Merge pull request kodecocodes#336 from rzaccone/serialize-with-array

Serialize with array

Author: kelvinlauKL

Trie/Trie/Trie.xcodeproj/project.pbxproj

@@ -51,6 +51,7 @@
 		EB798E1C1DFEF79900F0628D /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		EB798E281DFEF81400F0628D /* Trie.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Trie.swift; sourceTree = "<group>"; };
 		EB798E2B1DFEF90B00F0628D /* dictionary.txt */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = dictionary.txt; sourceTree = "<group>"; };
+		EB8369AC1E15C5710003A7F8 /* ReadMe.md */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = net.daringfireball.markdown; path = ReadMe.md; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -101,6 +102,7 @@
 		EB798DFC1DFEF79900F0628D /* Trie */ = {
 			isa = PBXGroup;
 			children = (
+				EB8369AC1E15C5710003A7F8 /* ReadMe.md */,
 				EB798DFD1DFEF79900F0628D /* AppDelegate.swift */,
 				EB798DFF1DFEF79900F0628D /* ViewController.swift */,
 				EB798E011DFEF79900F0628D /* Assets.xcassets */,

Trie/Trie/Trie.xcodeproj/xcshareddata/xcbaselines/EB798E0A1DFEF79900F0628D.xcbaseline/6ABF2F62-9363-4450-8DE1-D20F57026950.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>classNames</key>
+	<dict>
+		<key>TrieTests</key>
+		<dict>
+			<key>testInsertPerformance()</key>
+			<dict>
+				<key>com.apple.XCTPerformanceMetric_WallClockTime</key>
+				<dict>
+					<key>baselineAverage</key>
+					<real>3.407</real>
+					<key>baselineIntegrationDisplayName</key>
+					<string>Local Baseline</string>
+				</dict>
+			</dict>
+		</dict>
+	</dict>
+</dict>
+</plist>

Trie/Trie/Trie.xcodeproj/xcshareddata/xcbaselines/EB798E0A1DFEF79900F0628D.xcbaseline/Info.plist

@@ -0,0 +1,33 @@
+<?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>runDestinationsByUUID</key>
+	<dict>
+		<key>6ABF2F62-9363-4450-8DE1-D20F57026950</key>
+		<dict>
+			<key>localComputer</key>
+			<dict>
+				<key>busSpeedInMHz</key>
+				<integer>100</integer>
+				<key>cpuCount</key>
+				<integer>1</integer>
+				<key>cpuKind</key>
+				<string>Intel Core i7</string>
+				<key>cpuSpeedInMHz</key>
+				<integer>3300</integer>
+				<key>logicalCPUCoresPerPackage</key>
+				<integer>4</integer>
+				<key>modelCode</key>
+				<string>MacBookPro13,2</string>
+				<key>physicalCPUCoresPerPackage</key>
+				<integer>2</integer>
+				<key>platformIdentifier</key>
+				<string>com.apple.platform.macosx</string>
+			</dict>
+			<key>targetArchitecture</key>
+			<string>x86_64</string>
+		</dict>
+	</dict>
+</dict>
+</plist>

Trie/Trie/Trie/ReadMe.md

@@ -0,0 +1,33 @@
+# Changes
+
+- Corrected a spelling error in a comment.
+
+- Got rid of the `get` syntax for a read only property as the coding guidelines suggest.
+
+- Changed several tests so that they are more Swift-like.  That is, they now feel like they are using the features of the language better.
+
+- Fixed a problem in the test method `testRemovePerformance`.  The `measure` method runs the block of code 10 times.  Previously, all words would get removed after the first run and the next 9 runs were very fast because there was nothing to do!  That is corrected now.
+
+- Made the `Trie` class a subclass of `NSObject` and had it conform to `NSCoding`.  Added a test to verify that this works.
+
+---
+
+I wasn't able to figure out how to recursively archive the trie.  Instead, I tried Kelvin's suggestion to use the `words` property to create an array of words in the trie, then archiving the array.
+
+There are a couple of nice aspects to this approach.
+
+- The `TrieNode` class can remain generic since it doesn't need to conform to `NSCoding`.
+
+- It doesn't require much new code.
+
+There are several downsides though.
+
+- The size of the archived words is three times the size of the original file of words!  Did I do this right?  The tests pass, so it seems correct.  I question whether archiving is worth the effort if the resulting archive is so much larger than the original file.
+
+- I would expect that archiving the trie would result in a file that was smaller than the original since a trie doesn't repeat leading character sequences when they are the same.
+
+- This requires that the trie get reconstructed when it is unarchived.
+
+- My gut tells me that it would be faster to archive and unarchive the trie itself, but I don't have any hard data to support this.
+
+I would like to see code that recursively archives the trie so we can compare the performance.

