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93 lines
1.9 KiB
Go
93 lines
1.9 KiB
Go
// Copyright 2020, Chef. All rights reserved.
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// https://github.com/q191201771/naza
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//
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// Use of this source code is governed by a MIT-style license
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// that can be found in the License file.
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//
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// Author: Chef (191201771@qq.com)
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package circularqueue
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import "errors"
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// 底层基于切片实现的固定容量大小的FIFO的环形队列
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var ErrCircularQueue = errors.New("circular queue: fxxk")
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type CircularQueue struct {
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capacity int
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core []interface{}
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first int
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last int
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}
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func New(capacity int) *CircularQueue {
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return &CircularQueue{
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capacity: capacity + 1,
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core: make([]interface{}, capacity+1, capacity+1),
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first: 0,
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last: 0,
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}
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}
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// @return 如果队列满了，则返回错误
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func (c *CircularQueue) PushBack(v interface{}) error {
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if c.Full() {
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return ErrCircularQueue
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}
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c.core[c.last] = v
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c.last = (c.last + 1) % c.capacity
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return nil
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}
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// @return 如果队列为空，则返回错误
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func (c *CircularQueue) PopFront() (interface{}, error) {
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if c.Empty() {
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return nil, ErrCircularQueue
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}
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v := c.core[c.first]
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c.first = (c.first + 1) % c.capacity
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return v, nil
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}
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// @return 如果队列为空，则返回错误
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func (c *CircularQueue) Front() (interface{}, error) {
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if c.Empty() {
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return nil, ErrCircularQueue
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}
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return c.core[c.first], nil
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}
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// @return 如果队列为空，则返回错误
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func (c *CircularQueue) Back() (interface{}, error) {
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if c.Empty() {
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return nil, ErrCircularQueue
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}
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return c.core[(c.last+c.capacity-1)%c.capacity], nil
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}
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// 获取第i个元素
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func (c *CircularQueue) At(i int) (interface{}, error) {
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if i > c.Size()-1 {
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return nil, ErrCircularQueue
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}
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return c.core[(c.first+i)%c.capacity], nil
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}
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func (c *CircularQueue) Size() int {
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return (c.last + c.capacity - c.first) % c.capacity
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}
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func (c *CircularQueue) Full() bool {
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return (c.last+1)%c.capacity == c.first
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}
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func (c *CircularQueue) Empty() bool {
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return c.first == c.last
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}
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