Behavioral Patterns updated to Swift2.

source/behavioral/chain_of_responsibility.swift

@@ -6,70 +6,73 @@ The chain of responsibility pattern is used to process varied requests, each of
 
 ### Example:
 */
-class MoneyPile {
+final class MoneyPile {
+
     let value: Int
     var quantity: Int
     var nextPile: MoneyPile?
-    
+
     init(value: Int, quantity: Int, nextPile: MoneyPile?) {
         self.value = value
         self.quantity = quantity
         self.nextPile = nextPile
     }
-
-    func canWithdraw(v: Int) -> Bool {
 
-        var v = v
+    func canWithdraw(amount: Int) -> Bool {
+
+        var amount = amount
 
         func canTakeSomeBill(want: Int) -> Bool {
             return (want / self.value) > 0
         }
-
-        var q = self.quantity
 
-        while canTakeSomeBill(v) {
+        var quantity = self.quantity
 
-            if q == 0 {
+        while canTakeSomeBill(want: amount) {
+
+            if quantity == 0 {
                 break
             }
 
-            v -= self.value
-            q -= 1
+            amount -= self.value
+            quantity -= 1
         }
 
-        if v == 0 {
+        guard amount > 0 else {
             return true
-        } else if let next = self.nextPile {
-            return next.canWithdraw(v)
+        }
+
+        if let next = self.nextPile {
+            return next.canWithdraw(amount: amount)
         }
 
         return false
     }
 }
 
-class ATM {
+final class ATM {
     private var hundred: MoneyPile
     private var fifty: MoneyPile
     private var twenty: MoneyPile
     private var ten: MoneyPile
-    
+
     private var startPile: MoneyPile {
         return self.hundred
     }
-    
-    init(hundred: MoneyPile, 
-           fifty: MoneyPile, 
-          twenty: MoneyPile, 
+
+    init(hundred: MoneyPile,
+           fifty: MoneyPile,
+          twenty: MoneyPile,
              ten: MoneyPile) {
 
         self.hundred = hundred
         self.fifty = fifty
         self.twenty = twenty
         self.ten = ten
     }
-    
-    func canWithdraw(value: Int) -> String {
-        return "Can withdraw: \(self.startPile.canWithdraw(value))"
+
+    func canWithdraw(amount: Int) -> String {
+        return "Can withdraw: \(self.startPile.canWithdraw(amount: amount))"
     }
 }
 /*:
@@ -83,10 +86,10 @@ let hundred = MoneyPile(value: 100, quantity: 1, nextPile: fifty)
 
 // Build ATM.
 var atm = ATM(hundred: hundred, fifty: fifty, twenty: twenty, ten: ten)
-atm.canWithdraw(310) // Cannot because ATM has only 300
-atm.canWithdraw(100) // Can withdraw - 1x100
-atm.canWithdraw(165) // Cannot withdraw because ATM doesn't has bill with value of 5
-atm.canWithdraw(30)  // Can withdraw - 1x20, 2x10
+atm.canWithdraw(amount: 310) // Cannot because ATM has only 300
+atm.canWithdraw(amount: 100) // Can withdraw - 1x100
+atm.canWithdraw(amount: 165) // Cannot withdraw because ATM doesn't has bill with value of 5
+atm.canWithdraw(amount: 30)  // Can withdraw - 1x20, 2x10
 /*:
 >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Chain-Of-Responsibility)
 */

source/behavioral/interpreter.swift

@@ -7,87 +7,86 @@ The interpreter pattern is used to evaluate sentences in a language.
 ### Example
 */
 
-protocol IntegerExp {
-    func evaluate(context: IntegerContext) -> Int
-    func replace(character: Character, integerExp: IntegerExp) -> IntegerExp
-    func copy() -> IntegerExp
+protocol IntegerExpression {
+    func evaluate(_ context: IntegerContext) -> Int
+    func replace(character: Character, integerExpression: IntegerExpression) -> IntegerExpression
+    func copied() -> IntegerExpression
 }
 
