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package stack
type (
Stack struct {
top *node
length int
}
node struct {
value interface{}
prev *node
}
)
// Create a new stack
func New() *Stack {
return &Stack{nil,0}
}
// Return the number of items in the stack
func (this *Stack) Len() int {
return this.length
}
// View the top item on the stack
func (this *Stack) Peek() interface{} {
if this.length == 0 {
return nil
}
return this.top.value
}
// Pop the top item of the stack and return it
func (this *Stack) Pop() interface{} {
if this.length == 0 {
return nil
}
n := this.top
this.top = n.prev
this.length--
return n.value
}
// Push a value onto the top of the stack
func (this *Stack) Push(value interface{}) {
n := &node{value,this.top}
this.top = n
this.length++
}
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