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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 <string>
#include "mongo/db/pipeline/parsed_aggregation_projection.h"
#include "mongo/db/pipeline/parsed_aggregation_projection_node.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 final : public ProjectionNode {
public:
ExclusionNode(ProjectionPolicies policies, std::string pathToNode = "")
: ProjectionNode(policies, std::move(pathToNode)) {
// Computed fields are not supported by exclusion projections.
invariant(_policies.computedFieldsPolicy ==
ProjectionPolicies::ComputedFieldsPolicy::kBanComputedFields);
}
ExclusionNode* addOrGetChild(const std::string& field) {
return static_cast<ExclusionNode*>(ProjectionNode::addOrGetChild(field));
}
void reportDependencies(DepsTracker* deps) const final {
// We have no dependencies on specific fields, since we only know the fields to be removed.
}
protected:
std::unique_ptr<ProjectionNode> makeChild(std::string fieldName) const final {
return std::make_unique<ExclusionNode>(
_policies, FieldPath::getFullyQualifiedPath(_pathToNode, fieldName));
}
Document initializeOutputDocument(const Document& inputDoc) const final {
return inputDoc;
}
Value applyLeafProjectionToValue(const Value& value) const final {
return Value();
}
Value transformSkippedValueForOutput(const Value& value) const final {
return value;
}
};
/**
* 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,
ProjectionPolicies policies)
: ParsedAggregationProjection(
expCtx,
{policies.idPolicy,
policies.arrayRecursionPolicy,
ProjectionPolicies::ComputedFieldsPolicy::kBanComputedFields}),
_root(new ExclusionNode(_policies)) {}
TransformerType getType() const final {
return TransformerType::kExclusionProjection;
}
Document serializeTransformation(
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;
DepsTracker::State addDependencies(DepsTracker* deps) const final {
return DepsTracker::State::SEE_NEXT;
}
DocumentSource::GetModPathsReturn getModifiedPaths() const final {
std::set<std::string> modifiedPaths;
_root->reportProjectedPaths(&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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