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1   /*
2    * Copyright  2000-2004 The Apache Software Foundation
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 org.apache.bcel.verifier.structurals;
18  
19  
20  import java.util.HashSet;
21  import java.util.Hashtable;
22  import java.util.Set;
23  import org.apache.bcel.generic.CodeExceptionGen;
24  import org.apache.bcel.generic.InstructionHandle;
25  import org.apache.bcel.generic.MethodGen;
26  
27  /***
28   * This class allows easy access to ExceptionHandler objects.
29   *
30   * @version $Id: ExceptionHandlers.java 386056 2006-03-15 11:31:56Z tcurdt $
31   * @author Enver Haase
32   */
33  public class ExceptionHandlers{
34  	/***
35  	 * The ExceptionHandler instances.
36  	 * Key: InstructionHandle objects, Values: HashSet<ExceptionHandler> instances.
37  	 */
38  	private Hashtable exceptionhandlers;
39  	 
40  	/***
41  	 * Constructor. Creates a new ExceptionHandlers instance.
42  	 */
43  	public ExceptionHandlers(MethodGen mg){
44  		exceptionhandlers = new Hashtable();
45  		CodeExceptionGen[] cegs = mg.getExceptionHandlers();
46  		for (int i=0; i<cegs.length; i++){
47  			ExceptionHandler eh = new ExceptionHandler(cegs[i].getCatchType(), cegs[i].getHandlerPC());
48  			for (InstructionHandle ih=cegs[i].getStartPC(); ih != cegs[i].getEndPC().getNext(); ih=ih.getNext()){
49  				Set hs;
50  				hs = (Set) exceptionhandlers.get(ih);
51  				if (hs == null){
52  					hs = new HashSet();
53  					exceptionhandlers.put(ih, hs);
54  				}
55  				hs.add(eh);
56  			}
57  		}
58  	}
59  	
60  	/***
61  	 * Returns all the ExceptionHandler instances representing exception
62  	 * handlers that protect the instruction ih.
63  	 */
64  	public ExceptionHandler[] getExceptionHandlers(InstructionHandle ih){
65  		Set hs = (Set) exceptionhandlers.get(ih);
66  		if (hs == null) {
67              return new ExceptionHandler[0];
68          } else{
69  			ExceptionHandler[] ret = new ExceptionHandler[hs.size()];
70  			return (ExceptionHandler[]) (hs.toArray(ret));
71  		}
72  	}
73  
74  }