Rename Rotor.swift -> Components.swift

Enigma.xcodeproj/project.pbxproj

@@ -15,7 +15,7 @@
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 		C0DA3AA61B5AACB300D8D68E /* EnigmaTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = C0DA3AA51B5AACB300D8D68E /* EnigmaTests.swift */; };
 		C0DA3AB11B5AACB300D8D68E /* EnigmaUITests.swift in Sources */ = {isa = PBXBuildFile; fileRef = C0DA3AB01B5AACB300D8D68E /* EnigmaUITests.swift */; };
-		C0DA3ABF1B5AB49200D8D68E /* Rotor.swift in Sources */ = {isa = PBXBuildFile; fileRef = C0DA3ABE1B5AB49200D8D68E /* Rotor.swift */; };
+		C0DA3ABF1B5AB49200D8D68E /* Components.swift in Sources */ = {isa = PBXBuildFile; fileRef = C0DA3ABE1B5AB49200D8D68E /* Components.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -50,7 +50,7 @@
 		C0DA3AAC1B5AACB300D8D68E /* EnigmaUITests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = EnigmaUITests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		C0DA3AB01B5AACB300D8D68E /* EnigmaUITests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = EnigmaUITests.swift; sourceTree = "<group>"; };
 		C0DA3AB21B5AACB300D8D68E /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
-		C0DA3ABE1B5AB49200D8D68E /* Rotor.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Rotor.swift; sourceTree = "<group>"; };
+		C0DA3ABE1B5AB49200D8D68E /* Components.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Components.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -107,7 +107,7 @@
 				C0DA3A971B5AACB300D8D68E /* Assets.xcassets */,
 				C0DA3A991B5AACB300D8D68E /* LaunchScreen.storyboard */,
 				C0DA3A9C1B5AACB300D8D68E /* Info.plist */,
-				C0DA3ABE1B5AB49200D8D68E /* Rotor.swift */,
+				C0DA3ABE1B5AB49200D8D68E /* Components.swift */,
 				C04D337E1B5B3F6100E2888E /* Enigma.swift */,
 			);
 			path = Enigma;
@@ -262,7 +262,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				C04D337F1B5B3F6100E2888E /* Enigma.swift in Sources */,
-				C0DA3ABF1B5AB49200D8D68E /* Rotor.swift in Sources */,
+				C0DA3ABF1B5AB49200D8D68E /* Components.swift in Sources */,
 				C0DA3A931B5AACB300D8D68E /* ViewController.swift in Sources */,
 				C0DA3A911B5AACB300D8D68E /* AppDelegate.swift in Sources */,
 			);

Enigma/Components.swift

@@ -0,0 +1,104 @@
+//
+//  Components.swift
+//  Enigma
+//
+//  Created by Eryn Wells on 2015-07-18.
+//  Copyright © 2015 Eryn Wells. All rights reserved.
+//
+
+import Foundation
+
+
+enum EncoderError: ErrorType {
+    /** Thrown when an input character is found that is not in the alphabet. */
+    case InvalidCharacter(ch: Character)
+}
+
+
+protocol Encoder {
+    func encode(c: Character) throws -> Character
+}
+
+
+class Cryptor {
+    /** Array of all possible characters to encrypt. */
+    static let alphabet: [Character] = Array("ABCDEFGHIJKLMNOPQRSTUVWXYZ".characters)
+}
+
+
+class FixedRotor: Cryptor, Encoder {
+    enum Error: ErrorType {
+        /** Thrown when the initializer is given an invalid series. */
+        case InvalidSeries
+    }
+
+    /** The series of characters that this rotor cycles through. */
+    let series: [Character]!
+
+    convenience init(series: String) throws {
+        try self.init(series: Array(series.characters))
+    }
+
+    init(series: [Character]) throws {
+        self.series = series
+        super.init()
+        guard series.count == Cryptor.alphabet.count else {
+            throw Error.InvalidSeries
+        }
+    }
+
+    func encode(c: Character) throws -> Character {
+        if let offset = FixedRotor.alphabet.indexOf(c) {
+            return series[offset]
+        } else {
+            throw EncoderError.InvalidCharacter(ch: c)
+        }
+    }
+}
+
+
+/** Rotors are FixedRotors that have a variable position, which offsets the alphabet from the series and changes which character is substituted for a given input. */
+class Rotor: FixedRotor {
+    /** The position of first letter in `series` in the `alphabet`. */
+    var position: Int = 0 {
+        willSet {
+            self.position = newValue % Cryptor.alphabet.count
+        }
+    }
+
+    func advance(count: Int = 1) {
+        position = (position + count) % Rotor.alphabet.count
+    }
+
+    override func encode(c: Character) throws -> Character {
+        if let offset = Rotor.alphabet.indexOf(c) {
+            return series[(offset + position) % series.count]
+        } else {
+            throw EncoderError.InvalidCharacter(ch: c)
+        }
+    }
+}
+
+
+class Reflector: FixedRotor { }
+
+
+/** A Plugboard is a Cryptor that substitutes one character for another based on a set of pairs. A pair of characters is mutually exclusive of other pairs; that is, a character can only belong to one pair. Furthermore, the Plugboard always trades one character for the same character and vice versa. */
+class Plugboard: Cryptor, Encoder {
+    private(set) var plugs: [Character: Character] = [:]
+
+    func addPlug(a: Character, b: Character) {
+        plugs[a] = b
+        plugs[b] = a
+    }
+
+    func encode(c: Character) throws -> Character {
+        if let output = plugs[c] {
+            return output
+        } else if Plugboard.alphabet.contains(c) {
+            return c
+        } else {
+            throw EncoderError.InvalidCharacter(ch: c)
+        }
+    }
+}