[WIP] Generics Challenge

Sprint 7/Concurrency II (7.3)/HungryDevelopers.playground/Contents.swift

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+import UIKit
+
+import Foundation
+
+// 1
+class Spoon {
+    // 2
+    func pickUp() {
+        while isPickedUp { continue }
+        lock.lock()
+        isPickedUp = true
+        lock.unlock()
+    }
+
+    func putDown() {
+        lock.lock()
+        isPickedUp = false
+        lock.unlock()
+    }
+
+    private let lock = NSLock()
+    private var isPickedUp: Bool = false
+}
+// 3
+class Developer {
+
+    init(leftSpoon: Spoon, rightSpoon: Spoon, developer: String) {
+        self.leftSpoon = leftSpoon
+        self.rightSpoon = rightSpoon
+        self.developer = developer
+    }
+    // 5
+    func think() {
+        print("\(developer) is thinking.")
+        usleep(useconds_t(Int.random(in: 1...1000)))
+
+        leftSpoon.pickUp()
+        print("\(developer) picked up left spoon.")
+
+        rightSpoon.pickUp()
+        print("\(developer) picked up right spoon.")
+
+        return
+    }
+    // 6
+    func eat() {
+        print("\(developer) is eating.")
+        usleep(useconds_t(Int.random(in: 1...1000)))
+
+        leftSpoon.putDown()
+        print("\(developer) put down left spoon.")
+
+        rightSpoon.putDown()
+        print("\(developer) put down right spoon.")
+    }
+
+    func run() {
+        while true {
+            think()
+            eat()
+        }
+    }
+
+    var leftSpoon: Spoon
+    var rightSpoon: Spoon
+    let developer: String
+}
+
+// 7
+var spoon1 = Spoon()
+var spoon2 = Spoon()
+var spoon3 = Spoon()
+var spoon4 = Spoon()
+var spoon5 = Spoon()
+
+var developer1 = Developer(leftSpoon: spoon1, rightSpoon: spoon2, developer: "Paul")
+var developer2 = Developer(leftSpoon: spoon2, rightSpoon: spoon3, developer: "Nate")
+var developer3 = Developer(leftSpoon: spoon3, rightSpoon: spoon4, developer: "Jaspal")
+var developer4 = Developer(leftSpoon: spoon4, rightSpoon: spoon5, developer: "Frulwinn")
+var developer5 = Developer(leftSpoon: spoon5, rightSpoon: spoon1, developer: "Julian")
+
+let developers = [developer1, developer2, developer3, developer4, developer5]
+
+DispatchQueue.concurrentPerform(iterations: 5) {
+    // 8
+    developers[$0].run()
+
+}

Sprint 7/Concurrency II (7.3)/HungryDevelopers.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' executeOnSourceChanges='false'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

Sprint 7/Concurrency II (7.3)/HungryDevelopers.playground/timeline.xctimeline

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+<?xml version="1.0" encoding="UTF-8"?>
+<Timeline
+   version = "3.0">
+   <TimelineItems>
+      <LoggerValueHistoryTimelineItem
+         documentLocation = "file:///Users/paulyi/Desktop/Development/Lambda%20iOS/ios-projects/Sprint%207/Concurrency%20II%20(7.3)/HungryDevelopers.playground#CharacterRangeLen=2081&amp;CharacterRangeLoc=33&amp;EndingColumnNumber=0&amp;EndingLineNumber=88&amp;StartingColumnNumber=0&amp;StartingLineNumber=4&amp;Timestamp=573004958.715552"
+         selectedRepresentationIndex = "0"
+         shouldTrackSuperviewWidth = "NO">
+      </LoggerValueHistoryTimelineItem>
+   </TimelineItems>
+</Timeline>

Sprint 7/Generics (7.2)/GenericsChallenge.playground/Contents.swift

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+import UIKit
+
+/// An unordered collection of unique elements that
+/// may appear more than once in the collection.
+public struct CountedSet<Element: Hashable> {
+    /// Inserts the given element to the set, with
+    /// a count of 1 if the element is not yet present
+    /// or adding 1 to the count if it is.
+    @discardableResult
+    public mutating func insert(_ member: Element) -> Int {
+        _counts[member, default: 0] += 1
+        return _counts[member]!
+    }
+
+    /// Removes one instance of the given element from
+    /// the set. If the count goes to zero, the element is
+    /// removed from the set. If the element is not present,
+    /// the request is ignored.
+    @discardableResult
+    public mutating func remove(_ member: Element) -> Int {
+
+        let memberCount = _counts[member, default: 0]
+        guard memberCount > 0 else { return 0 }
+
+        guard memberCount > 1 else { _counts.removeValue(forKey: member); return 0 }
+        let newCount = _counts[member]! - 1
+        _counts[member] = newCount
+
+        return newCount
+    }
+
+    /// Access an element count, returning 0 for any
+    /// element that does not appear in the counted set
+    public subscript(_ member: Element) -> Int {
+        return _counts[member, default: 0]
+    }
+
+    /// Return the number of unique elements in the counted set
+    public var count: Int { return _counts.keys.count }
+
+    /// A Boolean value that indicates whether the counted set is empty.
+    public var isEmpty: Bool {
+        return count == 0
+    }
+
+    internal var _counts: [Element: Int]
+}
+
+extension CountedSet: ExpressibleByArrayLiteral {
+    //
+    // `ExpressibleByArrayLiteral` conformance
+    //
+
+    /// Creates a counted set containing the elements of the given array literal.
+    ///
+    /// Do not call this initializer directly. It is used by the compiler when
+    /// you use an array literal. Instead, create a new counted set using an array
+    /// literal as its value by enclosing a comma-separated list of values in
+    /// square brackets. You can use an array literal anywhere a set is expected
+    /// by the type context.
+    public init(arrayLiteral elements: Element...) {
+        _counts = [:]
+        for element in elements {
+            _counts[element] = _counts[element, default: 0] + 1
+        }
+    }
+}
+
+enum Arrow { case iron, wooden, elven, dwarvish, magic, silver }
+var aCountedSet = CountedSet<Arrow>()
+aCountedSet[.iron] // 0
+var myCountedSet: CountedSet<Arrow> = [.iron, .magic, .iron, .silver, .iron, .iron]
+myCountedSet[.iron] // 4
+myCountedSet.remove(.iron) // 3
+myCountedSet.remove(.dwarvish) // 0
+myCountedSet.remove(.magic) // 0
+
+
+
+

Sprint 7/Generics (7.2)/GenericsChallenge.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' executeOnSourceChanges='false'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>