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/**
* Copyright (C) 2019-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 <set>
#include <string>
#include "mongo/db/pipeline/document_source.h"
#include "mongo/db/pipeline/pipeline.h"
namespace mongo::semantic_analysis {
enum class Direction { kForward, kBackward };
/**
* Takes in a set of paths the caller is interested in, a pipeline stage, and a direction. If the
* direction is "forward", the paths given must exist before the stage is executed in the pipeline.
* If the direction is "backward," the paths must exist after the stage is executed in the pipeline.
* Returns boost::none if any of the pathsOfInterest are modified by the current stage. If all of
* the pathsOfInterest are preserved (but possibly renamed), we return a mapping from
* [pathOfInterest] --> [newName], where "newName" is the name of "pathOfInterest" on the "other
* side" of the stage with respect to the given direction.
*
* For example, say pathsOfInterest contains "a", a path name that exists before nextStage is run in
* the pipeline, and direction is forward. Say nextStage preserves all the paths but renames "a" to
* "b"; we would return a mapping a-->b.
*
* Conversely, say pathsOfInterest contains "b", a path name that exists after nextStage is run in
* the pipeline, and direction is backward. Say nextStage preserves all the paths but renamed "a" to
* "b"; we would return a mapping b-->a.
*/
boost::optional<StringMap<std::string>> renamedPaths(const std::set<std::string>& pathsOfInterest,
const DocumentSource& stage,
const Direction& traversalDir);
/**
* Tracks renames by walking a pipeline forwards. Takes two forward iterators that represent two
* stages in an aggregation pipeline, with 'start' coming before 'end,' as well as a set of path
* names the caller is interested in. Returns boost::none if any of these paths are modified by the
* pipeline from stages ['start' - 'end'); otherwise returns a mapping for each path in
* 'pathsOfInterest' from its name before stage 'start' to its name before stage 'end'. To track
* renames through an entire pipeline, 'start' should refer to the first stage in the pipeline while
* 'end' should be an iterator referring to the past-the-end stage.
*/
boost::optional<StringMap<std::string>> renamedPaths(
const Pipeline::SourceContainer::const_iterator start,
const Pipeline::SourceContainer::const_iterator end,
const std::set<std::string>& pathsOfInterest);
/**
* Tracks renames by walking a pipeline backwards. Takes two reverse iterators that represent two
* stages in an aggregation pipeline, with 'start' coming after 'end,' as well as a set of path
* names the caller is interested in. Returns boost::none if any of these paths were modified by the
* pipeline from stages ('end' - 'start']; otherwise returns a mapping for each path in
* 'pathsOfInterest' from its name after stage 'start' to its name as it was after stage 'end'. To
* track renames through an entire pipeline, 'start' should refer to the last stage in the pipeline
* while 'end' should refer to the (hypothetical) stage preceeding the first stage in the pipeline
* (the 'reverse end').
*/
boost::optional<StringMap<std::string>> renamedPaths(
const Pipeline::SourceContainer::const_reverse_iterator start,
const Pipeline::SourceContainer::const_reverse_iterator end,
const std::set<std::string>& pathsOfInterest);
/**
* Given a set of paths 'dependencies', determines which of those paths will be modified if all
* paths except those in 'preservedPaths' are modified.
*
* For example, extractModifiedDependencies({'a', 'b', 'c.d', 'e'}, {'a', 'b.c', c'}) returns
* {'b', 'e'}, since 'b' and 'e' are not preserved (only 'b.c' is preserved).
*/
std::set<std::string> extractModifiedDependencies(const std::set<std::string>& dependencies,
const std::set<std::string>& preservedPaths);
} // namespace mongo::semantic_analysis
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