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设计模式--迭代器(Iterator)模式

 2 years ago
source link: https://segmentfault.com/a/1190000040406672
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提供一中方法顺序访问一个聚合对象中的各个元素，而又不暴露（稳定）该对象的内部表示

  • 迭代抽象：访问一个聚合对象的内部而无需暴露它的内部表示
  • 迭代多态：为遍历不同的集合结构提供一个统一的接口，从而支持同样的算法在不同的集合结构上进行操作
  • 迭代器的健壮性考虑：遍历的同时更改迭代器所在的集合结构，会导致问题

Go语言代码实现

iterator.go

package Iterator

type Iterator interface {
   Index() int
   Value() interface{}
   HasNext() bool
   Next()
}

type ArrayIterator struct {
   array []interface{}
   index *int
}

func (a *ArrayIterator) Index() *int{
   return a.index
}

func (a *ArrayIterator) Value() interface{} {
   return a.array[*a.index]
}

func (a *ArrayIterator) HasNext() bool {
   return *a.index + 1 <= len(a.array)
}

func (a *ArrayIterator) Next() {
   if a.HasNext(){
      *a.index++
   }
}

iterator_test.go

package Iterator

import (
   "fmt"
   "testing"
)

func TestArrayIterator(t *testing.T) {
   array := []interface{}{1,3,9,2,8,7}
   a := 0
   iterator := ArrayIterator{array: array, index: &a}
   for it := iterator; iterator.HasNext(); iterator.Next(){
      index, value := it.Index(), it.Value().(int)
      for value != array[*index]{
         fmt.Println("error")
      }
      fmt.Println(*index, value)
   }
}

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