Coverage Report - org.apache.tapestry.util.IdAllocator
 
Classes in this File Line Coverage Branch Coverage Complexity
IdAllocator
82% 
86% 
1.9
 
 1  
 // Copyright 2004, 2005 The Apache Software Foundation
 2  
 //
 3  
 // Licensed under the Apache License, Version 2.0 (the "License");
 4  
 // you may not use this file except in compliance with the License.
 5  
 // You may obtain a copy of the License at
 6  
 //
 7  
 //     http://www.apache.org/licenses/LICENSE-2.0
 8  
 //
 9  
 // Unless required by applicable law or agreed to in writing, software
 10  
 // distributed under the License is distributed on an "AS IS" BASIS,
 11  
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 12  
 // See the License for the specific language governing permissions and
 13  
 // limitations under the License.
 14  
 
 15  
 package org.apache.tapestry.util;
 16  
 
 17  
 import org.apache.hivemind.ApplicationRuntimeException;
 18  
 import org.apache.hivemind.util.Defense;
 19  
 
 20  
 import java.util.HashMap;
 21  
 import java.util.Map;
 22  
 
 23  
 /**
 24  
  * Used to "uniquify" names within a given context. A base name is passed in,
 25  
  * and the return value is the base name, or the base name extended with a
 26  
  * suffix to make it unique.
 27  
  * 
 28  
  * @author Howard Lewis Ship
 29  
  * @since 3.0
 30  
  */
 31  
 
 32  
 public class IdAllocator
 33  
 {
 34  
 
 35  
     private static final String SEPARATOR = "_";
 36  
 
 37  225
     private final Map _generatorMap = new HashMap();
 38  
 
 39  
     private final String _namespace;
 40  
     
 41  
     /** Class used only by IdAllocator. */
 42  
     private class NameGenerator implements Cloneable
 43  
     {
 44  
 
 45  
         private final String _baseId;
 46  
 
 47  
         private int _index;
 48  
 
 49  
         NameGenerator(String baseId)
 50  336
         {
 51  336
             _baseId = baseId + SEPARATOR;
 52  336
         }
 53  
 
 54  
         public String nextId()
 55  
         {
 56  53
             return _baseId + _index++;
 57  
         }
 58  
         
 59  
         public String peekId()
 60  
         {
 61  6
             return _baseId + _index;
 62  
         }
 63  
 
 64  
         /**
 65  
          * {@inheritDoc}
 66  
          */
 67  
         protected Object clone()
 68  
             throws CloneNotSupportedException
 69  
         {
 70  0
             return super.clone();
 71  
         }
 72  
     }
 73  
 
 74  
     public IdAllocator()
 75  
     {
 76  213
         this("");
 77  213
     }
 78  
 
 79  
     public IdAllocator(String namespace)
 80  225
     {
 81  225
         Defense.notNull(namespace, "namespace");
 82  
 
 83  225
         _namespace = namespace;
 84  225
     }
 85  
 
 86  
     /**
 87  
      * Utility for stripping out the standard allocator generated portion of a component id string
 88  
      * in order to get what the most likely original component id was.
 89  
      *
 90  
      * @param input
 91  
      *          The generated component id.
 92  
      * @return The id stripped of any allocated id meta, if any was found.
 93  
      */
 94  
     public static String convertAllocatedComponentId(String input)
 95  
     {
 96  4
         if (input == null)
 97  0
             return null;
 98  
 
 99  4
         int index = input.indexOf(SEPARATOR);
 100  
         
 101  4
         return index > -1 ? input.substring(0, index) : input;
 102  
     }
 103  
 
 104  
     /**
 105  
      * Allocates the id. Repeated calls for the same name will return "name",
 106  
      * "name_0", "name_1", etc.
 107  
      */
 108  
 
 109  
     public String allocateId(String name)
 110  
     {
 111  387
         String key = name + _namespace;
 112  
 
 113  387
         NameGenerator g = (NameGenerator) _generatorMap.get(key.toLowerCase());
 114  387
         String result = null;
 115  
 
 116  387
         if (g == null)
 117  
         {
 118  335
             g = new NameGenerator(key);
 119  335
             result = key;
 120  
         }
 121  
         else 
 122  52
             result = g.nextId();
 123  
 
 124  
         // Handle the degenerate case, where a base name of the form "foo$0" has
 125  
         // been
 126  
         // requested. Skip over any duplicates thus formed.
 127  
 
 128  388
         while(_generatorMap.containsKey(result.toLowerCase()))
 129  1
             result = g.nextId();
 130  
         
 131  387
         _generatorMap.put(result.toLowerCase(), g);
 132  
         
 133  387
         return result;
 134  
     }
 135  
     
 136  
     /**
 137  
      * Should return the exact same thing as {@link #allocateId(String)}, with the difference
 138  
      * that the calculated id is not allocated and stored so multiple calls will always return the 
 139  
      * same thing. 
 140  
      * 
 141  
      * @param name The name to peek at.
 142  
      * @return The next id that will be allocated for the given name.
 143  
      */
 144  
     public String peekNextId(String name)
 145  
     {
 146  7
         String key = name + _namespace;
 147  
 
 148  7
         NameGenerator g = (NameGenerator) _generatorMap.get(key.toLowerCase());
 149  7
         String result = null;
 150  
         
 151  7
         if (g == null)
 152  
         {
 153  1
             g = new NameGenerator(key);
 154  1
             result = key;
 155  
         } else 
 156  6
             result = g.peekId();
 157  
         
 158  
         // Handle the degenerate case, where a base name of the form "foo_0" has
 159  
         // been
 160  
         // requested. Skip over any duplicates thus formed.
 161  
         
 162  
         // in a peek we don't want to actually increment any id state so we must
 163  
         // clone
 164  
         
 165  7
         if (_generatorMap.containsKey(result.toLowerCase())) {
 166  
             
 167  
             try {
 168  0
                 NameGenerator cg = (NameGenerator)g.clone();
 169  
                 
 170  0
                 while (_generatorMap.containsKey(result.toLowerCase()))
 171  0
                     result = cg.nextId();
 172  
                 
 173  0
             } catch (CloneNotSupportedException e) {
 174  0
                 throw new ApplicationRuntimeException(e);
 175  0
             }
 176  
         }
 177  
         
 178  7
         return result;
 179  
     }
 180  
     
 181  
     /**
 182  
      * Clears the allocator, resetting it to freshly allocated state.
 183  
      */
 184  
 
 185  
     public void clear()
 186  
     {
 187  51
         _generatorMap.clear();
 188  51
     }
 189  
 }