Code clean-up.

Source/InputMethodController.mm

@@ -628,7 +628,7 @@ static inline NSString *LocalizationNotNeeded(NSString *s) {
 
 @implementation McBopomofoInputMethodController (KeyHandlerDelegate)
 
-- (nonnull VTCandidateController *)candidateControllerForKeyHanlder:(nonnull KeyHandler *)keyHandler
+- (nonnull VTCandidateController *)candidateControllerForKeyHandler:(nonnull KeyHandler *)keyHandler
 {
     return gCurrentCandidateController;
 }

Source/InputState.swift

@@ -23,7 +23,37 @@
 
 import Cocoa
 
-/// Represents the states for the input controller.
+/// Represents the states for the input method controller.
+///
+/// An input method is actually a finite state machine. It receives the inputs
+/// from hardware like keyboard and mouse, changes its state, updates user
+/// interface by the state, and finally produces the text output and then them
+/// to the client apps. It should be a one-way data flow, and the user interface
+/// and text output should follow unconditionally one single data source.
+///
+/// The InputState class is for representing what the input controller is doing,
+/// and the place to store the variables that could be used. For example, the
+/// array for the candidate list is useful only when the user is choosing a
+/// candidate, and the array should not exist when the input controller is in
+/// another state.
+///
+/// They are immutable objects. When the state changes, the controller should
+/// create a new state object to replace the current state instead of modifying
+/// the existing one.
+///
+/// McBopomofo's input controller has following possible states:
+///
+/// - Deactivated: The user is not using McBopomofo yet.
+/// - Empty: The user has switched to McBopomofo but did not input anything yet,
+///   or, he or she has committed text into the client apps and starts a new
+///   input phase.
+/// - Committing: The input controller is sending text to the client apps.
+/// - Inputting: The user has inputted something and the input buffer is
+///   visible.
+/// - Marking: The user is creating a area in the input buffer and about to
+///   create a new user phrase.
+/// - Choosing Candidate: The candidate window is open to let the user to choose
+///   one among the candidates.
 class InputState: NSObject {
 }
 
@@ -128,13 +158,14 @@ class InputStateMarking: InputStateNotEmpty {
         return String(format: NSLocalizedString("You are now selecting \"%@\". Press enter to add a new phrase.", comment: ""), text)
     }
 
-    @objc var readings: [String] = []
+    @objc private(set) var readings: [String] = []
 
-    @objc init(composingBuffer: String, cursorIndex: UInt, markerIndex: UInt) {
+    @objc init(composingBuffer: String, cursorIndex: UInt, markerIndex: UInt, readings: [String]) {
         self.markerIndex = markerIndex
         let begin = min(cursorIndex, markerIndex)
         let end = max(cursorIndex, markerIndex)
         markedRange = NSMakeRange(Int(begin), Int(end - begin))
+        self.readings = readings
         super.init(composingBuffer: composingBuffer, cursorIndex: cursorIndex)
     }
 

Source/KeyHandler.h

@@ -33,7 +33,7 @@ extern NSString *const kPlainBopomofoModeIdentifier;
 @class KeyHandler;
 
 @protocol KeyHandlerDelegate <NSObject>
-- (VTCandidateController *)candidateControllerForKeyHanlder:(KeyHandler *)keyHandler;
+- (VTCandidateController *)candidateControllerForKeyHandler:(KeyHandler *)keyHandler;
 - (void)keyHandler:(KeyHandler *)keyHandler didSelectCandidateAtIndex:(NSInteger)index candidateController:(VTCandidateController *)controller;
 - (BOOL)keyHandler:(KeyHandler *)keyHandler didRequestWriteUserPhraseWithState:(InputStateMarking *)state;
 @end

Source/KeyHandler.mm

@@ -525,8 +525,7 @@ static NSString *const kGraphVizOutputfile = @"/tmp/McBopomofo-visualization.dot
     if ([input isShiftHold]) {
         // Shift + left
         if (_builder->cursorIndex() > 0) {
-            InputStateMarking *marking = [[InputStateMarking alloc] initWithComposingBuffer:currentState.composingBuffer cursorIndex:currentState.cursorIndex markerIndex:currentState.cursorIndex - 1];
+            InputStateMarking *marking = [[InputStateMarking alloc] initWithComposingBuffer:currentState.composingBuffer cursorIndex:currentState.cursorIndex markerIndex:currentState.cursorIndex - 1 readings: [self _currentReadings]];
-            marking.readings = [self _currentReadings];
             stateCallback(marking);
         } else {
             errorCallback();
@@ -562,8 +561,7 @@ static NSString *const kGraphVizOutputfile = @"/tmp/McBopomofo-visualization.dot
     if ([input isShiftHold]) {
         // Shift + Right
         if (_builder->cursorIndex() < _builder->length()) {
-            InputStateMarking *marking = [[InputStateMarking alloc] initWithComposingBuffer:currentState.composingBuffer cursorIndex:currentState.cursorIndex markerIndex:currentState.cursorIndex + 1];
+            InputStateMarking *marking = [[InputStateMarking alloc] initWithComposingBuffer:currentState.composingBuffer cursorIndex:currentState.cursorIndex markerIndex:currentState.cursorIndex + 1 readings: [self _currentReadings]];
-            marking.readings = [self _currentReadings];
             stateCallback(marking);
         } else {
             errorCallback();
@@ -773,8 +771,7 @@ static NSString *const kGraphVizOutputfile = @"/tmp/McBopomofo-visualization.dot
         NSUInteger index = state.markerIndex;
         if (index > 0) {
             index -= 1;
-            InputStateMarking *marking = [[InputStateMarking alloc] initWithComposingBuffer:state.composingBuffer cursorIndex:state.cursorIndex markerIndex:index];
+            InputStateMarking *marking = [[InputStateMarking alloc] initWithComposingBuffer:state.composingBuffer cursorIndex:state.cursorIndex markerIndex:index readings:state.readings];
-            marking.readings = state.readings;
             stateCallback(marking);
         } else {
             errorCallback();
@@ -789,8 +786,7 @@ static NSString *const kGraphVizOutputfile = @"/tmp/McBopomofo-visualization.dot
         NSUInteger index = state.markerIndex;
         if (index < state.composingBuffer.length) {
             index += 1;
-            InputStateMarking *marking = [[InputStateMarking alloc] initWithComposingBuffer:state.composingBuffer cursorIndex:state.cursorIndex markerIndex:index];
+            InputStateMarking *marking = [[InputStateMarking alloc] initWithComposingBuffer:state.composingBuffer cursorIndex:state.cursorIndex markerIndex:index readings:state.readings];
-            marking.readings = state.readings;
             stateCallback(marking);
         } else {
             errorCallback();
@@ -810,7 +806,7 @@ static NSString *const kGraphVizOutputfile = @"/tmp/McBopomofo-visualization.dot
 {
     NSString *inputText = input.inputText;
     UniChar charCode = input.charCode;
-    VTCandidateController *gCurrentCandidateController = [self.delegate candidateControllerForKeyHanlder:self];
+    VTCandidateController *gCurrentCandidateController = [self.delegate candidateControllerForKeyHandler:self];
 
     BOOL cancelCandidateKey = (charCode == 27) || [input isDelete] ||
             ((_inputMode == kPlainBopomofoModeIdentifier) && (charCode == 8));