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Standard library for the Scala Programming Language
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2007-2013, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala.reflect
import scala.collection.mutable.{ ArrayBuilder, WrappedArray }
/** A `Manifest[T]` is an opaque descriptor for type T. Its supported use
* is to give access to the erasure of the type as a `Class` instance, as
* is necessary for the creation of native `Arrays` if the class is not
* known at compile time.
*
* The type-relation operators `<:<` and `=:=` should be considered
* approximations only, as there are numerous aspects of type conformance
* which are not yet adequately represented in manifests.
*
* Example usages:
{{{
def arr[T] = new Array[T](0) // does not compile
def arr[T](implicit m: Manifest[T]) = new Array[T](0) // compiles
def arr[T: Manifest] = new Array[T](0) // shorthand for the preceding
// Methods manifest, classManifest, and optManifest are in [[scala.Predef]].
def isApproxSubType[T: Manifest, U: Manifest] = manifest[T] <:< manifest[U]
isApproxSubType[List[String], List[AnyRef]] // true
isApproxSubType[List[String], List[Int]] // false
def methods[T: ClassManifest] = classManifest[T].erasure.getMethods
def retType[T: ClassManifest](name: String) =
methods[T] find (_.getName == name) map (_.getGenericReturnType)
retType[Map[_, _]]("values") // Some(scala.collection.Iterable)
}}}
*
*/
@scala.annotation.implicitNotFound(msg = "No Manifest available for ${T}.")
// TODO undeprecated until Scala reflection becomes non-experimental
// @deprecated("Use scala.reflect.ClassTag (to capture erasures) or scala.reflect.runtime.universe.TypeTag (to capture types) or both instead", "2.10.0")
trait Manifest[T] extends ClassManifest[T] with Equals {
override def typeArguments: List[Manifest[_]] = Nil
override def arrayManifest: Manifest[Array[T]] =
Manifest.classType[Array[T]](arrayClass[T](erasure), this)
override def canEqual(that: Any): Boolean = that match {
case _: Manifest[_] => true
case _ => false
}
/** Note: testing for erasure here is important, as it is many times
* faster than <:< and rules out most comparisons.
*/
override def equals(that: Any): Boolean = that match {
case m: Manifest[_] => (m canEqual this) && (this.erasure == m.erasure) && (this <:< m) && (m <:< this)
case _ => false
}
override def hashCode = this.erasure.##
}
// TODO undeprecated until Scala reflection becomes non-experimental
// @deprecated("Use type tags and manually check the corresponding class or type instead", "2.10.0")
abstract class AnyValManifest[T <: AnyVal](override val toString: String) extends Manifest[T] with Equals {
override def <:<(that: ClassManifest[_]): Boolean =
(that eq this) || (that eq Manifest.Any) || (that eq Manifest.AnyVal)
override def canEqual(other: Any) = other match {
case _: AnyValManifest[_] => true
case _ => false
}
override def equals(that: Any): Boolean = this eq that.asInstanceOf[AnyRef]
override val hashCode = System.identityHashCode(this)
}
/** `ManifestFactory` defines factory methods for manifests.
* It is intended for use by the compiler and should not be used in client code.
*
* Unlike `Manifest`, this factory isn't annotated with a deprecation warning.
* This is done to prevent avalanches of deprecation warnings in the code that calls methods with manifests.
* Why so complicated? Read up the comments for `ClassManifestFactory`.
*/
object ManifestFactory {
def valueManifests: List[AnyValManifest[_]] =
List(Byte, Short, Char, Int, Long, Float, Double, Boolean, Unit)
val Byte: AnyValManifest[Byte] = new AnyValManifest[scala.Byte]("Byte") {
def runtimeClass = java.lang.Byte.TYPE
override def newArray(len: Int): Array[Byte] = new Array[Byte](len)
override def newWrappedArray(len: Int): WrappedArray[Byte] = new WrappedArray.ofByte(new Array[Byte](len))
override def newArrayBuilder(): ArrayBuilder[Byte] = new ArrayBuilder.ofByte()
private def readResolve(): Any = Manifest.Byte
}
val Short: AnyValManifest[Short] = new AnyValManifest[scala.Short]("Short") {
def runtimeClass = java.lang.Short.TYPE
override def newArray(len: Int): Array[Short] = new Array[Short](len)
override def newWrappedArray(len: Int): WrappedArray[Short] = new WrappedArray.ofShort(new Array[Short](len))
override def newArrayBuilder(): ArrayBuilder[Short] = new ArrayBuilder.ofShort()
private def readResolve(): Any = Manifest.Short
}
val Char: AnyValManifest[Char] = new AnyValManifest[scala.Char]("Char") {
def runtimeClass = java.lang.Character.TYPE
override def newArray(len: Int): Array[Char] = new Array[Char](len)
override def newWrappedArray(len: Int): WrappedArray[Char] = new WrappedArray.ofChar(new Array[Char](len))
