/*

  * Copyright 2004-2011 the Seasar Foundation and the Others.

  *

  * 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.seasar.teeda.core.util;

 import java.io.IOException;

 import java.util.Collection;

 import java.util.Enumeration;

 import java.util.Iterator;

 import java.util.Map;

 import org.apache.commons.collections.iterators.IteratorChain;

 import org.seasar.framework.exception.IORuntimeException;

 import org.seasar.framework.util.EmptyIterator;

 import org.seasar.framework.util.EnumerationIterator;

 public class IteratorUtil {

     private static final EmptyIterator EMPTY_ITERATOR = new EmptyIterator();

     private IteratorUtil() {

     }

     public static Iterator getIterator(Collection collection) {

         if (collection != null && !collection.isEmpty()) {

             return collection.iterator();

         } else {

             return EMPTY_ITERATOR;

         }

     }

     public static Iterator getEntryIterator(Map map) {

         if (map != null && !map.isEmpty()) {

             return map.entrySet().iterator();

         } else {

             return EMPTY_ITERATOR;

         }

     }

     public static Iterator getCompositeIterator(Map map1, Map map2) {

         IteratorChain chain = new IteratorChain();

         chain.addIterator(map1.keySet().iterator());

         chain.addIterator(map2.keySet().iterator());

         return chain;

     }

     public static Iterator getResourcesIterator(ClassLoader loader, String path) {

         try {

             Enumeration e = loader.getResources(path);

             return new EnumerationIterator(e);

         } catch (IOException e) {

             throw new IORuntimeException(e);

         }

     }

 }