/*
* ModeShape (http://www.modeshape.org)
*
* 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.modeshape.common.collection;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/**
* A set of utilities for more easily creating various kinds of collections.
*/
public class Collections {
@SafeVarargs
public static <T> Set<T> unmodifiableSet(T... values ) {
return unmodifiableSet(Arrays.asList(values));
}
public static <T> Set<T> unmodifiableSet( Collection<T> values ) {
return java.util.Collections.unmodifiableSet(new HashSet<>(values));
}
public static <T> Set<T> unmodifiableSet( Set<T> values ) {
return java.util.Collections.unmodifiableSet(values);
}
private Collections() {
}
/**
* Concatenate two Iterable sources
*
* @param a a non-null Iterable value
* @param b a non-null Iterable value
* @return an Iterable that will iterate through all the values from 'a' and then all the values from 'b'
* @param <T> the value type
*/
public static <T> Iterable<T> concat( final Iterable<T> a,
final Iterable<T> b ) {
assert (a != null);
assert (b != null);
return () -> Collections.concat(a.iterator(), b.iterator());
}
/**
* Concatenate two Iterators
*
* @param a a non-null Iterator
* @param b a non-null Iterator
* @return an Iterator that will iterate through all the values of 'a', and then all the values of 'b'
* @param <T> the value type
*/
public static <T> Iterator<T> concat( final Iterator<T> a,
final Iterator<T> b ) {
assert (a != null);
assert (b != null);
return new Iterator<T>() {
@Override
public boolean hasNext() {
return a.hasNext() || b.hasNext();
}
@Override
public T next() {
if (a.hasNext()) {
return a.next();
}
return b.next();
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
};
}
}