stack.go

type stack []rune

func (s *stack) push(n rune) {
	*s = append(*s, n)
}

func (s *stack) pop() rune {
	if s.empty() {
		panic("stack is empty")
	}

	n := len(*s) - 1
	v := (*s)[n]
	*s = (*s)[:n]
	return v
}

func (s *stack) empty() bool {
	return len(*s) == 0
}