1 // Copyright (C) 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 //      http://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 ICING_STORE_DOCUMENT_ID_H_
16 #define ICING_STORE_DOCUMENT_ID_H_
17 
18 #include <cstdint>
19 
20 namespace icing {
21 namespace lib {
22 
23 // Id of a document
24 using DocumentId = int32_t;
25 
26 // We use 20 bits to encode document_ids and use the largest value (1M - 1) to
27 // represent an invalid document_id.
28 inline constexpr int kDocumentIdBits = 20;
29 inline constexpr DocumentId kInvalidDocumentId = (1u << kDocumentIdBits) - 1;
30 inline constexpr DocumentId kMinDocumentId = 0;
31 inline constexpr DocumentId kMaxDocumentId = kInvalidDocumentId - 1;
32 
IsDocumentIdValid(DocumentId document_id)33 constexpr bool IsDocumentIdValid(DocumentId document_id) {
34   return document_id >= kMinDocumentId && document_id <= kMaxDocumentId;
35 }
36 
37 }  // namespace lib
38 }  // namespace icing
39 
40 #endif  // ICING_STORE_DOCUMENT_ID_H_
41