InputHandler // +Enum: TypingMethod.

Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler/InputHandler_Core.swift

@@ -22,7 +22,6 @@ public protocol InputHandlerProtocol {
   var currentLM: vChewingLM.LMInstantiator { get set }
   var currentUOM: vChewingLM.LMUserOverride { get set }
   var delegate: InputHandlerDelegate? { get set }
-  var composer: Tekkon.Composer { get set }
   var keySeparator: String { get }
   static var keySeparator: String { get }
   var isCompositorEmpty: Bool { get }
@@ -89,13 +88,17 @@ public class InputHandler: InputHandlerProtocol {
 
   /// 用來記錄「叫出選字窗前」的游標位置的變數。
   var backupCursor: Int?
+  /// 當前的打字模式。
+  var currentTypingMethod: TypingMethod = .vChewingFactory
 
   /// 半衰模組的衰減指數
   let kEpsilon: Double = 0.000_001
 
-  public var calligrapher = "" // 磁帶專用組筆區
+  var strCodePointBuffer = "" // 內碼輸入專用組碼區
-  public var composer: Tekkon.Composer = .init() // 注拼槽
+  var calligrapher = "" // 磁帶專用組筆區
-  public var compositor: Megrez.Compositor // 組字器
+  var composer: Tekkon.Composer = .init() // 注拼槽
+  var compositor: Megrez.Compositor // 組字器
+
   public var currentUOM: vChewingLM.LMUserOverride
   public var currentLM: vChewingLM.LMInstantiator {
     didSet {
@@ -120,43 +123,13 @@ public class InputHandler: InputHandlerProtocol {
   public func clear() {
     clearComposerAndCalligrapher()
     compositor.clear()
-    isCodePointInputMode = false
+    currentTypingMethod = .vChewingFactory
-    isHaninKeyboardSymbolMode = false
     backupCursor = nil
   }
 
   /// 警告：該參數僅代指組音區/組筆區域與組字區在目前狀態下被視為「空」。
   var isConsideredEmptyForNow: Bool {
-    compositor.isEmpty && isComposerOrCalligrapherEmpty && !isCodePointInputMode && !isHaninKeyboardSymbolMode
+    compositor.isEmpty && isComposerOrCalligrapherEmpty && currentTypingMethod == .vChewingFactory
-  }
-
-  // MARK: - Hanin Keyboard Symbol Mode.
-
-  var isHaninKeyboardSymbolMode = false
-
-  static let tooltipHaninKeyboardSymbolMode: String = "\("Hanin Keyboard Symbol Input.".localized)"
-
-  // MARK: - Codepoint Input Buffer.
-
-  var isCodePointInputMode = false {
-    willSet {
-      strCodePointBuffer.removeAll()
-    }
-  }
-
-  var strCodePointBuffer = ""
-
-  var tooltipCodePointInputMode: String {
-    let commonTerm = NSMutableString()
-    commonTerm.insert("Code Point Input.".localized, at: 0)
-    if !(delegate?.isVerticalTyping ?? false) {
-      switch IMEApp.currentInputMode {
-      case .imeModeCHS: commonTerm.insert("[GB] ", at: 0)
-      case .imeModeCHT: commonTerm.insert("[Big5] ", at: 0)
-      default: break
-      }
-    }
-    return commonTerm.description
   }
 
   // MARK: - Functions dealing with Megrez.

Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler/InputHandler_HandleCandidate.swift

@@ -311,7 +311,8 @@ extension InputHandler {
         if !updated { delegate.callError("66F3477B") }
         return true
       case .option where state.type == .ofSymbolTable:
-        return handleHaninKeyboardSymbolModeToggle()
+        // 繞過內碼輸入模式，直接進入漢音鍵盤符號模式。
+        return revolveTypingMethod(to: .haninKeyboardSymbol)
       default: break
       }
     }

Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler/InputHandler_HandleComposition.swift

@@ -17,37 +17,29 @@ extension InputHandler {
   /// - Parameter input: 輸入訊號。
   /// - Returns: 告知 IMK「該按鍵是否已經被輸入法攔截處理」。
   func handleComposition(input: InputSignalProtocol) -> Bool? {
-    guard let delegate = delegate else { return nil }
     // 不處理任何包含不可列印字元的訊號。
-    guard !input.text.isEmpty, input.charCode.isPrintable else { return nil }
+    let hardRequirementMet = !input.text.isEmpty && input.charCode.isPrintable
-    if isCodePointInputMode { return handleCodePointComposition(input: input) }
+    switch currentTypingMethod {
-    if prefs.cassetteEnabled {
+    case .codePoint where hardRequirementMet:
-      // 準備處理 `%quick` 選字行為。
+      return handleCodePointComposition(input: input)
-      var handleQuickCandidate = true
+    case .haninKeyboardSymbol where [[], .shift].contains(input.keyModifierFlags):
-      if currentLM.areCassetteCandidateKeysShiftHeld { handleQuickCandidate = input.isShiftHold }
+      return handleHaninKeyboardSymbolModeInput(input: input)
-      let hasQuickCandidates: Bool = delegate.state.type == .ofInputting && delegate.state.isCandidateContainer
+    case .vChewingFactory where hardRequirementMet && prefs.cassetteEnabled:
-
-      // 處理 `%symboldef` 選字行為。
-      if handleCassetteSymbolTable(input: input) {
-        return true
-      } else if hasQuickCandidates, input.text != currentLM.cassetteWildcardKey {
-        // 處理 `%quick` 選字行為（當且僅當與 `%symboldef` 衝突的情況下）。
-        guard !(handleQuickCandidate && handleCandidate(input: input, ignoringModifiers: true)) else { return true }
-      } else {
-        // 處理 `%quick` 選字行為。
-        guard !(hasQuickCandidates && handleQuickCandidate && handleCandidate(input: input)) else { return true }
-      }
       return handleCassetteComposition(input: input)
+    case .vChewingFactory where hardRequirementMet && !prefs.cassetteEnabled:
+      return handlePhonabetComposition(input: input)
+    default: return nil
     }
-    return handlePhonabetComposition(input: input)
   }
+}
 
-  // MARK: 注音按鍵輸入處理 (Handle BPMF Keys)
+// MARK: - 注音按鍵輸入處理 (Handle BPMF Keys)
 
+private extension InputHandler {
   /// 用來處理 InputHandler.HandleInput() 當中的與注音输入有關的組字行為。
   /// - Parameter input: 輸入訊號。
   /// - Returns: 告知 IMK「該按鍵是否已經被輸入法攔截處理」。
-  private func handlePhonabetComposition(input: InputSignalProtocol) -> Bool? {
+  func handlePhonabetComposition(input: InputSignalProtocol) -> Bool? {
     guard let delegate = delegate else { return nil }
     var inputText = (input.inputTextIgnoringModifiers ?? input.text)
     inputText = inputText.lowercased().applyingTransformFW2HW(reverse: false)
@@ -241,13 +233,31 @@ extension InputHandler {
 
