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| 1 | +package main |
| 2 | + |
| 3 | +import ( |
| 4 | + "fmt" |
| 5 | +) |
| 6 | + |
| 7 | +// Stack defines the interface for a LIFO stack. |
| 8 | +type Stack interface { |
| 9 | + Push(item string) |
| 10 | + Pop() (string, error) |
| 11 | + Print() |
| 12 | +} |
| 13 | + |
| 14 | +// Queue defines the interface for a FIFO queue. |
| 15 | +type Queue interface { |
| 16 | + Enqueue(item string) |
| 17 | + Dequeue() (string, error) |
| 18 | + Print() |
| 19 | +} |
| 20 | + |
| 21 | +type StringStack struct { |
| 22 | + items []string |
| 23 | +} |
| 24 | + |
| 25 | +func NewStringStack() *StringStack { |
| 26 | + return &StringStack{items: []string{}} |
| 27 | +} |
| 28 | + |
| 29 | +func (s *StringStack) Push(item string) { |
| 30 | + s.items = append(s.items, item) |
| 31 | +} |
| 32 | + |
| 33 | +func (s *StringStack) Pop() (string, error) { |
| 34 | + if len(s.items) == 0 { |
| 35 | + return "", fmt.Errorf("stack is empty") |
| 36 | + } |
| 37 | + item := s.items[len(s.items)-1] |
| 38 | + s.items = s.items[:len(s.items)-1] |
| 39 | + return item, nil |
| 40 | +} |
| 41 | + |
| 42 | +func (s *StringStack) Print() { |
| 43 | + fmt.Println(s.items) |
| 44 | +} |
| 45 | + |
| 46 | +type StringQueue struct { |
| 47 | + items []string |
| 48 | +} |
| 49 | + |
| 50 | +func NewStringQueue() *StringQueue { |
| 51 | + return &StringQueue{items: []string{}} |
| 52 | +} |
| 53 | + |
| 54 | +func (q *StringQueue) Enqueue(item string) { |
| 55 | + q.items = append(q.items, item) |
| 56 | +} |
| 57 | + |
| 58 | +func (q *StringQueue) Dequeue() (string, error) { |
| 59 | + if len(q.items) == 0 { |
| 60 | + return "", fmt.Errorf("queue is empty") |
| 61 | + } |
| 62 | + item := q.items[0] |
| 63 | + q.items = q.items[1:] |
| 64 | + return item, nil |
| 65 | +} |
| 66 | + |
| 67 | +func (q *StringQueue) Print() { |
| 68 | + fmt.Println(q.items) |
| 69 | +} |
| 70 | + |
| 71 | +type WebNavigator struct { |
| 72 | + stack Stack |
| 73 | +} |
| 74 | + |
| 75 | +func NewWebNavigator(stack Stack) *WebNavigator { |
| 76 | + return &WebNavigator{stack: stack} |
| 77 | +} |
| 78 | + |
| 79 | +func (wn *WebNavigator) Navigate() { |
| 80 | + for { |
| 81 | + var action string |
| 82 | + fmt.Println("Enter a URL or type 'forward', 'back', or 'exit':") |
| 83 | + fmt.Scan(&action) |
| 84 | + switch action { |
| 85 | + case "exit": |
| 86 | + fmt.Println("Exiting web navigator.") |
| 87 | + return |
| 88 | + case "forward": |
| 89 | + fmt.Println("Forwarding to next page.") |
| 90 | + _, err := wn.stack.Pop() |
| 91 | + if err != nil { |
| 92 | + fmt.Println("No next pages.") |
| 93 | + } |
| 94 | + case "back": |
| 95 | + _, err := wn.stack.Pop() |
| 96 | + if err != nil { |
| 97 | + fmt.Println("No previous pages.") |
| 98 | + } |
| 99 | + default: |
| 100 | + wn.stack.Push(action) |
| 101 | + } |
| 102 | + wn.stack.Print() |
| 103 | + } |
| 104 | +} |
| 105 | + |
| 106 | +type SharedPrinter struct { |
| 107 | + queue Queue |
| 108 | +} |
| 109 | + |
| 110 | +func NewSharedPrinter(queue Queue) *SharedPrinter { |
| 111 | + return &SharedPrinter{queue: queue} |
| 112 | +} |
| 113 | + |
| 114 | +func (sp *SharedPrinter) PrintDocuments() { |
| 115 | + for { |
| 116 | + var action string |
| 117 | + fmt.Println("Add a document or type 'print' or 'exit':") |
| 118 | + fmt.Scan(&action) |
| 119 | + switch action { |
| 120 | + case "exit": |
| 121 | + return |
| 122 | + case "print": |
| 123 | + doc, err := sp.queue.Dequeue() |
| 124 | + if err != nil { |
| 125 | + fmt.Println("No documents to print.") |
| 126 | + } else { |
| 127 | + fmt.Printf("Printing: %s\n", doc) |
| 128 | + } |
| 129 | + default: |
| 130 | + sp.queue.Enqueue(action) |
| 131 | + } |
| 132 | + sp.queue.Print() |
| 133 | + } |
| 134 | +} |
| 135 | + |
| 136 | +func main() { |
| 137 | + stack := NewStringStack() |
| 138 | + stack.Push("1") |
| 139 | + stack.Push("2") |
| 140 | + stack.Push("3") |
| 141 | + stack.Print() |
| 142 | + item, _ := stack.Pop() |
| 143 | + fmt.Println("Popped item:", item) |
| 144 | + stack.Print() |
| 145 | + |
| 146 | + queue := NewStringQueue() |
| 147 | + queue.Enqueue("1") |
| 148 | + queue.Enqueue("2") |
| 149 | + queue.Enqueue("3") |
| 150 | + queue.Print() |
| 151 | + item, _ = queue.Dequeue() |
| 152 | + fmt.Println("Dequeued item:", item) |
| 153 | + queue.Print() |
| 154 | + |
| 155 | + webNavigator := NewWebNavigator(NewStringStack()) |
| 156 | + webNavigator.Navigate() |
| 157 | + |
| 158 | + sharedPrinter := NewSharedPrinter(NewStringQueue()) |
| 159 | + sharedPrinter.PrintDocuments() |
| 160 | +} |
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