def chop(find: Byte, in: ByteString, res: Seq[ByteString] = Nil):
Seq[ByteString] = in.indexOf(find) match {
case -1 => res
case x =>
val chunk = in.take(x)
chop(find, in.drop(x + 1), if (chunk.isEmpty) res else res :+ chunk)
}
scala> chop('.', ByteString(""))
res10: Seq[akka.util.ByteString] = List()
scala> chop('.', ByteString("...."))
res11: Seq[akka.util.ByteString] = List()
scala> chop('.', ByteString("Lorem Ipsum is simply.Dummy text of the
printing.And typesetting industry.")).map(_.utf8String)
res12: Seq[String] = List(Lorem Ipsum is simply, Dummy text of the
printing, And typesetting industry)
Flow(data).mapConcat(bs => chop('.', bs)).etc
On Wed, Sep 3, 2014 at 2:15 PM, Chris Baxter <[email protected]> wrote:
> Posted this on Stackoverflow but haven't seen any activity on it so I
> figured I'd post it here as well.
>
> I've been playing around with the experimental Akka Streams API a bit and
> I have a use case that I wanted to see how to implement. For my use case,
> I have a `StreamTcp` based `Flow` that is being fed from binding the input
> stream of connections to my server socket. The Flow that I have is based
> on `ByteString` data coming into it. The data that is coming in is going
> to have a delimiter in it that means I should treat everything before the
> delimiter as one message and everything after and up to the next delimiter
> as the next message. So playing around with a simpler example, using no
> sockets and just static text, this is what I came up with:
>
> import akka.actor.ActorSystem
> import akka.stream.{ FlowMaterializer, MaterializerSettings }
> import akka.stream.scaladsl.Flow
> import scala.util.{ Failure, Success }
> import akka.util.ByteString
> object BasicTransformation {
> def main(args: Array[String]): Unit = {
> implicit val system = ActorSystem("Sys")
> val data = ByteString("Lorem Ipsum is simply.Dummy text of the
> printing.And typesetting industry.")
> Flow(data).
> splitWhen(c => c == '.').
> foreach{producer =>
> Flow(producer).
> filter(c => c != '.').
> fold(new StringBuilder)((sb, c) => sb.append(c.toChar)).
> map(_.toString).
> filter(!_.isEmpty).
> foreach(println(_)).
> consume(FlowMaterializer(MaterializerSettings()))
> }.
> onComplete(FlowMaterializer(MaterializerSettings())) {
> case any =>
> system.shutdown
> }
> }
> }
>
> The main function on the `Flow` that I found to accomplish my goal was
> `splitWhen`, which then produces additional sub-flows, one for each message
> per that `.` delimiter. I then process each sub-flow with another pipeline
> of steps, finally printing the individual messages at the end.
>
> This all seems a bit verbose, to accomplish what I thought to be a pretty
> simple and common use case. So my question is, is there a cleaner and less
> verbose way to do this or is this the correct and preferred way to split a
> stream up by a delimiter?
>
> The link to the SO question is:
> http://stackoverflow.com/questions/25631099/how-to-split-an-inbound-stream-on-a-delimiter-character-using-akka-streams
>
> --
> >>>>>>>>>> Read the docs: http://akka.io/docs/
> >>>>>>>>>> Check the FAQ:
> http://doc.akka.io/docs/akka/current/additional/faq.html
> >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user
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--
Cheers,
√
--
>>>>>>>>>> Read the docs: http://akka.io/docs/
>>>>>>>>>> Check the FAQ:
>>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html
>>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user
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