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