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package scala.reflect
import java.lang.{ Class => jClass }
import language.{implicitConversions, existentials}
import scala.runtime.ScalaRunTime.arrayClass
/** A `ClassTag[T]` wraps a runtime class, which can be accessed via the `runtimeClass` method.
*
* This is useful in itself, but also enables very important use case.
* Having this knowledge ClassTag can instantiate `Arrays`
* in those cases where the element type is unknown at compile time.
*
* If an implicit value of type u.ClassTag[T] is required, the compiler will make one up on demand.
* The implicitly created value contains in its `runtimeClass` field the runtime class that is the result of erasing type T.
* In that value, any occurrences of type parameters or abstract types U which come themselves with a ClassTag
* are represented by the type referenced by that tag.
* If the type T contains unresolved references to type parameters or abstract types, a static error results.
*
* @see [[scala.reflect.base.TypeTags]]
*/
@annotation.implicitNotFound(msg = "No ClassTag available for ${T}")
trait ClassTag[T] extends Equals with Serializable {
// please, don't add any APIs here, like it was with `newWrappedArray` and `newArrayBuilder`
// class tags, and all tags in general, should be as minimalistic as possible
/** Returns a runtime class of type `T` */
def runtimeClass: jClass[_]
/** Produces a `ClassTag` that knows how to build `Array[Array[T]]` */
def wrap: ClassTag[Array[T]] = ClassTag[Array[T]](arrayClass(runtimeClass))
/** Produces a new array with element type `T` and length `len` */
def newArray(len: Int): Array[T] =
runtimeClass match {
case java.lang.Byte.TYPE => new Array[Byte](len).asInstanceOf[Array[T]]
case java.lang.Short.TYPE => new Array[Short](len).asInstanceOf[Array[T]]
case java.lang.Character.TYPE => new Array[Char](len).asInstanceOf[Array[T]]
case java.lang.Integer.TYPE => new Array[Int](len).asInstanceOf[Array[T]]
case java.lang.Long.TYPE => new Array[Long](len).asInstanceOf[Array[T]]
case java.lang.Float.TYPE => new Array[Float](len).asInstanceOf[Array[T]]
case java.lang.Double.TYPE => new Array[Double](len).asInstanceOf[Array[T]]
case java.lang.Boolean.TYPE => new Array[Boolean](len).asInstanceOf[Array[T]]
case java.lang.Void.TYPE => new Array[Unit](len).asInstanceOf[Array[T]]
case _ => java.lang.reflect.Array.newInstance(runtimeClass, len).asInstanceOf[Array[T]]
}
/** A ClassTag[T] can serve as an extractor that matches only objects of type T.
*
* The compiler tries to turn unchecked type tests in pattern matches into checked ones
* by wrapping a `(_: T)` type pattern as `ct(_: T)`, where `ct` is the `ClassTag[T]` instance.
* Type tests necessary before calling other extractors are treated similarly.
* `SomeExtractor(...)` is turned into `ct(SomeExtractor(...))` if `T` in `SomeExtractor.unapply(x: T)`
* is uncheckable, but we have an instance of `ClassTag[T]`.
