package main
//file to implement expanding/shrinking intlist with a map
import "fmt"
type IntList struct {
list map[int]int
//for keeping track of placement indices and insertion spots
record map[string]int
}
//creates an IntList and returns it
func createIntList() IntList {
lst := IntList{list:make(map[int]int), record:make(map[string]int)}
lst.record["insert"] = 0
lst.record["last"] = -1
return lst
}
//appends a new element to the end of the list, and updates the insertion and last element positions
func (il IntList) push(elem int) {
il.list[il.record["insert"]] = elem
il.record["insert"] += 1
il.record["last"] += 1
}
func main() {
tester := createIntList()
tester.push(5)
fmt.Println(tester)
//{map[0:5] map[last:0 insert:1]}
}
golang Go（Golang）中的并发安全SET数据结构
// A very simple example about how to use concurrent-safe SETs (using string as keys) in GO
package main
import (
"fmt"
"sync"
)
type Set struct {
m map[string]bool
sync.RWMutex
}
func New() *Set {
return &Set{
m: make(map[string]bool),
}
}
func main() {
// Initialize our Set
s := New()
// Add example items
s.Add("item1")
s.Add("item1") // duplicate item
s.Add("item2")
fmt.Printf("%d items\n", s.Len())
// Clear all items
s.Clear()
if s.IsEmpty() {
fmt.Printf("0 items\n")
}
s.Add("item2")
s.Add("item3")
s.Add("item4")
// Check for existence
if s.Has("item2") {
fmt.Println("item2 does exist")
}
// Remove some of our items
s.Remove("item2")
s.Remove("item4")
fmt.Println("list of all items:", s.List())
}
// Add add
func (s *Set) Add(item string) {
s.Lock()
defer s.Unlock()
s.m[item] = true
}
// Remove deletes the specified item from the map
func (s *Set) Remove(item string) {
s.Lock()
defer s.Unlock()
delete(s.m, item)
}
// Has looks for the existence of an item
func (s *Set) Has(item string) bool {
s.RLock()
defer s.RUnlock()
_, ok := s.m[item]
return ok
}
// Len returns the number of items in a set.
func (s *Set) Len() int {
return len(s.List())
}
// Clear removes all items from the set
func (s *Set) Clear() {
s.Lock()
defer s.Unlock()
s.m = make(map[string]bool)
}
// IsEmpty checks for emptiness
func (s *Set) IsEmpty() bool {
if s.Len() == 0 {
return true
}
return false
}
// Set returns a slice of all items
func (s *Set) List() []string {
s.RLock()
defer s.RUnlock()
list := make([]string, 0)
for item := range s.m {
list = append(list, item)
}
return list
}