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
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
|
/**
* 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/bson/bsonobj.h"
#include "mongo/bson/bsonobjbuilder.h"
#include "mongo/db/field_ref.h"
#include "mongo/db/matcher/path.h"
namespace mongo {
class MatchableDocument {
public:
// Inlining to allow subclasses to see that this is a no-op and avoid a function call.
// Speeds up query execution measurably.
virtual ~MatchableDocument() {}
virtual BSONObj toBSON() const = 0;
/**
* The neewly returned ElementIterator is allowed to keep a pointer to path.
* So the caller of this function should make sure path is in scope until
* the ElementIterator is deallocated
*/
virtual ElementIterator* allocateIterator(const ElementPath* path) const = 0;
virtual void releaseIterator(ElementIterator* iterator) const = 0;
class IteratorHolder {
public:
IteratorHolder(const MatchableDocument* doc, const ElementPath* path) {
_doc = doc;
_iterator = _doc->allocateIterator(path);
}
~IteratorHolder() {
_doc->releaseIterator(_iterator);
}
ElementIterator* operator->() const {
return _iterator;
}
private:
const MatchableDocument* _doc;
ElementIterator* _iterator;
};
};
class BSONMatchableDocument : public MatchableDocument {
public:
BSONMatchableDocument(const BSONObj& obj);
virtual ~BSONMatchableDocument();
virtual BSONObj toBSON() const {
return _obj;
}
virtual ElementIterator* allocateIterator(const ElementPath* path) const {
if (_iteratorUsed)
return new BSONElementIterator(path, _obj);
_iteratorUsed = true;
_iterator.reset(path, _obj);
return &_iterator;
}
virtual void releaseIterator(ElementIterator* iterator) const {
if (iterator == &_iterator) {
_iteratorUsed = false;
} else {
delete iterator;
}
}
private:
BSONObj _obj;
mutable BSONElementIterator _iterator;
mutable bool _iteratorUsed;
};
/**
* A MatchableDocument interface for viewing a BSONElement as if it were wrapped in the top-level
* field of any given path. For example, given the object obj={a: [5]}, we can create a view over
* the element obj["a"]["0"]. An iterator over this view with path "i" would behave identically to
* an iterator over {i: 5} with path "i".
*/
class BSONElementViewMatchableDocument : public MatchableDocument {
public:
BSONElementViewMatchableDocument(BSONElement elem) : _elem(elem), _iteratorUsed(false) {}
BSONObj toBSON() const override {
return BSON("" << _elem);
}
/**
* Creates an iterator over '_elem' as if '_elem' were wrapped in the first field of 'path'.
* 'path' must have at least one field.
*/
ElementIterator* allocateIterator(const ElementPath* path) const override {
// Skip the first field in the path when traversing the document.
const size_t suffixIndex = 1;
if (_iteratorUsed) {
return new BSONElementIterator(path, suffixIndex, _elem);
}
_iteratorUsed = true;
_iterator.reset(path, suffixIndex, _elem);
return &_iterator;
}
void releaseIterator(ElementIterator* iterator) const override {
if (iterator == &_iterator) {
_iteratorUsed = false;
} else {
delete iterator;
}
}
private:
BSONElement _elem;
mutable BSONElementIterator _iterator;
mutable bool _iteratorUsed;
};
}
|
