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package lexer
type stackNode struct {
r rune
next *stackNode
}
type stack struct {
start *stackNode
}
func newStack() stack {
return stack{}
}
func (s *stack) push(r rune) {
node := &stackNode{r: r}
if s.start == nil {
s.start = node
} else {
node.next = s.start
s.start = node
}
}
func (s *stack) pop() rune {
if s.start == nil {
return EOFRune
}
n := s.start
s.start = n.next
return n.r
}
func (s *stack) clear() {
s.start = nil
}
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