1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
/**
* 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 "mongo/db/exec/document_value/document.h"
#include "mongo/db/pipeline/dependencies.h"
#include "mongo/db/pipeline/document_source.h"
#include "mongo/db/query/explain_options.h"
namespace mongo {
/**
* This class defines the minimal interface that every parser wishing to take advantage of
* DocumentSourceSingleDocumentTransformation must implement.
*
* This interface ensures that DocumentSourceSingleDocumentTransformations are passed parsed
* objects that can execute the transformation and provide additional features like
* serialization and reporting and returning dependencies. The parser must also provide
* implementations for optimizing and adding the expression context, even if those functions do
* nothing.
*/
class TransformerInterface {
public:
enum class TransformerType {
kExclusionProjection,
kInclusionProjection,
kComputedProjection,
kReplaceRoot,
kGroupFromFirstDocument,
};
virtual ~TransformerInterface() = default;
virtual Document applyTransformation(const Document& input) = 0;
virtual TransformerType getType() const = 0;
virtual void optimize() = 0;
virtual DepsTracker::State addDependencies(DepsTracker* deps) const = 0;
virtual void addVariableRefs(std::set<Variables::Id>* refs) const = 0;
virtual DocumentSource::GetModPathsReturn getModifiedPaths() const = 0;
/**
* Returns a document describing this transformation. For example, this function will return
* {_id: 0, x: 1} for the stage parsed from {$project: {_id: 0, x: 1}}.
*/
virtual Document serializeTransformation(boost::optional<ExplainOptions::Verbosity> explain,
SerializationOptions options = {}) const = 0;
/**
* Method used by inclusion and add fields projecton executors to extract computed projections
* that depend only on the 'oldName' field. Returns a pair of <BSONObj, bool>. The BSONObj
* contains the extracted projections. The boolean flag is true if the original projection has
* become empty after the extraction and can be deleted by the caller.
*/
virtual std::pair<BSONObj, bool> extractComputedProjections(
const StringData& oldName,
const StringData& newName,
const std::set<StringData>& reservedNames) {
return {BSONObj{}, false};
}
virtual std::pair<BSONObj, bool> extractProjectOnFieldAndRename(const StringData& oldName,
const StringData& newName) {
return {BSONObj{}, false};
}
};
} // namespace mongo
|