From 2deb4ba69a18305bae52b6566c5e368c61aa719e Mon Sep 17 00:00:00 2001 From: Alexander Kuleshov Date: Wed, 8 Mar 2017 00:21:07 +0600 Subject: [PATCH] reimplement queue based on pointers --- queue/queue.go | 84 +++++++++++++++++++++++++++++++++------------ queue/queue_test.go | 58 ++++++++++++++++++++----------- 2 files changed, 101 insertions(+), 41 deletions(-) diff --git a/queue/queue.go b/queue/queue.go index 56d08cc..30ff39a 100644 --- a/queue/queue.go +++ b/queue/queue.go @@ -1,33 +1,75 @@ +/* queue.go - A generic queue implementation + * + * This file is part of ds library. + * + * The MIT License (MIT) + * Copyright (c) <2016> Alexander Kuleshov + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies + * of the Software, and to permit persons to whom the Software is furnished to do + * so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in all + * copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, + * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A + * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT + * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF + * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE + * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + */ + package queue +type QueueItem struct { + item interface{} + prev *QueueItem +} + +// Base data structure for Queue type Queue struct { - queue []interface{} - len int + current *QueueItem + last *QueueItem + depth uint64 } +// Initializes new Queue and return it func New() *Queue { - queue := &Queue{} - queue.queue = make([]interface{}, 0) - queue.len = 0 - return queue + var queue *Queue = new(Queue) + + queue.depth = 0 + + return queue } -func (queue *Queue) Length() int { - return queue.len +// Puts a given item into Queue +func (queue *Queue) Enqueue(item interface{}) { + if (queue.depth == 0) { + queue.current = &QueueItem{item: item, prev: nil} + queue.last = queue.current + queue.depth++ + return + } + + q := &QueueItem{item: item, prev: nil} + queue.last.prev = q + queue.last = q + queue.depth++ } -func (q *Queue) Remove() interface{} { - tmp := q.queue[0] - q.queue = q.queue[1:] - q.len -= 1 - return tmp -} +// Extracts first item from the Queue +func (queue *Queue) Dequeue() interface{} { + if (queue.depth > 0) { + item := queue.current.item + queue.current = queue.current.prev + queue.depth-- + + return item + } -func (q *Queue) Peek() interface{} { - return q.queue[0] -} - -func (q *Queue) Add(value interface{}) { - q.len += 1 - q.queue = append(q.queue, value) + return nil } diff --git a/queue/queue_test.go b/queue/queue_test.go index 32361cf..fb3f3d6 100644 --- a/queue/queue_test.go +++ b/queue/queue_test.go @@ -1,29 +1,47 @@ +/* queue_test.go - Test for generic queue implementation + * + * This file is part of ds library. + * + * The MIT License (MIT) + * Copyright (c) <2016> Alexander Kuleshov + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies + * of the Software, and to permit persons to whom the Software is furnished to do + * so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in all + * copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, + * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A + * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT + * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF + * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE + * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + */ + package queue import "testing" -func Test_Queue(t *testing.T) { - queue := New() +func TestQueue(t *testing.T) { + var queue *Queue = New() - queue.Add(1) - queue.Add(2) - queue.Add(3) + queue.Enqueue(1) + queue.Enqueue(2) + queue.Enqueue(3) + queue.Enqueue(4) + queue.Enqueue(5) - if queue.Length() != 3 { - t.Error("[Error] queue length is wrong") - } + for i := 1; i < 6; i++ { + item := queue.Dequeue() - element := queue.Remove() + if (item != i) { + t.Error("TestQueue failed...", i) + } + } - if element != 1 { - t.Error("[Error] remove is wrong") - } - - if queue.Length() != 2 { - t.Error("[Error] queue length is wrong after pop") - } - - if queue.Peek() != 2 { - t.Error("[Error] queue Peek is wrong") - } }