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Scala example source code file (ScalaRunTime.scala)

This example Scala source code file (ScalaRunTime.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Scala tags/keywords

a, any, any, anyref, anyref, array, array, b, boolean, int, int, nullpointerexception, product, reflection, string

The Scala ScalaRunTime.scala source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2002-2011, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */


/* INSTRUMENTED VERSION */


package scala.runtime

import scala.reflect.ClassManifest
import scala.collection.{ Seq, IndexedSeq, TraversableView }
import scala.collection.mutable.WrappedArray
import scala.collection.immutable.{ NumericRange, List, Stream, Nil, :: }
import scala.collection.generic.{ Sorted }
import scala.xml.{ Node, MetaData }
import scala.util.control.ControlThrowable
import java.lang.reflect.{ Modifier, Method => JMethod }

/* The object <code>ScalaRunTime provides ...
 */
object ScalaRunTime {
  def isArray(x: AnyRef): Boolean = isArray(x, 1)
  def isArray(x: Any, atLevel: Int): Boolean = 
    x != null && isArrayClass(x.asInstanceOf[AnyRef].getClass, atLevel)

  private def isArrayClass(clazz: Class[_], atLevel: Int): Boolean =
    clazz.isArray && (atLevel == 1 || isArrayClass(clazz.getComponentType, atLevel - 1))

  def isValueClass(clazz: Class[_]) = clazz.isPrimitive() 
  
  var arrayApplyCount = 0
  var arrayUpdateCount = 0
  
  /** Retrieve generic array element */
  def array_apply(xs: AnyRef, idx: Int): Any = {
    arrayApplyCount += 1
    xs match {
      case x: Array[AnyRef]  => x(idx).asInstanceOf[Any]
      case x: Array[Int]     => x(idx).asInstanceOf[Any]
      case x: Array[Double]  => x(idx).asInstanceOf[Any]
      case x: Array[Long]    => x(idx).asInstanceOf[Any]
      case x: Array[Float]   => x(idx).asInstanceOf[Any]
      case x: Array[Char]    => x(idx).asInstanceOf[Any]
      case x: Array[Byte]    => x(idx).asInstanceOf[Any]
      case x: Array[Short]   => x(idx).asInstanceOf[Any]
      case x: Array[Boolean] => x(idx).asInstanceOf[Any]
      case x: Array[Unit]    => x(idx).asInstanceOf[Any]
      case null => throw new NullPointerException
    }
  }

  /** update generic array element */
  def array_update(xs: AnyRef, idx: Int, value: Any): Unit = {
    arrayUpdateCount += 1
    xs match {
      case x: Array[AnyRef]  => x(idx) = value.asInstanceOf[AnyRef]
      case x: Array[Int]     => x(idx) = value.asInstanceOf[Int]
      case x: Array[Double]  => x(idx) = value.asInstanceOf[Double]
      case x: Array[Long]    => x(idx) = value.asInstanceOf[Long]
      case x: Array[Float]   => x(idx) = value.asInstanceOf[Float]
      case x: Array[Char]    => x(idx) = value.asInstanceOf[Char]
      case x: Array[Byte]    => x(idx) = value.asInstanceOf[Byte]
      case x: Array[Short]   => x(idx) = value.asInstanceOf[Short]
      case x: Array[Boolean] => x(idx) = value.asInstanceOf[Boolean]
      case x: Array[Unit]    => x(idx) = value.asInstanceOf[Unit]
      case null => throw new NullPointerException
    }
  }

  /** Get generic array length */
  def array_length(xs: AnyRef): Int = xs match {
    case x: Array[AnyRef]  => x.length
    case x: Array[Int]     => x.length
    case x: Array[Double]  => x.length
    case x: Array[Long]    => x.length
    case x: Array[Float]   => x.length
    case x: Array[Char]    => x.length
    case x: Array[Byte]    => x.length
    case x: Array[Short]   => x.length
    case x: Array[Boolean] => x.length
    case x: Array[Unit]    => x.length
    case null => throw new NullPointerException
  }    

  def array_clone(xs: AnyRef): AnyRef = xs match {
    case x: Array[AnyRef]  => ArrayRuntime.cloneArray(x)
    case x: Array[Int]     => ArrayRuntime.cloneArray(x)
    case x: Array[Double]  => ArrayRuntime.cloneArray(x)
    case x: Array[Long]    => ArrayRuntime.cloneArray(x)
    case x: Array[Float]   => ArrayRuntime.cloneArray(x)
    case x: Array[Char]    => ArrayRuntime.cloneArray(x)
    case x: Array[Byte]    => ArrayRuntime.cloneArray(x)
    case x: Array[Short]   => ArrayRuntime.cloneArray(x)
    case x: Array[Boolean] => ArrayRuntime.cloneArray(x)
    case x: Array[Unit]    => x
    case null => throw new NullPointerException
  }

