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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2002-2011, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala
import scala.collection.{ mutable, immutable, generic }
import immutable.StringOps
import mutable.ArrayOps
import generic.CanBuildFrom
import annotation.elidable
import annotation.elidable.ASSERTION
/** The <code>Predef</code> object provides definitions that are
* accessible in all Scala compilation units without explicit
* qualification.
*/
object Predef extends LowPriorityImplicits {
/** Return the runtime representation of a class type. This is a stub method.
* The actual implementation is filled in by the compiler.
*/
def classOf[T]: Class[T] = null
type String = java.lang.String
type Class[T] = java.lang.Class[T]
// miscelleaneous -----------------------------------------------------
scala.`package` // to force scala package object to be seen.
scala.collection.immutable.List // to force Nil, :: to be seen.
type Function[-A, +B] = Function1[A, B]
type Map[A, +B] = immutable.Map[A, B]
type Set[A] = immutable.Set[A]
val Map = immutable.Map
val Set = immutable.Set
val AnyRef = new SpecializableCompanion {} // a dummy used by the specialization annotation
// Manifest types, companions, and incantations for summoning
type ClassManifest[T] = scala.reflect.ClassManifest[T]
type Manifest[T] = scala.reflect.Manifest[T]
type OptManifest[T] = scala.reflect.OptManifest[T]
val ClassManifest = scala.reflect.ClassManifest
val Manifest = scala.reflect.Manifest
val NoManifest = scala.reflect.NoManifest
def manifest[T](implicit m: Manifest[T]) = m
def classManifest[T](implicit m: ClassManifest[T]) = m
def optManifest[T](implicit m: OptManifest[T]) = m
// Minor variations on identity functions
def identity[A](x: A): A = x // @see `conforms` for the implicit version
def implicitly[T](implicit e: T) = e // for summoning implicit values from the nether world
@inline def locally[T](x: T): T = x // to communicate intent and avoid unmoored statements
// Deprecated
@deprecated("Use sys.error(message) instead")
def error(message: String): Nothing = sys.error(message)
@deprecated("Use sys.exit() instead")
def exit(): Nothing = sys.exit()
@deprecated("Use sys.exit(status) instead")
def exit(status: Int): Nothing = sys.exit(status)
@deprecated("Use formatString.format(args: _*) or arg.formatted(formatString) instead")
def format(text: String, xs: Any*) = augmentString(text).format(xs: _*)
// errors and asserts -------------------------------------------------
/** Tests an expression, throwing an AssertionError if false.
* Calls to this method will not be generated if -Xelide-below
* is at least ASSERTION.
*
* @see elidable
* @param p the expression to test
*/
@elidable(ASSERTION)
def assert(assertion: Boolean) {
if (!assertion)
throw new java.lang.AssertionError("assertion failed")
}
/** Tests an expression, throwing an AssertionError if false.
* Calls to this method will not be generated if -Xelide-below
* is at least ASSERTION.
*
* @see elidable
* @param p the expression to test
* @param msg a String to include in the failure message
*/
@elidable(ASSERTION)
def assert(assertion: Boolean, message: => Any) {
if (!assertion)
throw new java.lang.AssertionError("assertion failed: "+ message)
}
/** Tests an expression, throwing an AssertionError if false.
* This method differs from assert only in the intent expressed:
* assert contains a predicate which needs to be proven, while
* assume contains an axiom for a static checker. Calls to this method
* will not be generated if -Xelide-below is at least ASSERTION.
*
* @see elidable
* @param p the expression to test
*/
@elidable(ASSERTION)
def assume(assumption: Boolean) {
if (!assumption)
throw new java.lang.AssertionError("assumption failed")
}
/** Tests an expression, throwing an AssertionError if false.
* This method differs from assert only in the intent expressed:
* assert contains a predicate which needs to be proven, while
* assume contains an axiom for a static checker. Calls to this method
* will not be generated if -Xelide-below is at least ASSERTION.
*
* @see elidable
* @param p the expression to test
* @param msg a String to include in the failure message
*/
@elidable(ASSERTION)
def assume(assumption: Boolean, message: => Any) {
if (!assumption)
throw new java.lang.AssertionError("assumption failed: "+ message)
}
/** Tests an expression, throwing an IllegalArgumentException if false.