-class IntegerContext {
+final class IntegerContext {
     private var data: [Character:Int] = [:]
-    
+
     func lookup(name: Character) -> Int {
         return self.data[name]!
     }
-    
-    func assign(integerVarExp: IntegerVarExp, value: Int) {
-        self.data[integerVarExp.name] = value
+
+    func assign(expression: IntegerVariableExpression, value: Int) {
+        self.data[expression.name] = value
     }
 }
 
-class IntegerVarExp: IntegerExp {
+final class IntegerVariableExpression: IntegerExpression {
     let name: Character
-    
+
     init(name: Character) {
         self.name = name
     }
-    
-    func evaluate(context: IntegerContext) -> Int {
-        return context.lookup(self.name)
+
+    func evaluate(_ context: IntegerContext) -> Int {
+        return context.lookup(name: self.name)
     }
-    
-    func replace(name: Character, integerExp: IntegerExp) -> IntegerExp {
+
+    func replace(character name: Character, integerExpression: IntegerExpression) -> IntegerExpression {
         if name == self.name {
-            return integerExp.copy()
+            return integerExpression.copied()
         } else {
-            return IntegerVarExp(name: self.name)
+            return IntegerVariableExpression(name: self.name)
         }
     }
-    
-    func copy() -> IntegerExp {
-        return IntegerVarExp(name: self.name)
+
+    func copied() -> IntegerExpression {
+        return IntegerVariableExpression(name: self.name)
     }
 }
 
-class AddExp: IntegerExp {
-    private var operand1: IntegerExp
-    private var operand2: IntegerExp
-    
-    init(op1: IntegerExp, op2: IntegerExp) {
+final class AddExpression: IntegerExpression {
+    private var operand1: IntegerExpression
+    private var operand2: IntegerExpression
+
+    init(op1: IntegerExpression, op2: IntegerExpression) {
         self.operand1 = op1
         self.operand2 = op2
     }
-    
-    func evaluate(context: IntegerContext) -> Int {
+
+    func evaluate(_ context: IntegerContext) -> Int {
         return self.operand1.evaluate(context) + self.operand2.evaluate(context)
     }
-    
-    func replace(character: Character, integerExp: IntegerExp) -> IntegerExp {
-        return AddExp(op1: operand1.replace(character, integerExp: integerExp),
-            op2: operand2.replace(character, integerExp: integerExp))
+
+    func replace(character: Character, integerExpression: IntegerExpression) -> IntegerExpression {
+        return AddExpression(op1: operand1.replace(character: character, integerExpression: integerExpression),
+                             op2: operand2.replace(character: character, integerExpression: integerExpression))
     }
-    
-    func copy() -> IntegerExp {
-        return AddExp(op1: self.operand1, op2: self.operand2)
+
+    func copied() -> IntegerExpression {
+        return AddExpression(op1: self.operand1, op2: self.operand2)
     }
 }
 /*:
 ### Usage
 */
-var expression: IntegerExp?
-var intContext = IntegerContext()
+var context = IntegerContext()
 
-var a = IntegerVarExp(name: "A")
-var b = IntegerVarExp(name: "B")
-var c = IntegerVarExp(name: "C")
+var a = IntegerVariableExpression(name: "A")
+var b = IntegerVariableExpression(name: "B")
+var c = IntegerVariableExpression(name: "C")
 
-expression = AddExp(op1: a, op2: AddExp(op1: b, op2: c)) // a + (b + c)
+var expression = AddExpression(op1: a, op2: AddExpression(op1: b, op2: c)) // a + (b + c)
 
-intContext.assign(a, value: 2)
-intContext.assign(b, value: 1)
-intContext.assign(c, value: 3)
+context.assign(expression: a, value: 2)
+context.assign(expression: b, value: 1)
+context.assign(expression: c, value: 3)
 