  /** Convert a numeric value array to an object array.
   *  Needed to deal with vararg arguments of primitive types that are passed
   *  to a generic Java vararg parameter T ...
   */
  def toObjectArray(src: AnyRef): Array[Object] = {
    val length = array_length(src)
    val dest = new Array[Object](length)
    for (i <- 0 until length)
      array_update(dest, i, array_apply(src, i))
    dest
  }

  def toArray[T](xs: collection.Seq[T]) = {
    val arr = new Array[AnyRef](xs.length)
    var i = 0
    for (x <- xs) {
      arr(i) = x.asInstanceOf[AnyRef]
      i += 1
    }
    arr
  }
  
  // Java bug: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4071957
  // More background at ticket #2318.
  def ensureAccessible(m: JMethod): JMethod = {
    if (!m.isAccessible) {
      try m setAccessible true
      catch { case _: SecurityException => () }
    }
    m    
  }

  def checkInitialized[T <: AnyRef](x: T): T = 
    if (x == null) throw new UninitializedError else x

  abstract class Try[+A] {
    def Catch[B >: A](handler: PartialFunction[Throwable, B]): B
    def Finally(fin: => Unit): A
  }

  def Try[A](block: => A): Try[A] = new Try[A] with Runnable {
    private var result: A = _
    private var exception: Throwable = 
      try   { run() ; null }
      catch { 
        case e: ControlThrowable  => throw e  // don't catch non-local returns etc
        case e: Throwable         => e
      }

    def run() { result = block }

    def Catch[B >: A](handler: PartialFunction[Throwable, B]): B =
      if (exception == null) result
      else if (handler isDefinedAt exception) handler(exception)
      else throw exception

    def Finally(fin: => Unit): A = {
      fin

      if (exception == null) result
      else throw exception
    }
  }

  def _toString(x: Product): String =
    x.productIterator.mkString(x.productPrefix + "(", ",", ")")
  
  def _hashCode(x: Product): Int = {
    import scala.util.MurmurHash._
    val arr =  x.productArity
    var h = startHash(arr)
    var c = startMagicA
    var k = startMagicB
    var i = 0
    while (i < arr) {
      val elem = x.productElement(i)
      h = extendHash(h, if (elem == null) 0 else elem.##, c, k)
      c = nextMagicA(c)
      k = nextMagicB(k)
      i += 1
    }
    finalizeHash(h)
  }

  /** Fast path equality method for inlining; used when -optimise is set.
   */
  @inline def inlinedEquals(x: Object, y: Object): Boolean = 
    if (x eq y) true
    else if (x eq null) false
    else if (x.isInstanceOf[java.lang.Number]) BoxesRunTime.equalsNumObject(x.asInstanceOf[java.lang.Number], y)
    else if (x.isInstanceOf[java.lang.Character]) BoxesRunTime.equalsCharObject(x.asInstanceOf[java.lang.Character], y)
    else x.equals(y)

  def _equals(x: Product, y: Any): Boolean = y match {
    case y: Product if x.productArity == y.productArity => x.productIterator sameElements y.productIterator
    case _                                              => false
  }
  
  // hashcode -----------------------------------------------------------
  //
  // Note that these are the implementations called by ##, so they
  // must not call ## themselves.
 
  @inline def hash(x: Any): Int =
    if (x.isInstanceOf[java.lang.Number]) BoxesRunTime.hashFromNumber(x.asInstanceOf[java.lang.Number])
    else x.hashCode
  
  @inline def hash(dv: Double): Int = {
    val iv = dv.toInt
    if (iv == dv) return iv
    
    val lv = dv.toLong
    if (lv == dv) return lv.hashCode

    val fv = dv.toFloat
    if (fv == dv) fv.hashCode else dv.hashCode
  }
  @inline def hash(fv: Float): Int = {
    val iv = fv.toInt
    if (iv == fv) return iv
    
    val lv = fv.toLong
    if (lv == fv) return lv.hashCode
    else fv.hashCode
  }
  @inline def hash(lv: Long): Int = {
    val iv = lv.toInt
    if (iv == lv) iv else lv.hashCode
  }
  @inline def hash(x: Int): Int = x
  @inline def hash(x: Short): Int = x.toInt
  @inline def hash(x: Byte): Int = x.toInt
  @inline def hash(x: Char): Int = x.toInt
  @inline def hash(x: Boolean): Int = x.hashCode
  @inline def hash(x: Unit): Int = 0
  
