org.apache.commons.collections4.functors.FunctorUtils Maven / Gradle / Ivy
Show all versions of commons-collections4 Show documentation
/*
* 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.collections4.functors;
import java.util.Collection;
import org.apache.commons.collections4.Closure;
import org.apache.commons.collections4.Predicate;
import org.apache.commons.collections4.Transformer;
/**
* Internal utilities for functors.
*
* @since 3.0
*/
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 is
* able to be coerced to Predicate without casting issues.
*
* @param predicates the predicates to copy
* @return the cloned predicates
*/
@SuppressWarnings("unchecked")
static Predicate[] copy(final Predicate... predicates) {
if (predicates == null) {
return null;
}
return (Predicate[]) predicates.clone();
}
/**
* A very simple method that coerces Predicate to Predicate.
* Due to the {@link Predicate#evaluate(T)} method, Predicate is
* able to be coerced to Predicate without casting issues.
* This method exists
* simply as centralised documentation and atomic unchecked warning
* suppression.
*
* @param the type of object the returned predicate should "accept"
* @param predicate the predicate to coerce.
* @return the coerced predicate.
*/
@SuppressWarnings("unchecked")
static Predicate coerce(final Predicate predicate) {
return (Predicate) predicate;
}
/**
* Validate the predicates to ensure that all is well.
*
* @param predicates the predicates to validate
*/
static void validate(final Predicate... predicates) {
if (predicates == null) {
throw new NullPointerException("The predicate array must not be null");
}
for (int i = 0; i < predicates.length; i++) {
if (predicates[i] == null) {
throw new NullPointerException(
"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 Predicate[] validate(final Collection> predicates) {
if (predicates == null) {
throw new NullPointerException("The predicate collection must not be null");
}
// convert to array like this to guarantee iterator() ordering
@SuppressWarnings("unchecked") // OK
final Predicate[] preds = new Predicate[predicates.size()];
int i = 0;
for (final Predicate predicate : predicates) {
preds[i] = predicate;
if (preds[i] == null) {
throw new NullPointerException(
"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 Closure[] copy(final Closure... closures) {
if (closures == null) {
return null;
}
return (Closure[]) closures.clone();
}
/**
* Validate the closures to ensure that all is well.
*
* @param closures the closures to validate
*/
static void validate(final Closure... closures) {
if (closures == null) {
throw new NullPointerException("The closure array must not be null");
}
for (int i = 0; i < closures.length; i++) {
if (closures[i] == null) {
throw new NullPointerException(
"The closure array must not contain a null closure, index " + i + " was null");
}
}
}
/**
* A very simple method that coerces Closure to Closure.
* This method exists
* simply as centralised documentation and atomic unchecked warning
* suppression.
*
* @param the type of object the returned closure should "accept"
* @param closure the closure to coerce.
* @return the coerced closure.
*/
@SuppressWarnings("unchecked")
static Closure coerce(final Closure closure) {
return (Closure) closure;
}
/**
* Copy method
*
* @param transformers the transformers to copy
* @return a clone of the transformers
*/
@SuppressWarnings("unchecked")
static Transformer[] copy(final Transformer... transformers) {
if (transformers == null) {
return null;
}
return (Transformer[]) transformers.clone();
}
/**
* Validate method
*
* @param transformers the transformers to validate
*/
static void validate(final Transformer... transformers) {
if (transformers == null) {
throw new NullPointerException("The transformer array must not be null");
}
for (int i = 0; i < transformers.length; i++) {
if (transformers[i] == null) {
throw new NullPointerException(
"The transformer array must not contain a null transformer, index " + i + " was null");
}
}
}
/**
* A very simple method that coerces Transformer to Transformer.
* This method exists
* simply as centralised documentation and atomic unchecked warning
* suppression.
*
* @param the type of object the returned transformer should "accept"
* @param the type of object the returned transformer should "produce"
* @param transformer the transformer to coerce.
* @return the coerced transformer.
*/
@SuppressWarnings("unchecked")
static Transformer coerce(final Transformer transformer) {
return (Transformer) transformer;
}
}