-var result = expression?.evaluate(intContext)
+var result = expression.evaluate(context)
 /*:
 >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Interpreter)
 */

source/behavioral/iterator.swift

@@ -6,22 +6,38 @@ The iterator pattern is used to provide a standard interface for traversing a co
 
 ### Example:
 */
-struct NovellasCollection<T> {
-    let novellas: [T]
+struct Novella {
+    let name: String
 }
 
-extension NovellasCollection: SequenceType {
-    typealias Generator = AnyGenerator<T>
-
-    func generate() -> AnyGenerator<T> {
-        var i = 0
-        return AnyGenerator { i += 1; return i >= self.novellas.count ? nil : self.novellas[i] }
+struct Novellas {
+    let novellas: [Novella]
+}
+
+struct NovellasIterator: IteratorProtocol {
+
+    private var current = 0
+    private let novellas: [Novella]
+
+    init(novellas: [Novella]) {
+        self.novellas = novellas
+    }
+
+    mutating func next() -> Novella? {
+        defer { current += 1 }
+        return novellas.count > current ? novellas[current] : nil
+    }
+}
+
+extension Novellas: Sequence {
+    func makeIterator() -> NovellasIterator {
+        return NovellasIterator(novellas: novellas)
     }
 }
 /*:
 ### Usage
 */
-let greatNovellas = NovellasCollection(novellas:["Mist"])
+let greatNovellas = Novellas(novellas: [Novella(name: "The Mist")] )
 
 for novella in greatNovellas {
     print("I've read: \(novella)")

source/behavioral/mediator.swift

@@ -6,62 +6,52 @@ The mediator pattern is used to reduce coupling between classes that communicate
 
 ### Example
 */
+struct Programmer {
 
-class Colleague {
     let name: String
-    let mediator: Mediator
-
-    init(name: String, mediator: Mediator) {
+
+    init(name: String) {
         self.name = name
-        self.mediator = mediator
-    }
-
-    func send(message: String) {
-        mediator.send(message, colleague: self)
     }
-    
+
     func receive(message: String) {
-        assert(false, "Method should be overriden")
+        print("\(name) received: \(message)")
     }
 }
 
-protocol Mediator {
-    func send(message: String, colleague: Colleague)
+protocol MessageSending {
+    func send(message: String)
 }
 
-class MessageMediator: Mediator {
-    private var colleagues: [Colleague] = []
-
-    func addColleague(colleague: Colleague) {
-        colleagues.append(colleague)
-    }
-
-    func send(message: String, colleague: Colleague) {
-        for c in colleagues {
-            if c !== colleague { //for simplicity we compare object references
-                c.receive(message)
-            }
-        }
+final class MessageMediator: MessageSending {
+
+    private var recipients: [Programmer] = []
+
+    func add(recipient: Programmer) {
+        recipients.append(recipient)
     }
-}
 
-class ConcreteColleague: Colleague {
-    override func receive(message: String) {
-        print("Colleague \(name) received: \(message)")
+    func send(message: String) {
+        for recipient in recipients {
+            recipient.receive(message: message)
+        }
     }
 }
-
 /*:
 ### Usage
 */
+func spamMonster(message: String, worker: MessageSending) {
+    worker.send(message: message)
+}
 
 let messagesMediator = MessageMediator()
-let user0 = ConcreteColleague(name: "0", mediator: messagesMediator)
-let user1 = ConcreteColleague(name: "1", mediator: messagesMediator)
-messagesMediator.addColleague(user0)
-messagesMediator.addColleague(user1)
 
-user0.send("Hello") // user1 receives message
+let user0 = Programmer(name: "Linus Torvalds")
+let user1 = Programmer(name: "Avadis 'Avie' Tevanian")
+messagesMediator.add(recipient: user0)
+messagesMediator.add(recipient: user1)
+
+spamMonster(message: "I'd Like to Add you to My Professional Network", worker: messagesMediator)
 /*:
 >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Mediator)
 */