Migrates Ternary Search Tree to Swift 3 syntax (kodecocodes#352)

* migrates Ternary Search Tree to Swift 3 syntax * aligning function names as suggested * adds unit tests to TernarySearchTree * adds guards as suggested

Author: pbodsk

.travis.yml

@@ -43,3 +43,4 @@ script:
 - xcodebuild test -project ./Topological\ Sort/Tests/Tests.xcodeproj -scheme Tests
 - xcodebuild test -project ./Treap/Treap/Treap.xcodeproj -scheme Tests
 - xcodebuild test -project ./Palindromes/Test/Test.xcodeproj -scheme Test
+- xcodebuild test -project ./Ternary\ Search\ Tree/Tests/Tests.xcodeproj -scheme Tests

Ternary Search Tree/TST.playground/Contents.swift

@@ -4,39 +4,23 @@ import Cocoa
 import Foundation
 
 let treeOfStrings = TernarySearchTree<String>()
-let allowedChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
-
-//Random string generator from:
-//http://stackoverflow.com/questions/26845307/generate-random-alphanumeric-string-in-swift/26845710
-func randomAlphaNumericString(length: Int) -> String {
- let allowedCharsCount = UInt32(allowedChars.characters.count)
- var randomString = ""
-
- for _ in (0..<length) {
- let randomNum = Int(arc4random_uniform(allowedCharsCount))
- let newCharacter = allowedChars[allowedChars.startIndex.advancedBy(randomNum)]
- randomString += String(newCharacter)
- }
-
- return randomString
-}
 
 var testStrings: [(key: String, data: String)] = []
 let testCount = 30
 for _ in (1...testCount) {
  let randomLength = Int(arc4random_uniform(10))
- let key = randomAlphaNumericString(randomLength)
- let data = randomAlphaNumericString(randomLength)
+ let key = Utils.shared.randomAlphaNumericString(withLength: randomLength)
+ let data = Utils.shared.randomAlphaNumericString(withLength: randomLength)
 // print("Key: \(key) Data: \(data)")
 
  if key != "" && data != "" {
  testStrings.append((key, data))
- treeOfStrings.insert(data, withKey: key)
+ treeOfStrings.insert(data: data, withKey: key)
  }
 }
 
 for aTest in testStrings {
- let data = treeOfStrings.find(aTest.key)
+ let data = treeOfStrings.find(key: aTest.key)
 
  if data == nil {
  print("TEST FAILED. Key: \(aTest.key) Data: \(aTest.data)")
@@ -51,16 +35,16 @@ let treeOfInts = TernarySearchTree<Int>()
 for _ in (1...testCount) {
  let randomNum = Int(arc4random_uniform(UInt32.max))
  let randomLength = Int(arc4random_uniform(10))
- let key = randomAlphaNumericString(randomLength)
+ let key = Utils.shared.randomAlphaNumericString(withLength: randomLength)
 
  if key != "" {
  testNums.append((key, randomNum))
- treeOfInts.insert(randomNum, withKey: key)
+ treeOfInts.insert(data: randomNum, withKey: key)
  }
 }
 
 for aTest in testNums {
- let data = treeOfInts.find(aTest.key)
+ let data = treeOfInts.find(key: aTest.key)
  if data == nil {
  print("TEST FAILED. Key: \(aTest.key) Data: \(aTest.data)")
  }

Ternary Search Tree/TST.playground/Sources/TernarySearchTree.swift

@@ -18,42 +18,41 @@ public class TernarySearchTree<Element> {
  //MARK: - Insertion
 
  public func insert(data: Element, withKey key: String) -> Bool {
- return insertNode(&root, withData: data, andKey: key, atIndex: 0)
-
+ return insert(node: &root, withData: data, andKey: key, atIndex: 0)
  }
 
- private func insertNode(inout aNode: TSTNode<Element>?, withData data: Element, andKey key: String, atIndex charIndex: Int) -> Bool {
+ private func insert(node: inout TSTNode<Element>?, withData data: Element, andKey key: String, atIndex charIndex: Int) -> Bool {
 
  //sanity check.
  if key.characters.count == 0 {
  return false
  }
 
  //create a new node if necessary.
- if aNode == nil {
- let index = key.startIndex.advancedBy(charIndex)
- aNode = TSTNode<Element>(key: key[index])
+ if node == nil {
+ let index = key.index(key.startIndex, offsetBy: charIndex)
+ node = TSTNode<Element>(key: key[index])
  }
 
