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.

Source
  ControlContext.scala
Note

  `fun` and `x` are allowed to be `null`.

See also

  scala.util.continutations.shiftR

Linear Supertypes
Serializable, Serializable, AnyRef, Any
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1. ControlContext
2. Serializable
3. Serializable
4. AnyRef
5. Any

Visibility

1. Public
2. All

### 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

   Test two objects for inequality.

   Test two objects for inequality.

   returns

     `true` if !(this == that), false otherwise.

   Definition Classes
     Any

3. #### final def ##(): Int

   Equivalent to `x.hashCode` except for boxed numeric types and `null`.

   Equivalent to `x.hashCode` except for boxed numeric types and `null`. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For `null` returns a hashcode where `null.hashCode` throws a `NullPointerException`.

   returns

     a hash value consistent with ==

   Definition Classes
     AnyRef → Any

4. #### final def ==(arg0: AnyRef): Boolean

   Definition Classes
     AnyRef

5. #### final def ==(arg0: Any): Boolean

   Test two objects for equality.

   Test two objects for equality. The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

   returns

     `true` if the receiver object is equivalent to the argument; `false` otherwise.

   Definition Classes
     Any

6. #### final def asInstanceOf[T0]: T0

   Cast the receiver object to be of type `T0`.

   Cast the receiver object to be of type `T0`.

   Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression `1.asInstanceOf[String]` will throw a `ClassCastException` at runtime, while the expression `List(1).asInstanceOf[List[String]]` will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

   returns

     the receiver object.

   Definition Classes
     Any
   Exceptions thrown
     ClassCastException

     if the receiver object is not an instance of the erasure of type `T0`.

7. #### def clone(): AnyRef

   Create a copy of the receiver object.

   Create a copy of the receiver object.

   The default implementation of the `clone` method is platform dependent.

   returns

     a copy of the receiver object.

   Attributes
     protected[lang]
   Definition Classes
     AnyRef
   Annotations
     @throws()
   Note

     not specified by SLS as a member of AnyRef

8. #### final def eq(arg0: AnyRef): Boolean

   Tests whether the argument (`arg0`) is a reference to the receiver object (`this`).

   Tests whether the argument (`arg0`) is a reference to the receiver object (`this`).

   The `eq` method implements an equivalence relation on non-null instances of `AnyRef`, and has three additional properties:

   - It is consistent: for any non-null instances `x` and `y` of type `AnyRef`, multiple invocations of `x.eq(y)` consistently returns `true` or consistently returns `false`.
   - For any non-null instance `x` of type `AnyRef`, `x.eq(null)` and `null.eq(x)` returns `false`.
   - `null.eq(null)` returns `true`.

   When overriding the `equals` or `hashCode` methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (`o1 eq o2`), they should be equal to each other (`o1 == o2`) and they should hash to the same value (`o1.hashCode == o2.hashCode`).

   returns

     `true` if the argument is a reference to the receiver object; `false` otherwise.

   Definition Classes
     AnyRef

9. #### def equals(arg0: Any): Boolean

   The equality method for reference types.

   The equality method for reference types. Default implementation delegates to `eq`.

   See also `equals` in Any.

   returns

     `true` if the receiver object is equivalent to the argument; `false` otherwise.

   Definition Classes
     AnyRef → Any

10. #### def finalize(): Unit

    Called by the garbage collector on the receiver object when there are no more references to the object.

    Called by the garbage collector on the receiver object when there are no more references to the object.

    The details of when and if the `finalize` method is invoked, as well as the interaction between `finalize` and non-local returns and exceptions, are all platform dependent.

    Attributes
      protected[lang]
    Definition Classes
      AnyRef
    Annotations
      @throws()
    Note

      not specified by SLS as a member of AnyRef

11. #### 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`.

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

13. #### 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.

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

15. #### 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`.

16. #### final def getClass(): Class[_]

    A representation that corresponds to the dynamic class of the receiver object.

    A representation that corresponds to the dynamic class of the receiver object.

    The nature of the representation is platform dependent.

    returns

      a representation that corresponds to the dynamic class of the receiver object.

    Definition Classes
      AnyRef → Any
    Note

      not specified by SLS as a member of AnyRef

17. #### final def getTrivialValue: A

    returns

      The current state value.

18. #### def hashCode(): Int

    The hashCode method for reference types.

    The hashCode method for reference types. See hashCode in Any.

    returns

      the hash code value for this object.

    Definition Classes
      AnyRef → Any

19. #### final def isInstanceOf[T0]: Boolean

    Test whether the dynamic type of the receiver object is `T0`.

    Test whether the dynamic type of the receiver object is `T0`.

    Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression `1.isInstanceOf[String]` will return `false`, while the expression `List(1).isInstanceOf[List[String]]` will return `true`. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

    returns

      `true` if the receiver object is an instance of erasure of type `T0`; `false` otherwise.

    Definition Classes
      Any

20. #### final def isTrivial: Boolean

    returns

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

21. #### 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()

22. #### final def mapFinally(f: () ⇒ Unit): ControlContext[A, B, C]

23. #### final def ne(arg0: AnyRef): Boolean

    Equivalent to `!(this eq that)`.

    Equivalent to `!(this eq that)`.

    returns

      `true` if the argument is not a reference to the receiver object; `false` otherwise.

    Definition Classes
      AnyRef

24. #### final def notify(): Unit

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Definition Classes
      AnyRef
    Note

      not specified by SLS as a member of AnyRef

25. #### final def notifyAll(): Unit

    Wakes up all threads that are waiting on the receiver object's monitor.

    Wakes up all threads that are waiting on the receiver object's monitor.

    Definition Classes
      AnyRef
    Note

      not specified by SLS as a member of AnyRef

26. #### final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
      AnyRef

27. #### def toString(): String

    Creates a String representation of this object.

    Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.

    returns

      a String representation of the object.

    Definition Classes
      AnyRef → Any

28. #### final def wait(): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws()

29. #### final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws()

30. #### final def wait(arg0: Long): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws()

31. #### 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.

### Inherited from Serializable

### Inherited from AnyRef

### Inherited from Any