Scala - how to print case classes like (pretty printed) tree

Question

I\'m making a parser with Scala Combinators. It is awesome. What I end up with is a long list of entagled case classes, like: ClassDecl(Complex,List(VarDecl(Real,float

Answer 1

import java.lang.reflect.Field
...

/**
  * Pretty prints case classes with field names.
  * Handles sequences and arrays of such values.
  * Ideally, one could take the output and paste it into source code and have it compile.
  */
def prettyPrint(a: Any): String = {
  // Recursively get all the fields; this will grab vals declared in parents of case classes.
  def getFields(cls: Class[_]): List[Field] =
    Option(cls.getSuperclass).map(getFields).getOrElse(Nil) ++
        cls.getDeclaredFields.toList.filterNot(f =>
          f.isSynthetic || java.lang.reflect.Modifier.isStatic(f.getModifiers))
  a match {
    // Make Strings look similar to their literal form.
    case s: String =>
      '"' + Seq("\n" -> "\\n", "\r" -> "\\r", "\t" -> "\\t", "\"" -> "\\\"", "\\" -> "\\\\").foldLeft(s) {
        case (acc, (c, r)) => acc.replace(c, r) } + '"'
    case xs: Seq[_] =>
      xs.map(prettyPrint).toString
    case xs: Array[_] =>
      s"Array(${xs.map(prettyPrint) mkString ", "})"
    // This covers case classes.
    case p: Product =>
      s"${p.productPrefix}(${
        (getFields(p.getClass) map { f =>
          f setAccessible true
          s"${f.getName} = ${prettyPrint(f.get(p))}"
        }) mkString ", "
      })"
    // General objects and primitives end up here.
    case q =>
      Option(q).map(_.toString).getOrElse("¡null!")
  }
}