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sequential_id_generator.h
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1 // Copyright 2013 The Flutter Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_SEQUENTIAL_ID_GENERATOR_H_
6 #define FLUTTER_SHELL_PLATFORM_WINDOWS_SEQUENTIAL_ID_GENERATOR_H_
7
8 #include <cstdint>
9 #include <unordered_map>
10
11 #include "flutter/fml/macros.h"
12
13 namespace flutter {
14
15 // This is used to generate a series of sequential ID numbers in a way that a
16 // new ID is always the lowest possible ID in the sequence.
17 //
18 // based on
19 // https://source.chromium.org/chromium/chromium/src/+/main:ui/gfx/sequential_id_generator.h
20 class SequentialIdGenerator {
21 public:
22 // Creates a new generator with the specified lower bound and uppoer bound for
23 // the IDs.
24 explicit SequentialIdGenerator(uint32_t min_id, uint32_t max_id);
25 ~SequentialIdGenerator();
26
27 // Generates a unique ID to represent |number|. The generated ID is the
28 // smallest available ID greater than or equal to the |min_id| specified
29 // during creation of the generator.
30 uint32_t GetGeneratedId(uint32_t number);
31
32 // Checks to see if the generator currently has a unique ID generated for
33 // |number|.
34 bool HasGeneratedIdFor(uint32_t number) const;
35
36 // Removes the ID previously generated for |number| by calling
37 // |GetGeneratedID()| - does nothing if the number is not mapped.
38 void ReleaseNumber(uint32_t number);
39
40 // Releases ID previously generated by calling |GetGeneratedID()|. Does
41 // nothing if the ID is not mapped.
42 void ReleaseId(uint32_t id);
43
44 private:
45 typedef std::unordered_map<uint32_t, uint32_t> IdMap;
46
47 uint32_t GetNextAvailableId();
48
49 void UpdateNextAvailableIdAfterRelease(uint32_t id);
50
51 IdMap number_to_id_;
52 IdMap id_to_number_;
53
54 const uint32_t min_id_;
55 const uint32_t max_id_;
56 uint32_t min_available_id_;
57
58 FML_DISALLOW_COPY_AND_ASSIGN(SequentialIdGenerator);
59 };
60
61 } // namespace flutter
62
63 #endif // FLUTTER_SHELL_PLATFORM_WINDOWS_SEQUENTIAL_ID_GENERATOR_H_
flutter::SequentialIdGenerator
Definition: sequential_id_generator.h:20
flutter::SequentialIdGenerator::~SequentialIdGenerator
~SequentialIdGenerator()
Definition: sequential_id_generator.cc:30
flutter::SequentialIdGenerator::HasGeneratedIdFor
bool HasGeneratedIdFor(uint32_t number) const
Definition: sequential_id_generator.cc:43
flutter::SequentialIdGenerator::ReleaseId
void ReleaseId(uint32_t id)
Definition: sequential_id_generator.cc:54
flutter::SequentialIdGenerator::SequentialIdGenerator
SequentialIdGenerator(uint32_t min_id, uint32_t max_id)
Definition: sequential_id_generator.cc:27
flutter::SequentialIdGenerator::ReleaseNumber
void ReleaseNumber(uint32_t number)
Definition: sequential_id_generator.cc:47
flutter::SequentialIdGenerator::GetGeneratedId
uint32_t GetGeneratedId(uint32_t number)
Definition: sequential_id_generator.cc:32
flutter
Definition: accessibility_bridge_windows.cc:11