/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2002-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */



package scala
package collection
package mutable

import scala.reflect.ClassTag
import scala.runtime.BoxedUnit
import scala.collection.generic._
import scala.util.hashing.MurmurHash3

import java.util.Arrays

/**
 *  A class representing `Array[T]`.
 *
 *  @tparam T    type of the elements in this wrapped array.
 *
 *  @author  Martin Odersky, Stephane Micheloud
 *  @version 1.0
 *  @since 2.8
 *  @define Coll `WrappedArray`
 *  @define coll wrapped array
 *  @define orderDependent
 *  @define orderDependentFold
 *  @define mayNotTerminateInf
 *  @define willNotTerminateInf
 */
abstract class WrappedArray[T]
extends AbstractSeq[T]
    with IndexedSeq[T]
    with ArrayLike[T, WrappedArray[T]]
{

  override protected[this] def thisCollection: WrappedArray[T] = this
  override protected[this] def toCollection(repr: WrappedArray[T]): WrappedArray[T] = repr

  /** The tag of the element type */
  def elemTag: ClassTag[T]

  /** The length of the array */
  def length: Int

  /** The element at given index */
  def apply(index: Int): T

  /** Update element at given index */
  def update(index: Int, elem: T): Unit

  /** The underlying array */
  def array: Array[T]

  private def elementClass: Class[_] =
    array.getClass.getComponentType

  override def toArray[U >: T : ClassTag]: Array[U] = {
    val thatElementClass = implicitly[ClassTag[U]].runtimeClass
    if (elementClass eq thatElementClass)
      array.asInstanceOf[Array[U]]
    else
      super.toArray[U]
  }

  override def stringPrefix = "WrappedArray"

  /** Clones this object, including the underlying Array. */
  override def clone(): WrappedArray[T] = WrappedArray make array.clone()

  /** Creates new builder for this collection ==> move to subclasses
   */
  override protected[this] def newBuilder: Builder[T, WrappedArray[T]] =
    new WrappedArrayBuilder[T](elemTag)

}

/** A companion object used to create instances of `WrappedArray`.
 */
object WrappedArray {
  // This is reused for all calls to empty.
  private val EmptyWrappedArray  = new ofRef[AnyRef](new Array[AnyRef](0))
  def empty[T <: AnyRef]: WrappedArray[T] = EmptyWrappedArray.asInstanceOf[WrappedArray[T]]

  // If make is called explicitly we use whatever we're given, even if it's
  // empty.  This may be unnecessary (if WrappedArray is to honor the collections
  // contract all empty ones must be equal, so discriminating based on the reference
  // equality of an empty array should not come up) but we may as well be
  // conservative since wrapRefArray contributes most of the unnecessary allocations.
  def make[T](x: AnyRef): WrappedArray[T] = (x match {
    case null              => null
    case x: Array[AnyRef]  => new ofRef[AnyRef](x)
    case x: Array[Int]     => new ofInt(x)
    case x: Array[Double]  => new ofDouble(x)
    case x: Array[Long]    => new ofLong(x)
    case x: Array[Float]   => new ofFloat(x)
    case x: Array[Char]    => new ofChar(x)
    case x: Array[Byte]    => new ofByte(x)
    case x: Array[Short]   => new ofShort(x)
    case x: Array[Boolean] => new ofBoolean(x)
    case x: Array[Unit]    => new ofUnit(x)
  }).asInstanceOf[WrappedArray[T]]

  implicit def canBuildFrom[T](implicit m: ClassTag[T]): CanBuildFrom[WrappedArray[_], T, WrappedArray[T]] =
    new CanBuildFrom[WrappedArray[_], T, WrappedArray[T]] {
      def apply(from: WrappedArray[_]): Builder[T, WrappedArray[T]] =
        ArrayBuilder.make[T]()(m) mapResult WrappedArray.make[T]
      def apply: Builder[T, WrappedArray[T]] =
        ArrayBuilder.make[T]()(m) mapResult WrappedArray.make[T]
  }

  def newBuilder[T](implicit t: ClassTag[T]): Builder[T, WrappedArray[T]] = new WrappedArrayBuilder[T](t)

  final class ofRef[T <: AnyRef](val array: Array[T]) extends WrappedArray[T] with Serializable {
    lazy val elemTag = ClassTag[T](array.getClass.getComponentType)
    def length: Int = array.length
    def apply(index: Int): T = array(index).asInstanceOf[T]
    def update(index: Int, elem: T) { array(index) = elem }
    override def hashCode = MurmurHash3.wrappedArrayHash(array)
    override def equals(that: Any) = that match {
      case that: ofRef[_] => Arrays.equals(array.asInstanceOf[Array[AnyRef]], that.array.asInstanceOf[Array[AnyRef]])
      case _ => super.equals(that)
    }
  }

