net.sf.jga.fn.adaptor
Class ComposeUnary<T,F1,F2,R>

java.lang.Object
  net.sf.jga.fn.Functor<R>
      net.sf.jga.fn.UnaryFunctor<T,R>
          net.sf.jga.fn.adaptor.ComposeUnary<T,F1,F2,R>

All Implemented Interfaces:

java.io.Serializable, Visitable

public class ComposeUnary<T,F1,F2,R>
extends UnaryFunctor<T,R>

Unary Functor that passes the results of two Unary Functors as the arguments to a Binary Functor. This allows for the construction of compound functors from the primitives found in the arithmetic, logical, property, and comparison packages.

For example: LogicalAnd is of limited utility since it takes only Boolean arguments. To use LogicalAnd for something a little more interesting (eg, is the given integer between 1 and 10), combine LogicalAnd with GreaterEqual and LessEqual using Binary Compose and Bind1st as follows:

 new ComposeUnary<Integer,Boolean,Boolean,Boolean> (
     new Bind1st<Integer,Integer,Boolean> (1, new LessEqual<Integer>()),
     new Bind1st<Integer,Integer,Boolean> (10, new GreaterEqual<Integer>()),
     new LogicalAnd());
 

While it may not be the most readable construction in the world, it does become easier over time.

Copyright © 2002-2005 David A. Hall

Author:

David A. Hall

See Also:

Serialized Form

Nested Class Summary

static interface

ComposeUnary.Visitor Interface for classes that may interpret a ComposeUnary functor.

Constructor Summary

ComposeUnary(UnaryFunctor<T,F1> f, UnaryFunctor<T,F2> g, BinaryFunctor<F1,F2,R> h)
Builds a ComposeUnary functor, given two inner functors f and g, and outer functor h.

Method Summary

void	accept(Visitor v) Calls the Visitor's visit(ComposeUnary) method, if it implements the nested Visitor interface.
R	fn(T x) Given argument x, passes x to both inner functors, and passes the results of those functors to the outer functor.
UnaryFunctor<T,F1>	getFirstInnerFunctor() Returns the first of two inner functors
BinaryFunctor<F1,F2,R>	getOuterFunctor() Returns the outer functor
UnaryFunctor<T,F2>	getSecondInnerFunctor() Returns the second of two inner functors
java.lang.String	toString()

Methods inherited from class net.sf.jga.fn.UnaryFunctor

bind, bind0th, bindNth, compose, compose, compose, composeNth, composeNth, eval, generate, generateNth

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ComposeUnary

public ComposeUnary(UnaryFunctor<T,F1> f,
                    UnaryFunctor<T,F2> g,
                    BinaryFunctor<F1,F2,R> h)

Builds a ComposeUnary functor, given two inner functors f and g, and outer functor h.

Throws:

java.lang.IllegalArgumentException - if any of the functors is missing

Method Detail

getFirstInnerFunctor

public UnaryFunctor<T,F1> getFirstInnerFunctor()

Returns the first of two inner functors

Returns:

the first of two inner functors

getSecondInnerFunctor

public UnaryFunctor<T,F2> getSecondInnerFunctor()

Returns the second of two inner functors

Returns:

the second of two inner functors

getOuterFunctor

public BinaryFunctor<F1,F2,R> getOuterFunctor()

Returns the outer functor

Returns:

the outer functor

fn

public R fn(T x)

Given argument x, passes x to both inner functors, and passes the results of those functors to the outer functor.

Specified by:

fn in class UnaryFunctor<T,R>

Returns:

h(f(x), g(x))

accept

public void accept(Visitor v)

Calls the Visitor's visit(ComposeUnary) method, if it implements the nested Visitor interface.

Specified by:

accept in interface Visitable

Overrides:

accept in class Functor<R>

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object