Scala version

scala/.gitignore

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+
+# Created by https://www.gitignore.io/api/sbt,scala,intellij
+
+### Intellij ###
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio and Webstorm
+# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
+
+# User-specific stuff:
+.idea/
+
+# CMake
+cmake-build-debug/
+
+# Mongo Explorer plugin:
+.idea/**/mongoSettings.xml
+
+## File-based project format:
+*.iws
+
+## Plugin-specific files:
+
+# IntelliJ
+/out/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
+fabric.properties
+
+### Intellij Patch ###
+# Comment Reason: https://github.com/joeblau/gitignore.io/issues/186#issuecomment-215987721
+
+# *.iml
+# modules.xml
+# .idea/misc.xml
+# *.ipr
+
+# Sonarlint plugin
+.idea/sonarlint
+
+### SBT ###
+# Simple Build Tool
+# http://www.scala-sbt.org/release/docs/Getting-Started/Directories.html#configuring-version-control
+
+dist/*
+target/
+lib_managed/
+src_managed/
+project/boot/
+project/plugins/project/
+.history
+.cache
+.lib/
+
+### Scala ###
+*.class
+*.log
+
+# End of https://www.gitignore.io/api/sbt,scala,intellij
+

scala/README.md

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+Client requirement : scala 2.12 & sbt 0.13
+
+To build and run : ''' sbt 'run ../data/0.json' '''
+
+

scala/build.sbt

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+name := "scala"
+
+version := "1.0"
+
+scalaVersion := "2.12.2"
+
+mainClass in (Compile,run) := Some("be.playing.withrojections.Main")
+
+libraryDependencies += "org.scala-lang.modules" %% "scala-parser-combinators" % "1.0.4"

scala/project/build.properties

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+sbt.version = 0.13.15

scala/src/main/scala/be/playing/withrojections/Main.scala

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+package be.playing.withrojections
+
+import be.playing.withrojections.utils.JsonElement
+
+import scala.io.Source
+
+object Main {
+  def main(args: Array[String]): Unit = {
+    if (args.length != 1) throw new Exception("Usage : Main 'path/to/file.json'")
+
+    val fileName = args(0)
+
+    if (!fileName.endsWith(".json")) throw new Exception("Usage : Main 'path/to/file.json'")
+
+    val content = Source.fromFile(fileName).mkString
+
+    // Lightweight library : https://gist.github.com/piotrga/5233317
+    val events = JsonElement.parse(content).get.asArray
+
+    println("Number of events " + CountEventProjection(events))
+  }
+}
+
+object CountEventProjection {
+  def apply(events: List[JsonElement]) = events.map(x => 1).sum
+}

scala/src/main/scala/be/playing/withrojections/utils/Json.scala

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+package be.playing.withrojections.utils
+
+import scala.language.dynamics
+import scala.util.parsing.json.JSON
+
+trait JsonElement extends Dynamic{ self =>
+  def selectDynamic(field: String) : JsonElement = EmptyElement
+  def applyDynamic(field: String)(i: Int) : JsonElement = EmptyElement
+  def toList : List[String] = sys.error(s"$this is not a list.")
+  def asArray : List[JsonElement] = sys.error(s"$this is not a list.")
+  def asString: String = sys.error(s"$this has no string representation.")
+  def length$ : Int = sys.error(s"$this has no length")
+}
+
+
+object JsonElement{
+
+  def ^(s: String) = {
+    require(!s.isEmpty, "Element is empty")
+    s
+  }
+
+  implicit def toString(e: JsonElement) : String = e.asString
+  implicit def toBoolean(e: JsonElement) : Boolean = (^(e.asString)).toBoolean
+  implicit def toBigDecimal(e: JsonElement) : BigDecimal = BigDecimal(^(e.asString))
+  implicit def toDouble(e: JsonElement) : Double = ^(e.asString).toDouble
+  implicit def toFloat(e: JsonElement) : Float = ^(e.asString).toFloat
+  implicit def toByte(e: JsonElement) : Byte = ^(e.asString).stripSuffix(".0").toByte
+  implicit def toShort(e: JsonElement) : Short = ^(e.asString).stripSuffix(".0").toShort
+  implicit def toInt(e: JsonElement) : Int = ^(e.asString).stripSuffix(".0").toInt
+  implicit def toLong(e: JsonElement) : Long = ^(e.asString).stripSuffix(".0").toLong
+  implicit def toList(e: JsonElement) : List[String] = e.toList
+  implicit def asArray(e: JsonElement) : List[JsonElement] = e.asArray
+
+
+
+  def parse(json: String) = JSON.parseFull(json) map (JsonElement(_))
+
+  def apply(any : Any) : JsonElement = any match {
+    case x : Seq[Any] => new ArrayElement(x)
+    case x : Map[String, Any] => new ComplexElement(x)
+    case x => new PrimitiveElement(x)
+  }
+}
+
+case class PrimitiveElement(x: Any) extends JsonElement{
+  override def asString = x.toString
+}
+
+case object EmptyElement extends JsonElement{
+  override def asString = ""
+  override def toList = Nil
+  override def asArray = Nil
+}
+
+case class ArrayElement(private val x: Seq[Any]) extends JsonElement{
+  private lazy val elements = x.map((JsonElement(_))).toArray
+
+  override def applyDynamic(field: String)(i: Int) : JsonElement = elements.lift(i).getOrElse(EmptyElement)
+  override def toList : List[String] = elements map (_.asString) toList
+  override def asArray: List[JsonElement] = elements toList
+  override def length$ : Int = elements.length
+}
+
+case class ComplexElement(private val fields : Map[String, Any]) extends JsonElement{
+  override def selectDynamic(field: String) : JsonElement = fields.get(field) map(JsonElement(_)) getOrElse(EmptyElement)
+}
+