 // MARK: - 磁帶模式的組字支援。
 
-extension InputHandler {
+private extension InputHandler {
-  /// 用來處理 InputHandler.HandleInput() 當中的與磁帶模組有關的組字行為。
+  /// 用來處理 InputHandler.HandleInput() 當中的與磁帶模組有關的組字行為。（前置處理）
   /// - Parameter input: 輸入訊號。
   /// - Returns: 告知 IMK「該按鍵是否已經被輸入法攔截處理」。
-  private func handleCassetteComposition(input: InputSignalProtocol) -> Bool? {
+  func handleCassetteComposition(input: InputSignalProtocol) -> Bool? {
     guard let delegate = delegate else { return nil }
     let state = delegate.state
+
+    // 準備處理 `%quick` 選字行為。
+    var handleQuickCandidate = true
+    if currentLM.areCassetteCandidateKeysShiftHeld { handleQuickCandidate = input.isShiftHold }
+    let hasQuickCandidates: Bool = state.type == .ofInputting && state.isCandidateContainer
+
+    // 處理 `%symboldef` 選字行為。
+    if handleCassetteSymbolTable(input: input) {
+      return true
+    } else if hasQuickCandidates, input.text != currentLM.cassetteWildcardKey {
+      // 處理 `%quick` 選字行為（當且僅當與 `%symboldef` 衝突的情況下）。
+      guard !(handleQuickCandidate && handleCandidate(input: input, ignoringModifiers: true)) else { return true }
+    } else {
+      // 處理 `%quick` 選字行為。
+      guard !(hasQuickCandidates && handleQuickCandidate && handleCandidate(input: input)) else { return true }
+    }
+
+    // 正式處理。
     var wildcardKey: String { currentLM.cassetteWildcardKey } // 花牌鍵。
     let inputText = input.text
     let isWildcardKeyInput: Bool = (inputText == wildcardKey && !wildcardKey.isEmpty)
@@ -266,7 +276,7 @@ extension InputHandler {
       calligrapher.count >= currentLM.maxCassetteKeyLength || isLongestPossibleKeyFormed
     }
 
-    prehandling: if !skipStrokeHandling && currentLM.isThisCassetteKeyAllowed(key: inputText) {
+  prehandling: if !skipStrokeHandling && currentLM.isThisCassetteKeyAllowed(key: inputText) {
       if calligrapher.isEmpty, isWildcardKeyInput {
         delegate.callError("3606B9C0")
         if input.beganWithLetter {
@@ -385,16 +395,17 @@ extension InputHandler {
       // 將「這個按鍵訊號已經被輸入法攔截處理了」的結果藉由 SessionCtl 回報給 IMK。
       return true
     }
-
     return nil
   }
+}
 
-  // MARK: 內碼區位輸入處理 (Handle Code Point Input)
+// MARK: - 內碼區位輸入處理 (Handle Code Point Input)
 
