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李海彬
发布2018-03-26 14:14:28
9690
发布2018-03-26 14:14:28
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文章被收录于专栏:Golang语言社区Golang语言社区

要点

  • Element表示链表的一个元素,List表示链表
  • 访问元素的值: .Value
  • list是双向链表,可以在指定的位置插入元素
  • 初始化: New()。——和var x List 是等价的,但New()可读性更好。
  • 元素个数: Len()
  • 遍历: (1) Front()和Back()分别取链表的第一个元素和最后一个元素。如果为空,则返回nil。(2) Next()和Prev()分别返回当前元素的写一个或前一个元素。如果为空,则返回nil。 (3) 遍历整个链表的通用方法就是先Front(),然后依次Next()。
  • 插入: InsertAfter(), InsertBefore(), PushBack(), PushBackList(), PushFront(), PushFrontList(). ——xxxList()是把另外一个链表的原始添加到当前链表上。
  • 移动元素: MoveAfter(), MoveBefore(), MoveToBack(), MoveToFront()
  • 删除元素: Remove()

注: - 之前在讲述struct的时候,并没有特别提到类函数或对象函数,或者类方法或对象方法。这里的New()即为类函数,或者说普通的函数。——也可以认为在Go中没有类函数的概念,说成package function可能更合适。因为在调用的时候,需要package_name.FunctionName()。 - 几乎list所有的成员方法都返回*Element类型,而这个返回值又可以作为其他成员方法的入参。 - 建议阅读list的源码,以了解进一步的详细信息。

示例

以src/Container/list/example_est.go为素材。

package main

import (
    "fmt"
    "container/list"
)

/*
D:\examples>go run helloworld.go
0       1       2       3       4       5
D:\examples>
*/
func main() {
    var x list.List // or "x := list.New()"
    e1 := x.PushBack(1)
    x.PushBack(3)
    e5 := x.PushBack(5)
    x.PushFront(0)
    x.InsertAfter(2, e1)
    x.InsertBefore(4, e5)

    for e := x.Front(); e != nil; e = e.Next() {
        fmt.Print(e.Value.(int), "\t")
    }
}

list-Elment的数据类型

前面提到了Element的Value数据成员或Value field. 注意到示例代码中的fmt.Print()一行。另注意到如下定义:

// Element is an element of a linked list.
type Element struct {
    // ...

    // The value stored with this element.
    Value interface{}
}

即这里的Value可以是任意的数据类型,包括Go的基本数据类型,以及用户自定义的数据类型。

进一步地,我们可以预期:一个List中可以放各种不同的数据类型。为此,给出如下示例予以说明。

package main

import (
    "fmt"
    "container/list"
)

type Point struct {
    x, y int
}

/*
D:\examples>go run helloworld.go
1       2       3       Four    Five    {6 66}  {7 77}
D:\examples>
*/
func main() {
    var x list.List 
    x.PushBack(1)
    x.PushBack(2)
    x.PushBack(3)
    x.PushBack("Four")
    x.PushBack("Five")
    x.PushBack(Point{6, 66})
    x.PushBack(Point{7, 77})

    for e := x.Front(); e != nil; e = e.Next() {
        fmt.Print(e.Value, "\t")
    }
}

特别注意到ftm.Print()和之前示例的区别。——请参考Go-Errors一文中的“Println()的入参”一节,以初步了解Print()的处理流程。

godoc list

执行命令:godoc cmd/container/list

PACKAGE DOCUMENTATION

package list
    import "."

    Package list implements a doubly linked list.

    To iterate over a list (where l is a *List):

        for e := l.Front(); e != nil; e = e.Next() {
                // do something with e.Value
        }

TYPES

type Element struct {

    // The value stored with this element.
    Value interface{}
    // contains filtered or unexported fields
}
    Element is an element of a linked list.

func (e *Element) Next() *Element
    Next returns the next list element or nil.

func (e *Element) Prev() *Element
    Prev returns the previous list element or nil.

type List struct {
    // contains filtered or unexported fields
}
    List represents a doubly linked list. The zero value for List is an
    empty list ready to use.

func New() *List
    New returns an initialized list.

func (l *List) Back() *Element
    Back returns the last element of list l or nil.

func (l *List) Front() *Element
    Front returns the first element of list l or nil.

func (l *List) Init() *List
    Init initializes or clears list l.

func (l *List) InsertAfter(v interface{}, mark *Element) *Element
    InsertAfter inserts a new element e with value v immediately after mark
    and returns e. If mark is not an element of l, the list is not modified.

func (l *List) InsertBefore(v interface{}, mark *Element) *Element
    InsertBefore inserts a new element e with value v immediately before
    mark and returns e. If mark is not an element of l, the list is not
    modified.

func (l *List) Len() int
    Len returns the number of elements of list l. The complexity is O(1).

func (l *List) MoveAfter(e, mark *Element)
    MoveAfter moves element e to its new position after mark. If e or mark
    is not an element of l, or e == mark, the list is not modified.

func (l *List) MoveBefore(e, mark *Element)
    MoveBefore moves element e to its new position before mark. If e or mark
    is not an element of l, or e == mark, the list is not modified.

func (l *List) MoveToBack(e *Element)
    MoveToBack moves element e to the back of list l. If e is not an element
    of l, the list is not modified.

func (l *List) MoveToFront(e *Element)
    MoveToFront moves element e to the front of list l. If e is not an
    element of l, the list is not modified.

func (l *List) PushBack(v interface{}) *Element
    PushBack inserts a new element e with value v at the back of list l and
    returns e.

func (l *List) PushBackList(other *List)
    PushBackList inserts a copy of an other list at the back of list l. The
    lists l and other may be the same.

func (l *List) PushFront(v interface{}) *Element
    PushFront inserts a new element e with value v at the front of list l
    and returns e.

func (l *List) PushFrontList(other *List)
    PushFrontList inserts a copy of an other list at the front of list l.
    The lists l and other may be the same.

func (l *List) Remove(e *Element) interface{}
    Remove removes e from l if e is an element of list l. It returns the
    element value e.Value.
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目录
  • 要点
  • 示例
  • list-Elment的数据类型
  • godoc list
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