/*
* Copyright 2003-2011 JetBrains s.r.o.
*
* 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 jetbrains.mps.util.iterable;
import org.jetbrains.annotations.NotNull;
import java.util.Iterator;
/**
* XXX what's the benefit having distinct MergeIterator when there's FlattenIterable (@see IterableUtul#merge())?
* Evgeny Gryaznov, 9/13/11
*/
public class MergeIterator<T> implements Iterable<T>, Iterator<T> {
private final Iterable<T> myFirst, mySecond;
private boolean firstHasNext;
private Iterator<T> myIt1, myIt2;
public MergeIterator(@NotNull Iterable<T> it1, @NotNull Iterable<T> it2) {
myFirst = it1;
mySecond = it2;
}
@Override
public Iterator<T> iterator() {
myIt1 = myFirst.iterator();
myIt2 = mySecond.iterator();
firstHasNext = myIt1.hasNext();
return this;
}
@Override
public boolean hasNext() {
if (!firstHasNext) return myIt2.hasNext();
firstHasNext = myIt1.hasNext();
return firstHasNext || myIt2.hasNext();
}
@Override
public T next() {
return firstHasNext ? myIt1.next() : myIt2.next();
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
}