Scala パーサーコンビネータ で 適当JSONリード

jsonread.scala

import scala.util.parsing.combinator.JavaTokenParsers

sealed trait JsValue

case class JsString(value: String) extends JsValue

case class JsNumber(value: BigDecimal) extends JsValue

case object JsNull extends JsValue

case class JsBoolean(value: Boolean) extends JsValue

case class JsArray(value: Seq[JsValue]) extends JsValue

case class JsObject(value: Map[JsKey, JsValue]) extends JsValue

case class JsKey(key: String)

class JsonParser extends JavaTokenParsers {

  def jsString: Parser[JsString] = stringLiteral ^^ {x => JsString(x)}

  def jsBoolean: Parser[JsBoolean] = ("false" ^^ {x => JsBoolean(false)} | "true" ^^ {x => JsBoolean(true)})

  def jsNull: Parser[JsNull.type] = "null" ^^ {_ => JsNull}

  def jsNumber: Parser[JsNumber] = floatingPointNumber ^^ {x => JsNumber(BigDecimal(x))}

  def array: Parser[JsArray] = "["~>repsep(value, ",")<~"]" ^^ {JsArray}

  def obj: Parser[JsObject] = "{"~>repsep(member, ",")<~"}" ^^ { x =>
    JsObject(x.toMap)
  }

  def value: Parser[JsValue] = jsNumber | jsString | array | obj | jsNull | jsBoolean

  def member: Parser[(JsKey, JsValue)] = stringLiteral~":"~value ^^ {
    case key~":"~value => JsKey(key) -> value
  }
}