Trie/Trie/Trie/Trie.swift

@@ -11,13 +11,12 @@ import Foundation
 
 /// A node in the trie
 class TrieNode<T: Hashable> {
-  var value: T?
-  weak var parentNode: TrieNode?
-  var children: [T: TrieNode] = [:]
-  var isTerminating = false
-  var isLeaf: Bool {
-    get {
-      return children.count == 0
+    var value: T?
+    weak var parentNode: TrieNode?
+    var children: [T: TrieNode] = [:]
+    var isTerminating = false
+    var isLeaf: Bool {
+        return children.count == 0
     }
   }
 
@@ -45,28 +44,50 @@ class TrieNode<T: Hashable> {
 
 /// A trie data structure containing words.  Each node is a single
 /// character of a word.
-class Trie {
-  typealias Node = TrieNode<Character>
-  /// The number of words in the trie
-  public var count: Int {
-    return wordCount
-  }
-  /// Is the trie empty?
-  public var isEmpty: Bool {
-    return wordCount == 0
-  }
-  /// All words currently in the trie
-  public var words: [String] {
-    return wordsInSubtrie(rootNode: root, partialWord: "")
-  }
-  fileprivate let root: Node
-  fileprivate var wordCount: Int
-  
-  /// Creats an empty trie.
-  init() {
-    root = Node()
-    wordCount = 0
-  }
+class Trie: NSObject, NSCoding {
+    typealias Node = TrieNode<Character>
+    /// The number of words in the trie
+    public var count: Int {
+        return wordCount
+    }
+    /// Is the trie empty?
+    public var isEmpty: Bool {
+        return wordCount == 0
+    }
+    /// All words currently in the trie
+    public var words: [String] {
+        return wordsInSubtrie(rootNode: root, partialWord: "")
+    }
+    fileprivate let root: Node
+    fileprivate var wordCount: Int
+
+    /// Creates an empty trie.
+    override init() {
+        root = Node()
+        wordCount = 0
+        super.init()
+    }
+
+    // MARK: NSCoding
+
+    /// Initializes the trie with words from an archive
+    ///
+    /// - Parameter decoder: Decodes the archive
+    required convenience init?(coder decoder: NSCoder) {
+        self.init()
+        let words = decoder.decodeObject(forKey: "words") as? [String]
+        for word in words! {
+            self.insert(word: word)
+        }
+    }
+
+    /// Encodes the words in the trie by putting them in an array then encoding
+    /// the array.
+    ///
+    /// - Parameter coder: The object that will encode the array
+    func encode(with coder: NSCoder) {
+        coder.encode(self.words, forKey: "words")
+    }
 }
 
