a covered projection.
//
// StringDatas are owned by the ParsedProjection.
//
// The order of the fields is the order they were in the projection object.
std::vector<StringData> _requiredFields;
// _hasId determines whether the _id field of the input is included in the output.
bool _hasId = false;
// Tracks the fields that have been explicitly included and excluded, respectively, in this
// projection.
//
// StringDatas are owned by the ParsedProjection.
//
// The ordering of the paths is the order that they appeared within the projection, and should
// be maintained.
std::vector<StringData> _includedFields;
std::vector<StringData> _excludedFields;
// Tracks fields referenced within the projection that are meta or array projections,
// respectively.
//
// StringDatas are owned by the ParsedProjection.
//
// The order of the fields is not significant.
std::vector<StringData> _metaFields;
std::vector<StringData> _arrayFields;
// Tracks whether this projection is an inclusion projection, i.e., {a: 1}, or an exclusion
// projection, i.e., {a: 0}. The projection {_id: 0} is ambiguous but will result in this field
// being set to false.
bool _isInclusionProjection = false;
bool _requiresMatchDetails = false;
bool _requiresDocument = true;
BSONObj _source;
bool _wantTextScore = false;
bool _wantGeoNearDistance = false;
bool _wantGeoNearPoint = false;
bool _returnKey = false;
// Whether this projection includes a sortKey meta-projection.
bool _wantSortKey = false;
bool _hasDottedFieldPath = false;
};
} // namespace mongo
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