+private extension InputHandler {
   /// 用來處理 InputHandler.HandleInput() 當中的與內碼區位輸入有關的組字行為。
   /// - Parameter input: 輸入訊號。
   /// - Returns: 告知 IMK「該按鍵是否已經被輸入法攔截處理」。
-  private func handleCodePointComposition(input: InputSignalProtocol) -> Bool? {
+  func handleCodePointComposition(input: InputSignalProtocol) -> Bool? {
     guard !input.isReservedKey else { return nil }
     guard let delegate = delegate, input.text.count == 1 else { return nil }
     guard !input.text.compactMap(\.hexDigitValue).isEmpty else {
@@ -407,7 +418,7 @@ extension InputHandler {
         strCodePointBuffer.append(input.text)
         var updatedState = generateStateOfInputting(guarded: true)
         updatedState.tooltipDuration = 0
-        updatedState.tooltip = tooltipCodePointInputMode
+        updatedState.tooltip = TypingMethod.codePoint.getTooltip(vertical: delegate.isVerticalTyping)
         delegate.switchState(updatedState)
         return true
       }
@@ -427,7 +438,7 @@ extension InputHandler {
         updatedState.tooltipDuration = 0
         updatedState.tooltip = "Invalid Code Point.".localized
         delegate.switchState(updatedState)
-        isCodePointInputMode = true
+        currentTypingMethod = .codePoint
         return true
       }
       // 某些舊版 macOS 會在這裡生成的字元後面插入垃圾字元。這裡只保留起始字元。
@@ -435,14 +446,46 @@ extension InputHandler {
       delegate.switchState(IMEState.ofCommitting(textToCommit: char))
       var updatedState = generateStateOfInputting(guarded: true)
       updatedState.tooltipDuration = 0
-      updatedState.tooltip = tooltipCodePointInputMode
+      updatedState.tooltip = TypingMethod.codePoint.getTooltip(vertical: delegate.isVerticalTyping)
       delegate.switchState(updatedState)
-      isCodePointInputMode = true
+      currentTypingMethod = .codePoint
       return true
     default:
       delegate.switchState(generateStateOfInputting())
-      isCodePointInputMode = true
+      currentTypingMethod = .codePoint
       return true
     }
   }
 }
+
+// MARK: - 處理漢音鍵盤符號輸入狀態（Handle Hanin Keyboard Symbol Inputs）
+
+private extension InputHandler {
+  /// 處理漢音鍵盤符號輸入。
+  /// - Parameters:
+  ///   - input: 輸入按鍵訊號。
+  /// - Returns: 將按鍵行為「是否有處理掉」藉由 SessionCtl 回報給 IMK。
+  func handleHaninKeyboardSymbolModeInput(input: InputSignalProtocol) -> Bool {
+    guard let delegate = delegate, delegate.state.type != .ofDeactivated else { return false }
+    let charText = input.text.lowercased().applyingTransformFW2HW(reverse: false)
+    guard CandidateNode.mapHaninKeyboardSymbols.keys.contains(charText) else {
+      return revolveTypingMethod(to: .vChewingFactory)
+    }
+    guard
+      charText.count == 1, let symbols = CandidateNode.queryHaninKeyboardSymbols(char: charText)
+    else {
+      delegate.callError("C1A760C7")
+      return true
+    }
+    // 得在這裡先 commit buffer，不然會導致「在摁 ESC 離開符號選單時會重複輸入上一次的組字區的內容」的不當行為。
+    let textToCommit = generateStateOfInputting(sansReading: true).displayedText
+    delegate.switchState(IMEState.ofCommitting(textToCommit: textToCommit))
+    if symbols.members.count == 1 {
+      delegate.switchState(IMEState.ofCommitting(textToCommit: symbols.members.map(\.name).joined()))
+    } else {
+      delegate.switchState(IMEState.ofSymbolTable(node: symbols))
+    }
+    currentTypingMethod = .vChewingFactory // 用完就關掉，但保持選字窗開啟，所以這裡不用呼叫 toggle 函式。
+    return true
+  }
+}

Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler/InputHandler_HandleStates.swift

@@ -27,17 +27,18 @@ extension InputHandler {
     if isConsideredEmptyForNow, !guarded { return IMEState.ofAbortion() }
     restoreBackupCursor() // 只要叫了 Inputting 狀態，就盡可能還原游標備份。
     var segHighlightedAt: Int?
-    let cpInput = isCodePointInputMode && !sansReading
+    let handleAsCodePointInput = currentTypingMethod == .codePoint && !sansReading
     /// 「更新內文組字區 (Update the composing buffer)」是指要求客體軟體將組字緩衝區的內容
     /// 換成由此處重新生成的原始資料在 IMEStateData 當中生成的 NSAttributeString。
-    var displayTextSegments: [String] = cpInput
+    var displayTextSegments: [String] = handleAsCodePointInput
       ? [strCodePointBuffer]
       : compositor.walkedNodes.values
-    var cursor = cpInput
+    var cursor = handleAsCodePointInput
       ? displayTextSegments.joined().count
       : convertCursorForDisplay(compositor.cursor)
     let cursorSansReading = cursor
-    let reading: String = (sansReading || isCodePointInputMode) ? "" : readingForDisplay // 先提出來，減輕運算負擔。
+    // 先提出來讀音資料，減輕運算負擔。
+    let reading: String = (sansReading || currentTypingMethod == .codePoint) ? "" : readingForDisplay
     if !reading.isEmpty {
       var newDisplayTextSegments = [String]()
       var temporaryNode = ""
@@ -361,8 +362,9 @@ extension InputHandler {
     guard let delegate = delegate else { return false }
     let state = delegate.state
 
