Let's assume you're starting with an iterator producing one String for each line. The Source class can do this if you're loading from a file, or you can use val lines = input.split("\n") if you're already starting with everything in a single String
This also works with List, Seq, etc. Iterator isn't a pre-requisite.
So you map over the input to parse each line
val lines = input split "\n"
val output = lines map { line => parse(line) }
or (in point-free style)
val output = lines map parse
All you need is the parse method, and a type that lines should be parsed to. Case classes are a good bet here:
case class Line(id: String, num1: Int, num2: Int)
So to parse. I'm going too wrap the results in a Try so you can capture errors:
def parse(line: String): Try[Line] = Try {
//split on commas and trim whitespace
line.split(",").trim match {
//String.split produces an Array, so we pattern-match on an Array of 3 elems
case Array(id,n1,n2) =>
// if toInt fails it'll throw an Exception to be wrapped in the Try
Line(id, n1.toInt, n2.toInt)
case x => throw new RuntimeException("Invalid line: " + x)
}
}
Put it all together and you end up with output being a CC[Try[Line]], where CC is the collection-type of lines (e.g. Iterator, Seq, etc.)
You can then isolate the errors:
val (goodLines, badLines) = output.partition(_.isSuccess)
Or if you simply want to strip out the intermediate Trys and discard the errors:
val goodLines: Seq[Line] = output collect { case Success(line) => line }
ALL TOGETHER
case class Line(id: String, num1: Int, num2: Int)
def parse(line: String): Try[Line] = Try {
line.split(",").trim match {
case Array(id,n1,n2) => Line(id, n1.toInt, n2.toInt)
case x => throw new RuntimeException("Invalid line: " + x)
}
}
val lines = input split "\n"
val output = lines map parse
val (successes, failures) = output.partition(_.isSuccess)
val goodLines = successes collect { case Success(line) => line }
