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
|
/**
* Copyright (C) 2020-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 <sstream>
#include <string>
#include <vector>
#include "mongo/base/string_data.h"
#include "mongo/bson/bsonobj.h"
#include "mongo/stdx/variant.h"
#include "mongo/util/visit_helper.h"
namespace mongo {
/**
* Represents the location of a specific token in a BSON object.
*/
class BSONLocation {
public:
using LocationPrefix = stdx::variant<unsigned int, StringData>;
// A location may be either the payload of a BSONElement, or a string representing a fieldname
// or metadata token (e.g. '{' for the start of an object). Array indices are not represented as
// a BSONLocation, per se, but instead are part of the list of prefix descriptors.
using LocationType = stdx::variant<BSONElement, StringData>;
BSONLocation() = default;
/**
* Builds a location of a token in the input BSON. The 'prefix' argument is a list of elements
* that describe the path to 'location'. There must be at least one element in 'prefix',
* detailing the parser entry point.
*/
BSONLocation(LocationType location, std::vector<LocationPrefix> prefix)
: _location(std::move(location)), _prefix(std::move(prefix)) {}
/**
* Prints this location along with the prefix strings that describe the path to the element. The
* resulting string is verbose and useful in debugging or syntax errors.
*/
std::string toString() const {
std::ostringstream stream;
stdx::visit(
visit_helper::Overloaded{
[&](const BSONElement& elem) { stream << "'" << elem.toString(false) << "'"; },
[&](const StringData& elem) { stream << "'" << elem << "'"; }},
_location);
// The assumption is that there is always at least one prefix that represents the entry
// point to the parser (e.g. the 'pipeline' argument for an aggregation command).
invariant(_prefix.size() > 0);
for (auto it = _prefix.rbegin(); it != _prefix.rend() - 1; ++it) {
stdx::visit(visit_helper::Overloaded{[&](const unsigned int& index) {
stream << " within array at index " << index;
},
[&](const StringData& pref) {
stream << " within '" << pref << "'";
}},
*it);
}
// The final prefix (or first element in the vector) is the input description.
stdx::visit(visit_helper::Overloaded{[&](const unsigned int& index) { MONGO_UNREACHABLE; },
[&](const StringData& pref) {
stream << " of input " << pref;
}},
_prefix[0]);
return stream.str();
}
friend std::ostream& operator<<(std::ostream& stream, const BSONLocation& location) {
return stream << location.toString();
}
friend StringBuilder& operator<<(StringBuilder& stream, const BSONLocation& location) {
return stream << location.toString();
}
private:
LocationType _location;
std::vector<LocationPrefix> _prefix;
};
} // namespace mongo
|
