org.apache.commons.collections.functors.TransformerPredicate Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.commons.collections.FunctorException;
import org.apache.commons.collections.Predicate;
import org.apache.commons.collections.Transformer;
/**
* Predicate implementation that returns the result of a transformer.
*
* @since Commons Collections 3.0
* @version $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
*
* @author Stephen Colebourne
*/
public final class TransformerPredicate implements Predicate, Serializable {
/** Serial version UID */
private static final long serialVersionUID = -2407966402920578741L;
/** The transformer to call */
private final Transformer iTransformer;
/**
* Factory to create the predicate.
*
* @param transformer the transformer to decorate
* @return the predicate
* @throws IllegalArgumentException if the transformer is null
*/
public static Predicate getInstance(Transformer transformer) {
if (transformer == null) {
throw new IllegalArgumentException("The transformer to call must not be null");
}
return new TransformerPredicate(transformer);
}
/**
* Constructor that performs no validation.
* Use getInstance if you want that.
*
* @param transformer the transformer to decorate
*/
public TransformerPredicate(Transformer transformer) {
super();
iTransformer = transformer;
}
/**
* Evaluates the predicate returning the result of the decorated transformer.
*
* @param object the input object
* @return true if decorated transformer returns Boolean.TRUE
* @throws FunctorException if the transformer returns an invalid type
*/
public boolean evaluate(Object object) {
Object result = iTransformer.transform(object);
if (result instanceof Boolean == false) {
throw new FunctorException(
"Transformer must return an instanceof Boolean, it was a "
+ (result == null ? "null object" : result.getClass().getName()));
}
return ((Boolean) result).booleanValue();
}
/**
* Gets the transformer.
*
* @return the transformer
* @since Commons Collections 3.1
*/
public Transformer getTransformer() {
return iTransformer;
}
}