  @inline def hash(x: Number): Int  = runtime.BoxesRunTime.hashFromNumber(x)
  
  /** XXX Why is there one boxed implementation in here? It would seem
   *  we should have all the numbers or none of them.
   */
  @inline def hash(x: java.lang.Long): Int = {
    val iv = x.intValue
    if (iv == x.longValue) iv else x.hashCode
  }

  /** A helper method for constructing case class equality methods,
   *  because existential types get in the way of a clean outcome and
   *  it's performing a series of Any/Any equals comparisons anyway.
   *  See ticket #2867 for specifics.
   */
  def sameElements(xs1: collection.Seq[Any], xs2: collection.Seq[Any]) = xs1 sameElements xs2

  /** Given any Scala value, convert it to a String.
   *
   * The primary motivation for this method is to provide a means for
   * correctly obtaining a String representation of a value, while
   * avoiding the pitfalls of naïvely calling toString on said value.
   * In particular, it addresses the fact that (a) toString cannot be
   * called on null and (b) depending on the apparent type of an
   * array, toString may or may not print it in a human-readable form.
   *
   * @param arg the value to stringify 
   * @return a string representation of <code>arg
   *
   */  
  def stringOf(arg: Any): String = stringOf(arg, scala.Int.MaxValue)
  def stringOf(arg: Any, maxElements: Int): String = {    
    def isScalaClass(x: AnyRef) =
      Option(x.getClass.getPackage) exists (_.getName startsWith "scala.")
    
    def isTuple(x: AnyRef) =
      x.getClass.getName matches """^scala\.Tuple(\d+).*"""

    // When doing our own iteration is dangerous
    def useOwnToString(x: Any) = x match {
      // Node extends NodeSeq extends Seq[Node] and MetaData extends Iterable[MetaData]
      case _: Node | _: MetaData => true
      // Range/NumericRange have a custom toString to avoid walking a gazillion elements
      case _: Range | _: NumericRange[_] => true
      // Sorted collections to the wrong thing (for us) on iteration - ticket #3493
      case _: Sorted[_, _]  => true
      // StringBuilder(a, b, c) is not so attractive
      case _: StringBuilder => true
      // Don't want to evaluate any elements in a view
      case _: TraversableView[_, _] => true
      // Don't want to a) traverse infinity or b) be overly helpful with peoples' custom
      // collections which may have useful toString methods - ticket #3710
      case x: Traversable[_]  => !x.hasDefiniteSize || !isScalaClass(x)
      // Otherwise, nothing could possibly go wrong
      case _ => false
    }

    // A variation on inner for maps so they print -> instead of bare tuples
    def mapInner(arg: Any): String = arg match {
      case (k, v)   => inner(k) + " -> " + inner(v)
      case _        => inner(arg)
    }
    // The recursively applied attempt to prettify Array printing
    def inner(arg: Any): String = arg match {
      case null                         => "null"
      case ""                           => "\"\""
      case x: String                    => if (x.head.isWhitespace || x.last.isWhitespace) "\"" + x + "\"" else x
      case x if useOwnToString(x)       => x.toString
      case x: AnyRef if isArray(x)      => WrappedArray make x take maxElements map inner mkString ("Array(", ", ", ")")
      case x: collection.Map[_, _]      => x take maxElements map mapInner mkString (x.stringPrefix + "(", ", ", ")")
      case x: Traversable[_]            => x take maxElements map inner mkString (x.stringPrefix + "(", ", ", ")")
      case x: Product1[_] if isTuple(x) => "(" + inner(x._1) + ",)" // that special trailing comma
      case x: Product if isTuple(x)     => x.productIterator map inner mkString ("(", ",", ")")
      case x                            => x toString
    }

    // The try/catch is defense against iterables which aren't actually designed
    // to be iterated, such as some scala.tools.nsc.io.AbstractFile derived classes.
    val s = 
      try inner(arg)
      catch { 
        case _: StackOverflowError | _: UnsupportedOperationException => arg.toString
      }
        
    val nl = if (s contains "\n") "\n" else ""
    nl + s + "\n"    
  }
}

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