1. package com.sun.org.apache.bcel.internal.generic;

  2. 

  3. /* ====================================================================

  4.  * The Apache Software License, Version 1.1

  5.  *

  6.  * Copyright (c) 2001 The Apache Software Foundation.  All rights

  7.  * reserved.

  8.  *

  9.  * Redistribution and use in source and binary forms, with or without

  10.  * modification, are permitted provided that the following conditions

  11.  * are met:

  12.  *

  13.  * 1. Redistributions of source code must retain the above copyright

  14.  *    notice, this list of conditions and the following disclaimer.

  15.  *

  16.  * 2. Redistributions in binary form must reproduce the above copyright

  17.  *    notice, this list of conditions and the following disclaimer in

  18.  *    the documentation and/or other materials provided with the

  19.  *    distribution.

  20.  *

  21.  * 3. The end-user documentation included with the redistribution,

  22.  *    if any, must include the following acknowledgment:

  23.  *       "This product includes software developed by the

  24.  *        Apache Software Foundation (http://www.apache.org/)."

  25.  *    Alternately, this acknowledgment may appear in the software itself,

  26.  *    if and wherever such third-party acknowledgments normally appear.

  27.  *

  28.  * 4. The names "Apache" and "Apache Software Foundation" and

  29.  *    "Apache BCEL" must not be used to endorse or promote products

  30.  *    derived from this software without prior written permission. For

  31.  *    written permission, please contact apache@apache.org.

  32.  *

  33.  * 5. Products derived from this software may not be called "Apache",

  34.  *    "Apache BCEL", nor may "Apache" appear in their name, without

  35.  *    prior written permission of the Apache Software Foundation.

  36.  *

  37.  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED

  38.  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

  39.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

  40.  * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR

  41.  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

  42.  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

  43.  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

  44.  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

  45.  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,

  46.  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT

  47.  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

  48.  * SUCH DAMAGE.

  49.  * ====================================================================

  50.  *

  51.  * This software consists of voluntary contributions made by many

  52.  * individuals on behalf of the Apache Software Foundation.  For more

  53.  * information on the Apache Software Foundation, please see

  54.  * <http://www.apache.org/>.

  55.  */

  56. import java.io.*;

  57. import com.sun.org.apache.bcel.internal.util.ByteSequence;

  58. import com.sun.org.apache.bcel.internal.classfile.Utility;

  59. import com.sun.org.apache.bcel.internal.Constants;

  60. 

  61. /**

  62.  * Abstract super class for instructions dealing with local variables.

  63.  *

  64.  * @version $Id: LocalVariableInstruction.java,v 1.1.1.1 2001/10/29 20:00:23 jvanzyl Exp $

  65.  * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>

  66.  */

  67. public abstract class LocalVariableInstruction extends Instruction

  68.   implements TypedInstruction, IndexedInstruction {

  69.   protected int     n         = -1; // index of referenced variable

  70.   private short     c_tag     = -1; // compact version, such as ILOAD_0

  71.   private short     canon_tag = -1; // canonical tag such as ILOAD

  72. 

  73.   private final boolean wide() { return n > Constants.MAX_BYTE; }

  74. 

  75.   /**

  76.    * Empty constructor needed for the Class.newInstance() statement in

  77.    * Instruction.readInstruction(). Not to be used otherwise.

  78.    * tag and length are defined in readInstruction and initFromFile, respectively.

  79.    */

  80.   LocalVariableInstruction(short canon_tag, short c_tag) {

  81.     super();

  82.     this.canon_tag = canon_tag;

  83.     this.c_tag     = c_tag;

  84.   }

  85. 

  86.   /**

  87.    * Empty constructor needed for the Class.newInstance() statement in

  88.    * Instruction.readInstruction(). Also used by IINC()!

  89.    */

  90.   LocalVariableInstruction() {

  91.   }

  92. 

  93.   /**

  94.    * @param opcode Instruction opcode

  95.    * @param c_tag Instruction number for compact version, ALOAD_0, e.g.

  96.    * @param n local variable index (unsigned short)

  97.    */

  98.   protected LocalVariableInstruction(short opcode, short c_tag, int n) {

  99.     super(opcode, (short)2);

  100. 

  101.     this.c_tag = c_tag;

  102.     canon_tag  = opcode;

  103. 

  104.     setIndex(n);

  105.   }

  106. 

  107.   /**

  108.    * Dump instruction as byte code to stream out.

  109.    * @param out Output stream

  110.    */

  111.   public void dump(DataOutputStream out) throws IOException {

  112.     if(wide()) // Need WIDE prefix ?

