1 
2 /**
3  *    Copyright (C) 2018-present MongoDB, Inc.
4  *
5  *    This program is free software: you can redistribute it and/or modify
6  *    it under the terms of the Server Side Public License, version 1,
7  *    as published by MongoDB, Inc.
8  *
9  *    This program is distributed in the hope that it will be useful,
10  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
11  *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  *    Server Side Public License for more details.
13  *
14  *    You should have received a copy of the Server Side Public License
15  *    along with this program. If not, see
16  *    <http://www.mongodb.com/licensing/server-side-public-license>.
17  *
18  *    As a special exception, the copyright holders give permission to link the
19  *    code of portions of this program with the OpenSSL library under certain
20  *    conditions as described in each individual source file and distribute
21  *    linked combinations including the program with the OpenSSL library. You
22  *    must comply with the Server Side Public License in all respects for
23  *    all of the code used other than as permitted herein. If you modify file(s)
24  *    with this exception, you may extend this exception to your version of the
25  *    file(s), but you are not obligated to do so. If you do not wish to do so,
26  *    delete this exception statement from your version. If you delete this
27  *    exception statement from all source files in the program, then also delete
28  *    it in the license file.
29  */
30 
31 #pragma once
32 
33 #include <map>
34 #include <string>
35 
36 #include "mongo/base/clonable_ptr.h"
37 #include "mongo/db/field_ref.h"
38 #include "mongo/db/update/update_node.h"
39 
40 namespace mongo {
41 
42 /**
43  * An internal node in the prefix tree of update modifier expressions. See comment in class
44  * definition of UpdateNode for more details.
45  */
46 class UpdateInternalNode : public UpdateNode {
47 public:
48     /**
49      * Helper class for appending to a FieldRef for the duration of the current scope and then
50      * restoring the FieldRef at the end of the scope.
51      */
52     class FieldRefTempAppend {
53     public:
FieldRefTempAppend(FieldRef & fieldRef,StringData part)54         FieldRefTempAppend(FieldRef& fieldRef, StringData part) : _fieldRef(fieldRef) {
55             _fieldRef.appendPart(part);
56         }
57 
~FieldRefTempAppend()58         ~FieldRefTempAppend() {
59             _fieldRef.removeLastPart();
60         }
61 
62     private:
63         FieldRef& _fieldRef;
64     };
65 
UpdateInternalNode(UpdateNode::Type type)66     UpdateInternalNode(UpdateNode::Type type) : UpdateNode(type) {}
67 
68     /**
69      * Returns the child with field name 'field' or nullptr if there is no such child.
70      */
71     virtual UpdateNode* getChild(const std::string& field) const = 0;
72 
73     /**
74      * Adds a child with field name 'field'. The node must not already have a child with field
75      * name 'field'.
76      */
77     virtual void setChild(std::string field, std::unique_ptr<UpdateNode> child) = 0;
78 
79 protected:
80     /**
81      * Helper for subclass implementations of createUpdateNodeByMerging. Any UpdateNode value whose
82      * key is only in 'leftMap' or only in 'rightMap' is cloned and added to the output map. If the
83      * key is in both maps, the two UpdateNodes are merged and added to the output map. If
84      * wrapFieldNameAsArrayFilterIdentifier is true, field names are wrapped as $[<field name>] for
85      * error reporting.
86      */
87     static std::map<std::string, clonable_ptr<UpdateNode>> createUpdateNodeMapByMerging(
88         const std::map<std::string, clonable_ptr<UpdateNode>>& leftMap,
89         const std::map<std::string, clonable_ptr<UpdateNode>>& rightMap,
90         FieldRef* pathTaken,
91         bool wrapFieldNameAsArrayFilterIdentifier = false);
92 
93     /**
94      * Helper for subclass implementations of createUpdateNodeByMerging. If one of 'leftNode' or
95      * 'rightNode' is non-null, we clone it. If 'leftNode' and 'rightNode' are both non-null, we
96      * merge them recursively. If 'leftNode' and 'rightNode' are both null, we return nullptr. If
97      * wrapFieldNameAsArrayFilterIdentifier is true, field names are wrapped as $[<field name>] for
98      * error reporting.
99      */
100     static std::unique_ptr<UpdateNode> copyOrMergeAsNecessary(
101         UpdateNode* leftNode,
102         UpdateNode* rightNode,
103         FieldRef* pathTaken,
104         const std::string& nextField,
105         bool wrapFieldNameAsArrayFilterIdentifier = false);
106 };
107 
108 }  // namespace mongo
109