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76 lines
2.1 KiB
Go
76 lines
2.1 KiB
Go
/* queue.go - A generic queue implementation
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*
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* This file is part of ds library.
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*
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* The MIT License (MIT)
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* Copyright (c) <2016> Alexander Kuleshov <kuleshovmail@gmail.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
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* of the Software, and to permit persons to whom the Software is furnished to do
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* so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
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* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
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* PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
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* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
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* OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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package queue
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type QueueItem struct {
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item interface{}
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prev *QueueItem
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}
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// Base data structure for Queue
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type Queue struct {
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current *QueueItem
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last *QueueItem
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depth uint64
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}
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// Initializes new Queue and return it
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func New() *Queue {
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var queue *Queue = new(Queue)
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queue.depth = 0
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return queue
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}
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// Puts a given item into Queue
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func (queue *Queue) Enqueue(item interface{}) {
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if (queue.depth == 0) {
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queue.current = &QueueItem{item: item, prev: nil}
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queue.last = queue.current
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queue.depth++
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return
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}
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q := &QueueItem{item: item, prev: nil}
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queue.last.prev = q
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queue.last = q
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queue.depth++
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}
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// Extracts first item from the Queue
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func (queue *Queue) Dequeue() interface{} {
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if (queue.depth > 0) {
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item := queue.current.item
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queue.current = queue.current.prev
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queue.depth--
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return item
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}
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return nil
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}
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