parse iTunes library XML, compile stats. shows how to use Scala's XML pull API, by putting some DSL-y goodness on top of it

.gitignore

/tunes.txt

tunes.scala

/// nicer API/DSL for dealing with XMLEventReader

class Reader(source: io.Source) {
  import scala.xml.pull._
  private val reader =
    new XMLEventReader(source) { override val preserveWS = false }
  private val it: BufferedIterator[XMLEvent] = reader.buffered
  def start() = it.next() match { case EvElemStart(_, s, _, _) => s }
  def start(s: String) { it.next() match { case EvElemStart(_, `s`, _, _) => } }
  def end() = it.next() match { case EvElemEnd(_, s) => s}
  def end(s: String) { it.next() match { case EvElemEnd(_, `s`) => } }
  // it would be nice to use BufferedIterator.takeWhile here, but it advances the iterator one too
  // far; see lampsvn.epfl.ch/trac/scala/ticket/3581 - ST 7/15/10
  def text() = Iterator.continually(it.head)
                 .takeWhile(_.isInstanceOf[EvText])
                 .collect{case EvText(x) => it.next(); x}
                 .mkString
  def slurp() = (start(), text(), end())._2
  def slurp(s: String) = (start(s), text(), end(s))._2
  def atEnd = it.head.isInstanceOf[EvElemEnd]
  def atEnd(s: String) = it.head match {
    case EvElemEnd(_, `s`) => true
    case _ => false
  }
  def stop() { reader.stop() }
}

/// read the XML file

case class Track(name: String, artist: String, album: String, time: Long, plays: Int, lastPlayed: Long)

def getTracks(source: io.Source): Traversable[Track] =
  new Traversable[Track] {
    override def foreach[T](fn: Track => T) {
      val reader = new Reader(source)
      import reader._
      start("plist")
      start("dict")
      while(slurp("key") != "Tracks")
        slurp()
      start("dict")
      while(!atEnd) {
        slurp("key")
        start("dict")
        val entries = {
          val temp = collection.mutable.Map[String, String]()
          while(!atEnd("dict"))
            temp += slurp("key") -> slurp()
          end("dict")
          temp.toMap
        }
        fn(Track(name = entries("Name"),
                 artist = entries.getOrElse("Sort Artist", entries("Artist")),
                 album = entries.getOrElse("Album", ""),
                 time = entries("Total Time").toLong,
                 plays = entries.getOrElse("Play Count", "0").toInt,
                 lastPlayed = entries.getOrElse("Play Date", "0").toLong))
      }
      reader.stop()
    }
  }

def read(source: io.Source) = {  
  def newMap = collection.mutable.Map[String, Long]()
  val (trackNames, artists, artistLengths, albums, albumLengths, playDates) = (newMap, newMap, newMap, newMap, newMap, newMap)
  def loop() {
    for(track <- getTracks(source)) {
      import track._
      trackNames(artist + " - " + name) = time * plays
      artists(artist) = time * plays + artists.getOrElse(artist, 0L)
      artistLengths(artist) = time + artistLengths.getOrElse(artist, 0L)
      val artistAlbum = artist + " - " + album
      albums(artistAlbum) = time * plays + albums.getOrElse(artistAlbum, 0L)
      albumLengths(artistAlbum) = time + albumLengths.getOrElse(artistAlbum, 0L)
      if(!playDates.isDefinedAt(artist) || playDates(artist) < lastPlayed)
        playDates(artist) = lastPlayed
      // if(artists.size >= 200) return
    }
  }
  loop()
  (trackNames.toMap, artists.toMap, artistLengths.toMap, albums.toMap, albumLengths.toMap, playDates.toMap)
}

/// reports

def artistReport1(artists: Map[String, Long]) {
  println("ARTISTS (TOTAL LISTENING TIME)")
  val totalTime = artists.map(_._2).sum
  artists.toList.sortBy(_._2).reverse.zipWithIndex.foreach{
    case ((artist, time), index) =>
      println((index + 1) + ". " + artist + " - " + (100000 * time / totalTime) / 1000.0 + "%")
  }
}

def artistReport2(artists: Map[String, Long], artistLengths: Map[String, Long]) {
  println("ARTISTS (TOTAL LISTENING TIME VS. LENGTH, 20 MIN MIN)")
  artistLengths.toList.filter(_._2 > 1200000)
    .map{case (artist, time) => (artist, artists(artist) / time.toDouble)}
    .sortBy(_._2).reverse.map(_._1).zipWithIndex.foreach{
      case (artist, index) =>
        println((index + 1) + ". " + artist)
  }
}

def albumReport1(albums: Map[String, Long]) {
  println("ALBUMS (TOTAL LISTENING TIME)")
  albums.toList.filter(_._2 > 0)
    .sortWith(_._2 > _._2).map(_._1).zipWithIndex.foreach{
      case (album, index) =>
        println((index + 1) + ". " + album)
  }
}

def albumReport2(albums: Map[String, Long], albumLengths: Map[String, Long]) {
  println("ALL ALBUMS (LISTENING TIME VS. LENGTH)")
  albums.toList.filter(_._2 > 0)
    .map{case (album, time) => (album, time.toDouble / albumLengths(album))}
    .sortBy(_._2).reverse.map(_._1).zipWithIndex.foreach{
      case (album, index) =>
        println((index + 1) + ". " + album)
  }
}

def albumReport3(albums: Map[String, Long], albumLengths: Map[String, Long]) {
  println("FULL ALBUMS (LISTENING TIME VS. LENGTH)")
  albums.toList.filter(a => a._2 > 0 && albumLengths(a._1) > 600000)
    .map{case (album, time) => (album, time.toDouble / albumLengths(album))}
    .sortBy(_._2).reverse.map(_._1).zipWithIndex.foreach{
      case (album, index) =>
        println((index + 1) + ". " + album)
  }
}

def trackReport(trackNames: Map[String, Long]) {
  println("TRACKS (TOTAL LISTENING TIME)")
  trackNames.toList.filter(_._2 > 0)
    .sortBy(_._2).reverse.map(_._1).take(1000).zipWithIndex.foreach{
      case (track, index) =>
        println((index + 1) + ". " + track)
  }
}

def lastPlayedReport(playDates: Map[String, Long]) {
  println("RECENTLY LISTENED ARTISTS")
  playDates.toList.filter(_._2 > 0)
    .sortBy(_._2).reverse.map(_._1).zipWithIndex.foreach{
      case (artist, index) =>
        println((index + 1) + ". " + artist)
    }
  println()
  println("NEVER LISTENED ARTISTS")
  playDates.toList.filter(_._2 == 0).map(_._1).sorted.foreach{println}
}

/// do it!

val path = "/Users/tisue/Dropbox/Archive/iTunes/iTunes Music Library.xml"
val (trackNames, artists, artistLengths, albums, albumLengths, playDates) =
  read(io.Source.fromFile(path))
artistReport1(artists)
println()
artistReport2(artists, artistLengths)
println()
albumReport1(albums)
println()
albumReport2(albums, albumLengths)
println()
albumReport3(albums, albumLengths)
println()
trackReport(trackNames)
println()
lastPlayedReport(playDates)