Package org.apache.commons.functor.core.composite

Class CompositeUnaryFunction<A,​T>

  • Type Parameters:
    A - the argument type.
    T - the returned value type.
    All Implemented Interfaces:
    java.io.Serializable, Functor, UnaryFunction<A,​T>, UnaryFunctor<A>
    public class CompositeUnaryFunction<A,​T>
extends java.lang.Object
implements UnaryFunction<A,​T>, java.io.Serializable
    A UnaryFunction representing the composition of UnaryFunctions, "chaining" the output of one to the input of another. For example, 
    new CompositeUnaryFunction(f).of(g)
    evaluates to f.evaluate(g.evaluate(obj)), and 
    new CompositeUnaryFunction(f).of(g).of(h)
    evaluates to f.evaluate(g.evaluate(h.evaluate(obj))).

    When the collection is empty, this function is an identity function.

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

    Version:
    $Revision$ $Date$
    See Also:
    Serialized Form

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      private static class  CompositeUnaryFunction.Helper<X,​A,​T>
      Encapsulates a double function evaluation.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private UnaryFunction<? super A,​? extends T> function
      The adapted function.
      private static int HASH_SHIFT
      Base hash integer used to shift hash.
      private static long serialVersionUID
      serialVersionUID declaration.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      boolean equals​(java.lang.Object that)
      Indicates whether some other object is "equal to" this functor.
      boolean equals​(CompositeUnaryFunction<?,​?> that)
      Learn whether another CompositeUnaryFunction is equal to this.
      T evaluate​(A obj)
      Evaluate this function.
      int hashCode()
      Returns a hash code for this functor adhering to the general Object.hashCode contract.
      <P> CompositeUnaryFunction<P,​T> of​(UnaryFunction<? super P,​? extends A> preceding)
      Fluently obtain a CompositeUnaryFunction that is "this function" applied to the specified preceding function.
      java.lang.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

    • Field Detail

      • serialVersionUID

        private static final long serialVersionUID
        serialVersionUID declaration.
        See Also:
        Constant Field Values

      • HASH_SHIFT

        private static final int HASH_SHIFT
        Base hash integer used to shift hash.
        See Also:
        Constant Field Values

      • function

        private final UnaryFunction<? super A,​? extends T> function
        The adapted function.

    • Constructor Detail

      • CompositeUnaryFunction

        public CompositeUnaryFunction​(UnaryFunction<? super A,​? extends T> function)
        Create a new CompositeUnaryFunction.
        Parameters:
        function - UnaryFunction to call

      • CompositeUnaryFunction

        private CompositeUnaryFunction​(UnaryFunction<? super X,​? extends T> following,
                               UnaryFunction<? super A,​? extends X> preceding)
        Creates a new CompositeUnaryFunction instance given the input functions.
        Type Parameters:
        X - the argument type.
        Parameters:
        following - The first evaluator function.
        preceding - The last evaluator function.

    • Method Detail

      • evaluate

        public final T evaluate​(A obj)
        Evaluate this function.
        Specified by:
        evaluate in interface UnaryFunction<A,​T>
        Parameters:
        obj - the A object to evaluate
        Returns:
        the T result of this evaluation

      • of

        public final <P> CompositeUnaryFunction<P,​T> of​(UnaryFunction<? super P,​? extends A> preceding)
        Fluently obtain a CompositeUnaryFunction that is "this function" applied to the specified preceding function.
        Type Parameters:
        P - argument type of the resulting function.
        Parameters:
        preceding - UnaryFunction
        Returns:
        CompositeUnaryFunction

      • equals

        public final boolean equals​(java.lang.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 java.lang.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 final boolean equals​(CompositeUnaryFunction<?,​?> that)
        Learn whether another CompositeUnaryFunction is equal to this.
        Parameters:
        that - CompositeUnaryFunction 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 java.lang.Object
        Returns:
        a hash code for this functor
        See Also:
        Functor.equals(java.lang.Object)

      • toString

        public java.lang.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 java.lang.Object
        Returns:
        a human readable description of this functor