JSON to YML converter

YmlRenderer.swift

extension Array where Iterator.Element == Substring {
  
  var ancestors:[String] {
    var _tempSelf = self
    _tempSelf.popLast()
    
    return _tempSelf.flatMap { $0.stringValue }
  }
}

extension String {
  
  static func tab(_ count: Int, spacePerTab:Int = 2) -> String {
    let _a = String(repeatElement(" ", count: count * spacePerTab))
    return _a
  }
}

extension Substring {
  var stringValue:String {
    return String(describing: self)
  }
}

protocol BaseRenderer {
  
  init(JSON:[String:Any])
  
  func render() -> String
}


class YmlRenderer:BaseRenderer {
  
  private var json:[String:Any]
  
  required init(JSON: [String:Any]) {
    json = JSON
  }
  
  func render() -> String {
    
    var tempNamespaceText = ""
    var column = 0
    
    var text = ""
    json
      .sorted { $0.key < $1.key}
      .forEach { kv in
        
        let currentNamespaceText = kv.key
        let currentNamespaces = currentNamespaceText.split(separator: ".")
        let tempNamespaces = tempNamespaceText.split(separator: ".")
        var thisKey = ""
        
        let tempAncestors = tempNamespaces.ancestors
        let currentAncestors = currentNamespaces.ancestors
        
        let maxColumn = min(tempAncestors.count, currentAncestors.count)
        if currentAncestors != tempAncestors {
          // Reset but check the previous namespaces.
          column = 0
          while (column < maxColumn ) && currentAncestors[column] == tempAncestors[column]  {
            column += 1
          }
        }
        
        while column < (currentAncestors.count) {
          // Append the parent namespaces
          thisKey = currentNamespaces[column].stringValue
          text.append("\(String.tab(column))\(thisKey):\n")
          column += 1
        }
        
        thisKey = currentNamespaces[column].stringValue
        text.append("\(String.tab(column))\(thisKey): \(kv.value) \n")
        
        // Update the tempNamespaceText
        tempNamespaceText = currentNamespaceText
    }
    return text
  }
}


let keystrings = [
  "login.form.name": "Name",
  "login.xxx.name": "Name",
  "login.form.password": "Password",
  "login.form.headerx": "Login",
  "login.form.header.xxx.yyy.z.a.b.x.d.s": "Login",
  "registration.form.header": "Registration",
  "registration.form.name": "Name of the Registrant",
  "start.xxxx.yyy.zzzz": "ZZZZ",
  "aa.bb.cc.dd.ee.ff.gg.Name": "ZZZZ",
  "aa.bb.cc.dd.ee.ff.gg.name": "ZZZZ",
]
let ymlRenderer = YmlRenderer(JSON: keystrings)
print(ymlRenderer.render())