*/
def unapply(x: Any): Option[T] = if (runtimeClass.isAssignableFrom(x.getClass)) Some(x.asInstanceOf[T]) else None
/** case class accessories */
override def canEqual(x: Any) = x.isInstanceOf[ClassTag[_]]
override def equals(x: Any) = x.isInstanceOf[ClassTag[_]] && this.runtimeClass == x.asInstanceOf[ClassTag[_]].runtimeClass
override def hashCode = scala.runtime.ScalaRunTime.hash(runtimeClass)
override def toString = "ClassTag[" + runtimeClass + "]"
}
object ClassTag {
private val NothingTYPE = classOf[scala.runtime.Nothing$]
private val NullTYPE = classOf[scala.runtime.Null$]
private val ObjectTYPE = classOf[java.lang.Object]
private val StringTYPE = classOf[java.lang.String]
val Byte : ClassTag[scala.Byte] = new ClassTag[scala.Byte]{ def runtimeClass = java.lang.Byte.TYPE; private def readResolve() = ClassTag.Byte }
val Short : ClassTag[scala.Short] = new ClassTag[scala.Short]{ def runtimeClass = java.lang.Short.TYPE; private def readResolve() = ClassTag.Short }
val Char : ClassTag[scala.Char] = new ClassTag[scala.Char]{ def runtimeClass = java.lang.Character.TYPE; private def readResolve() = ClassTag.Char }
val Int : ClassTag[scala.Int] = new ClassTag[scala.Int]{ def runtimeClass = java.lang.Integer.TYPE; private def readResolve() = ClassTag.Int }
val Long : ClassTag[scala.Long] = new ClassTag[scala.Long]{ def runtimeClass = java.lang.Long.TYPE; private def readResolve() = ClassTag.Long }
val Float : ClassTag[scala.Float] = new ClassTag[scala.Float]{ def runtimeClass = java.lang.Float.TYPE; private def readResolve() = ClassTag.Float }
val Double : ClassTag[scala.Double] = new ClassTag[scala.Double]{ def runtimeClass = java.lang.Double.TYPE; private def readResolve() = ClassTag.Double }
val Boolean : ClassTag[scala.Boolean] = new ClassTag[scala.Boolean]{ def runtimeClass = java.lang.Boolean.TYPE; private def readResolve() = ClassTag.Boolean }
val Unit : ClassTag[scala.Unit] = new ClassTag[scala.Unit]{ def runtimeClass = java.lang.Void.TYPE; private def readResolve() = ClassTag.Unit }
val Any : ClassTag[scala.Any] = new ClassTag[scala.Any]{ def runtimeClass = ObjectTYPE; private def readResolve() = ClassTag.Any }
val Object : ClassTag[java.lang.Object] = new ClassTag[java.lang.Object]{ def runtimeClass = ObjectTYPE; private def readResolve() = ClassTag.Object }
val AnyVal : ClassTag[scala.AnyVal] = new ClassTag[scala.AnyVal]{ def runtimeClass = ObjectTYPE; private def readResolve() = ClassTag.AnyVal }
val AnyRef : ClassTag[scala.AnyRef] = new ClassTag[scala.AnyRef]{ def runtimeClass = ObjectTYPE; private def readResolve() = ClassTag.AnyRef }
val Nothing : ClassTag[scala.Nothing] = new ClassTag[scala.Nothing]{ def runtimeClass = NothingTYPE; private def readResolve() = ClassTag.Nothing }
val Null : ClassTag[scala.Null] = new ClassTag[scala.Null]{ def runtimeClass = NullTYPE; private def readResolve() = ClassTag.Null }
val String : ClassTag[java.lang.String] = new ClassTag[java.lang.String]{ def runtimeClass = StringTYPE; private def readResolve() = ClassTag.String }
def apply[T](runtimeClass1: jClass[_]): ClassTag[T] =
runtimeClass1 match {
case java.lang.Byte.TYPE => ClassTag.Byte.asInstanceOf[ClassTag[T]]
case java.lang.Short.TYPE => ClassTag.Short.asInstanceOf[ClassTag[T]]
case java.lang.Character.TYPE => ClassTag.Char.asInstanceOf[ClassTag[T]]
case java.lang.Integer.TYPE => ClassTag.Int.asInstanceOf[ClassTag[T]]
case java.lang.Long.TYPE => ClassTag.Long.asInstanceOf[ClassTag[T]]
case java.lang.Float.TYPE => ClassTag.Float.asInstanceOf[ClassTag[T]]
case java.lang.Double.TYPE => ClassTag.Double.asInstanceOf[ClassTag[T]]
case java.lang.Boolean.TYPE => ClassTag.Boolean.asInstanceOf[ClassTag[T]]
case java.lang.Void.TYPE => ClassTag.Unit.asInstanceOf[ClassTag[T]]
case ObjectTYPE => ClassTag.Object.asInstanceOf[ClassTag[T]]
case StringTYPE => ClassTag.String.asInstanceOf[ClassTag[T]]
case _ => new ClassTag[T]{ def runtimeClass = runtimeClass1 }
}
def unapply[T](ctag: ClassTag[T]): Option[Class[_]] = Some(ctag.runtimeClass)
}
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