-    if isHaninKeyboardSymbolMode { return handleHaninKeyboardSymbolModeToggle() }
+    guard currentTypingMethod == .vChewingFactory else {
-    if isCodePointInputMode { return handleCodePointInputToggle() }
+      return revolveTypingMethod(to: .vChewingFactory)
+    }
 
     guard state.type == .ofInputting else { return false }
 
@@ -470,31 +472,28 @@ extension InputHandler {
     guard let delegate = delegate else { return false }
     let state = delegate.state
     guard state.type == .ofInputting else {
-      isCodePointInputMode = false
+      currentTypingMethod = .vChewingFactory
       return false
     }
 
-    if isCodePointInputMode {
+    if currentTypingMethod == .codePoint {
       if !strCodePointBuffer.isEmpty {
         func refreshState() {
           var updatedState = generateStateOfInputting(guarded: true)
           updatedState.tooltipDuration = 0
-          updatedState.tooltip = tooltipCodePointInputMode
+          updatedState.tooltip = delegate.state.tooltip
           delegate.switchState(updatedState)
         }
         strCodePointBuffer = strCodePointBuffer.dropLast(1).description
         if input.commonKeyModifierFlags == .option {
-          strCodePointBuffer.removeAll()
+          return revolveTypingMethod(to: .codePoint)
-          refreshState()
-          isCodePointInputMode = true
-          return true
         }
         if !strCodePointBuffer.isEmpty {
           refreshState()
           return true
         }
       }
-      return handleCodePointInputToggle()
+      return revolveTypingMethod(to: .vChewingFactory)
     }
 
     // 引入 macOS 內建注音輸入法的行為，允許用 Shift+BackSpace 解構前一個漢字的讀音。
@@ -575,8 +574,9 @@ extension InputHandler {
     guard let delegate = delegate else { return false }
     let state = delegate.state
 
-    if isHaninKeyboardSymbolMode { return handleHaninKeyboardSymbolModeToggle() }
+    guard currentTypingMethod == .vChewingFactory else {
-    if isCodePointInputMode { return handleCodePointInputToggle() }
+      return revolveTypingMethod(to: .vChewingFactory)
+    }
 
     guard state.type == .ofInputting else { return false }
 
@@ -684,8 +684,9 @@ extension InputHandler {
     guard let delegate = delegate else { return false }
     let state = delegate.state
 
-    if isHaninKeyboardSymbolMode { return handleHaninKeyboardSymbolModeToggle() }
+    guard currentTypingMethod == .vChewingFactory else {
-    if isCodePointInputMode { return handleCodePointInputToggle() }
+      return revolveTypingMethod(to: .vChewingFactory)
+    }
 
