code gardening

* Add a NSRange.empty for easy access
* Rewrite preedit attributed string creation

sources/BridgingFunctions.swift

@@ -58,3 +58,7 @@ func ?=<T>(left: inout T?, right: T?) {
     left = right
   }
 }
+
+extension NSRange {
+  static let empty = NSRange(location: NSNotFound, length: 0)
+}

sources/SquirrelInputController.swift

@@ -13,7 +13,7 @@ final class SquirrelInputController: IMKInputController {
   private var client: IMKTextInput?
   private let rimeAPI: RimeApi_stdbool = rime_get_api_stdbool().pointee
   private var preedit: String = ""
-  private var selRange: NSRange = NSRange(location: NSNotFound, length: 0)
+  private var selRange: NSRange = .empty
   private var caretPos: Int = 0
   private var lastModifiers: NSEvent.ModifierFlags = .init()
   private var session: RimeSessionId = 0
@@ -411,8 +411,8 @@ private extension SquirrelInputController {
     if rimeAPI.get_commit(session, &commitText) {
       if let text = commitText.text {
         commit(string: String(cString: text))
-        _ = rimeAPI.free_commit(&commitText)
       }
+      _ = rimeAPI.free_commit(&commitText)
     }
   }
 
@@ -512,7 +512,7 @@ private extension SquirrelInputController {
   func commit(string: String) {
     guard let client = client else { return }
     // print("[DEBUG] commitString: \(string)")
-    client.insertText(string, replacementRange: NSRange(location: NSNotFound, length: 0))
+    client.insertText(string, replacementRange: .empty)
     preedit = ""
     hidePalettes()
   }
@@ -538,7 +538,7 @@ private extension SquirrelInputController {
     let remainingRange = NSRange(location: start, length: preedit.utf16.count - start)
     let attrs = mark(forStyle: kTSMHiliteSelectedRawText, at: remainingRange)! as! [NSAttributedString.Key: Any]
     attrString.setAttributes(attrs, range: remainingRange)
-    client.setMarkedText(attrString, selectionRange: NSRange(location: caretPos, length: 0), replacementRange: NSRange(location: NSNotFound, length: 0))
+    client.setMarkedText(attrString, selectionRange: NSRange(location: caretPos, length: 0), replacementRange: .empty)
   }
 
   // swiftlint:disable:next function_parameter_count

sources/SquirrelPanel.swift

@@ -20,7 +20,7 @@ final class SquirrelPanel: NSPanel {
   private var statusTimer: Timer?
 
   private var preedit: String = ""
-  private var selRange: NSRange = .init(location: NSNotFound, length: 0)
+  private var selRange: NSRange = .empty
   private var caretPos: Int = 0
   private var candidates: [String] = .init()
   private var comments: [String] = .init()
@@ -171,32 +171,26 @@ final class SquirrelPanel: NSPanel {
     currentScreen()
 
     let text = NSMutableAttributedString()
-    var preeditRange = NSRange(location: NSNotFound, length: 0)
-    var highlightedPreeditRange = NSRange(location: NSNotFound, length: 0)
+    let preeditRange: NSRange
+    let highlightedPreeditRange: NSRange
 
     // preedit
     if !preedit.isEmpty {
-      let line = NSMutableAttributedString()
-      let startIndex = String.Index(utf16Offset: selRange.location, in: preedit)
-      let endIndex = String.Index(utf16Offset: selRange.upperBound, in: preedit)
-      if selRange.location > 0 {
-        line.append(NSAttributedString(string: String(preedit[..<startIndex]), attributes: theme.preeditAttrs))
-      }
-      if selRange.length > 0 {
-        let highlightedPreeditStart = line.length
-        line.append(NSAttributedString(string: String(preedit[startIndex..<endIndex]), attributes: theme.preeditHighlightedAttrs))
-        highlightedPreeditRange = NSRange(location: highlightedPreeditStart, length: line.length - highlightedPreeditStart)
-      }
-      if selRange.upperBound < preedit.utf16.count {
-        line.append(NSAttributedString(string: String(preedit[endIndex...]), attributes: theme.preeditAttrs))
-      }
+      preeditRange = NSRange(location: 0, length: preedit.utf16.count)
+      highlightedPreeditRange = selRange
+
+      let line = NSMutableAttributedString(string: preedit)
+      line.addAttributes(theme.preeditAttrs, range: preeditRange)
+      line.addAttributes(theme.preeditHighlightedAttrs, range: selRange)
       text.append(line)
 
       text.addAttribute(.paragraphStyle, value: theme.preeditParagraphStyle, range: NSRange(location: 0, length: text.length))
-      preeditRange = NSRange(location: 0, length: text.length)
       if !candidates.isEmpty {
         text.append(NSAttributedString(string: "\n", attributes: theme.preeditAttrs))
       }
+    } else {
+      preeditRange = .empty
+      highlightedPreeditRange = .empty
     }
 
     // candidates
@@ -441,7 +435,7 @@ private extension SquirrelPanel {
     view.textContentStorage.attributedString = text
     view.textView.setLayoutOrientation(vertical ? .vertical : .horizontal)
     view.drawView(candidateRanges: [NSRange(location: 0, length: text.length)], hilightedIndex: -1,
-                  preeditRange: NSRange(location: NSNotFound, length: 0), highlightedPreeditRange: NSRange(location: NSNotFound, length: 0))
+                  preeditRange: .empty, highlightedPreeditRange: .empty)
     show()
 
     statusTimer?.invalidate()

sources/SquirrelView.swift

@@ -28,8 +28,8 @@ final class SquirrelView: NSView {
   private let squirrelLayoutDelegate: SquirrelLayoutDelegate
   var candidateRanges: [NSRange] = []
   var hilightedIndex = 0
-  var preeditRange = NSRange(location: NSNotFound, length: 0)
-  var highlightedPreeditRange = NSRange(location: NSNotFound, length: 0)
+  var preeditRange: NSRange = .empty
+  var highlightedPreeditRange: NSRange = .empty
   var separatorWidth: CGFloat = 0
   var shape = CAShapeLayer()
 
@@ -72,7 +72,7 @@ final class SquirrelView: NSView {
   }
 
   func convert(range: NSRange) -> NSTextRange? {
-    guard range.location != NSNotFound else { return nil }
+    guard range != .empty else { return nil }
     guard let startLocation = textLayoutManager.location(textLayoutManager.documentRange.location, offsetBy: range.location) else { return nil }
     guard let endLocation = textLayoutManager.location(startLocation, offsetBy: range.length) else { return nil }
     return NSTextRange(location: startLocation, end: endLocation)
@@ -668,7 +668,7 @@ private extension SquirrelView {
         if highlightedRange.upperBound == (textView.string as NSString).length {
           highlightedRect.size.height += theme.edgeInset.height - halfLinespace
         }
-        if highlightedRange.location - ((preeditRange.location == NSNotFound ? 0 : preeditRange.location) + preeditRange.length) <= 1 {
+        if highlightedRange.location - (preeditRange == .empty ? 0 : preeditRange.upperBound) <= 1 {
           if preeditRange.length == 0 {
             highlightedRect.size.height += theme.edgeInset.height - halfLinespace
             highlightedRect.origin.y -= theme.edgeInset.height - halfLinespace