| /** |
| * Copyright 2012, Big Switch Networks, Inc. |
| * Originally created by David Erickson, Stanford University |
| * |
| * 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 net.floodlightcontroller.util; |
| |
| import java.util.Iterator; |
| import java.util.NoSuchElementException; |
| |
| /** |
| * An iterator that will filter values from an iterator and return only |
| * those values that match the predicate. |
| */ |
| public abstract class FilterIterator<T> implements Iterator<T> { |
| protected Iterator<T> subIterator; |
| protected T next; |
| |
| /** |
| * Construct a filter iterator from the given sub iterator |
| * @param subIterator the sub iterator over which we'll filter |
| */ |
| public FilterIterator(Iterator<T> subIterator) { |
| super(); |
| this.subIterator = subIterator; |
| } |
| |
| /** |
| * Check whether the given value should be returned by the |
| * filter |
| * @param value the value to check |
| * @return true if the value should be included |
| */ |
| protected abstract boolean matches(T value); |
| |
| // *********** |
| // Iterator<T> |
| // *********** |
| |
| @Override |
| public boolean hasNext() { |
| if (next != null) return true; |
| |
| while (subIterator.hasNext()) { |
| next = subIterator.next(); |
| if (matches(next)) |
| return true; |
| } |
| next = null; |
| return false; |
| } |
| |
| @Override |
| public T next() { |
| if (hasNext()) { |
| T cur = next; |
| next = null; |
| return cur; |
| } |
| throw new NoSuchElementException(); |
| } |
| |
| @Override |
| public void remove() { |
| throw new UnsupportedOperationException(); |
| } |
| |
| } |