| // Copyright 2004, 2005, 2006, 2010 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.tapestry5.ioc.util; |
| |
| import java.util.HashMap; |
| import java.util.IdentityHashMap; |
| import java.util.List; |
| import java.util.Map; |
| |
| import org.apache.tapestry5.ioc.internal.util.CollectionFactory; |
| import org.apache.tapestry5.ioc.internal.util.InternalUtils; |
| |
| /** |
| * 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. |
| * <p/> |
| * This class is not threadsafe. |
| */ |
| |
| public final class IdAllocator |
| { |
| private static final String SEPARATOR = "_"; |
| |
| /** |
| * Map from allocated id to a generator for names associated with the allocated id. |
| */ |
| private final Map<String, NameGenerator> generatorMap; |
| |
| private final String namespace; |
| |
| /** |
| * Generates unique names with a particular prefix. |
| */ |
| private static class NameGenerator implements Cloneable |
| { |
| private final String baseId; |
| |
| private int index; |
| |
| NameGenerator(String baseId) |
| { |
| this.baseId = baseId + SEPARATOR; |
| } |
| |
| public String nextId() |
| { |
| return baseId + index++; |
| } |
| |
| /** |
| * Clones this instance, returning an equivalent but separate copy. |
| */ |
| @SuppressWarnings( |
| { "CloneDoesntDeclareCloneNotSupportedException" }) |
| @Override |
| public NameGenerator clone() |
| { |
| try |
| { |
| return (NameGenerator) super.clone(); |
| } |
| catch (CloneNotSupportedException ex) |
| { |
| // Unreachable! |
| throw new RuntimeException(ex); |
| } |
| } |
| } |
| |
| /** |
| * Creates a new allocator with no namespace. |
| */ |
| public IdAllocator() |
| { |
| this(""); |
| } |
| |
| /** |
| * Creates a new allocator with the provided namespace. |
| */ |
| public IdAllocator(String namespace) |
| { |
| this(namespace, new HashMap<String, NameGenerator>()); |
| } |
| |
| private IdAllocator(String namespace, Map<String, NameGenerator> generatorMap) |
| { |
| this.namespace = namespace; |
| this.generatorMap = generatorMap; |
| } |
| |
| /** |
| * Returns a list of all allocated ids, sorted alphabetically. |
| */ |
| public List<String> getAllocatedIds() |
| { |
| return InternalUtils.sortedKeys(generatorMap); |
| } |
| |
| /** |
| * Creates a clone of this IdAllocator instance, copying the allocator's namespace and key map. |
| */ |
| @SuppressWarnings( |
| { "CloneDoesntCallSuperClone" }) |
| @Override |
| public IdAllocator clone() |
| { |
| // Copying the generatorMap is tricky; multiple keys will point to the same NameGenerator |
| // instance. We need to clone the NameGenerators, then build a new map around the clones. |
| |
| IdentityHashMap<NameGenerator, NameGenerator> transformMap = new IdentityHashMap<NameGenerator, NameGenerator>(); |
| |
| for (NameGenerator original : generatorMap.values()) |
| { |
| NameGenerator copy = original.clone(); |
| |
| transformMap.put(original, copy); |
| } |
| |
| Map<String, NameGenerator> mapCopy = CollectionFactory.newMap(); |
| |
| for (String key : generatorMap.keySet()) |
| { |
| NameGenerator original = generatorMap.get(key); |
| NameGenerator copy = transformMap.get(original); |
| |
| mapCopy.put(key, copy); |
| } |
| |
| return new IdAllocator(namespace, mapCopy); |
| } |
| |
| /** |
| * Allocates the id. Repeated calls for the same name will return "name", "name_0", "name_1", etc. |
| */ |
| public String allocateId(String name) |
| { |
| String key = name + namespace; |
| |
| NameGenerator g = generatorMap.get(key); |
| String result; |
| |
| if (g == null) |
| { |
| g = new NameGenerator(key); |
| result = key; |
| } |
| 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; |
| } |
| |
| /** |
| * Checks to see if a given name has been allocated. |
| */ |
| public boolean isAllocated(String name) |
| { |
| return generatorMap.containsKey(name); |
| } |
| |
| /** |
| * Clears the allocator, resetting it to freshly allocated state. |
| */ |
| public void clear() |
| { |
| generatorMap.clear(); |
| } |
| } |