 // MARK: - Adds methods: insert, remove, contains

Trie/Trie/TrieTests/TrieTests.swift

@@ -12,20 +12,20 @@ import XCTest
 class TrieTests: XCTestCase {
     var wordArray: [String]?
     var trie = Trie()
-    
+
     /// Makes sure that the wordArray and trie are initialized before each test.
     override func setUp() {
         super.setUp()
         createWordArray()
         insertWordsIntoTrie()
     }
-    
-    /// Don't need to do anything here because the wordArrayu and trie should
+
+    /// Don't need to do anything here because the wordArray and trie should
     /// stay around.
     override func tearDown() {
         super.tearDown()
     }
-    
+
     /// Reads words from the dictionary file and inserts them into an array.  If
     /// the word array already has words, do nothing.  This allows running all
     /// tests without repeatedly filling the array with the same values.
@@ -36,7 +36,7 @@ class TrieTests: XCTestCase {
         let resourcePath = Bundle.main.resourcePath! as NSString
         let fileName = "dictionary.txt"
         let filePath = resourcePath.appendingPathComponent(fileName)
-        
+
         var data: String?
         do {
             data = try String(contentsOfFile: filePath, encoding: String.Encoding.utf8)
@@ -48,24 +48,21 @@ class TrieTests: XCTestCase {
         wordArray = data!.components(separatedBy: "\n")
         XCTAssertEqual(wordArray!.count, dictionarySize)
     }
-    
+
     /// Inserts words into a trie.  If the trie is non-empty, don't do anything.
     func insertWordsIntoTrie() {
-        guard trie.count == 0 else {
-            return
-        }
-        let numberOfWordsToInsert = wordArray!.count
-        for i in 0..<numberOfWordsToInsert {
-            trie.insert(word: wordArray![i])
+        guard let wordArray = wordArray, trie.count == 0 else { return }
+        for word in wordArray {
+            trie.insert(word: word)
         }
     }
-    
+
     /// Tests that a newly created trie has zero words.
     func testCreate() {
         let trie = Trie()
         XCTAssertEqual(trie.count, 0)
     }
-    
+
     /// Tests the insert method
     func testInsert() {
         let trie = Trie()
@@ -78,7 +75,7 @@ class TrieTests: XCTestCase {
         XCTAssertTrue(trie.contains(word: "cut"))
         XCTAssertEqual(trie.count, 4)
     }
-    
+
     /// Tests the remove method
     func testRemove() {
         let trie = Trie()
@@ -90,7 +87,7 @@ class TrieTests: XCTestCase {
         XCTAssertFalse(trie.contains(word: "cute"))
         XCTAssertEqual(trie.count, 1)
     }
-    
+
     /// Tests the words property
     func testWords() {
         let trie = Trie()
@@ -101,52 +98,53 @@ class TrieTests: XCTestCase {
         XCTAssertEqual(words[0], "foobar")
         XCTAssertEqual(words.count, 1)
     }
-    
+
     /// Tests the performance of the insert method.
     func testInsertPerformance() {
-        let trie = Trie()
         self.measure() {
-            let numberOfWordsToInsert = self.wordArray!.count
-            for i in 0..<numberOfWordsToInsert {
-                trie.insert(word: self.wordArray![i])
+            let trie = Trie()
+            for word in self.wordArray! {
+                trie.insert(word: word)
             }
         }
         XCTAssertGreaterThan(trie.count, 0)
         XCTAssertEqual(trie.count, wordArray?.count)
     }
-    
+
     /// Tests the performance of the insert method when the words are already
     /// present.
     func testInsertAgainPerformance() {
         self.measure() {
-            let numberOfWordsToInsert = self.wordArray!.count
-            for i in 0..<numberOfWordsToInsert {
-                self.trie.insert(word: self.wordArray![i])
+            for word in self.wordArray! {
+                self.trie.insert(word: word)
             }
         }
     }
-    
+
     /// Tests the performance of the contains method.
     func testContainsPerformance() {
         self.measure() {
-            for i in 0..<self.wordArray!.count {
-                XCTAssertTrue(self.trie.contains(word: self.wordArray![i]))
+            for word in self.wordArray! {
+                XCTAssertTrue(self.trie.contains(word: word))
             }
-            
         }
     }
-    
-    /// Tests the performance of the remove method.
+
+    /// Tests the performance of the remove method.  Since setup has already put
+    /// words into the trie, remove them before measuring performance.
     func testRemovePerformance() {
+        for word in self.wordArray! {
+            self.trie.remove(word: word)
+        }
         self.measure() {
-            let numberOfWordsToRemove = self.wordArray!.count
-            for i in 0..<numberOfWordsToRemove {
-                self.trie.remove(word: self.wordArray![i])
+            self.insertWordsIntoTrie()
+            for word in self.wordArray! {
+                self.trie.remove(word: word)
             }
         }
         XCTAssertEqual(trie.count, 0)
     }
-    
+
     /// Tests the performance of the words computed property.  Also tests to see
     /// if it worked properly.
     func testWordsPerformance() {
@@ -159,4 +157,15 @@ class TrieTests: XCTestCase {
             XCTAssertTrue(self.trie.contains(word: word))
         }
     }
+
+    /// Tests the archiving and unarchiving of the trie.
+    func testArchiveAndUnarchive() {
+        let resourcePath = Bundle.main.resourcePath! as NSString
+        let fileName = "dictionary-archive"
+        let filePath = resourcePath.appendingPathComponent(fileName)
+        NSKeyedArchiver.archiveRootObject(trie, toFile: filePath)
+        let trieCopy = NSKeyedUnarchiver.unarchiveObject(withFile: filePath) as! Trie
+        XCTAssertEqual(trieCopy.count, trie.count)
+
+    }
 }