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      1 /*
      2  * Copyright (C) 2009 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package signature.model.impl;
     18 
     19 import java.lang.reflect.InvocationHandler;
     20 import java.lang.reflect.Method;
     21 import java.lang.reflect.Proxy;
     22 import java.util.List;
     23 import java.util.Set;
     24 
     25 import signature.model.IAnnotationField;
     26 import signature.model.IClassDefinition;
     27 import signature.model.IClassReference;
     28 import signature.model.IPackage;
     29 import signature.model.ITypeReference;
     30 import signature.model.ITypeVariableDefinition;
     31 import signature.model.ITypeVariableReference;
     32 import signature.model.Kind;
     33 
     34 /**
     35  *
     36  */
     37 public class Uninitialized {
     38 
     39     private static final Object UNINITIALIZED;
     40 
     41     static {
     42         UNINITIALIZED = Proxy.newProxyInstance(Uninitialized.class
     43                 .getClassLoader(), new Class[] {
     44                 ITypeReference.class, IPackage.class, IClassDefinition.class,
     45                 IClassReference.class, ITypeVariableReference.class,
     46                 ITypeVariableDefinition.class, IAnnotationField.class,
     47                 Set.class, List.class}, new InvocationHandler() {
     48             public Object invoke(Object proxy, Method method, Object[] args)
     49                     throws Throwable {
     50                 if (method.getName().equals("toString")) {
     51                     return "Uninitialized";
     52                 }
     53 
     54                 throw new UnsupportedOperationException();
     55             }
     56         });
     57     }
     58 
     59     @SuppressWarnings("unchecked")
     60     public static <T> T unset() {
     61         return (T) UNINITIALIZED;
     62     }
     63 
     64     public static boolean isInitialized(Object o) {
     65         return o != UNINITIALIZED && o != Kind.UNINITIALIZED;
     66     }
     67 }
     68