scala.util.continuations

ControlContext

final class ControlContext[+A, -B, +C] extends Serializable

This class represent a portion of computation that has a 'hole' in it. The class has the ability to compute state up until a certain point where the state has the A type. If this context is given a function of type A => B to move the state to the B type, then the entire computation can be completed resulting in a value of type C.

An Example:

val cc = new ControlContext[String, String, String](
    fun = { (f: String=>String, err: Exception => String) =>
      val updatedState =
        try f("State")
        catch {
          case e: Exception => err(e)
        }
      updatedState + "-Complete!"
    },
    x = null.asIntanceOf[String]
}
cc.foreach(_ + "-Continued")  // Results in "State-Continued-Complete!"

This class is used to transform calls to shift in the continuations package. Direct use and instantiation is possible, but usually reserved for advanced cases.

A context may either be trivial or non-trivial. A trivial context just has a state of type A. When completing the computation, it's only necessary to use the function of type A => B directly against the trivial value. A non-trivial value stores a computation around the state transformation of type A => B and cannot be short-circuited.

A

The type of the state currently held in the context.

B

The type of the transformed state needed to complete this computation.

C

The return type of the entire computation stored in this context.

Note

fun and x are allowed to be null.

See also

scala.util.continutations.shiftR

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  1. ControlContext
  2. Serializable
  3. Serializable
  4. AnyRef
  5. Any
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  1. by StringAdd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Instance Constructors

  1. new ControlContext(fun: ((A) ⇒ B, (Exception) ⇒ B) ⇒ C, x: A)

    fun

    The captured computation so far. The type (A => B, Exception => B) => C is a function where:

    • The first parameter A=>B represents the computation defined against the current state held in the ControlContext.
    • The second parameter Exception => B represents a computation to perform if an exception is thrown from the first parameter's computation.
    • The return value is the result of the entire computation contained in this ControlContext.
    x

    The current state stored in this context. Allowed to be null if the context is non-trivial.

Value Members

  1. final def !=(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  2. final def !=(arg0: Any): Boolean

    Definition Classes
    Any
  3. final def ##(): Int

    Definition Classes
    AnyRef → Any
  4. def +(other: String): String

    Implicit information
    This member is added by an implicit conversion from ControlContext[A, B, C] to StringAdd[ControlContext[A, B, C]] performed by method StringAdd in scala.Predef.
    Definition Classes
    StringAdd
  5. def ->[B](y: B): (ControlContext[A, B, C], B)

    Implicit information
    This member is added by an implicit conversion from ControlContext[A, B, C] to ArrowAssoc[ControlContext[A, B, C]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  6. final def ==(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  7. final def ==(arg0: Any): Boolean

    Definition Classes
    Any
  8. final def asInstanceOf[T0]: T0

    Definition Classes
    Any
  9. def clone(): AnyRef

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  10. def ensuring(cond: (ControlContext[A, B, C]) ⇒ Boolean, msg: ⇒ Any): ControlContext[A, B, C]

    Implicit information
    This member is added by an implicit conversion from ControlContext[A, B, C] to Ensuring[ControlContext[A, B, C]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  11. def ensuring(cond: (ControlContext[A, B, C]) ⇒ Boolean): ControlContext[A, B, C]

    Implicit information
    This member is added by an implicit conversion from ControlContext[A, B, C] to Ensuring[ControlContext[A, B, C]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  12. def ensuring(cond: Boolean, msg: ⇒ Any): ControlContext[A, B, C]

    Implicit information
    This member is added by an implicit conversion from ControlContext[A, B, C] to Ensuring[ControlContext[A, B, C]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  13. def ensuring(cond: Boolean): ControlContext[A, B, C]

    Implicit information
    This member is added by an implicit conversion from ControlContext[A, B, C] to Ensuring[ControlContext[A, B, C]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  14. final def eq(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  15. def equals(arg0: Any): Boolean

    Definition Classes
    AnyRef → Any
  16. def finalize(): Unit

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  17. final def flatMap[A1, B1, C1 <: B](f: (A) ⇒ ControlContext[A1, B1, C1]): ControlContext[A1, B1, C]

    Maps and flattens this ControlContext with another ControlContext generated from the current state.