override def newArrayBuilder(): ArrayBuilder[Char] = new ArrayBuilder.ofChar()
private def readResolve(): Any = Manifest.Char
}
val Int: AnyValManifest[Int] = new AnyValManifest[scala.Int]("Int") {
def runtimeClass = java.lang.Integer.TYPE
override def newArray(len: Int): Array[Int] = new Array[Int](len)
override def newWrappedArray(len: Int): WrappedArray[Int] = new WrappedArray.ofInt(new Array[Int](len))
override def newArrayBuilder(): ArrayBuilder[Int] = new ArrayBuilder.ofInt()
private def readResolve(): Any = Manifest.Int
}
val Long: AnyValManifest[Long] = new AnyValManifest[scala.Long]("Long") {
def runtimeClass = java.lang.Long.TYPE
override def newArray(len: Int): Array[Long] = new Array[Long](len)
override def newWrappedArray(len: Int): WrappedArray[Long] = new WrappedArray.ofLong(new Array[Long](len))
override def newArrayBuilder(): ArrayBuilder[Long] = new ArrayBuilder.ofLong()
private def readResolve(): Any = Manifest.Long
}
val Float: AnyValManifest[Float] = new AnyValManifest[scala.Float]("Float") {
def runtimeClass = java.lang.Float.TYPE
override def newArray(len: Int): Array[Float] = new Array[Float](len)
override def newWrappedArray(len: Int): WrappedArray[Float] = new WrappedArray.ofFloat(new Array[Float](len))
override def newArrayBuilder(): ArrayBuilder[Float] = new ArrayBuilder.ofFloat()
private def readResolve(): Any = Manifest.Float
}
val Double: AnyValManifest[Double] = new AnyValManifest[scala.Double]("Double") {
def runtimeClass = java.lang.Double.TYPE
override def newArray(len: Int): Array[Double] = new Array[Double](len)
override def newWrappedArray(len: Int): WrappedArray[Double] = new WrappedArray.ofDouble(new Array[Double](len))
override def newArrayBuilder(): ArrayBuilder[Double] = new ArrayBuilder.ofDouble()
private def readResolve(): Any = Manifest.Double
}
val Boolean: AnyValManifest[Boolean] = new AnyValManifest[scala.Boolean]("Boolean") {
def runtimeClass = java.lang.Boolean.TYPE
override def newArray(len: Int): Array[Boolean] = new Array[Boolean](len)
override def newWrappedArray(len: Int): WrappedArray[Boolean] = new WrappedArray.ofBoolean(new Array[Boolean](len))
override def newArrayBuilder(): ArrayBuilder[Boolean] = new ArrayBuilder.ofBoolean()
private def readResolve(): Any = Manifest.Boolean
}
val Unit: AnyValManifest[Unit] = new AnyValManifest[scala.Unit]("Unit") {
def runtimeClass = java.lang.Void.TYPE
override def newArray(len: Int): Array[Unit] = new Array[Unit](len)
override def newWrappedArray(len: Int): WrappedArray[Unit] = new WrappedArray.ofUnit(new Array[Unit](len))
override def newArrayBuilder(): ArrayBuilder[Unit] = new ArrayBuilder.ofUnit()
private def readResolve(): Any = Manifest.Unit
}
private val ObjectTYPE = classOf[java.lang.Object]
private val NothingTYPE = classOf[scala.runtime.Nothing$]
private val NullTYPE = classOf[scala.runtime.Null$]
val Any: Manifest[scala.Any] = new PhantomManifest[scala.Any](ObjectTYPE, "Any") {
override def newArray(len: Int) = new Array[scala.Any](len)
override def <:<(that: ClassManifest[_]): Boolean = (that eq this)
private def readResolve(): Any = Manifest.Any
}
val Object: Manifest[java.lang.Object] = new PhantomManifest[java.lang.Object](ObjectTYPE, "Object") {
override def newArray(len: Int) = new Array[java.lang.Object](len)
override def <:<(that: ClassManifest[_]): Boolean = (that eq this) || (that eq Any)
private def readResolve(): Any = Manifest.Object
}
val AnyRef: Manifest[scala.AnyRef] = Object.asInstanceOf[Manifest[scala.AnyRef]]
val AnyVal: Manifest[scala.AnyVal] = new PhantomManifest[scala.AnyVal](ObjectTYPE, "AnyVal") {
override def newArray(len: Int) = new Array[scala.AnyVal](len)
override def <:<(that: ClassManifest[_]): Boolean = (that eq this) || (that eq Any)
private def readResolve(): Any = Manifest.AnyVal
}
val Null: Manifest[scala.Null] = new PhantomManifest[scala.Null](NullTYPE, "Null") {
override def newArray(len: Int) = new Array[scala.Null](len)
override def <:<(that: ClassManifest[_]): Boolean =
(that ne null) && (that ne Nothing) && !(that <:< AnyVal)
private def readResolve(): Any = Manifest.Null
}
val Nothing: Manifest[scala.Nothing] = new PhantomManifest[scala.Nothing](NothingTYPE, "Nothing") {
override def newArray(len: Int) = new Array[scala.Nothing](len)
override def <:<(that: ClassManifest[_]): Boolean = (that ne null)
private def readResolve(): Any = Manifest.Nothing
}
private class SingletonTypeManifest[T <: AnyRef](value: AnyRef) extends Manifest[T] {
lazy val runtimeClass = value.getClass
override lazy val toString = value.toString + ".type"
}
/** Manifest for the singleton type `value.type`. */
def singleType[T <: AnyRef](value: AnyRef): Manifest[T] =
new SingletonTypeManifest[T](value)
/** Manifest for the class type `clazz[args]`, where `clazz` is
* a top-level or static class.
