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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 <boost/optional.hpp>
#include <memory>
#include <vector>
#include "mongo/db/auth/privilege.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/pipeline/aggregation_request.h"
#include "mongo/db/repl/read_concern_args.h"
#include "mongo/stdx/functional.h"
#include "mongo/stdx/memory.h"
#include "mongo/stdx/unordered_set.h"
namespace mongo {
/**
* A lightly parsed version of a DocumentSource. It is not executable and not guaranteed to return a
* parse error when encountering an invalid specification. Instead, the purpose of this class is to
* make certain DocumentSource properties available before full parsing (e.g., getting the involved
* foreign collections).
*/
class LiteParsedDocumentSource {
public:
virtual ~LiteParsedDocumentSource() = default;
/*
* This is the type of parser you should register using REGISTER_DOCUMENT_SOURCE. It need not
* do any validation of options, only enough parsing to be able to implement the interface.
*
* The AggregationRequest can be used to determine related information like the namespace on
* which this aggregation is being performed, and the BSONElement will be the element whose
* field name is the name of this stage (e.g. the first and only element in {$limit: 1}).
*/
using Parser = stdx::function<std::unique_ptr<LiteParsedDocumentSource>(
const AggregationRequest&, const BSONElement&)>;
/**
* Registers a DocumentSource with a spec parsing function, so that when a stage with the given
* name is encountered, it will call 'parser' to construct that stage's specification object.
*
* DO NOT call this method directly. Instead, use the REGISTER_DOCUMENT_SOURCE macro defined in
* document_source.h.
*/
static void registerParser(const std::string& name, Parser parser);
/**
* Constructs a LiteParsedDocumentSource from the user-supplied BSON, or throws a
* AssertionException.
*
* Extracts the first field name from 'spec', and delegates to the parser that was registered
* with that field name using registerParser() above.
*/
static std::unique_ptr<LiteParsedDocumentSource> parse(const AggregationRequest& request,
const BSONObj& spec);
/**
* Returns the foreign collection(s) referenced by this stage, if any.
*/
virtual stdx::unordered_set<NamespaceString> getInvolvedNamespaces() const = 0;
/**
* Returns a list of the privileges required for this stage.
*/
virtual PrivilegeVector requiredPrivileges(bool isMongos) const = 0;
/**
* Returns true if this is a $collStats stage.
*/
virtual bool isCollStats() const {
return false;
}
/**
* Returns true if this is a $changeStream stage.
*/
virtual bool isChangeStream() const {
return false;
}
/**
* Returns true if this stage does not require an input source.
*/
virtual bool isInitialSource() const {
return false;
}
/**
* Returns true if this stage may be forwarded to shards from a mongos.
*/
virtual bool allowedToForwardFromMongos() const {
return true;
}
/**
* Returns true if this stage may be forwarded from Mongos unmodified.
*/
virtual bool allowedToPassthroughFromMongos() const {
return true;
}
/**
* Returns true if the involved namespace 'nss' is allowed to be sharded. The behavior is to
* allow by default and stages should opt-out if foreign collections are not allowed to be
* sharded.
*/
virtual bool allowShardedForeignCollection(NamespaceString nss) const {
return true;
}
/**
* Verifies that this stage is allowed to run with the specified read concern. Throws a
* UserException if not compatible.
*/
virtual void assertSupportsReadConcern(const repl::ReadConcernArgs& readConcern) const {}
};
class LiteParsedDocumentSourceDefault final : public LiteParsedDocumentSource {
public:
/**
* Creates the default LiteParsedDocumentSource. This should be used with caution. Make sure
* your stage doesn't need to communicate any special behavior before registering a
* DocumentSource using this parser.
*/
static std::unique_ptr<LiteParsedDocumentSourceDefault> parse(const AggregationRequest& request,
const BSONElement& spec) {
return stdx::make_unique<LiteParsedDocumentSourceDefault>();
}
LiteParsedDocumentSourceDefault() = default;
stdx::unordered_set<NamespaceString> getInvolvedNamespaces() const final {
return stdx::unordered_set<NamespaceString>();
}
PrivilegeVector requiredPrivileges(bool isMongos) const final {
return {};
}
};
/**
* Helper class for DocumentSources which reference one or more foreign collections.
*/
class LiteParsedDocumentSourceForeignCollections : public LiteParsedDocumentSource {
public:
LiteParsedDocumentSourceForeignCollections(NamespaceString foreignNss,
PrivilegeVector privileges)
: _foreignNssSet{std::move(foreignNss)}, _requiredPrivileges(std::move(privileges)) {}
LiteParsedDocumentSourceForeignCollections(stdx::unordered_set<NamespaceString> foreignNssSet,
PrivilegeVector privileges)
: _foreignNssSet(std::move(foreignNssSet)), _requiredPrivileges(std::move(privileges)) {}
stdx::unordered_set<NamespaceString> getInvolvedNamespaces() const final {
return {_foreignNssSet};
}
PrivilegeVector requiredPrivileges(bool isMongos) const final {
return _requiredPrivileges;
}
protected:
stdx::unordered_set<NamespaceString> _foreignNssSet;
private:
PrivilegeVector _requiredPrivileges;
};
} // namespace mongo
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