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
|
/**
* Copyright (C) 2019-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/exec/sort_key_comparator.h"
namespace mongo {
SortKeyComparator::SortKeyComparator(const SortPattern& sortPattern) {
_pattern.reserve(sortPattern.size());
std::transform(sortPattern.begin(),
sortPattern.end(),
std::back_inserter(_pattern),
[](const SortPattern::SortPatternPart& part) {
return part.isAscending ? SortDirection::kAscending
: SortDirection::kDescending;
});
}
int SortKeyComparator::operator()(const Value& lhsKey, const Value& rhsKey) const {
// Note that 'comparator' must use binary comparisons here, as both 'lhs' and 'rhs' are
// collation comparison keys.
ValueComparator comparator;
const size_t n = _pattern.size();
if (n == 1) { // simple fast case
if (_pattern[0] == SortDirection::kAscending)
return comparator.compare(lhsKey, rhsKey);
else
return -comparator.compare(lhsKey, rhsKey);
}
// compound sort
for (size_t i = 0; i < n; i++) {
int cmp = comparator.compare(lhsKey[i], rhsKey[i]);
if (cmp) {
// If necessary, adjust the return value by the key ordering.
if (_pattern[i] == SortDirection::kDescending)
cmp = -cmp;
return cmp;
}
}
// If we got here, everything matched (or didn't exist), so we'll consider the documents equal
// for purposes of this sort.
return 0;
}
SortKeyComparator::SortKeyComparator(const BSONObj& sortPattern) {
_pattern.reserve(sortPattern.nFields());
std::transform(sortPattern.begin(),
sortPattern.end(),
std::back_inserter(_pattern),
[](const BSONElement& part) {
return (part.number() >= 0) ? SortDirection::kAscending
: SortDirection::kDescending;
});
}
} // namespace mongo
|