edu.rice.cs.plt.tuple
Class Null<T>

java.lang.Object
  edu.rice.cs.plt.tuple.Tuple
      edu.rice.cs.plt.tuple.Option<T>
          edu.rice.cs.plt.tuple.Null<T>

All Implemented Interfaces:

java.io.Serializable

public final class Null<T>
extends Option<T>

An empty tuple. There is only one accessible instance, the INSTANCE singleton, which has arbitrarily-chosen type argument Void (Option<null> would make more sense, but is not expressible). Clients needing a specific kind of Null can perform an unsafe cast on the singleton to produce the desired type (this is done in make()).

See Also:

Serialized Form

Field Summary

static Null<java.lang.Void>

INSTANCE A singleton null tuple

Method Summary

<Ret> Ret	apply(OptionVisitor<? super T,? extends Ret> visitor) Invokes visitor.forNone()
boolean	equals(java.lang.Object o) Defined in terms of identity (since the singleton is the only accessible instance)
protected int	generateHashCode() Defined in terms of identity (since the singleton is the only accessible instance)
boolean	isSome() Determine whether this Option is a "some" case.
static <T> Null<T>	make() Return a singleton, cast to the appropriate type.
java.lang.String	toString() Produces "()"
T	unwrap() Get the value wrapped by this Option, or throw an OptionUnwrapException if there is no wrapped value.
T	unwrap(T forNone) Get the value wrapped by this Option, or forNone if there is no wrapped value.

Methods inherited from class edu.rice.cs.plt.tuple.Option

comparator, comparator, isNone, none, some, unwrap, wrap

Methods inherited from class edu.rice.cs.plt.tuple.Tuple

hashCode

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

INSTANCE

public static final Null<java.lang.Void> INSTANCE

A singleton null tuple

Method Detail

apply

public <Ret> Ret apply(OptionVisitor<? super T,? extends Ret> visitor)

Invokes visitor.forNone()

Specified by:

apply in class Option<T>

isSome

public boolean isSome()

Description copied from class: Option

Determine whether this Option is a "some" case. Mutually exclusive with Option.isNone().

Specified by:

isSome in class Option<T>

unwrap

public T unwrap()

Description copied from class: Option

Get the value wrapped by this Option, or throw an OptionUnwrapException if there is no wrapped value.

Specified by:

unwrap in class Option<T>

unwrap

public T unwrap(T forNone)

Description copied from class: Option

Get the value wrapped by this Option, or forNone if there is no wrapped value.

Specified by:

unwrap in class Option<T>

toString

public java.lang.String toString()

Produces "()"

Overrides:

toString in class java.lang.Object

equals

public boolean equals(java.lang.Object o)

Defined in terms of identity (since the singleton is the only accessible instance)

Overrides:

equals in class java.lang.Object

generateHashCode

protected int generateHashCode()

Defined in terms of identity (since the singleton is the only accessible instance)

Specified by:

generateHashCode in class Tuple

make

public static <T> Null<T> make()

Return a singleton, cast to the appropriate type.