  final class ofByte(val array: Array[Byte]) extends WrappedArray[Byte] with Serializable {
    def elemTag = ClassTag.Byte
    def length: Int = array.length
    def apply(index: Int): Byte = array(index)
    def update(index: Int, elem: Byte) { array(index) = elem }
    override def hashCode = MurmurHash3.wrappedBytesHash(array)
    override def equals(that: Any) = that match {
      case that: ofByte => Arrays.equals(array, that.array)
      case _ => super.equals(that)
    }
  }

  final class ofShort(val array: Array[Short]) extends WrappedArray[Short] with Serializable {
    def elemTag = ClassTag.Short
    def length: Int = array.length
    def apply(index: Int): Short = array(index)
    def update(index: Int, elem: Short) { array(index) = elem }
    override def hashCode = MurmurHash3.wrappedArrayHash(array)
    override def equals(that: Any) = that match {
      case that: ofShort => Arrays.equals(array, that.array)
      case _ => super.equals(that)
    }
  }

  final class ofChar(val array: Array[Char]) extends WrappedArray[Char] with Serializable {
    def elemTag = ClassTag.Char
    def length: Int = array.length
    def apply(index: Int): Char = array(index)
    def update(index: Int, elem: Char) { array(index) = elem }
    override def hashCode = MurmurHash3.wrappedArrayHash(array)
    override def equals(that: Any) = that match {
      case that: ofChar => Arrays.equals(array, that.array)
      case _ => super.equals(that)
    }
  }

  final class ofInt(val array: Array[Int]) extends WrappedArray[Int] with Serializable {
    def elemTag = ClassTag.Int
    def length: Int = array.length
    def apply(index: Int): Int = array(index)
    def update(index: Int, elem: Int) { array(index) = elem }
    override def hashCode = MurmurHash3.wrappedArrayHash(array)
    override def equals(that: Any) = that match {
      case that: ofInt => Arrays.equals(array, that.array)
      case _ => super.equals(that)
    }
  }

  final class ofLong(val array: Array[Long]) extends WrappedArray[Long] with Serializable {
    def elemTag = ClassTag.Long
    def length: Int = array.length
    def apply(index: Int): Long = array(index)
    def update(index: Int, elem: Long) { array(index) = elem }
    override def hashCode = MurmurHash3.wrappedArrayHash(array)
    override def equals(that: Any) = that match {
      case that: ofLong => Arrays.equals(array, that.array)
      case _ => super.equals(that)
    }
  }

  final class ofFloat(val array: Array[Float]) extends WrappedArray[Float] with Serializable {
    def elemTag = ClassTag.Float
    def length: Int = array.length
    def apply(index: Int): Float = array(index)
    def update(index: Int, elem: Float) { array(index) = elem }
    override def hashCode = MurmurHash3.wrappedArrayHash(array)
    override def equals(that: Any) = that match {
      case that: ofFloat => Arrays.equals(array, that.array)
      case _ => super.equals(that)
    }
  }

  final class ofDouble(val array: Array[Double]) extends WrappedArray[Double] with Serializable {
    def elemTag = ClassTag.Double
    def length: Int = array.length
    def apply(index: Int): Double = array(index)
    def update(index: Int, elem: Double) { array(index) = elem }
    override def hashCode = MurmurHash3.wrappedArrayHash(array)
    override def equals(that: Any) = that match {
      case that: ofDouble => Arrays.equals(array, that.array)
      case _ => super.equals(that)
    }
  }

  final class ofBoolean(val array: Array[Boolean]) extends WrappedArray[Boolean] with Serializable {
    def elemTag = ClassTag.Boolean
    def length: Int = array.length
    def apply(index: Int): Boolean = array(index)
    def update(index: Int, elem: Boolean) { array(index) = elem }
    override def hashCode = MurmurHash3.wrappedArrayHash(array)
    override def equals(that: Any) = that match {
      case that: ofBoolean => Arrays.equals(array, that.array)
      case _ => super.equals(that)
    }
  }

  final class ofUnit(val array: Array[Unit]) extends WrappedArray[Unit] with Serializable {
    def elemTag = ClassTag.Unit
    def length: Int = array.length
    def apply(index: Int): Unit = array(index)
    def update(index: Int, elem: Unit) { array(index) = elem }
    override def hashCode = MurmurHash3.wrappedArrayHash(array)
    override def equals(that: Any) = that match {
      case that: ofUnit => array.length == that.array.length
      case _ => super.equals(that)
    }
  }
}
