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
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
/**
* Copyright (C) 2012 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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 <iosfwd>
#include <string>
#include <vector>
#include "mongo/base/disallow_copying.h"
#include "mongo/base/string_data.h"
namespace mongo {
/**
* A FieldPath represents a path in a document, starting from the root. The path
* is made of "field parts" separated by dots. The class provides an efficient means to
* "split" the dotted fields in its parts, but no validation is done.
*
* Any field part may be replaced, after the "original" field reference was parsed. Any
* part can be accessed through a StringData object.
*
* The class is not thread safe.
*/
class FieldRef {
MONGO_DISALLOW_COPYING(FieldRef);
public:
FieldRef();
explicit FieldRef(StringData path);
/**
* Field parts accessed through getPart() calls no longer would be valid, after the
* destructor ran.
*/
~FieldRef() {}
/**
* Builds a field path out of each field part in 'dottedField'.
*/
void parse(StringData dottedField);
/**
* Sets the 'i-th' field part to point to 'part'. Assumes i < size(). Behavior is
* undefined otherwise.
*/
void setPart(size_t i, StringData part);
/**
* Returns the 'i-th' field part. Assumes i < size(). Behavior is undefined otherwise.
*/
StringData getPart(size_t i) const;
/**
* Returns true when 'this' FieldRef is a prefix of 'other'. Equality is not considered
* a prefix.
*/
bool isPrefixOf(const FieldRef& other) const;
/**
* Returns the number of field parts in the prefix that 'this' and 'other' share.
*/
size_t commonPrefixSize(const FieldRef& other) const;
/**
* Returns a StringData of the full dotted field in its current state (i.e., some parts may
* have been replaced since the parse() call).
*/
StringData dottedField(size_t offsetFromStart = 0) const;
/**
* Returns a StringData of parts of the dotted field from startPart to endPart in its
* current state (i.e., some parts may have been replaced since the parse() call).
*/
StringData dottedSubstring(size_t startPart, size_t endPart) const;
/**
* Compares the full dotted path represented by this FieldRef to other
*/
bool equalsDottedField(StringData other) const;
/**
* Return 0 if 'this' is equal to 'other' lexicographically, -1 if is it less than or
* +1 if it is greater than.
*/
int compare(const FieldRef& other) const;
/**
* Resets the internal state. See note in parse() call.
*/
void clear();
//
// accessors
//
/**
* Returns the number of parts in this FieldRef.
*/
size_t numParts() const {
return _size;
}
bool empty() const {
return numParts() == 0;
}
private:
// Dotted fields are most often not longer than four parts. We use a mixed structure
// here that will not require any extra memory allocation when that is the case. And
// handle larger dotted fields if it is. The idea is not to penalize the common case
// with allocations.
static const size_t kReserveAhead = 4;
/**
* Parses 'path' into parts.
*/
void _parse(StringData path);
/** Converts the field part index to the variable part equivalent */
size_t getIndex(size_t i) const {
return i - kReserveAhead;
}
/**
* Returns the new number of parts after appending 'part' to this field path. It
* assumes that 'part' is pointing to an internally allocated area.
*/
size_t appendPart(StringData part);
/**
* Re-assemble _dotted from components, including any replacements in _replacements,
* and update the StringData components in _fixed and _variable to refer to the parts
* of the new _dotted. This is used to make the storage for the current value of this
* FieldRef contiguous so it can be returned as a StringData from the dottedField
* method above.
*/
void reserialize() const;
// number of field parts stored
size_t _size;
// first kResevedAhead field components
mutable StringData _fixed[kReserveAhead];
// remaining field components
mutable std::vector<StringData> _variable;
// cached dotted name
mutable std::string _dotted;
// back memory added with the setPart call pointed to by _fized and _variable
mutable std::vector<std::string> _replacements;
};
inline bool operator==(const FieldRef& lhs, const FieldRef& rhs) {
return lhs.compare(rhs) == 0;
}
inline bool operator!=(const FieldRef& lhs, const FieldRef& rhs) {
return lhs.compare(rhs) != 0;
}
inline bool operator<(const FieldRef& lhs, const FieldRef& rhs) {
return lhs.compare(rhs) < 0;
}
inline bool operator<=(const FieldRef& lhs, const FieldRef& rhs) {
return lhs.compare(rhs) <= 0;
}
inline bool operator>(const FieldRef& lhs, const FieldRef& rhs) {
return lhs.compare(rhs) > 0;
}
inline bool operator>=(const FieldRef& lhs, const FieldRef& rhs) {
return lhs.compare(rhs) >= 0;
}
std::ostream& operator<<(std::ostream& stream, const FieldRef& value);
} // namespace mongo
|