* This method is similar to assert, but blames the caller of the method
* for violating the condition.
*
* @param p the expression to test
*/
def require(requirement: Boolean) {
if (!requirement)
throw new IllegalArgumentException("requirement failed")
}
/** Tests an expression, throwing an IllegalArgumentException if false.
* This method is similar to assert, but blames the caller of the method
* for violating the condition.
*
* @param p the expression to test
* @param msg a String to include in the failure message
*/
def require(requirement: Boolean, message: => Any) {
if (!requirement)
throw new IllegalArgumentException("requirement failed: "+ message)
}
final class Ensuring[A](val x: A) {
def ensuring(cond: Boolean): A = { assert(cond); x }
def ensuring(cond: Boolean, msg: => Any): A = { assert(cond, msg); x }
def ensuring(cond: A => Boolean): A = { assert(cond(x)); x }
def ensuring(cond: A => Boolean, msg: => Any): A = { assert(cond(x), msg); x }
}
implicit def any2Ensuring[A](x: A): Ensuring[A] = new Ensuring(x)
// tupling ------------------------------------------------------------
type Pair[+A, +B] = Tuple2[A, B]
object Pair {
def apply[A, B](x: A, y: B) = Tuple2(x, y)
def unapply[A, B](x: Tuple2[A, B]): Option[Tuple2[A, B]] = Some(x)
}
type Triple[+A, +B, +C] = Tuple3[A, B, C]
object Triple {
def apply[A, B, C](x: A, y: B, z: C) = Tuple3(x, y, z)
def unapply[A, B, C](x: Tuple3[A, B, C]): Option[Tuple3[A, B, C]] = Some(x)
}
final class ArrowAssoc[A](val x: A) {
@inline def -> [B](y: B): Tuple2[A, B] = Tuple2(x, y)
def [B](y: B): Tuple2[A, B] = ->(y)
}
implicit def any2ArrowAssoc[A](x: A): ArrowAssoc[A] = new ArrowAssoc(x)
// printing and reading -----------------------------------------------
def print(x: Any) = Console.print(x)
def println() = Console.println()
def println(x: Any) = Console.println(x)
def printf(text: String, xs: Any*) = Console.print(text.format(xs: _*))
def readLine(): String = Console.readLine()
def readLine(text: String, args: Any*) = Console.readLine(text, args)
def readBoolean() = Console.readBoolean()
def readByte() = Console.readByte()
def readShort() = Console.readShort()
def readChar() = Console.readChar()
def readInt() = Console.readInt()
def readLong() = Console.readLong()
def readFloat() = Console.readFloat()
def readDouble() = Console.readDouble()
def readf(format: String) = Console.readf(format)
def readf1(format: String) = Console.readf1(format)
def readf2(format: String) = Console.readf2(format)
def readf3(format: String) = Console.readf3(format)
// views --------------------------------------------------------------
implicit def exceptionWrapper(exc: Throwable) = new runtime.RichException(exc)
implicit def zipped2ToTraversable[El1, El2](zz: Tuple2[_, _]#Zipped[_, El1, _, El2]): Traversable[(El1, El2)] =
new Traversable[(El1, El2)] {
def foreach[U](f: ((El1, El2)) => U): Unit = zz foreach Function.untupled(f)
}
implicit def zipped3ToTraversable[El1, El2, El3](zz: Tuple3[_, _, _]#Zipped[_, El1, _, El2, _, El3]): Traversable[(El1, El2, El3)] =
new Traversable[(El1, El2, El3)] {
def foreach[U](f: ((El1, El2, El3)) => U): Unit = zz foreach Function.untupled(f)
}
implicit def genericArrayOps[T](xs: Array[T]): ArrayOps[T] = xs match {
case x: Array[AnyRef] => refArrayOps[AnyRef](x).asInstanceOf[ArrayOps[T]]
case x: Array[Int] => intArrayOps(x).asInstanceOf[ArrayOps[T]]
