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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 <memory>
#include <utility>
#include "mongo/client/connpool.h"
#include "mongo/db/matcher/matcher.h"
#include "mongo/db/pipeline/document_source.h"
namespace mongo {
class DocumentSourceMatch : public DocumentSource {
public:
virtual ~DocumentSourceMatch() = default;
GetNextResult getNext() override;
boost::intrusive_ptr<DocumentSource> optimize() final;
BSONObjSet getOutputSorts() final {
return pSource ? pSource->getOutputSorts()
: SimpleBSONObjComparator::kInstance.makeBSONObjSet();
}
const char* getSourceName() const override;
StageConstraints constraints(Pipeline::SplitState pipeState) const override {
return {StreamType::kStreaming,
PositionRequirement::kNone,
HostTypeRequirement::kNone,
DiskUseRequirement::kNoDiskUse,
FacetRequirement::kAllowed,
TransactionRequirement::kAllowed,
ChangeStreamRequirement::kWhitelist};
}
Value serialize(
boost::optional<ExplainOptions::Verbosity> explain = boost::none) const override;
/**
* Attempts to combine with any subsequent $match stages, joining the query objects with a
* $and.
*/
Pipeline::SourceContainer::iterator doOptimizeAt(Pipeline::SourceContainer::iterator itr,
Pipeline::SourceContainer* container) final;
DepsTracker::State getDependencies(DepsTracker* deps) const final;
GetModPathsReturn getModifiedPaths() const final {
// This stage does not modify or rename any paths.
return {GetModPathsReturn::Type::kFiniteSet, std::set<std::string>{}, {}};
}
/**
* Convenience method for creating a $match stage.
*/
static boost::intrusive_ptr<DocumentSourceMatch> create(
BSONObj filter, const boost::intrusive_ptr<ExpressionContext>& expCtx);
/**
* Parses a $match stage from 'elem'.
*/
static boost::intrusive_ptr<DocumentSource> createFromBson(
BSONElement elem, const boost::intrusive_ptr<ExpressionContext>& pCtx);
/**
* Access the MatchExpression stored inside the DocumentSourceMatch. Does not release ownership.
*/
MatchExpression* getMatchExpression() const {
return _expression.get();
}
/**
* Combines the filter in this $match with the filter of 'other' using a $and, updating this
* match in place.
*/
void joinMatchWith(boost::intrusive_ptr<DocumentSourceMatch> other);
/**
* Returns the query in MatchExpression syntax.
*/
BSONObj getQuery() const;
/** Returns the portion of the match that can safely be promoted to before a $redact.
* If this returns an empty BSONObj, no part of this match may safely be promoted.
*
* To be safe to promote, removing a field from a document to be matched must not cause
* that document to be accepted when it would otherwise be rejected. As an example,
* {name: {$ne: "bob smith"}} accepts documents without a name field, which means that
* running this filter before a redact that would remove the name field would leak
* information. On the other hand, {age: {$gt:5}} is ok because it doesn't accept documents
* that have had their age field removed.
*/
BSONObj redactSafePortion() const;
static bool isTextQuery(const BSONObj& query);
bool isTextQuery() const {
return _isTextQuery;
}
/**
* Attempt to split this $match into two stages, where the first is not dependent upon any path
* from 'fields', and where applying them in sequence is equivalent to applying this stage once.
*
* Will return two intrusive_ptrs to new $match stages, where the first pointer is independent
* of 'fields', and the second is dependent. Either pointer may be null, so be sure to check the
* return value.
*
* For example, {$match: {a: "foo", "b.c": 4}} split by "b" will return pointers to two stages:
* {$match: {a: "foo"}}, and {$match: {"b.c": 4}}.
*
* The 'renames' structure maps from a field to an alias that should be used in the independent
* portion of the match. For example, suppose that we split by fields "a" with the rename "b" =>
* "c". The match {$match: {a: "foo", b: "bar", z: "baz"}} will split into {$match: {c: "bar",
* z: "baz"}} and {$match: {a: "foo"}}.
*/
std::pair<boost::intrusive_ptr<DocumentSourceMatch>, boost::intrusive_ptr<DocumentSourceMatch>>
splitSourceBy(const std::set<std::string>& fields, const StringMap<std::string>& renames);
/**
* Returns a new DocumentSourceMatch with a MatchExpression that, if executed on the
* sub-document at 'path', is equivalent to 'expression'.
*
* For example, if the original expression is {$and: [{'a.b': {$gt: 0}}, {'a.d': {$eq: 3}}]},
* the new $match will have the expression {$and: [{b: {$gt: 0}}, {d: {$eq: 3}}]} after
* descending on the path 'a'.
*
* Should be called _only_ on a MatchExpression that is a predicate on 'path', or subfields of
* 'path'. It is also invalid to call this method on an expression including a $elemMatch on
* 'path', for example: {'path': {$elemMatch: {'subfield': 3}}}
*/
static boost::intrusive_ptr<DocumentSourceMatch> descendMatchOnPath(
MatchExpression* matchExpr,
const std::string& path,
const boost::intrusive_ptr<ExpressionContext>& expCtx);
protected:
DocumentSourceMatch(const BSONObj& query,
const boost::intrusive_ptr<ExpressionContext>& expCtx);
private:
std::unique_ptr<MatchExpression> _expression;
BSONObj _predicate;
const bool _isTextQuery;
// Cache the dependencies so that we know what fields we need to serialize to BSON for matching.
DepsTracker _dependencies;
};
} // namespace mongo
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