org.apache.commons.functor.adapter
Class BoundFunction<T>

java.lang.Object
  org.apache.commons.functor.adapter.BoundFunction<T>

Type Parameters:

T - the returned value type.

All Implemented Interfaces:

Serializable, Function<T>, Functor, NullaryFunctor

public final class BoundFunction<T>
extends Object
implements Function<T>, Serializable

Adapts a UnaryFunction to the Function interface using a constant unary argument.

Note that although this class implements Serializable, a given instance will only be truly Serializable if the underlying objects are. Attempts to serialize an instance whose delegates are not Serializable will result in an exception.

Version:

$Revision: 1157604 $ $Date: 2011-08-14 21:29:42 +0200 (Sun, 14 Aug 2011) $

Author:

Rodney Waldhoff

See Also:

Serialized Form

Constructor Summary

BoundFunction(UnaryFunction<? super A,? extends T> function, A arg)
Create a new BoundFunction instance.

Method Summary

static <A,T> BoundFunction<T>	bind(UnaryFunction<? super A,? extends T> function, A arg) Adapt the given, possibly-null, UnaryFunction to the Function interface by binding the specified Object as a constant argument.
boolean	equals(BoundFunction<?> that) Learn whether another BoundFunction is equal to this.
boolean	equals(Object that) Indicates whether some other object is "equal to" this functor.
T	evaluate() Evaluate this function.
int	hashCode() Returns a hash code for this functor adhering to the general Object.hashCode contract.
String	toString() Returns a human readable description of this functor.

Methods inherited from class java.lang.Object

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

Constructor Detail

BoundFunction

public BoundFunction(UnaryFunction<? super A,? extends T> function,
                     A arg)

Create a new BoundFunction instance.

Type Parameters:

A - the argument value type

Parameters:

function - the function to adapt

arg - the constant argument to use

Method Detail

evaluate

public T evaluate()

Evaluate this function.

Specified by:

evaluate in interface Function<T>

Returns:

the T result of this evaluation

equals

public boolean equals(Object that)

Indicates whether some other object is "equal to" this functor. This method must adhere to general Object.equals contract. Additionally, this method can return true only if the specified Object implements the same functor interface and is known to produce the same results and/or side-effects for the same arguments (if any).

While implementators are strongly encouraged to override the default Object implementation of this method, note that the default Object implementation does in fact adhere to the functor equals contract.

Specified by:

equals in interface Functor

Overrides:

equals in class Object

Parameters:

that - the object to compare this functor to

Returns:

true iff the given object implements this functor interface, and is known to produce the same results and/or side-effects for the same arguments (if any).

See Also:

Functor.hashCode()

equals

public boolean equals(BoundFunction<?> that)

Learn whether another BoundFunction is equal to this.

Parameters:

that - BoundFunction to test

Returns:

boolean

hashCode

public int hashCode()

Returns a hash code for this functor adhering to the general Object.hashCode contract. Implementators are strongly encouraged but not strictly required to override the default Object implementation of this method.

Specified by:

hashCode in interface Functor

Overrides:

hashCode in class Object

Returns:

a hash code for this functor

See Also:

Functor.equals(java.lang.Object)

toString

public String toString()

Returns a human readable description of this functor. Implementators are strongly encouraged but not strictly required to override the default Object implementation of this method.

Specified by:

toString in interface Functor

Overrides:

toString in class Object

Returns:

a human readable description of this functor

bind

public static <A,T> BoundFunction<T> bind(UnaryFunction<? super A,? extends T> function,
                                          A arg)

Adapt the given, possibly-null, UnaryFunction to the Function interface by binding the specified Object as a constant argument. When the given UnaryFunction is null, returns null.

Type Parameters:

A - input type

T - result type

Parameters:

function - the possibly-null UnaryFunction to adapt

arg - the object to bind as a constant argument

Returns:

a BoundFunction wrapping the given UnaryFunction, or null if the given UnaryFunction is null