    Maps and flattens this ControlContext with another ControlContext generated from the current state.

    A1

    The new type of the contained state.

    B1

    The new type of the state after the stored continuation has executed.

    C1

    The result type of the nested ControlContext. Because the nested ControlContext is executed within the outer ControlContext, this type must >: B so that the resulting nested computation can be fed through the current continuation.

    f

    A transformation function from the current state to a nested ControlContext.

    returns

    The transformed ControlContext.

    Annotations
    @noinline()
    Note

    The resulting comuptation is still the type C.

  18. final def flatMapCatch[A1 >: A, B1 <: B, C1 >: C <: B1](pf: PartialFunction[Exception, ControlContext[A1, B1, C1]]): ControlContext[A1, B1, C1]

  19. final def foreach(f: (A) ⇒ B): C

    Runs the computation against the state stored in this ControlContext.

    Runs the computation against the state stored in this ControlContext.

    f

    the computation that modifies the current state of the context.

    Note

    This method could throw exceptions from the computations.

  20. def foreachFull(f: (A) ⇒ B, g: (Exception) ⇒ B): C

  21. def formatted(fmtstr: String): String

    Implicit information
    This member is added by an implicit conversion from ControlContext[A, B, C] to StringFormat[ControlContext[A, B, C]] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  22. val fun: ((A) ⇒ B, (Exception) ⇒ B) ⇒ C

    The captured computation so far.

    The captured computation so far. The type (A => B, Exception => B) => C is a function where:

    • The first parameter A=>B represents the computation defined against the current state held in the ControlContext.
    • The second parameter Exception => B represents a computation to perform if an exception is thrown from the first parameter's computation.
    • The return value is the result of the entire computation contained in this ControlContext.
  23. final def getClass(): Class[_]

    Definition Classes
    AnyRef → Any
  24. final def getTrivialValue: A

    returns

    The current state value.

  25. def hashCode(): Int

    Definition Classes
    AnyRef → Any
  26. final def isInstanceOf[T0]: Boolean

    Definition Classes
    Any
  27. final def isTrivial: Boolean

    returns

    true if this context only stores a state value and not any deferred computation.

  28. final def map[A1](f: (A) ⇒ A1): ControlContext[A1, B, C]

    Modifies the currently captured state in this ControlContext.

    Modifies the currently captured state in this ControlContext.

    A1

    The new type of state in this context.

    f

    A transformation function on the current state of the ControlContext.

    returns

    The new ControlContext.

    Annotations
    @noinline()
  29. final def mapFinally(f: () ⇒ Unit): ControlContext[A, B, C]

  30. final def ne(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  31. final def notify(): Unit

    Definition Classes
    AnyRef
  32. final def notifyAll(): Unit

    Definition Classes
    AnyRef
  33. final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
    AnyRef
  34. def toString(): String

    Definition Classes
    AnyRef → Any
  35. final def wait(): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  36. final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  37. final def wait(arg0: Long): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  38. val x: A

    The current state stored in this context.

    The current state stored in this context. Allowed to be null if the context is non-trivial.

  39. def [B](y: B): (ControlContext[A, B, C], B)

    Implicit information
    This member is added by an implicit conversion from ControlContext[A, B, C] to ArrowAssoc[ControlContext[A, B, C]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc

Inherited from Serializable

Inherited from java.io.Serializable

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion StringAdd from ControlContext[A, B, C] to StringAdd[ControlContext[A, B, C]]

Inherited by implicit conversion StringFormat from ControlContext[A, B, C] to StringFormat[ControlContext[A, B, C]]

Inherited by implicit conversion Ensuring from ControlContext[A, B, C] to Ensuring[ControlContext[A, B, C]]

Inherited by implicit conversion ArrowAssoc from ControlContext[A, B, C] to ArrowAssoc[ControlContext[A, B, C]]

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