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1 // Copyright 2012 The Chromium Authors. All rights reserved. | 1 // Copyright 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef SYNC_INTERNAL_API_PUBLIC_BASE_NODE_ORDINAL_H_ | 5 #ifndef COMPONENTS_SYNC_BASE_NODE_ORDINAL_H_ |
6 #define SYNC_INTERNAL_API_PUBLIC_BASE_NODE_ORDINAL_H_ | 6 #define COMPONENTS_SYNC_BASE_NODE_ORDINAL_H_ |
7 | 7 |
8 #include <stddef.h> | 8 #include <stddef.h> |
9 #include <stdint.h> | 9 #include <stdint.h> |
10 | 10 |
11 #include "sync/base/sync_export.h" | 11 #include "components/sync/base/ordinal.h" |
12 #include "sync/internal_api/public/base/ordinal.h" | 12 #include "components/sync/base/sync_export.h" |
13 | 13 |
14 namespace syncer { | 14 namespace syncer { |
15 | 15 |
16 // A NodeOrdinal is an Ordinal whose internal value comes from the | 16 // A NodeOrdinal is an Ordinal whose internal value comes from the |
17 // ordinal_in_parent field of SyncEntity (see sync.proto). It uses | 17 // ordinal_in_parent field of SyncEntity (see sync.proto). It uses |
18 // the entire uint8_t range for backwards compatibility with the old | 18 // the entire uint8_t range for backwards compatibility with the old |
19 // int64_t-based positioning. | 19 // int64_t-based positioning. |
20 | 20 |
21 struct NodeOrdinalTraits { | 21 struct NodeOrdinalTraits { |
22 static const uint8_t kZeroDigit = 0; | 22 static const uint8_t kZeroDigit = 0; |
23 static const uint8_t kMaxDigit = UINT8_MAX; | 23 static const uint8_t kMaxDigit = UINT8_MAX; |
24 static const size_t kMinLength = 8; | 24 static const size_t kMinLength = 8; |
25 }; | 25 }; |
26 | 26 |
27 typedef Ordinal<NodeOrdinalTraits> NodeOrdinal; | 27 typedef Ordinal<NodeOrdinalTraits> NodeOrdinal; |
28 | 28 |
29 static_assert(static_cast<char>(NodeOrdinal::kZeroDigit) == '\x00', | 29 static_assert(static_cast<char>(NodeOrdinal::kZeroDigit) == '\x00', |
30 "NodeOrdinal has incorrect zero digit"); | 30 "NodeOrdinal has incorrect zero digit"); |
31 static_assert(static_cast<char>(NodeOrdinal::kOneDigit) == '\x01', | 31 static_assert(static_cast<char>(NodeOrdinal::kOneDigit) == '\x01', |
32 "NodeOrdinal has incorrect one digit"); | 32 "NodeOrdinal has incorrect one digit"); |
33 static_assert(static_cast<char>(NodeOrdinal::kMidDigit) == '\x80', | 33 static_assert(static_cast<char>(NodeOrdinal::kMidDigit) == '\x80', |
34 "NodeOrdinal has incorrect mid digit"); | 34 "NodeOrdinal has incorrect mid digit"); |
35 static_assert(static_cast<char>(NodeOrdinal::kMaxDigit) == '\xff', | 35 static_assert(static_cast<char>(NodeOrdinal::kMaxDigit) == '\xff', |
36 "NodeOrdinal has incorrect max digit"); | 36 "NodeOrdinal has incorrect max digit"); |
37 static_assert(NodeOrdinal::kMidDigitValue == 128, | 37 static_assert(NodeOrdinal::kMidDigitValue == 128, |
38 "NodeOrdinal has incorrect mid digit value"); | 38 "NodeOrdinal has incorrect mid digit value"); |
39 static_assert(NodeOrdinal::kMaxDigitValue == 255, | 39 static_assert(NodeOrdinal::kMaxDigitValue == 255, |
40 "NodeOrdinal has incorrect max digit value"); | 40 "NodeOrdinal has incorrect max digit value"); |
41 static_assert(NodeOrdinal::kRadix == 256, | 41 static_assert(NodeOrdinal::kRadix == 256, "NodeOrdinal has incorrect radix"); |
42 "NodeOrdinal has incorrect radix"); | |
43 | 42 |
44 // Converts an int64_t position (usually from the position_in_parent | 43 // Converts an int64_t position (usually from the position_in_parent |
45 // field of SyncEntity) to a NodeOrdinal. This transformation | 44 // field of SyncEntity) to a NodeOrdinal. This transformation |
46 // preserves the ordering relation: a < b under integer ordering if | 45 // preserves the ordering relation: a < b under integer ordering if |
47 // and only if Int64ToNodeOrdinal(a) < Int64ToNodeOrdinal(b). | 46 // and only if Int64ToNodeOrdinal(a) < Int64ToNodeOrdinal(b). |
48 SYNC_EXPORT NodeOrdinal Int64ToNodeOrdinal(int64_t x); | 47 SYNC_EXPORT NodeOrdinal Int64ToNodeOrdinal(int64_t x); |
49 | 48 |
50 // The inverse of Int64ToNodeOrdinal. This conversion is, in general, | 49 // The inverse of Int64ToNodeOrdinal. This conversion is, in general, |
51 // lossy: NodeOrdinals can have arbitrary fidelity, while numeric | 50 // lossy: NodeOrdinals can have arbitrary fidelity, while numeric |
52 // positions contain only 64 bits of information (in fact, this is the | 51 // positions contain only 64 bits of information (in fact, this is the |
53 // reason we've moved away from them). | 52 // reason we've moved away from them). |
54 SYNC_EXPORT int64_t NodeOrdinalToInt64(const NodeOrdinal& ordinal); | 53 SYNC_EXPORT int64_t NodeOrdinalToInt64(const NodeOrdinal& ordinal); |
55 | 54 |
56 } // namespace syncer | 55 } // namespace syncer |
57 | 56 |
58 #endif // SYNC_INTERNAL_API_PUBLIC_BASE_NODE_ORDINAL_H_ | 57 #endif // COMPONENTS_SYNC_BASE_NODE_ORDINAL_H_ |
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