org.jboss.weld.util.collections.Iterables Maven / Gradle / Ivy
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* JBoss, Home of Professional Open Source
* Copyright 2014, Red Hat, Inc., and individual contributors
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* 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.jboss.weld.util.collections;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import org.jboss.weld.util.Function;
/**
* Static utility methods for {@link Iterable}.
*
* @author Martin Kouba
*/
public final class Iterables {
private Iterables() {
}
/**
* Add all elements in the iterable to the collection.
*
* @param target
* @param iterable
* @return true if the target was modified, false otherwise
*/
public static boolean addAll(Collection target, Iterable iterable) {
if (iterable instanceof Collection) {
return target.addAll((Collection) iterable);
}
return Iterators.addAll(target, iterable.iterator());
}
/**
* @param iterable
* @return
* @see WeldCollections#toMultiRowString(java.util.Collection)
*/
public static String toMultiRowString(Iterable iterable) {
StringBuilder builder = new StringBuilder("\n - ");
for (Iterator iterator = iterable.iterator(); iterator.hasNext(); ) {
T element = iterator.next();
builder.append(element);
if (iterator.hasNext()) {
builder.append(",\n - ");
}
}
return builder.toString();
}
public static Iterable flatMap(Iterable iterable, Function> function) {
return concat(transform(iterable, function));
}
/**
* Combine the iterables into a single one.
*
* @param iterables
* @return a single combined iterable
*/
public static Iterable concat(final Iterable> iterables) {
return new Iterable() {
@Override
public Iterator iterator() {
return Iterators.concat(iterators(iterables));
}
};
}
/**
* Combine the iterables into a single one.
*/
public static Iterable concat(Iterable a, Iterable b) {
return concat(Arrays.asList(a, b));
}
/**
* @param iterables
* @return an iterator over iterators from the given iterable of iterables
*/
public static Iterator> iterators(Iterable> iterables) {
return Iterators.transform(iterables.iterator(), new Function, Iterator>() {
@Override
public Iterator apply(Iterable ts) {
return ts.iterator();
}
});
}
public static Iterable transform(final Iterable iterable, final Function function) {
return new Iterable() {
@Override
public Iterator iterator() {
return new Iterators.TransformingIterator(iterable.iterator(), function);
}
};
}
}