ExceptionHandlers


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  }
75
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