package main

import (

    "fmt"

    "sync"

)

type object interface{}

type Set struct {

    m map[object]bool

    sync.RWMutex //线程安全实现，记录下

}

//初始化

func New() *Set {

    return &Set{

        m: map[object]bool{},

    }

}

func (s *Set) Add(item object) {

    s.Lock()

    defer s.Unlock()

    s.m[item] = true

}

func (s *Set) Remove(item object) {

    s.Lock()

    defer s.Unlock()

    delete(s.m, item)

}

func (s *Set) Clean() {

    s.m = map[object]bool{}

}

func (s *Set) Len() int {

    return len(s.m)

}

func (s *Set) Contains(item object) bool {

    _, ok := s.m[item];

    return ok

}

func (s *Set) IsEmpty() bool {

    fmt.Println(len(s.m))

    return len(s.m) > 0

}

func main() {

    s := New()

    fmt.Println(s.IsEmpty())

    s.Add("aaa")

    fmt.Println(s.IsEmpty())

    s.Add("1")

    s.Add("2")

    s.Add("3")

    fmt.Println(s.Contains("3"))

    //s.Clean()

    for key, _ := range s.m {

        fmt.Println("Key:", key)

    }

}