Google Cloud Spanner C++ Client  2.1.0
A C++ Client Library for Google Cloud Spanner
read_options.h
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1 // Copyright 2019 Google LLC
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 #ifndef GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_SPANNER_READ_OPTIONS_H
16 #define GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_SPANNER_READ_OPTIONS_H
17 
18 #include "google/cloud/spanner/request_priority.h"
19 #include "google/cloud/spanner/version.h"
20 #include "google/cloud/optional.h"
21 #include "google/cloud/options.h"
22 #include "absl/types/optional.h"
23 #include <cstdint>
24 #include <string>
25 
26 namespace google {
27 namespace cloud {
28 namespace spanner {
30 
31 /// Options passed to `Client::Read` or `Client::PartitionRead`.
32 struct ReadOptions {
33  /**
34  * If non-empty, the name of an index on a database table. This index is
35  * used instead of the table primary key when interpreting the `KeySet`
36  * and sorting result rows.
37  */
38  std::string index_name;
39 
40  /**
41  * Limit on the number of rows to yield, or 0 for no limit.
42  * A limit cannot be specified when calling `PartitionRead`.
43  */
44  std::int64_t limit = 0;
45 
46  /**
47  * Priority for the read request.
48  */
50 
51  /**
52  * Tag for the read request.
53  */
54  absl::optional<std::string> request_tag;
55 };
56 
57 inline bool operator==(ReadOptions const& lhs, ReadOptions const& rhs) {
58  return lhs.limit == rhs.limit &&
60  lhs.request_tag == rhs.request_tag && lhs.index_name == rhs.index_name;
61 }
62 
63 inline bool operator!=(ReadOptions const& lhs, ReadOptions const& rhs) {
64  return !(lhs == rhs);
65 }
66 
67 /// Converts `ReadOptions` to common `Options`.
69 
70 /// Converts common `Options` to `ReadOptions`.
72 
74 } // namespace spanner
75 } // namespace cloud
76 } // namespace google
77 
78 #endif // GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_SPANNER_READ_OPTIONS_H