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/bson/bsonelement.h"
38 #include "mongo/db/matcher/expression_with_placeholder.h"
39 #include "mongo/db/update/modifier_table.h"
40 #include "mongo/db/update/update_internal_node.h"
41 #include "mongo/stdx/memory.h"
42 #include "mongo/stdx/unordered_map.h"
43 
44 namespace mongo {
45 
46 /**
47  * An internal node in the prefix tree of update modifier expressions, representing updates to an
48  * object. See comment in class definition of UpdateNode for more details.
49  */
50 class UpdateObjectNode : public UpdateInternalNode {
51 
52 public:
53     /**
54      * Parses 'modExpr' as an update modifier expression and merges with it with 'root'. Returns a
55      * non-OK status if 'modExpr' is not a valid update modifier expression, if merging would
56      * cause a conflict, or if there is an array filter identifier in 'modExpr' without a
57      * corresponding filter in 'arrayFilters'. Returns true if the path of 'modExpr' contains a
58      * positional $ element, e.g. 'a.$.b'. Any array filter identifiers are added to
59      * 'foundIdentifiers'.
60      */
61     static StatusWith<bool> parseAndMerge(
62         UpdateObjectNode* root,
63         modifiertable::ModifierType type,
64         BSONElement modExpr,
65         const boost::intrusive_ptr<ExpressionContext>& expCtx,
66         const std::map<StringData, std::unique_ptr<ExpressionWithPlaceholder>>& arrayFilters,
67         std::set<std::string>& foundIdentifiers);
68 
69     /**
70      * Creates a new UpdateObjectNode by merging two input UpdateObjectNode objects and their
71      * children. Each field that lives on one side of the merge but not the other (according to
72      * field name) is cloned to the newly created UpdateObjectNode. Fields that exist on both sides
73      * of the merge get merged recursively before being added to the resulting UpdateObjectNode.
74      * This merge operation is a deep copy: the new UpdateObjectNode is a brand new tree that does
75      * not contain any references to the objects in the original input trees.
76      */
77     static std::unique_ptr<UpdateNode> createUpdateNodeByMerging(const UpdateObjectNode& leftNode,
78                                                                  const UpdateObjectNode& rightNode,
79                                                                  FieldRef* pathTaken);
80 
UpdateObjectNode()81     UpdateObjectNode() : UpdateInternalNode(Type::Object) {}
82 
clone()83     std::unique_ptr<UpdateNode> clone() const final {
84         return stdx::make_unique<UpdateObjectNode>(*this);
85     }
86 
setCollator(const CollatorInterface * collator)87     void setCollator(const CollatorInterface* collator) final {
88         for (auto&& child : _children) {
89             child.second->setCollator(collator);
90         }
91         if (_positionalChild) {
92             _positionalChild->setCollator(collator);
93         }
94     }
95 
96     ApplyResult apply(ApplyParams applyParams) const final;
97 
98     UpdateNode* getChild(const std::string& field) const final;
99 
100     void setChild(std::string field, std::unique_ptr<UpdateNode> child) final;
101 
102 private:
103     std::map<std::string, clonable_ptr<UpdateNode>> _children;
104     clonable_ptr<UpdateNode> _positionalChild;
105 
106     // When calling apply() causes us to merge an element of '_children' with '_positionalChild', we
107     // store the result of the merge in case we need it in a future call to apply().
108     mutable stdx::unordered_map<std::string, clonable_ptr<UpdateNode>> _mergedChildrenCache;
109 };
110 
111 }  // namespace mongo
112