27 lines
387 B
Go
27 lines
387 B
Go
package expression
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type Stack []Token
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func (s *Stack) Push(item Token) {
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*s = append(*s, item)
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}
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func (s *Stack) Pop() (item Token) {
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if len(*s) == 0 {
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return
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}
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*s, item = (*s)[:len(*s)-1], (*s)[len(*s)-1]
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return item
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}
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func (s *Stack) Empty() bool {
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return len(*s) == 0
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}
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func (s *Stack) Head() (item *Token) {
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if s.Empty() {
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return nil
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}
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return &((*s)[len(*s)-1])
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}
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