com.phoenixst.collections.TransformerChain.java Source code

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Here is the source code for com.phoenixst.collections.TransformerChain.java

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/*
 *  $Id: TransformerChain.java,v 1.4 2006/06/07 19:14:57 rconner Exp $
 *
 *  Copyright (C) 1994-2006 by Phoenix Software Technologists,
 *  Inc. and others.  All rights reserved.
 *
 *  THIS PROGRAM AND DOCUMENTATION IS PROVIDED UNDER THE TERMS OF THE
 *  COMMON PUBLIC LICENSE ("AGREEMENT") WHICH ACCOMPANIES IT.  ANY
 *  USE, REPRODUCTION OR DISTRIBUTION OF THE PROGRAM CONSTITUTES
 *  RECIPIENT'S ACCEPTANCE OF THE AGREEMENT.
 *
 *  The license text can also be found at
 *    http://opensource.org/licenses/cpl.php
 */

package com.phoenixst.collections;

import java.io.*;
import java.util.*;

import org.apache.commons.collections.Transformer;

/**
 *  A chain of <code>Transformers</code>.
 *
 *  @version    $Revision: 1.4 $
 *  @author     Ray A. Conner
 *
 *  @since      1.0
 */
public class TransformerChain implements Transformer, Serializable {

    private static final long serialVersionUID = 1L;

    /**
     *  The array of <code>Transformers</code>.
     *
     *  @serial
     */
    private final Transformer[] transformerArray;

    ////////////////////////////////////////
    // Constructors
    ////////////////////////////////////////

    /**
     *  Creates a new <code>TransformerChain</code>.
     */
    public TransformerChain(Transformer[] transformers) {
        super();
        transformerArray = transformers.clone();
        if (containsNull(transformerArray)) {
            throw new IllegalArgumentException("Transformer array has a null element.");
        }
    }

    /**
     *  Creates a new <code>TransformerChain</code>.
     */
    public TransformerChain(Collection transformers) {
        super();
        Transformer[] temp = new Transformer[transformers.size()];
        transformerArray = (Transformer[]) transformers.toArray(temp);
        if (containsNull(transformerArray)) {
            throw new IllegalArgumentException("Collection argument has a null element.");
        }
    }

    /**
     *  Creates a new <code>TransformerChain</code>.
     */
    public TransformerChain(Transformer first, Transformer second) {
        super();
        transformerArray = new Transformer[] { first, second };
        if (first == null) {
            throw new IllegalArgumentException("First Transformer is null.");
        }
        if (second == null) {
            throw new IllegalArgumentException("Second Transformer is null.");
        }
    }

    ////////////////////////////////////////
    // Serialization and construction assistance methods
    ////////////////////////////////////////

    private static boolean containsNull(Object[] array) {
        for (int i = array.length - 1; i >= 0; i--) {
            if (array[i] == null) {
                return true;
            }
        }
        return false;
    }

    private void readObject(ObjectInputStream in) throws ClassNotFoundException, IOException {
        in.defaultReadObject();
        if (transformerArray == null) {
            throw new InvalidObjectException("Transformer array is null.");
        }
        if (containsNull(transformerArray)) {
            throw new InvalidObjectException("Transformer array has a null element.");
        }
    }

    ////////////////////////////////////////
    // Transformer
    ////////////////////////////////////////

    public Object transform(Object object) {
        Object result = object;
        for (int i = 0; i < transformerArray.length; i++) {
            result = transformerArray[i].transform(result);
        }
        return result;
    }

    ////////////////////////////////////////
    // Other methods
    ////////////////////////////////////////

    /**
     *  Returns an unmodifiable <code>List</code> of the argument
     *  <code>Transformers</code> being used by this
     *  <code>TransformerChain</code>.
     */
    public List getOperands() {
        return Collections.unmodifiableList(Arrays.asList(transformerArray));
    }

    public String toString() {
        StringBuilder s = new StringBuilder(getClass().getSimpleName());
        s.append(Arrays.toString(transformerArray));
        return s.toString();
    }

}