     guard state.type == .ofInputting else { return false }
 
@@ -920,73 +921,6 @@ extension InputHandler {
     return true
   }
 
-  // MARK: - 處理內碼區位輸入狀態的啟動過程（CodePoint Input Toggle）
-
-  @discardableResult func handleCodePointInputToggle() -> Bool {
-    guard let delegate = delegate, delegate.state.type != .ofDeactivated else { return false }
-    if isCodePointInputMode {
-      isCodePointInputMode = false
-      delegate.switchState(IMEState.ofAbortion())
-      return true
-    }
-    var updatedState = generateStateOfInputting(sansReading: true)
-    delegate.switchState(IMEState.ofCommitting(textToCommit: updatedState.displayedText))
-    updatedState = generateStateOfInputting(guarded: true)
-    updatedState.tooltipDuration = 0
-    updatedState.tooltip = tooltipCodePointInputMode
-    delegate.switchState(updatedState)
-    isCodePointInputMode = true
-    return true
-  }
-
-  // MARK: - 處理漢音鍵盤符號輸入狀態的啟動過程（Hanin Pallete）
-
-  @discardableResult func handleHaninKeyboardSymbolModeToggle() -> Bool {
-    guard let delegate = delegate, delegate.state.type != .ofDeactivated else { return false }
-    if isCodePointInputMode { isCodePointInputMode = false }
-    if isHaninKeyboardSymbolMode {
-      isHaninKeyboardSymbolMode = false
-      delegate.switchState(IMEState.ofAbortion())
-      return true
-    }
-    var updatedState = generateStateOfInputting(sansReading: true)
-    delegate.switchState(IMEState.ofCommitting(textToCommit: updatedState.displayedText))
-    updatedState = generateStateOfInputting(guarded: true)
-    updatedState.tooltipDuration = 0
-    updatedState.tooltip = Self.tooltipHaninKeyboardSymbolMode
-    delegate.switchState(updatedState)
-    isHaninKeyboardSymbolMode = true
-    return true
-  }
-
-  /// 處理漢音鍵盤符號輸入。
-  /// - Parameters:
-  ///   - input: 輸入按鍵訊號。
-  /// - Returns: 將按鍵行為「是否有處理掉」藉由 SessionCtl 回報給 IMK。
-  func handleHaninKeyboardSymbolModeInput(input: InputSignalProtocol) -> Bool {
-    guard let delegate = delegate, delegate.state.type != .ofDeactivated else { return false }
-    let charText = input.text.lowercased().applyingTransformFW2HW(reverse: false)
-    guard CandidateNode.mapHaninKeyboardSymbols.keys.contains(charText) else {
-      return handleHaninKeyboardSymbolModeToggle()
-    }
-    guard
-      charText.count == 1, let symbols = CandidateNode.queryHaninKeyboardSymbols(char: charText)
-    else {
-      delegate.callError("C1A760C7")
-      return true
-    }
-    // 得在這裡先 commit buffer，不然會導致「在摁 ESC 離開符號選單時會重複輸入上一次的組字區的內容」的不當行為。
-    let textToCommit = generateStateOfInputting(sansReading: true).displayedText
-    delegate.switchState(IMEState.ofCommitting(textToCommit: textToCommit))
-    if symbols.members.count == 1 {
-      delegate.switchState(IMEState.ofCommitting(textToCommit: symbols.members.map(\.name).joined()))
-    } else {
-      delegate.switchState(IMEState.ofSymbolTable(node: symbols))
-    }
-    isHaninKeyboardSymbolMode = false // 用完就關掉，但保持選字窗開啟，所以這裡不用呼叫 toggle 函式。
-    return true
-  }
-
   // MARK: - 處理符號選單（Symbol Menu Input）
 
   /// 處理符號選單。

Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler/InputHandler_TriageInput.swift

@@ -48,7 +48,7 @@ public extension InputHandler {
       case .kCarriageReturn, .kLineFeed:
         let frontNode = compositor.walkedNodes.last
         return handleEnter(input: input) {
-          guard !self.isHaninKeyboardSymbolMode, !self.isCodePointInputMode else { return [] }
+          guard self.currentTypingMethod == .vChewingFactory else { return [] }
           guard let frontNode = frontNode else { return [] }
           let pair = Megrez.KeyValuePaired(keyArray: frontNode.keyArray, value: frontNode.value)
           let associates = self.generateArrayOfAssociates(withPair: pair)
@@ -62,13 +62,7 @@ public extension InputHandler {
         case [.option, .shift]:
           return handlePunctuationList(alternative: true, isJIS: isJIS)
         case .option:
-          switch (isCodePointInputMode, isHaninKeyboardSymbolMode) {
+          return revolveTypingMethod()
-          case (false, false): return handleCodePointInputToggle()
-          case (true, false), (false, true):
-            return handleHaninKeyboardSymbolModeToggle()
-          default: break
-          }
-          return true
         default: break
         }
       case .kSpace:
@@ -85,7 +79,7 @@ public extension InputHandler {
           if input.isShiftHold, !input.isControlHold, !input.isOptionHold {
             return revolveCandidate(reverseOrder: input.isCommandHold)
           }
-          if isCodePointInputMode {
+          if currentTypingMethod == .codePoint {
             delegate.callError("FDD88EDB")
             delegate.switchState(IMEState.ofAbortion())
             return true
@@ -148,13 +142,11 @@ public extension InputHandler {
         guard let x = input.inputTextIgnoringModifiers,
               "¥\\".contains(x), input.keyModifierFlags.isEmpty
         else { break haninSymbolInput }
-        return handleHaninKeyboardSymbolModeToggle()
+        return revolveTypingMethod(to: .haninKeyboardSymbol)
       }
 
