- /*
- * Copyright 2001-2004 The Apache Software Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- package org.apache.commons.collections.functors;
-
- import java.io.Serializable;
- import java.util.Collection;
- import java.util.Iterator;
-
- import org.apache.commons.collections.Transformer;
-
- /**
- * Transformer implementation that chains the specified transformers together.
- * <p>
- * The input object is passed to the first transformer. The transformed result
- * is passed to the second transformer and so on.
- *
- * @since Commons Collections 3.0
- * @version $Revision: 1.7 $ $Date: 2004/05/16 11:36:31 $
- *
- * @author Stephen Colebourne
- */
- public class ChainedTransformer implements Transformer, Serializable {
-
- /** Serial version UID */
- static final long serialVersionUID = 3514945074733160196L;
-
- /** The transformers to call in turn */
- private final Transformer[] iTransformers;
-
- /**
- * Factory method that performs validation and copies the parameter array.
- *
- * @param transformers the transformers to chain, copied, no nulls
- * @return the <code>chained</code> transformer
- * @throws IllegalArgumentException if the transformers array is null
- * @throws IllegalArgumentException if any transformer in the array is null
- */
- public static Transformer getInstance(Transformer[] transformers) {
- FunctorUtils.validate(transformers);
- if (transformers.length == 0) {
- return NOPTransformer.INSTANCE;
- }
- transformers = FunctorUtils.copy(transformers);
- return new ChainedTransformer(transformers);
- }
-
- /**
- * Create a new Transformer that calls each transformer in turn, passing the
- * result into the next transformer. The ordering is that of the iterator()
- * method on the collection.
- *
- * @param transformers a collection of transformers to chain
- * @return the <code>chained</code> transformer
- * @throws IllegalArgumentException if the transformers collection is null
- * @throws IllegalArgumentException if any transformer in the collection is null
- */
- public static Transformer getInstance(Collection transformers) {
- if (transformers == null) {
- throw new IllegalArgumentException("Transformer collection must not be null");
- }
- if (transformers.size() == 0) {
- return NOPTransformer.INSTANCE;
- }
- // convert to array like this to guarantee iterator() ordering
- Transformer[] cmds = new Transformer[transformers.size()];
- int i = 0;
- for (Iterator it = transformers.iterator(); it.hasNext();) {
- cmds[i++] = (Transformer) it.next();
- }
- FunctorUtils.validate(cmds);
- return new ChainedTransformer(cmds);
- }
-
- /**
- * Factory method that performs validation.
- *
- * @param transformer1 the first transformer, not null
- * @param transformer2 the second transformer, not null
- * @return the <code>chained</code> transformer
- * @throws IllegalArgumentException if either transformer is null
- */
- public static Transformer getInstance(Transformer transformer1, Transformer transformer2) {
- if (transformer1 == null || transformer2 == null) {
- throw new IllegalArgumentException("Transformers must not be null");
- }
- Transformer[] transformers = new Transformer[] { transformer1, transformer2 };
- return new ChainedTransformer(transformers);
- }
-
- /**
- * Constructor that performs no validation.
- * Use <code>getInstance</code> if you want that.
- *
- * @param transformers the transformers to chain, not copied, no nulls
- */
- public ChainedTransformer(Transformer[] transformers) {
- super();
- iTransformers = transformers;
- }
-
- /**
- * Transforms the input to result via each decorated transformer
- *
- * @param object the input object passed to the first transformer
- * @return the transformed result
- */
- public Object transform(Object object) {
- for (int i = 0; i < iTransformers.length; i++) {
- object = iTransformers[i].transform(object);
- }
- return object;
- }
-
- /**
- * Gets the transformers, do not modify the array.
- * @return the transformers
- * @since Commons Collections 3.1
- */
- public Transformer[] getTransformers() {
- return iTransformers;
- }
-
- }