So far my naive approach is
type stack []int
func (s *stack) Push(v int) {
*s = append(*s, v)
}
func (s *stack) Pop() int {
res:=(*s)[len(*s)-1]
*s=(*s)[:len(*s)-1]
return res
}
it works - playground, but looks ugly and has too much dereferencing. Can I do better?
It's a matter of style and personal taste, your code is fine (apart from not being thread safe and panicking if you pop from an empty stack). To simplify it a bit you can work with value methods and return the stack itself, it's slightly more elegant to some tastes. i.e.
type stack []int
func (s stack) Push(v int) stack {
return append(s, v)
}
func (s stack) Pop() (stack, int) {
// FIXME: What do we do if the stack is empty, though?
l := len(s)
return s[:l-1], s[l-1]
}
func main(){
s := make(stack,0)
s = s.Push(1)
s = s.Push(2)
s = s.Push(3)
s, p := s.Pop()
fmt.Println(p)
}
Another approach is to wrap it in a struct, so you can also easily add a mutex to avoid race conditions, etc. something like:
type stack struct {
lock sync.Mutex // you don't have to do this if you don't want thread safety
s []int
}
func NewStack() *stack {
return &stack {sync.Mutex{}, make([]int,0), }
}
func (s *stack) Push(v int) {
s.lock.Lock()
defer s.lock.Unlock()
s.s = append(s.s, v)
}
func (s *stack) Pop() (int, error) {
s.lock.Lock()
defer s.lock.Unlock()
l := len(s.s)
if l == 0 {
return 0, errors.New("Empty Stack")
}
res := s.s[l-1]
s.s = s.s[:l-1]
return res, nil
}
func main(){
s := NewStack()
s.Push(1)
s.Push(2)
s.Push(3)
fmt.Println(s.Pop())
fmt.Println(s.Pop())
fmt.Println(s.Pop())
}
Here is a LIFO implementation using linked data structure
package stack
import "sync"
type element struct {
data interface{}
next *element
}
type stack struct {
lock *sync.Mutex
head *element
Size int
}
func (stk *stack) Push(data interface{}) {
stk.lock.Lock()
element := new(element)
element.data = data
temp := stk.head
element.next = temp
stk.head = element
stk.Size++
stk.lock.Unlock()
}
func (stk *stack) Pop() interface{} {
if stk.head == nil {
return nil
}
stk.lock.Lock()
r := stk.head.data
stk.head = stk.head.next
stk.Size--
stk.lock.Unlock()
return r
}
func New() *stack {
stk := new(stack)
stk.lock = &sync.Mutex{}
return stk
}