-      // 注音按鍵輸入與漢音鍵盤符號輸入處理。
+      // 注音/磁帶按鍵輸入與漢音鍵盤符號輸入處理。
-      if isHaninKeyboardSymbolMode, [[], .shift].contains(input.keyModifierFlags) {
+      if let compositionHandled = handleComposition(input: input) {
-        return handleHaninKeyboardSymbolModeInput(input: input)
-      } else if let compositionHandled = handleComposition(input: input) {
         return compositionHandled
       }
 

Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler/InputHandler_TypingMethod.swift

@@ -0,0 +1,80 @@
+// (c) 2021 and onwards The vChewing Project (MIT-NTL License).
+// ====================
+// This code is released under the MIT license (SPDX-License-Identifier: MIT)
+// ... with NTL restriction stating that:
+// No trademark license is granted to use the trade names, trademarks, service
+// marks, or product names of Contributor, except as required to fulfill notice
+// requirements defined in MIT License.
+
+import Foundation
+import SwiftExtension
+
+// MARK: - Typing Method
+
+public extension InputHandler {
+  enum TypingMethod: Int, CaseIterable {
+    case vChewingFactory // 自動指派: 0
+    case codePoint // 自動指派: 1
+    case haninKeyboardSymbol // 自動指派: 2
+
+    mutating func revolveNext() {
+      var theInt = rawValue
+      theInt.revolveAsIndex(with: Self.allCases)
+      guard let nextMethod = TypingMethod(rawValue: theInt) else { return }
+      self = nextMethod
+    }
+
+    func getTooltip(vertical: Bool = false) -> String {
+      switch self {
+      case .vChewingFactory: return ""
+      case .codePoint:
+        let commonTerm = NSMutableString()
+        commonTerm.insert("Code Point Input.".localized, at: 0)
+        if !vertical {
+          switch IMEApp.currentInputMode {
+          case .imeModeCHS: commonTerm.insert("[GB] ", at: 0)
+          case .imeModeCHT: commonTerm.insert("[Big5] ", at: 0)
+          default: break
+          }
+        }
+        return commonTerm.description
+      case .haninKeyboardSymbol:
+        return "\("Hanin Keyboard Symbol Input.".localized)"
+      }
+    }
+  }
+}
+
+// MARK: - Handle Rotation Toggles
+
+public extension InputHandler {
+  @discardableResult func revolveTypingMethod(to specifiedMethod: TypingMethod? = nil) -> Bool {
+    guard let delegate = delegate else { return false }
+    var newMethod = currentTypingMethod
+    if let specified = specifiedMethod {
+      newMethod = specified
+    } else {
+      newMethod.revolveNext()
+    }
+    /// 接下來這行必須這樣 defer 處理，
+    /// 因為再接下來的 switch newMethod 的過程會影響到 currentTypingMethod 參數。
+    defer {
+      currentTypingMethod = newMethod
+    }
+    switch newMethod {
+    case .vChewingFactory:
+      delegate.switchState(IMEState.ofAbortion())
+      return true
+    case .codePoint:
+      strCodePointBuffer.removeAll()
+    case .haninKeyboardSymbol: break
+    }
+    var updatedState = generateStateOfInputting(sansReading: true)
+    delegate.switchState(IMEState.ofCommitting(textToCommit: updatedState.displayedText))
+    updatedState = generateStateOfInputting(guarded: true)
+    updatedState.tooltipDuration = 0
+    updatedState.tooltip = newMethod.getTooltip(vertical: delegate.isVerticalTyping)
+    delegate.switchState(updatedState)
+    return true
+  }
+}