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
|
/*
* Copyright 2018 Google
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_IMMUTABLE_KEYS_VIEW_H_
#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_IMMUTABLE_KEYS_VIEW_H_
#include <utility>
#include "Firestore/core/src/firebase/firestore/util/iterator_adaptors.h"
#include "Firestore/core/src/firebase/firestore/util/range.h"
namespace firebase {
namespace firestore {
namespace immutable {
namespace impl {
template <typename Iterator>
using KeysRange = util::range<util::iterator_first<Iterator>>;
template <typename Iterator>
KeysRange<Iterator> MakeKeysRange(Iterator begin, Iterator end) {
auto keys_begin = util::make_iterator_first(begin);
auto keys_end = util::make_iterator_first(end);
return util::make_range(keys_begin, keys_end);
}
/**
* Returns a view of the keys of the given key-value range.
*/
template <typename Range>
auto KeysView(const Range& range) -> KeysRange<decltype(std::begin(range))> {
return MakeKeysRange(std::begin(range), std::end(range));
}
template <typename Range, typename K>
auto KeysViewFrom(const Range& range, const K& key)
-> KeysRange<decltype(range.lower_bound(key))> {
auto keys_begin = util::make_iterator_first(range.lower_bound(key));
auto keys_end = util::make_iterator_first(std::end(range));
return util::make_range(keys_begin, keys_end);
}
/**
* Returns a view of keys of the given key-value range that are greater than or
* equal to the given start_key and less than the given end_key.
*
* If `end_key` is less than or equal to `start_key`, creates empty range.
*/
template <typename Range, typename K, typename C>
auto KeysViewIn(const Range& range,
const K& start_key,
const K& end_key,
const C& comparator)
-> KeysRange<decltype(range.lower_bound(start_key))> {
// Forward iterators can't ever reach the end if the end is behind the start:
// they just keep incrementing until address space runs out. Adjust the range
// accordingly.
bool empty_range = !comparator(start_key, end_key);
if (empty_range) {
return MakeKeysRange(std::end(range), std::end(range));
}
auto range_begin = range.lower_bound(start_key);
auto range_end = range.lower_bound(end_key);
return MakeKeysRange(std::move(range_begin), std::move(range_end));
}
} // namespace impl
} // namespace immutable
} // namespace firestore
} // namespace firebase
#endif // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_IMMUTABLE_KEYS_VIEW_H_
|
