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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.generic;
    18
    19  import org.apache.bcel.ExceptionConstants;
    20
    21  /***
    22   * CHECKCAST - Check whether object is of given type
    23   * <PRE>Stack: ..., objectref -&gt; ..., objectref</PRE>
    24   *
    25   * @version $Id: CHECKCAST.java 386056 2006-03-15 11:31:56Z tcurdt $
    26   * @author  <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
    27   */
    28  public class CHECKCAST extends CPInstruction implements LoadClass, ExceptionThrower, StackProducer,
    29          StackConsumer {
    30
    31      /***
    32       * Empty constructor needed for the Class.newInstance() statement in
    33       * Instruction.readInstruction(). Not to be used otherwise.
    34       */
    35      CHECKCAST() {
    36      }
    37
    38
    39      /*** Check whether object is of given type
    40       * @param index index to class in constant pool
    41       */
    42      public CHECKCAST(int index) {
    43          super(org.apache.bcel.Constants.CHECKCAST, index);
    44      }
    45
    46
    47      /*** @return exceptions this instruction may cause
    48       */
    49      public Class[] getExceptions() {
    50          Class[] cs = new Class[1 + ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length];
    51          System.arraycopy(ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION, 0, cs, 0,
    52                  ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length);
    53          cs[ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length] = ExceptionConstants.CLASS_CAST_EXCEPTION;
    54          return cs;
    55      }
    56
    57
    58      public ObjectType getLoadClassType( ConstantPoolGen cpg ) {
    59          Type t = getType(cpg);
    60          if (t instanceof ArrayType) {
    61              t = ((ArrayType) t).getBasicType();
    62          }
    63          return (t instanceof ObjectType) ? (ObjectType) t : null;
    64      }
    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  }