super-graph/core/internal/qcode/stack.go

48 lines
717 B
Go
Raw Permalink Normal View History

package qcode
type Stack struct {
stA [20]int32
st []int32
top int
}
// Create a new Stack
func NewStack() *Stack {
s := &Stack{top: -1}
s.st = s.stA[:0]
return s
}
// Return the number of items in the Stack
func (s *Stack) Len() int {
return (s.top + 1)
}
// View the top item on the Stack
func (s *Stack) Peek() int32 {
if s.top == -1 {
return -1
}
return s.st[s.top]
}
// Pop the top item of the Stack and return it
func (s *Stack) Pop() int32 {
if s.top == -1 {
return -1
}
s.top--
return s.st[(s.top + 1)]
}
// Push a value onto the top of the Stack
func (s *Stack) Push(value int32) {
s.top++
if len(s.st) <= s.top {
s.st = append(s.st, value)
} else {
s.st[s.top] = value
}
}