Custom text storage

OneWordTextStorage.swift

// https://stackoverflow.com/a/32671117/310159

/// Abstract custom text storage
class CustomTextStorage: NSTextStorage
{
  var contents: NSMutableAttributedString
  
  override var string: String { return contents.string }
  
  override init(attributedString attrStr: NSAttributedString)
  {
    self.contents = attrStr.mutableCopy() as! NSMutableAttributedString
    
    super.init()
  }
  
  override init()
  {
    self.contents = NSMutableAttributedString()
    
    super.init()
  }
  
  required init?(coder: NSCoder)
  {
    fatalError("init(coder:) has not been implemented")
  }
  
  required init?(pasteboardPropertyList propertyList: Any,
                 ofType type: NSPasteboard.PasteboardType)
  {
    fatalError("init(pasteboardPropertyList:ofType:) has not been implemented")
  }
  
  override func attributes(at location: Int,
                           effectiveRange range: NSRangePointer?)
    -> [NSAttributedString.Key : Any]
  {
    return contents.attributes(at: location, effectiveRange: range)
  }
  
  override func replaceCharacters(in range: NSRange, with str: String)
  {
    let originalLength = length
    
    contents.replaceCharacters(in: range, with: str)
    edited(.editedCharacters, range: range,
           changeInLength: length - originalLength)
  }
  
  override func setAttributes(_ attrs: [NSAttributedString.Key : Any]?, range: NSRange)
  {
    contents.setAttributes(attrs, range: range)
    edited(.editedAttributes, range: range, changeInLength: 0)
  }
}

/// The entire text is always a "word"
class OneWordTextStorage: CustomTextStorage
{
  override func doubleClick(at location: Int) -> NSRange
  {
    return string.fullNSRange // extension method
  }
}