Golang如何使用迭代器模式遍历集合元素_Golang Iterator模式实现技巧

type Iterator interface {
    HasNext() bool
    Next() interface{}
}

type SliceIterator struct {
    items []string
    index int
}

func NewSliceIterator(items []string) *SliceIterator {
    return &SliceIterator{items: items, index: 0}
}

func (it *SliceIterator) HasNext() bool {
    return it.index < len(it.items)
}

func (it *SliceIterator) Next() interface{} {
    if !it.HasNext() {
        return nil
    }
    item := it.items[it.index]
    it.index++
    return item
}

items := []string{"apple", "banana", "cherry"}
iter := NewSliceIterator(items)

for iter.HasNext() {
    fmt.Println(iter.Next())
}

func NewStringSliceIterator(items []string) func() (string, bool) {
    index := 0
    return func() (string, bool) {
        if index >= len(items) {
            return "", false
        }
        value := items[index]
        index++
        return value, true
    }
}

next := NewStringSliceIterator([]string{"a", "b", "c"})
for {
    val, ok := next()
    if !ok {
        break
    }
    fmt.Println(val)
}

type GenericIterator[T any] struct {
    items []T
    index int
}

func NewGenericIterator[T any](items []T) *GenericIterator[T] {
    return &GenericIterator[T]{items: items, index: 0}
}

func (it *GenericIterator[T]) HasNext() bool {
    return it.index < len(it.items)
}

func (it *GenericIterator[T]) Next() T {
    if !it.HasNext() {
        var zero T
        return zero
    }
    item := it.items[it.index]
    it.index++
    return item
}

iter := NewGenericIterator([]int{1, 2, 3})
for iter.HasNext() {
    fmt.Println(iter.Next())
}