| /* |
| * Copyright 2000-2010 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 com.intellij.util.containers; |
| |
| import java.util.Iterator; |
| |
| // only for those who cannot return null |
| public class CacheOneStepIterator<T> implements Iterator<T> { |
| private final Iterator<T> myProbableIterator; |
| private T myPreCalculated; |
| |
| public CacheOneStepIterator(final Iterator<T> probableIterator) { |
| myProbableIterator = probableIterator; |
| step(); |
| } |
| |
| private void step() { |
| if (! myProbableIterator.hasNext()) { |
| myPreCalculated = null; |
| } else { |
| myPreCalculated = myProbableIterator.next(); |
| } |
| } |
| |
| @Override |
| public boolean hasNext() { |
| return myPreCalculated != null; |
| } |
| |
| @Override |
| public T next() { |
| final T result = myPreCalculated; |
| step(); |
| return result; |
| } |
| |
| @Override |
| public void remove() { |
| throw new UnsupportedOperationException(); |
| } |
| } |