* @note This no-prefix, no-arguments case is separate because we
* it's called from ScalaRunTime.boxArray itself. If we
* pass varargs as arrays into this, we get an infinitely recursive call
* to boxArray. (Besides, having a separate case is more efficient)
*/
def classType[T](clazz: Predef.Class[_]): Manifest[T] =
new ClassTypeManifest[T](None, clazz, Nil)
/** Manifest for the class type `clazz`, where `clazz` is
* a top-level or static class and args are its type arguments. */
def classType[T](clazz: Predef.Class[T], arg1: Manifest[_], args: Manifest[_]*): Manifest[T] =
new ClassTypeManifest[T](None, clazz, arg1 :: args.toList)
/** Manifest for the class type `clazz[args]`, where `clazz` is
* a class with non-package prefix type `prefix` and type arguments `args`.
*/
def classType[T](prefix: Manifest[_], clazz: Predef.Class[_], args: Manifest[_]*): Manifest[T] =
new ClassTypeManifest[T](Some(prefix), clazz, args.toList)
private abstract class PhantomManifest[T](_runtimeClass: Predef.Class[_],
override val toString: String) extends ClassTypeManifest[T](None, _runtimeClass, Nil) {
override def equals(that: Any): Boolean = this eq that.asInstanceOf[AnyRef]
override val hashCode = System.identityHashCode(this)
}
/** Manifest for the class type `clazz[args]`, where `clazz` is
* a top-level or static class. */
private class ClassTypeManifest[T](prefix: Option[Manifest[_]],
val runtimeClass: Predef.Class[_],
override val typeArguments: List[Manifest[_]]) extends Manifest[T] {
override def toString =
(if (prefix.isEmpty) "" else prefix.get.toString+"#") +
(if (erasure.isArray) "Array" else erasure.getName) +
argString
}
def arrayType[T](arg: Manifest[_]): Manifest[Array[T]] =
arg.asInstanceOf[Manifest[T]].arrayManifest
/** Manifest for the abstract type `prefix # name'. `upperBound` is not
* strictly necessary as it could be obtained by reflection. It was
* added so that erasure can be calculated without reflection. */
def abstractType[T](prefix: Manifest[_], name: String, upperBound: Predef.Class[_], args: Manifest[_]*): Manifest[T] =
new Manifest[T] {
def runtimeClass = upperBound
override val typeArguments = args.toList
override def toString = prefix.toString+"#"+name+argString
}
/** Manifest for the unknown type `_ >: L <: U` in an existential.
*/
def wildcardType[T](lowerBound: Manifest[_], upperBound: Manifest[_]): Manifest[T] =
new Manifest[T] {
def runtimeClass = upperBound.runtimeClass
override def toString =
"_" +
(if (lowerBound eq Nothing) "" else " >: "+lowerBound) +
(if (upperBound eq Nothing) "" else " <: "+upperBound)
}
/** Manifest for the intersection type `parents_0 with ... with parents_n'. */
def intersectionType[T](parents: Manifest[_]*): Manifest[T] =
new Manifest[T] {
def runtimeClass = parents.head.runtimeClass
override def toString = parents.mkString(" with ")
}
/** Manifest for the refined type
* `parent { val fieldNames(0) : fieldTypes(0) ; ... ; val fieldNames(n) : fieldTypes(n) }`.
*/
def refinedType[T](parent: Manifest[_], fieldNames: List[String], fieldTypes: List[Manifest[_]]): Manifest[T] =
new RefinedManifest[T] {
def runtimeClass = parent.runtimeClass
def fields = fieldNames zip fieldTypes
override def toString = parent + (fieldNames zip fieldTypes).map{case(n, t) => "val "+ n +" : "+ t}.mkString("{","; ", "}")
}
// /** A generic manifest factory from a reflect.Type. Except where
// * mandated by performance considerations, we should replace most
// * other manifest factories by this one. There's just one thing
// * that needs to be done first: A Manifest's type can refer
// * to type variables that are controlled by manifests. In that
// * case the reified type needs to contain the type passed in the manifest
// * instead of the reference to the manifest. Note that splicing manifests
// * into manfifests is completely analogous to splicing code blocks into
// * code blocks. Manifest[T] and Code[T] are really the same thing, only one
// * works for types, the other for trees.
// * Another complication is that once we generate manifests from types, we really
// * should have reflection as a standard component shipped with the standard library,
// * instead of in scala-compiler.jar.
// */
// def apply[T](_tpe: mirror.Type): Manifest[T] = new Manifest[T] {
// override def symbol = _tpe.typeSymbol
// override lazy val tpe = _tpe
// override def erasure = mirror.typeToClass(_tpe.erasedType)
// override def toString = _tpe.toString
// }
}