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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 <memory>
#include <string>
#include "mongo/db/pipeline/parsed_aggregation_projection.h"
#include "mongo/stdx/unordered_map.h"
#include "mongo/stdx/unordered_set.h"
namespace mongo {
class FieldPath;
class Value;
namespace parsed_aggregation_projection {
/**
* A node used to define the parsed structure of an exclusion projection. Each ExclusionNode
* represents one 'level' of the parsed specification. The root ExclusionNode represents all top
* level exclusions, with any child ExclusionNodes representing dotted or nested exclusions.
*/
class ExclusionNode {
public:
ExclusionNode(std::string pathToNode = "");
/**
* Serialize this exclusion.
*/
Document serialize() const;
/**
* Mark this path to be excluded. 'path' is allowed to be dotted.
*/
void excludePath(FieldPath path);
/**
* Applies this tree of exclusions to the input document.
*/
Document applyProjection(const Document& input) const;
/**
* Creates the child if it doesn't already exist. 'field' is not allowed to be dotted.
*/
ExclusionNode* addOrGetChild(FieldPath field);
void addModifiedPaths(std::set<std::string>* modifiedPaths) const;
private:
// Helpers for addOrGetChild above.
ExclusionNode* getChild(std::string field) const;
ExclusionNode* addChild(std::string field);
// Helper for applyProjection above.
Value applyProjectionToValue(Value val) const;
// Fields excluded at this level.
stdx::unordered_set<std::string> _excludedFields;
std::string _pathToNode;
stdx::unordered_map<std::string, std::unique_ptr<ExclusionNode>> _children;
};
/**
* A ParsedExclusionProjection represents a parsed form of the raw BSON specification.
*
* This class is mostly a wrapper around an ExclusionNode tree. It contains logic to parse a
* specification object into the corresponding ExclusionNode tree, but defers most execution logic
* to the underlying tree.
*/
class ParsedExclusionProjection : public ParsedAggregationProjection {
public:
ParsedExclusionProjection(const boost::intrusive_ptr<ExpressionContext>& expCtx)
: ParsedAggregationProjection(expCtx), _root(new ExclusionNode()) {}
TransformerType getType() const final {
return TransformerType::kExclusionProjection;
}
Document serialize(boost::optional<ExplainOptions::Verbosity> explain) const final;
/**
* Parses the projection specification given by 'spec', populating internal data structures.
*/
void parse(const BSONObj& spec) final {
parse(spec, _root.get(), 0);
}
/**
* Exclude the fields specified.
*/
Document applyProjection(const Document& inputDoc) const final;
DocumentSource::GetDepsReturn addDependencies(DepsTracker* deps) const final {
return DocumentSource::SEE_NEXT;
}
DocumentSource::GetModPathsReturn getModifiedPaths() const final {
std::set<std::string> modifiedPaths;
_root->addModifiedPaths(&modifiedPaths);
return {DocumentSource::GetModPathsReturn::Type::kFiniteSet, std::move(modifiedPaths), {}};
}
private:
/**
* Helper for parse() above.
*
* Traverses 'spec' and parses each field. Adds any excluded fields at this level to 'node',
* and recurses on any sub-objects.
*/
void parse(const BSONObj& spec, ExclusionNode* node, size_t depth);
// The ExclusionNode tree does most of the execution work once constructed.
std::unique_ptr<ExclusionNode> _root;
};
} // namespace parsed_aggregation_projection
} // namespace mongo
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