Play 2.2 Enumeratees

// Code snippets to illustrate working with the
// Enumeratee api from Play Framework
// http://www.playframework.com/documentation/2.2.x/Iteratees
 
// You should create a play app and then launch the scala console from it.
// Then you can paste these snippets in to experiment with iteratees 
// in the scala REPL. 
 
import play.api.libs.iteratee._
import play.api.libs.concurrent.Execution.Implicits._
// And we'll need some extra imports to use Await.. which is really useful because
// Iteratees, Enumerators and Eneratees are all about asynchronous processing and futures
import scala.concurrent.Await
import scala.concurrent.duration._
import scala.language.postfixOps
// Note: all of these examples except the last one don't really need the Await, but it's cleaner to use it
// otherwise you end up with odd interleaving of the printlns and the console's output. 
 
// Create an Iteratee that will consume Strings and print them
val printlnIterateeForStrs = Iteratee.foreach[String](str => println(s"""printlnIterateeForStrs saw: $str"""))
 
// Create an Enumerator that will produce Strings
val strEnumerator: Enumerator[String] = Enumerator("1", "2", "3")
 
// Apply the Enumerator to the Iteratee
Await.result(strEnumerator(printlnIterateeForStrs), 2 seconds)
// Next line is the same as the above 
Await.result(strEnumerator |>> printlnIterateeForStrs, 2 seconds)

// Now make a joined enumerator,iteratee pair that let's us create an output (enumerator) transformed by a consumer (iteratee)
val (iteratee, enumerator) = Concurrent.joined[String]

val inputTransformerIteratee  =  Enumeratee.map { chunk: String =>  "before_" ++ chunk ++ "_after" } &>> iteratee 

strEnumerator |>> inputTransformerIteratee  // |>> alias for apply this will drive input that we'll see come out the enumerator
enumerator |>> printlnIterateeForStrs // now see the transformed output