Play Swift on IBM Swift Sandbox

Recently I read a news about IBM creating a website for swift: IBM Swift Sandbox. That's very interesting. I went to the site and played for a while. This is a good site for beginners to write some experiment codes in web browser.

There are some examples as initials. I picked up tree.swift to put my hands on writing and playing swift codes.

The output of this example shows notes added to a tree. I wanted to extend this class so that I can print out notes in the tree.

To do that, I added a var root as property value, and a func to print tree notes. Here are my updated codes:

Here is a command to set up swift syntax in VIM

 1 
 2 /* Generic sorted tree implementation. Shows generic
 3    classes and recursive functions in Swift.
 4 */
 5 
 6 class TreeNode<T: Comparable> {
 7 
 8     var val: T?
 9     var left: TreeNode?
10     var right: TreeNode?
11     var root : Bool = true
12 
13     func printMe() {
14         if (self.root) {
15             print("  root:\(self.val!)")
16         }
17 
18         if let leftVal = self.left {
19             print("  \(leftVal.val!)<-\(self.val!)")
20             leftVal.root = false
21             leftVal.printMe()
22         }
23         if let rightVal = self.right {
24             print("  \(self.val!)->\(rightVal.val!)")
25             rightVal.root = false;
26             rightVal.printMe()
27         }
28     }
29     //add item based on its value
30     func addNode(val: T) {
31 
32         if (self.val == nil) {
33             self.val = val
34             print("Added Head")
35             return
36         }
37 
38         if (val < self.val) {
39 
40             if let left = self.left {
41               left.addNode(val)
42             } else {
43                 let newLeft = TreeNode()
44                 newLeft.val = val
45                 self.left = newLeft
46                 print("Added Left")
47             }
48         }
49 
50         if (val > self.val) {
51 
52             if let right = self.right {
53                 right.addNode(val)
54             } else {
55                 let newRight = TreeNode()
56                 newRight.val = val
57                 self.right = newRight
58                 print("Added Right")
59             }
60         }
61 
62     }
63 }
64 
65 let numbers: Array<Int> = [8, 3, 5, 2, 7, 9, 13, 16, 10, 22]
66 var root = TreeNode<Int>()
67 
68 for n in numbers {
69     print(n)
70     root.addNode(n)
71 }
72 
73 print("\nTree Notes")
74 root.root = true
75 root.printMe()
76 

Here s the result after click on Run button:

Exercises

The above codes can be extended with following 4 exercises:

1. Add an enumeration type with three enumerators: "Added Head", "Added Left" and "Added Right".
2. Add above enum to TreeNote class member as an note's added type, or addType.
3. Update addNode(T) func with a return type of TreeNode, that is, the returning the added node.
4. Add a member to TreeNode: var parent: TreeNode. Update addNode() func to set this member value.

References

• IBM Swift Sandbox