  113.       out.writeByte(Constants.WIDE);

  114. 

  115.     out.writeByte(opcode);

  116. 

  117.     if(length > 1) { // Otherwise ILOAD_n, instruction, e.g.

  118.       if(wide())

  119. 	out.writeShort(n);

  120.       else

  121. 	out.writeByte(n);

  122.     }

  123.   }

  124. 

  125.   /**

  126.    * Long output format:

  127.    *

  128.    * <name of opcode> "["<opcode number>"]" 

  129.    * "("<length of instruction>")" "<"< local variable index>">"

  130.    *

  131.    * @param verbose long/short format switch

  132.    * @return mnemonic for instruction

  133.    */

  134.   public String toString(boolean verbose) {

  135.     if(((opcode >= Constants.ILOAD_0) &&

  136. 	(opcode <= Constants.ALOAD_3)) ||

  137.        ((opcode >= Constants.ISTORE_0) &&

  138. 	(opcode <= Constants.ASTORE_3)))

  139.       return super.toString(verbose);

  140.     else

  141.       return super.toString(verbose) + " " + n;

  142.   }

  143. 

  144.   /**

  145.    * Read needed data (e.g. index) from file.

  146.    * PRE: (ILOAD <= tag <= ALOAD_3) || (ISTORE <= tag <= ASTORE_3)

  147.    */

  148.   protected void initFromFile(ByteSequence bytes, boolean wide)

  149.     throws IOException

  150.   {

  151.     if(wide) {

  152.       n         = bytes.readUnsignedShort();

  153.       length    = 4;

  154.     } else if(((opcode >= Constants.ILOAD) &&

  155. 	       (opcode <= Constants.ALOAD)) ||

  156. 	      ((opcode >= Constants.ISTORE) &&

  157. 	       (opcode <= Constants.ASTORE))) {

  158.       n      = bytes.readUnsignedByte();

  159.       length = 2;

  160.     } else if(opcode <= Constants.ALOAD_3) { // compact load instruction such as ILOAD_2

  161.       n      = (opcode - Constants.ILOAD_0) % 4;

  162.       length = 1;

  163.     } else { // Assert ISTORE_0 <= tag <= ASTORE_3

  164.       n      = (opcode - Constants.ISTORE_0) % 4;

  165.       length = 1;

  166.     }

  167.  }

  168. 

  169.   /**

  170.    * @return local variable index  referred by this instruction.

  171.    */

  172.   public final int getIndex() { return n; }

  173. 

  174.   /**

  175.    * Set the local variable index

  176.    */

  177.   public void setIndex(int n) { 

  178.     if((n < 0) || (n > Constants.MAX_SHORT))

  179.       throw new ClassGenException("Illegal value: " + n);

  180. 

  181.     this.n = n;

  182. 

  183.     if(n >= 0 && n <= 3) { // Use more compact instruction xLOAD_n

  184.       opcode = (short)(c_tag + n);

  185.       length = 1;

  186.     } else {

  187.       opcode = canon_tag;

  188.       

  189.       if(wide()) // Need WIDE prefix ?

  190. 	length = 4;

  191.       else

  192. 	length = 2;

  193.     }

  194.   }

  195. 

  196.   /** @return canonical tag for instruction, e.g., ALOAD for ALOAD_0

  197.    */

  198.   public short getCanonicalTag() {

  199.     return canon_tag;

  200.   }

  201. 

  202.   /**

  203.    * Returns the type associated with the instruction - 

  204.    * in case of ALOAD or ASTORE Type.OBJECT is returned.

  205.    * This is just a bit incorrect, because ALOAD and ASTORE

  206.    * may work on every ReferenceType (including Type.NULL) and

  207.    * ASTORE may even work on a ReturnaddressType .

  208.    * @return type associated with the instruction

  209.    */

  210.   public Type getType(ConstantPoolGen cp) {

  211.     switch(canon_tag) {

  212.     case Constants.ILOAD: case Constants.ISTORE: 

  213.       return Type.INT;

  214.     case Constants.LLOAD: case Constants.LSTORE: 

  215.       return Type.LONG;

  216.     case Constants.DLOAD: case Constants.DSTORE: 

  217.       return Type.DOUBLE;

  218.     case Constants.FLOAD: case Constants.FSTORE: 

  219.       return Type.FLOAT;

  220.     case Constants.ALOAD: case Constants.ASTORE:

  221.       return Type.OBJECT;

  222. 

  223.     default: throw new ClassGenException("Oops: unknown case in switch" + canon_tag);

  224.     }

  225.   }

  226. }

  227.