Process Traversable

ProcTrav.scala

import scala.sys.process._
import scala.util.control.ControlThrowable

class ProcTrav(pb: ProcessBuilder) extends Traversable[String] {
  var iterating: Boolean = _
  var exception: Option[Throwable] = _
  // This is required to stop the process, but since we are not doing that...
  // var process: Process = _ // Need to synchronize access to this

  def logger[U](f: String => U): String => Unit = (input: String) => if (iterating) try { f(input) } catch {
    case ex: ControlThrowable => iterating = false
                                 exception = Some(ex)
                                 // but how to stop the Process?
    case other                => throw other
  }

  def foreach[U](f: String => U) {
    iterating = true
    exception = None
    // We need this to stop the process, but since we are not doing that...
    // process = pb run ProcessLogger(logger(f))
    // process.exitValue()
    pb ! ProcessLogger(logger(f))
    exception foreach (throw _)
  }
}

object ProcTrav {
  def apply(pb: ProcessBuilder) = new ProcTrav(pb)
}

Not thread-safe! I'm in no mood in making it thread-safe either. I'd like to stop the process that is executing, but I'm not sure that's possible at all. It seems there's no way other than passing a ProcessIO to run, which makes things suddenly much more complex. Doing that I can catch & handle IOException while reading from the stream, but I'm still getting NPE from... somewhere.

I could also put the whole run on a single thread, and try that, but, then, I don't have any way on logger to self-destroy.

So, at this point, I'm open for suggestions. I really need to stop the running process.

On SBT I could use runBuffered, which gets me the Process and calls buffer on ProcessLogger to wrap the execution. Perhaps this could make my job easier? I'll try that on trunk.