  //if current char is less than the current node's char, go left
- let index = key.startIndex.advancedBy(charIndex)
- if key[index] < aNode!.key {
- return insertNode(&aNode!.left, withData: data, andKey: key, atIndex: charIndex)
+ let index = key.index(key.startIndex, offsetBy: charIndex)
+ if key[index] < node!.key {
+ return insert(node: &node!.left, withData: data, andKey: key, atIndex: charIndex)
  }
  //if it's greater, go right.
- else if key[index] > aNode!.key {
- return insertNode(&aNode!.right, withData: data, andKey: key, atIndex: charIndex)
+ else if key[index] > node!.key {
+ return insert(node: &node!.right, withData: data, andKey: key, atIndex: charIndex)
  }
  //current char is equal to the current nodes, go middle
  else {
  //continue down the middle.
  if charIndex + 1 < key.characters.count {
- return insertNode(&aNode!.middle, withData: data, andKey: key, atIndex: charIndex + 1)
+ return insert(node: &node!.middle, withData: data, andKey: key, atIndex: charIndex + 1)
  }
  //otherwise, all done.
  else {
- aNode!.data = data
- aNode?.hasData = true
+ node!.data = data
+ node?.hasData = true
  return true
  }
  }
@@ -64,32 +63,31 @@ public class TernarySearchTree<Element> {
 
 
  public func find(key: String) -> Element? {
- return findNode(root, withKey: key, atIndex: 0)
+ return find(node: root, withKey: key, atIndex: 0)
  }
 
-
- private func findNode(aNode: TSTNode<Element>?, withKey key: String, atIndex charIndex: Int) -> Element? {
+ private func find(node: TSTNode<Element>?, withKey key: String, atIndex charIndex: Int) -> Element? {
 
  //Given key does not exist in tree.
- if aNode == nil {
+ if node == nil {
  return nil
  }
 
- let index = key.startIndex.advancedBy(charIndex)
+ let index = key.index(key.startIndex, offsetBy: charIndex)
  //go left
- if key[index] < aNode!.key {
- return findNode(aNode!.left, withKey: key, atIndex: charIndex)
+ if key[index] < node!.key {
+ return find(node: node!.left, withKey: key, atIndex: charIndex)
  }
  //go right
- else if key[index] > aNode!.key {
- return findNode(aNode!.right, withKey: key, atIndex: charIndex)
+ else if key[index] > node!.key {
+ return find(node: node!.right, withKey: key, atIndex: charIndex)
  }
  //go middle
  else {
  if charIndex + 1 < key.characters.count {
- return findNode(aNode!.middle, withKey: key, atIndex: charIndex + 1)
+ return find(node: node!.middle, withKey: key, atIndex: charIndex + 1)
  } else {
- return aNode!.data
+ return node!.data
  }
  }
  }

Ternary Search Tree/TST.playground/Sources/Utils.swift

@@ -0,0 +1,30 @@
+//
+// Utils.swift
+// 
+//
+// Created by Peter Bødskov on 10/01/17.
+//
+//
+
+import Foundation
+
+public struct Utils {
+ 
+ public static let shared = Utils()
+ 
+ let allowedChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+ //Random string generator from:
+ //http://stackoverflow.com/questions/26845307/generate-random-alphanumeric-string-in-swift/26845710
+ public func randomAlphaNumericString(withLength length: Int) -> String {
+ let allowedCharsCount = UInt32(allowedChars.characters.count)
+ var randomString = ""
+ 
+ for _ in (0..<length) {
+ let randomNum = Int(arc4random_uniform(allowedCharsCount))
+ let newCharacter = allowedChars[allowedChars.index(allowedChars.startIndex, offsetBy: randomNum)]
+ randomString += String(newCharacter)
+ }
+ 
+ return randomString
+ }
+}

Ternary Search Tree/TST.playground/contents.xcplayground

@@ -1,4 +1,4 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
-<playground version='5.0' target-platform='osx'>
+<playground version='5.0' target-platform='osx' last-migration='0810'>
  <timeline fileName='timeline.xctimeline'/>
 </playground>

Ternary Search Tree/TernarySearchTree.swift

@@ -33,52 +33,52 @@ public class TernarySearchTree<Element> {
 
  - returns: Value indicating insertion success/failure.
  */
- public func insert(data: Element, withKey key: String) -> Bool {
- return insertNode(&root, withData: data, andKey: key, atIndex: 0)
+ @discardableResult public func insert(data: Element, withKey key: String) -> Bool {
+ return insert(node: &root, withData: data, andKey: key, atIndex: 0)
  }
 
  /**
  Helper method for insertion that does the actual legwork. Insertion is performed recursively.
 
- - parameter aNode: The current node to insert below.
+ - parameter node:  The current node to insert below.
  - parameter data: The data being inserted.
  - parameter key: The key being used to find an insertion location for the given data
  - parameter charIndex: The index of the character in the key string to use to for the next node.
 
