| /* |
| * Copyright 2000-2012 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.Collections; |
| import java.util.Iterator; |
| |
| /** |
| * @author peter |
| */ |
| public abstract class FlatteningIterator<Group, Value> implements Iterator<Value> { |
| private final Iterator<Group> valuesIterator; |
| private Iterator<Value> groupIterator; |
| private Boolean hasNextCache; |
| |
| public FlatteningIterator(Iterator<Group> groups) { |
| valuesIterator = groups; |
| groupIterator = Collections.<Value>emptyList().iterator(); |
| } |
| |
| @Override |
| public boolean hasNext() { |
| if (hasNextCache != null) { |
| return hasNextCache.booleanValue(); |
| } |
| |
| while (!groupIterator.hasNext() && valuesIterator.hasNext()) { |
| groupIterator = createValueIterator(valuesIterator.next()); |
| } |
| return hasNextCache = groupIterator.hasNext(); |
| } |
| |
| protected abstract Iterator<Value> createValueIterator(Group group); |
| |
| @Override |
| public Value next() { |
| if (!hasNext()) { |
| throw new AssertionError(); |
| } |
| hasNextCache = null; |
| return groupIterator.next(); |
| } |
| |
| @Override |
| public void remove() { |
| throw new UnsupportedOperationException(); |
| } |
| } |