CPInstruction xref

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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 java.io.DataOutputStream;
    20  import java.io.IOException;
    21  import org.apache.bcel.classfile.Constant;
    22  import org.apache.bcel.classfile.ConstantClass;
    23  import org.apache.bcel.classfile.ConstantPool;
    24  import org.apache.bcel.util.ByteSequence;
    25
    26  /***
    27   * Abstract super class for instructions that use an index into the
    28   * constant pool such as LDC, INVOKEVIRTUAL, etc.
    29   *
    30   * @see ConstantPoolGen
    31   * @see LDC
    32   * @see INVOKEVIRTUAL
    33   *
    34   * @version $Id: CPInstruction.java 386056 2006-03-15 11:31:56Z tcurdt $
    35   * @author  <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
    36   */
    37  public abstract class CPInstruction extends Instruction implements TypedInstruction,
    38          IndexedInstruction {
    39
    40      protected int index; // index to constant pool
    41
    42
    43      /***
    44       * Empty constructor needed for the Class.newInstance() statement in
    45       * Instruction.readInstruction(). Not to be used otherwise.
    46       */
    47      CPInstruction() {
    48      }
    49
    50
    51      /***
    52       * @param index to constant pool
    53       */
    54      protected CPInstruction(short opcode, int index) {
    55          super(opcode, (short) 3);
    56          setIndex(index);
    57      }
    58
    59
    60      /***
    61       * Dump instruction as byte code to stream out.
    62       * @param out Output stream
    63       */
    64      public void dump( DataOutputStream out ) throws IOException {
    65          out.writeByte(opcode);
    66          out.writeShort(index);
    67      }
    68
    69
    70      /***
    71       * Long output format:
    72       *
    73       * &lt;name of opcode&gt; "["&lt;opcode number&gt;"]"
    74       * "("&lt;length of instruction&gt;")" "&lt;"&lt; constant pool index&gt;"&gt;"
    75       *
    76       * @param verbose long/short format switch
    77       * @return mnemonic for instruction
    78       */
    79      public String toString( boolean verbose ) {
    80          return super.toString(verbose) + " " + index;
    81      }
    82
    83
    84      /***
    85       * @return mnemonic for instruction with symbolic references resolved
    86       */
    87      public String toString( ConstantPool cp ) {
    88          Constant c = cp.getConstant(index);
    89          String str = cp.constantToString(c);
    90          if (c instanceof ConstantClass) {
    91              str = str.replace('.', '/');
    92          }
    93          return org.apache.bcel.Constants.OPCODE_NAMES[opcode] + " " + str;
    94      }
    95
    96
    97      /***
    98       * Read needed data (i.e., index) from file.
    99       * @param bytes input stream
    100      * @param wide wide prefix?
    101      */
    102     protected void initFromFile( ByteSequence bytes, boolean wide ) throws IOException {
    103         setIndex(bytes.readUnsignedShort());
    104         length = 3;
    105     }
    106
    107
    108     /***
    109      * @return index in constant pool referred by this instruction.
    110      */
    111     public final int getIndex() {
    112         return index;
    113     }
    114
    115
    116     /***
    117      * Set the index to constant pool.
    118      * @param index in  constant pool.
    119      */
    120     public void setIndex( int index ) {
    121         if (index < 0) {
    122             throw new ClassGenException("Negative index value: " + index);
    123         }
    124         this.index = index;
    125     }
    126
    127
    128     /*** @return type related with this instruction.
    129      */
    130     public Type getType( ConstantPoolGen cpg ) {
    131         ConstantPool cp = cpg.getConstantPool();
    132         String name = cp.getConstantString(index, org.apache.bcel.Constants.CONSTANT_Class);
    133         if (!name.startsWith("[")) {
    134             name = "L" + name + ";";
    135         }
    136         return Type.getType(name);
    137     }
    138 }