  - returns: Value indicating insertion success/failure.
  */
- private func insertNode(inout aNode: TSTNode<Element>?, withData data: Element, andKey key: String, atIndex charIndex: Int) -> Bool {
+ private func insert(node: inout TSTNode<Element>?, withData data: Element, andKey key: String, atIndex charIndex: Int) -> Bool {
 
  //sanity check.
- if key.characters.count == 0 {
+ guard key.characters.count > 0 else {
  return false
  }
 
  //create a new node if necessary.
- if aNode == nil {
- let index = key.startIndex.advancedBy(charIndex)
- aNode = TSTNode<Element>(key: key[index])
+ if node == nil {
+ let index = key.index(key.startIndex, offsetBy: charIndex)
+ node = TSTNode<Element>(key: key[index])
  }
 
  //if current char is less than the current node's char, go left
- let index = key.startIndex.advancedBy(charIndex)
- if key[index] < aNode!.key {
- return insertNode(&aNode!.left, withData: data, andKey: key, atIndex: charIndex)
+ let index = key.index(key.startIndex, offsetBy: charIndex)
+ if key[index] < node!.key {
+ return insert(node: &node!.left, withData: data, andKey: key, atIndex: charIndex)
  }
  //if it's greater, go right.
- else if key[index] > aNode!.key {
- return insertNode(&aNode!.right, withData: data, andKey: key, atIndex: charIndex)
+ else if key[index] > node!.key {
+ return insert(node: &node!.right, withData: data, andKey: key, atIndex: charIndex)
  }
  //current char is equal to the current nodes, go middle
  else {
  //continue down the middle.
  if charIndex + 1 < key.characters.count {
- return insertNode(&aNode!.middle, withData: data, andKey: key, atIndex: charIndex + 1)
+ return insert(node: &node!.middle, withData: data, andKey: key, atIndex: charIndex + 1)
  }
  //otherwise, all done.
  else {
- aNode!.data = data
- aNode?.hasData = true
+ node!.data = data
+ node?.hasData = true
  return true
  }
  }
@@ -95,40 +95,40 @@ public class TernarySearchTree<Element> {
  - returns: The element, if found. Otherwise, nil.
  */
  public func find(key: String) -> Element? {
- return findNode(root, withKey: key, atIndex: 0)
+ return find(node: root, withKey: key, atIndex: 0)
  }
 
  /**
  Helper method that performs actual legwork of find operation. Implemented recursively.
 
- - parameter aNode: The current node being evaluated.
+ - parameter node:  The current node being evaluated.
  - parameter key: The key being used for the search.
  - parameter charIndex: The index of the current char in the search key
 
  - returns: The element, if found. Nil otherwise.
  */
- private func findNode(aNode: TSTNode<Element>?, withKey key: String, atIndex charIndex: Int) -> Element? {
+ private func find(node: TSTNode<Element>?, withKey key: String, atIndex charIndex: Int) -> Element? {
 
  //Given key does not exist in tree.
- if aNode == nil {
+ guard let node = node else {
  return nil
  }
 
- let index = key.startIndex.advancedBy(charIndex)
+ let index = key.index(key.startIndex, offsetBy: charIndex)
  //go left
- if key[index] < aNode!.key {
- return findNode(aNode!.left, withKey: key, atIndex: charIndex)
+ if key[index] < node.key {
+ return find(node: node.left, withKey: key, atIndex: charIndex)
  }
  //go right
- else if key[index] > aNode!.key {
- return findNode(aNode!.right, withKey: key, atIndex: charIndex)
+ else if key[index] > node.key {
+ return find(node: node.right, withKey: key, atIndex: charIndex)
  }
  //go middle
  else {
  if charIndex + 1 < key.characters.count {
- return findNode(aNode!.middle, withKey: key, atIndex: charIndex + 1)
+ return find(node: node.middle, withKey: key, atIndex: charIndex + 1)
  } else {
- return aNode!.data
+ return node.data
  }
  }
  }

Ternary Search Tree/Tests/Info.plist

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+<key>CFBundleDevelopmentRegion</key>
+<string>en</string>
+<key>CFBundleExecutable</key>
+<string>$(EXECUTABLE_NAME)</string>
+<key>CFBundleIdentifier</key>
+<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
+<key>CFBundleInfoDictionaryVersion</key>
+<string>6.0</string>
+<key>CFBundleName</key>
+<string>$(PRODUCT_NAME)</string>
+<key>CFBundlePackageType</key>
+<string>BNDL</string>
+<key>CFBundleShortVersionString</key>
+<string>1.0</string>
+<key>CFBundleVersion</key>
+<string>1</string>
+</dict>
+</plist>