| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 freemarker.template; |
| |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.Map; |
| import java.util.Set; |
| |
| /** |
| * Read-only empty map. {@link #remove(Object)}, {@link #clear()} and |
| * {@link #putAll(Map)} with an empty {@link Map} as parameter are supported |
| * operations (and do nothing) since FreeMarker 2.3.20. |
| * |
| * @deprecated Use {@link Collections#EMPTY_MAP} on J2SE 1.3 or later. |
| */ |
| @Deprecated |
| public class EmptyMap implements Map, Cloneable { |
| public static final EmptyMap instance = new EmptyMap(); |
| |
| @Override |
| public void clear() { |
| // no op |
| } |
| |
| @Override |
| public boolean containsKey(Object arg0) { |
| return false; |
| } |
| |
| @Override |
| public boolean containsValue(Object arg0) { |
| return false; |
| } |
| |
| @Override |
| public Set entrySet() { |
| return Collections.EMPTY_SET; |
| } |
| |
| @Override |
| public Object get(Object arg0) { |
| return null; |
| } |
| |
| @Override |
| public boolean isEmpty() { |
| return true; |
| } |
| |
| @Override |
| public Set keySet() { |
| return Collections.EMPTY_SET; |
| } |
| |
| @Override |
| public Object put(Object arg0, Object arg1) { |
| throw new UnsupportedOperationException("This Map is read-only."); |
| } |
| |
| @Override |
| public void putAll(Map arg0) { |
| // Checking for arg0.isEmpty() wouldn't reflect precisely how putAll in |
| // AbstractMap works. |
| if (arg0.entrySet().iterator().hasNext()) { |
| throw new UnsupportedOperationException("This Map is read-only."); |
| } |
| } |
| |
| @Override |
| public Object remove(Object arg0) { |
| return null; |
| } |
| |
| @Override |
| public int size() { |
| return 0; |
| } |
| |
| @Override |
| public Collection values() { |
| return Collections.EMPTY_LIST; |
| } |
| |
| } |