match and case

A good explanation of match operator is in the Chisel tutorial

Here, we give some more advanced examples and walk through the details of what's going on.

val root = res match { //res is passed in, then we compare "case" values to it, and result of match is returned
      case ResourceMap(value, _) => value.toList match { //ResourceMap defined in diplomacy/Resources.scala
        case Seq(("/", Seq(subtree))) => subtree //"Seq" creates a list, to which the case checks for a match
        case _ => res
      }
      case _ => res
    }

The tricky parts are the use of ResourceMap and the embedded second level of match.

The ResourceMap is defined in diplomacy/Resources.scala as:

final case class ResourceMap(value: Map[String, Seq[ResourceValue]], labels: Seq[String] = Nil) extends ResourceValue

It's use results in embedded match takes the result of the ResourceMap as an input.. and the result of the second match is actually the valu