| // Copyright 2004 The Apache Software Foundation |
| // |
| // 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.apache.tapestry.util; |
| |
| import java.util.HashMap; |
| import java.util.Map; |
| |
| /** |
| * Used to "uniquify" names within a given context. A base name |
| * is passed in, and the return value is the base name, or the base name |
| * extended with a suffix to make it unique. |
| * |
| * @author Howard Lewis Ship |
| * @version $Id$ |
| * @since 3.0 |
| * |
| **/ |
| |
| public class IdAllocator |
| { |
| private Map _generatorMap = new HashMap(); |
| |
| private static class NameGenerator |
| { |
| private String _baseId; |
| private int _index; |
| |
| NameGenerator(String baseId) |
| { |
| _baseId = baseId + "$"; |
| } |
| |
| public String nextId() |
| { |
| return _baseId + _index++; |
| } |
| } |
| |
| /** |
| * Allocates the id. Repeated calls for the same name will return |
| * "name", "name_0", "name_1", etc. |
| * |
| **/ |
| |
| public String allocateId(String name) |
| { |
| NameGenerator g = (NameGenerator) _generatorMap.get(name); |
| String result = null; |
| |
| if (g == null) |
| { |
| g = new NameGenerator(name); |
| result = name; |
| } |
| else |
| result = g.nextId(); |
| |
| // Handle the degenerate case, where a base name of the form "foo$0" has been |
| // requested. Skip over any duplicates thus formed. |
| |
| while (_generatorMap.containsKey(result)) |
| result = g.nextId(); |
| |
| _generatorMap.put(result, g); |
| |
| return result; |
| } |
| |
| /** |
| * Clears the allocator, resetting it to freshly allocated state. |
| * |
| **/ |
| |
| public void clear() |
| { |
| _generatorMap.clear(); |
| } |
| } |