1 /*
   2  * reserved comment block
   3  * DO NOT REMOVE OR ALTER!
   4  */
   5 /*
   6  * Licensed to the Apache Software Foundation (ASF) under one or more
   7  * contributor license agreements.  See the NOTICE file distributed with
   8  * this work for additional information regarding copyright ownership.
   9  * The ASF licenses this file to You under the Apache License, Version 2.0
  10  * (the "License"); you may not use this file except in compliance with
  11  * the License.  You may obtain a copy of the License at
  12  *
  13  *      http://www.apache.org/licenses/LICENSE-2.0
  14  *
  15  * Unless required by applicable law or agreed to in writing, software
  16  * distributed under the License is distributed on an "AS IS" BASIS,
  17  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  18  * See the License for the specific language governing permissions and
  19  * limitations under the License.
  20  */
  21 
  22 package com.sun.org.apache.bcel.internal.generic;
  23 
  24 import com.sun.org.apache.bcel.internal.ExceptionConstants;
  25 /**
  26  * CHECKCAST - Check whether object is of given type
  27  * <PRE>Stack: ..., objectref -&gt; ..., objectref</PRE>
  28  *
  29  * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
  30  */
  31 public class CHECKCAST extends CPInstruction
  32   implements LoadClass, ExceptionThrower, StackProducer, StackConsumer {
  33   /**
  34    * Empty constructor needed for the Class.newInstance() statement in
  35    * Instruction.readInstruction(). Not to be used otherwise.
  36    */
  37   CHECKCAST() {}
  38 
  39   /** Check whether object is of given type
  40    * @param n index to class in constant pool
  41    */
  42   public CHECKCAST(int index) {
  43     super(com.sun.org.apache.bcel.internal.Constants.CHECKCAST, index);
  44   }
  45 
  46   /** @return exceptions this instruction may cause
  47    */
  48   public Class[] getExceptions() {
  49     Class[] cs = new Class[1 + ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length];
  50 
  51     System.arraycopy(ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION, 0,
  52                      cs, 0, ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length);
  53     cs[ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length] =
  54       ExceptionConstants.CLASS_CAST_EXCEPTION;
  55     return cs;
  56   }
  57 
  58   public ObjectType getLoadClassType(ConstantPoolGen cpg) {
  59     Type t = getType(cpg);
  60 
  61     if(t instanceof ArrayType)
  62       t = ((ArrayType) t).getBasicType();
  63 
  64     return (t instanceof ObjectType)? (ObjectType) t : null;
  65   }
  66 
  67   /**
  68    * Call corresponding visitor method(s). The order is:
  69    * Call visitor methods of implemented interfaces first, then
  70    * call methods according to the class hierarchy in descending order,
  71    * i.e., the most specific visitXXX() call comes last.
  72    *
  73    * @param v Visitor object
  74    */
  75   public void accept(Visitor v) {
  76     v.visitLoadClass(this);
  77     v.visitExceptionThrower(this);
  78     v.visitStackProducer(this);
  79     v.visitStackConsumer(this);
  80     v.visitTypedInstruction(this);
  81     v.visitCPInstruction(this);
  82     v.visitCHECKCAST(this);
  83   }
  84 }