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
|
/**
* 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.
*/
#include "mongo/db/fts/fts_element_iterator.h"
#include "mongo/db/fts/fts_spec.h"
#include "mongo/db/fts/fts_util.h"
#include "mongo/util/str.h"
#include <stack>
namespace mongo {
namespace fts {
using std::string;
extern const double DEFAULT_WEIGHT;
extern const double MAX_WEIGHT;
std::ostream& operator<<(std::ostream& os, FTSElementIterator::FTSIteratorFrame& frame) {
BSONObjIterator it = frame._it;
return os << "FTSIteratorFrame["
" element="
<< (*it).toString() << ", _language=" << frame._language->str()
<< ", _parentPath=" << frame._parentPath << ", _isArray=" << frame._isArray << "]";
}
FTSElementIterator::FTSElementIterator(const FTSSpec& spec, const BSONObj& obj)
: _frame(obj, spec, &spec.defaultLanguage(), "", false),
_spec(spec),
_currentValue(advance()) {}
namespace {
/** Check for exact match or path prefix match. */
inline bool _matchPrefix(const string& dottedName, const string& weight) {
if (weight == dottedName) {
return true;
}
return str::startsWith(weight, dottedName + '.');
}
} // namespace
bool FTSElementIterator::more() {
//_currentValue = advance();
return _currentValue.valid();
}
FTSIteratorValue FTSElementIterator::next() {
FTSIteratorValue result = _currentValue;
_currentValue = advance();
return result;
}
/**
* Helper method:
* if (current object iterator not exhausted) return true;
* while (frame stack not empty) {
* resume object iterator popped from stack;
* if (resumed iterator not exhausted) return true;
* }
* return false;
*/
bool FTSElementIterator::moreFrames() {
if (_frame._it.more())
return true;
while (!_frameStack.empty()) {
_frame = _frameStack.top();
_frameStack.pop();
if (_frame._it.more()) {
return true;
}
}
return false;
}
FTSIteratorValue FTSElementIterator::advance() {
while (moreFrames()) {
BSONElement elem = _frame._it.next();
string fieldName = elem.fieldName();
// Skip "language" specifier fields if wildcard.
if (_spec.wildcard() && _spec.languageOverrideField() == fieldName) {
continue;
}
// Compose the dotted name of the current field:
// 1. parent path empty (top level): use the current field name
// 2. parent path non-empty and obj is an array: use the parent path
// 3. parent path non-empty and obj is a sub-doc: append field name to parent path
string dottedName =
(_frame._parentPath.empty()
? fieldName
: _frame._isArray ? _frame._parentPath : _frame._parentPath + '.' + fieldName);
// Find lower bound of dottedName in _weights. lower_bound leaves us at the first
// weight that could possibly match or be a prefix of dottedName. And if this
// element fails to match, then no subsequent weight can match, since the weights
// are lexicographically ordered.
Weights::const_iterator i =
_spec.weights().lower_bound(elem.type() == Object ? dottedName + '.' : dottedName);
// possibleWeightMatch is set if the weight map contains either a match or some item
// lexicographically larger than fieldName. This boolean acts as a guard on
// dereferences of iterator 'i'.
bool possibleWeightMatch = (i != _spec.weights().end());
// Optimize away two cases, when not wildcard:
// 1. lower_bound seeks to end(): no prefix match possible
// 2. lower_bound seeks to a name which is not a prefix
if (!_spec.wildcard()) {
if (!possibleWeightMatch) {
continue;
} else if (!_matchPrefix(dottedName, i->first)) {
continue;
}
}
// Is the current field an exact match on a weight?
bool exactMatch = (possibleWeightMatch && i->first == dottedName);
double weight = (exactMatch ? i->second : DEFAULT_WEIGHT);
switch (elem.type()) {
case String:
// Only index strings on exact match or wildcard.
if (exactMatch || _spec.wildcard()) {
return FTSIteratorValue(elem.valuestr(), _frame._language, weight);
}
break;
case Object:
// Only descend into a sub-document on proper prefix or wildcard. Note that
// !exactMatch is a sufficient test for proper prefix match, because of
// if ( !matchPrefix( dottedName, i->first ) ) continue;
// block above.
if (!exactMatch || _spec.wildcard()) {
_frameStack.push(_frame);
_frame =
FTSIteratorFrame(elem.Obj(), _spec, _frame._language, dottedName, false);
}
break;
case Array:
// Only descend into arrays from non-array parents or on wildcard.
if (!_frame._isArray || _spec.wildcard()) {
_frameStack.push(_frame);
_frame =
FTSIteratorFrame(elem.Obj(), _spec, _frame._language, dottedName, true);
}
break;
default:
// Skip over all other BSON types.
break;
}
}
return FTSIteratorValue(); // valid()==false
}
} // namespace fts
} // namespace mongo
|
