/*
* 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.collections15.functors;
import java.util.Collection;
import org.apache.commons.collections15.Closure;
import org.apache.commons.collections15.Predicate;
import org.apache.commons.collections15.Transformer;
import org.apache.commons.collections15.util.CloneUtil;
/**
* Internal utilities for functors.
*
* @since Commons Collections 3.0
* @version $Revision$ $Date$
*
* @author Stephen Colebourne
* @author Matt Benson
*/
class FunctorUtils {
/**
* Restricted constructor.
*/
private FunctorUtils() {
super();
}
/**
* Clone the predicates to ensure that the internal reference can't be
* messed with. Due to the {@link Predicate#evaluate(T)} method, Predicate<?
* super T> is able to be coerced to Predicate<T> without casting issues.
*
* @param predicates
* the predicates to copy
* @return the cloned predicates
*/
@SuppressWarnings("unchecked")
static <T> Predicate<T>[] copy(Predicate<? super T>[] predicates) {
if (predicates == null) {
return null;
}
try {
return (Predicate<T>[]) CloneUtil.clone(predicates);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
/**
* A very simple method that coerces Predicate<? super T> to Predicate<T>.
* Due to the {@link Predicate#evaluate(T)} method, Predicate<? super T> is
* able to be coerced to Predicate<T> without casting issues.
* <p>
* This method exists simply as centralised documentation and atomic
* unchecked warning suppression.
*
* @param <T>
* the type of object the returned predicate should "accept"
* @param predicate
* the predicate to coerce.
* @return the coerced predicate.
*/
@SuppressWarnings("unchecked")
static <T> Predicate<T> coerce(Predicate<? super T> predicate) {
return (Predicate<T>) predicate;
}
/**
* Validate the predicates to ensure that all is well.
*
* @param predicates
* the predicates to validate
*/
static void validate(Predicate<?>[] predicates) {
if (predicates == null) {
throw new IllegalArgumentException(
"The predicate array must not be null");
}
for (int i = 0; i < predicates.length; i++) {
if (predicates[i] == null) {
throw new IllegalArgumentException(
"The predicate array must not contain a null predicate, index "
+ i + " was null");
}
}
}
/**
* Validate the predicates to ensure that all is well.
*
* @param predicates
* the predicates to validate
* @return predicate array
*/
static <T> Predicate<T>[] validate(
Collection<? extends Predicate<T>> predicates) {
if (predicates == null) {
throw new IllegalArgumentException(
"The predicate collection must not be null");
}
// convert to array like this to guarantee iterator() ordering
@SuppressWarnings("unchecked") // OK
Predicate<T>[] preds = new Predicate[predicates.size()];
int i = 0;
for (Predicate<T> predicate : predicates) {
preds[i] = predicate;
if (preds[i] == null) {
throw new IllegalArgumentException(
"The predicate collection must not contain a null predicate, index "
+ i + " was null");
}
i++;
}
return preds;
}
/**
* Clone the closures to ensure that the internal reference can't be messed
* with.
*
* @param closures
* the closures to copy
* @return the cloned closures
*/
@SuppressWarnings("unchecked")
static <E> Closure<E>[] copy(Closure<? super E>[] closures) {
if (closures == null) {
return null;
}
try {
return (Closure<E>[]) CloneUtil.clone(closures);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
/**
* Validate the closures to ensure that all is well.
*
* @param closures
* the closures to validate
*/
static void validate(Closure<?>[] closures) {
if (closures == null) {
throw new IllegalArgumentException(
"The closure array must not be null");
}
for (int i = 0; i < closures.length; i++) {
if (closures[i] == null) {
throw new IllegalArgumentException(
"The closure array must not contain a null closure, index "
+ i + " was null");
}
}
}
/**
* A very simple method that coerces Closure<? super T> to Closure<T>.
* <p>
* This method exists simply as centralised documentation and atomic
* unchecked warning suppression.
*
* @param <T>
* the type of object the returned closure should "accept"
* @param closure
* the closure to coerce.
* @return the coerced closure.
*/
@SuppressWarnings("unchecked")
static <T> Closure<T> coerce(Closure<? super T> closure) {
return (Closure<T>) closure;
}
/**
* Copy method
*
* @param transformers
* the transformers to copy
* @return a clone of the transformers
*/
@SuppressWarnings("unchecked")
static <I, O> Transformer<I, O>[] copy(
Transformer<? super I, ? extends O>[] transformers) {
if (transformers == null) {
return null;
}
try {
return (Transformer<I, O>[]) CloneUtil.clone(transformers);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
/**
* Validate method
*
* @param transformers
* the transformers to validate
*/
static void validate(Transformer<?, ?>[] transformers) {
if (transformers == null) {
throw new IllegalArgumentException(
"The transformer array must not be null");
}
for (int i = 0; i < transformers.length; i++) {
if (transformers[i] == null) {
throw new IllegalArgumentException(
"The transformer array must not contain a null transformer, index "
+ i + " was null");
}
}
}
/**
* A very simple method that coerces Transformer<? super I, ? extends O> to
* Transformer<I, O>.
* <p>
* This method exists simply as centralised documentation and atomic
* unchecked warning suppression.
*
* @param <T>
* the type of object the returned transformer should "accept"
* @param transformer
* the transformer to coerce.
* @return the coerced transformer.
*/
@SuppressWarnings("unchecked")
static <I, O> Transformer<I, O> coerce(
Transformer<? super I, ? extends O> transformer) {
return (Transformer<I, O>) transformer;
}
}