JSONValue.swift

public enum JSONValue {

  case object([String: JSONValue])
  case array([JSONValue])
  case string(String)
  case number(Double)
  case boolean(Bool)
  case null

  public var value: JSONPrimitive? {
    switch self {
    case .object(let value): return value
    case .array(let value): return value
    case .string(let value): return value
    case .number(let value): return value
    case .boolean(let value): return value
    case .null: return nil
    }
  }

}

extension JSONValue: Decodable {

  public init(from decoder: Decoder) throws {
    let container = try decoder.singleValueContainer()
    if let value = try? container.decode(Bool.self) {
      self = .boolean(value)
    } else if let value = try? container.decode(Double.self) {
      // Double covers Int as well
      self = .number(value)
    } else if let value = try? container.decode(String.self) {
      self = .string(value)
    } else if let value = try? container.decode([JSONValue].self) {
      self = .array(value)
    } else if let value = try? container.decode([String: JSONValue].self) {
      self = .object(value)
    } else {
      self = .null
    }
  }

}

extension JSONValue: Encodable {

  public func encode(to encoder: Encoder) throws {
    var container = encoder.singleValueContainer()

    switch self {
    case .object(let value): try container.encode(value)
    case .array(let value): try container.encode(value)
    case .string(let value): try container.encode(value)
    case .number(let value): try container.encode(value)
    case .boolean(let value): try container.encode(value)
    case .null: try container.encodeNil()
    }
  }

}