Garfield Tan | 73007b6 | 2019-08-29 17:28:41 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2019 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #ifndef _UI_INPUT_INPUTDISPATCHER_QUEUE_H |
| 18 | #define _UI_INPUT_INPUTDISPATCHER_QUEUE_H |
| 19 | |
| 20 | namespace android::inputdispatcher { |
| 21 | |
| 22 | // Generic queue implementation. |
| 23 | template <typename T> |
| 24 | struct Queue { |
| 25 | T* head; |
| 26 | T* tail; |
| 27 | uint32_t entryCount; |
| 28 | |
| 29 | inline Queue() : head(nullptr), tail(nullptr), entryCount(0) {} |
| 30 | |
| 31 | inline bool isEmpty() const { return !head; } |
| 32 | |
| 33 | inline void enqueueAtTail(T* entry) { |
| 34 | entryCount++; |
| 35 | entry->prev = tail; |
| 36 | if (tail) { |
| 37 | tail->next = entry; |
| 38 | } else { |
| 39 | head = entry; |
| 40 | } |
| 41 | entry->next = nullptr; |
| 42 | tail = entry; |
| 43 | } |
| 44 | |
| 45 | inline void enqueueAtHead(T* entry) { |
| 46 | entryCount++; |
| 47 | entry->next = head; |
| 48 | if (head) { |
| 49 | head->prev = entry; |
| 50 | } else { |
| 51 | tail = entry; |
| 52 | } |
| 53 | entry->prev = nullptr; |
| 54 | head = entry; |
| 55 | } |
| 56 | |
| 57 | inline void dequeue(T* entry) { |
| 58 | entryCount--; |
| 59 | if (entry->prev) { |
| 60 | entry->prev->next = entry->next; |
| 61 | } else { |
| 62 | head = entry->next; |
| 63 | } |
| 64 | if (entry->next) { |
| 65 | entry->next->prev = entry->prev; |
| 66 | } else { |
| 67 | tail = entry->prev; |
| 68 | } |
| 69 | } |
| 70 | |
| 71 | inline T* dequeueAtHead() { |
| 72 | entryCount--; |
| 73 | T* entry = head; |
| 74 | head = entry->next; |
| 75 | if (head) { |
| 76 | head->prev = nullptr; |
| 77 | } else { |
| 78 | tail = nullptr; |
| 79 | } |
| 80 | return entry; |
| 81 | } |
| 82 | |
| 83 | uint32_t count() const { return entryCount; } |
| 84 | }; |
| 85 | |
| 86 | } // namespace android::inputdispatcher |
| 87 | |
| 88 | #endif // _UI_INPUT_INPUTDISPATCHER_QUEUE_H |