case x: Array[Double] => doubleArrayOps(x).asInstanceOf[ArrayOps[T]]
case x: Array[Long] => longArrayOps(x).asInstanceOf[ArrayOps[T]]
case x: Array[Float] => floatArrayOps(x).asInstanceOf[ArrayOps[T]]
case x: Array[Char] => charArrayOps(x).asInstanceOf[ArrayOps[T]]
case x: Array[Byte] => byteArrayOps(x).asInstanceOf[ArrayOps[T]]
case x: Array[Short] => shortArrayOps(x).asInstanceOf[ArrayOps[T]]
case x: Array[Boolean] => booleanArrayOps(x).asInstanceOf[ArrayOps[T]]
case x: Array[Unit] => unitArrayOps(x).asInstanceOf[ArrayOps[T]]
case null => null
}
implicit def refArrayOps[T <: AnyRef](xs: Array[T]): ArrayOps[T] = new ArrayOps.ofRef[T](xs)
implicit def intArrayOps(xs: Array[Int]): ArrayOps[Int] = new ArrayOps.ofInt(xs)
implicit def doubleArrayOps(xs: Array[Double]): ArrayOps[Double] = new ArrayOps.ofDouble(xs)
implicit def longArrayOps(xs: Array[Long]): ArrayOps[Long] = new ArrayOps.ofLong(xs)
implicit def floatArrayOps(xs: Array[Float]): ArrayOps[Float] = new ArrayOps.ofFloat(xs)
implicit def charArrayOps(xs: Array[Char]): ArrayOps[Char] = new ArrayOps.ofChar(xs)
implicit def byteArrayOps(xs: Array[Byte]): ArrayOps[Byte] = new ArrayOps.ofByte(xs)
implicit def shortArrayOps(xs: Array[Short]): ArrayOps[Short] = new ArrayOps.ofShort(xs)
implicit def booleanArrayOps(xs: Array[Boolean]): ArrayOps[Boolean] = new ArrayOps.ofBoolean(xs)
implicit def unitArrayOps(xs: Array[Unit]): ArrayOps[Unit] = new ArrayOps.ofUnit(xs)
// Primitive Widenings --------------------------------------------------------------
implicit def byte2short(x: Byte): Short = x.toShort
implicit def byte2int(x: Byte): Int = x.toInt
implicit def byte2long(x: Byte): Long = x.toLong
implicit def byte2float(x: Byte): Float = x.toFloat
implicit def byte2double(x: Byte): Double = x.toDouble
implicit def short2int(x: Short): Int = x.toInt
implicit def short2long(x: Short): Long = x.toLong
implicit def short2float(x: Short): Float = x.toFloat
implicit def short2double(x: Short): Double = x.toDouble
implicit def char2int(x: Char): Int = x.toInt
implicit def char2long(x: Char): Long = x.toLong
implicit def char2float(x: Char): Float = x.toFloat
implicit def char2double(x: Char): Double = x.toDouble
implicit def int2long(x: Int): Long = x.toLong
implicit def int2float(x: Int): Float = x.toFloat
implicit def int2double(x: Int): Double = x.toDouble
implicit def long2float(x: Long): Float = x.toFloat
implicit def long2double(x: Long): Double = x.toDouble
implicit def float2double(x: Float): Double = x.toDouble
// "Autoboxing" and "Autounboxing" ---------------------------------------------------
implicit def byte2Byte(x: Byte) = java.lang.Byte.valueOf(x)
implicit def short2Short(x: Short) = java.lang.Short.valueOf(x)
implicit def char2Character(x: Char) = java.lang.Character.valueOf(x)
implicit def int2Integer(x: Int) = java.lang.Integer.valueOf(x)
implicit def long2Long(x: Long) = java.lang.Long.valueOf(x)
implicit def float2Float(x: Float) = java.lang.Float.valueOf(x)
implicit def double2Double(x: Double) = java.lang.Double.valueOf(x)
implicit def boolean2Boolean(x: Boolean) = java.lang.Boolean.valueOf(x)
// These next eight implicits exist solely to exclude AnyRef methods from the
// eight implicits above so that primitives are not coerced to AnyRefs. They
// only create such conflict for AnyRef methods, so the methods on the java.lang
// boxed types are unambiguously reachable.
