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111 lines
2.1 KiB
111 lines
2.1 KiB
/*
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* Copyright 2020-2021 the original author(https://github.com/wj596)
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*
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* <p>
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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* </p>
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*/
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package collections
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import "sync"
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type Queue struct {
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lock sync.RWMutex
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first *node
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last *node
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size int
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}
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type node struct {
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value interface{}
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next *node
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}
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func NewQueue(values ...interface{}) *Queue {
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q := &Queue{}
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if len(values) > 0 {
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q.Offer(values...)
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}
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return q
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}
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// 将元素插入到队列末尾
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func (q *Queue) Offer(values ...interface{}) {
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q.lock.Lock()
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defer q.lock.Unlock()
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for _, value := range values {
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element := &node{value: value}
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if q.size == 0 {
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q.first = element
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q.last = element
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} else {
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q.last.next = element
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q.last = element
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}
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q.size++
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}
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}
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//获取队首元素，若成功，则返回队首元素；否则返回null
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func (q *Queue) Peek() (interface{}, bool) {
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q.lock.RLock()
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defer q.lock.RUnlock()
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if q.size == 0 {
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return nil, false
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}
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return q.first.value, true
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}
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//移除并获取队首元素，若成功，则返回队首元素；否则返回null
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func (q *Queue) Poll() (interface{}, bool) {
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q.lock.Lock()
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defer q.lock.Unlock()
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if q.size == 0 {
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return nil, false
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}
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if q.size == 1 {
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val := q.first.value
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q.first = nil
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q.last = nil
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q.size = 0
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return val, true
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}
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element := q.first
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q.first = q.first.next
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val := element.value
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element = nil
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q.size--
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return val, true
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}
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func (q *Queue) Size() int {
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q.lock.RLock()
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defer q.lock.RUnlock()
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return q.size
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}
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func (q *Queue) Clear() {
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q.lock.Lock()
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defer q.lock.Unlock()
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q.size = 0
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q.first = nil
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q.last = nil
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}
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