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Diffstat (limited to 'src/mongo/db/exec/add_fields_projection_executor.h')
| -rw-r--r-- | src/mongo/db/exec/add_fields_projection_executor.h | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/src/mongo/db/exec/add_fields_projection_executor.h b/src/mongo/db/exec/add_fields_projection_executor.h new file mode 100644 index 00000000000..e17ce25e494 --- /dev/null +++ b/src/mongo/db/exec/add_fields_projection_executor.h @@ -0,0 +1,144 @@ +/** + * 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 "mongo/db/exec/inclusion_projection_executor.h" +#include "mongo/db/pipeline/expression.h" +#include "mongo/db/pipeline/expression_context.h" + +namespace mongo::projection_executor { +/** + * A AddFieldsProjectionExecutor represents a projection execution tree for the $addFields stage. + * + * This class is mostly a wrapper around an InclusionNode tree. It contains logic to parse a + * specification object into the corresponding InclusionNode tree, but defers most execution logic + * to the underlying tree. In this way it is similar to InclusionProjectionExecutor, but it differs + * by not applying inclusions before adding computed fields, thus keeping all existing fields. + */ +class AddFieldsProjectionExecutor : public ProjectionExecutor { +public: + /** + * TODO SERVER-25510: The ProjectionExecutor _id and array-recursion policies are not + * applicable to the $addFields "projection" stage. We make them non-configurable here. + */ + AddFieldsProjectionExecutor(const boost::intrusive_ptr<ExpressionContext>& expCtx) + : ProjectionExecutor(expCtx, + {ProjectionPolicies::DefaultIdPolicy::kIncludeId, + ProjectionPolicies::ArrayRecursionPolicy::kRecurseNestedArrays, + ProjectionPolicies::ComputedFieldsPolicy::kAllowComputedFields}), + _root(new InclusionNode(_policies)) {} + + /** + * Creates the data needed to perform an AddFields. + * Verifies that there are no conflicting paths in the specification. + */ + static std::unique_ptr<AddFieldsProjectionExecutor> create( + const boost::intrusive_ptr<ExpressionContext>& expCtx, const BSONObj& spec); + + TransformerType getType() const final { + return TransformerType::kComputedProjection; + } + + const InclusionNode& getRoot() const { + return *_root; + } + + /** + * Parses the addFields specification given by 'spec', populating internal data structures. + */ + void parse(const BSONObj& spec); + + Document serializeTransformation( + boost::optional<ExplainOptions::Verbosity> explain) const final { + return _root->serialize(explain); + } + + /** + * Optimizes any computed expressions. + */ + void optimize() final { + _root->optimize(); + } + + DepsTracker::State addDependencies(DepsTracker* deps) const final { + _root->reportDependencies(deps); + return DepsTracker::State::SEE_NEXT; + } + + DocumentSource::GetModPathsReturn getModifiedPaths() const final { + std::set<std::string> computedPaths; + StringMap<std::string> renamedPaths; + _root->reportComputedPaths(&computedPaths, &renamedPaths); + return {DocumentSource::GetModPathsReturn::Type::kFiniteSet, + std::move(computedPaths), + std::move(renamedPaths)}; + } + + /** + * Add the specified fields to 'inputDoc'. + * + * Replaced fields will remain in their original place in the document, while new added fields + * will be added to the end of the document in the order in which they were specified to the + * $addFields stage. + * + * Arrays will be traversed, with any dotted/nested computed fields applied to each element in + * the array. For example, setting "a.0": "hello" will add a field "0" to every object + * in the array "a". If there is an element in "a" that is not an object, it will be replaced + * with {"0": "hello"}. See SERVER-25200 for more details. + */ + Document applyProjection(const Document& inputDoc) const final; + +private: + /** + * Attempts to parse 'objSpec' as an expression like {$add: [...]}. Adds a computed field to + * '_root' and returns true if it was successfully parsed as an expression. Returns false if it + * was not an expression specification. + * + * Throws an error if it was determined to be an expression specification, but failed to parse + * as a valid expression. + */ + bool parseObjectAsExpression(StringData pathToObject, + const BSONObj& objSpec, + const VariablesParseState& variablesParseState); + + /** + * Traverses 'subObj' and parses each field. Adds any computed fields at this level + * to 'node'. + */ + void parseSubObject(const BSONObj& subObj, + const VariablesParseState& variablesParseState, + InclusionNode* node); + + // The InclusionNode tree does most of the execution work once constructed. + std::unique_ptr<InclusionNode> _root; +}; +} // namespace mongo::projection_executor |