在Scala中修改大文件

import scala.annotation.tailrec
import scala.io._

def isBatchLine(line:String):Boolean = ...

def batchLine(size: Int):String = ...

val it = Source.fromFile("in.ps").getLines
// cannot use it.toStream here because of SI-4835
def inLines = Stream.continually(i).takeWhile(_.hasNext).map(_.next)

// Note: using `def` instead of `val` here means we don't hold
// the entire stream in memory
def batchedLinesFrom(stream: Stream[String]):Stream[String] = {
  val (batch,remainder) = stream span { !isBatchLine(_) }
  if (batch.isEmpty && remainder.isEmpty) { 
    Stream.empty
  } else {
    batchLine(batch.size) #:: batch #::: batchedLinesFrom(remainder.drop(1))
  }
}

def newLines = batchedLinesFrom(inLines dropWhile isBatchLine)

val ps = new java.io.PrintStream(new java.io.File("out.ps"))

newLines foreach ps.println

ps.close()