implicit def byte2ByteConflict(x: Byte) = new AnyRef
implicit def short2ShortConflict(x: Short) = new AnyRef
implicit def char2CharacterConflict(x: Char) = new AnyRef
implicit def int2IntegerConflict(x: Int) = new AnyRef
implicit def long2LongConflict(x: Long) = new AnyRef
implicit def float2FloatConflict(x: Float) = new AnyRef
implicit def double2DoubleConflict(x: Double) = new AnyRef
implicit def boolean2BooleanConflict(x: Boolean) = new AnyRef
implicit def Byte2byte(x: java.lang.Byte): Byte = x.byteValue
implicit def Short2short(x: java.lang.Short): Short = x.shortValue
implicit def Character2char(x: java.lang.Character): Char = x.charValue
implicit def Integer2int(x: java.lang.Integer): Int = x.intValue
implicit def Long2long(x: java.lang.Long): Long = x.longValue
implicit def Float2float(x: java.lang.Float): Float = x.floatValue
implicit def Double2double(x: java.lang.Double): Double = x.doubleValue
implicit def Boolean2boolean(x: java.lang.Boolean): Boolean = x.booleanValue
// Strings and CharSequences --------------------------------------------------------------
implicit def any2stringadd(x: Any) = new runtime.StringAdd(x)
implicit def augmentString(x: String): StringOps = new StringOps(x)
implicit def unaugmentString(x: StringOps): String = x.repr
implicit def stringCanBuildFrom: CanBuildFrom[String, Char, String] =
new CanBuildFrom[String, Char, String] {
def apply(from: String) = apply()
def apply() = StringBuilder.newBuilder
}
implicit def seqToCharSequence(xs: collection.IndexedSeq[Char]): CharSequence = new CharSequence {
def length: Int = xs.length
def charAt(index: Int): Char = xs(index)
def subSequence(start: Int, end: Int): CharSequence = seqToCharSequence(xs.slice(start, end))
override def toString: String = xs.mkString("")
}
implicit def arrayToCharSequence(xs: Array[Char]): CharSequence = new CharSequence {
def length: Int = xs.length
def charAt(index: Int): Char = xs(index)
def subSequence(start: Int, end: Int): CharSequence = arrayToCharSequence(xs.slice(start, end))
override def toString: String = xs.mkString("")
}
// Type Constraints --------------------------------------------------------------
/** An instance of `A <:< B` witnesses that `A` is a subtype of `B`.
*
* Requiring an implicit argument of the type `A <:< B` encodes the generalized constraint `A <: B`.
*
* @note we need a new type constructor `<:<` and evidence `conforms`, as
* reusing `Function2` and `identity` leads to ambiguities in case of type errors (any2stringadd is inferred)
* to constrain any abstract type T that's in scope in a method's argument list (not just the method's own type parameters)
* simply add an implicit argument of type `T <:< U`, where U is the required upper bound (for lower-bounds, use: `L <:< T`,
* where L is the required lower bound).
* in part contributed by Jason Zaugg
*/
sealed abstract class <:<[-From, +To] extends (From => To) with Serializable
implicit def conforms[A]: A <:< A = new (A <:< A) { def apply(x: A) = x }
// not in the <:< companion object because it is also intended to subsume identity (which is no longer implicit)
/** An instance of `A =:= B` witnesses that the types `A` and `B` are equal.
*
* @see <:< for expressing subtyping constraints
*/
sealed abstract class =:=[From, To] extends (From => To) with Serializable
object =:= {
implicit def tpEquals[A]: A =:= A = new (A =:= A) {def apply(x: A) = x}
}
// less useful due to #2781
@deprecated("Use From => To instead")
sealed abstract class <%<[-From, +To] extends (From => To) with Serializable
object <%< {
implicit def conformsOrViewsAs[A <% B, B]: A <%< B = new (A <%< B) {def apply(x: A) = x}
}
/** A type for which there is always an implicit value.
* @see fallbackCanBuildFrom in Array.scala
*/
class DummyImplicit
object DummyImplicit {
/** An implicit value yielding a DummyImplicit.
* @see fallbackCanBuildFrom in Array.scala
*/
implicit def dummyImplicit: DummyImplicit = new DummyImplicit
}
}
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