- package com.sun.org.apache.bcel.internal.generic;
-
- /* ====================================================================
- * The Apache Software License, Version 1.1
- *
- * Copyright (c) 2001 The Apache Software Foundation. All rights
- * reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * 3. The end-user documentation included with the redistribution,
- * if any, must include the following acknowledgment:
- * "This product includes software developed by the
- * Apache Software Foundation (http://www.apache.org/)."
- * Alternately, this acknowledgment may appear in the software itself,
- * if and wherever such third-party acknowledgments normally appear.
- *
- * 4. The names "Apache" and "Apache Software Foundation" and
- * "Apache BCEL" must not be used to endorse or promote products
- * derived from this software without prior written permission. For
- * written permission, please contact apache@apache.org.
- *
- * 5. Products derived from this software may not be called "Apache",
- * "Apache BCEL", nor may "Apache" appear in their name, without
- * prior written permission of the Apache Software Foundation.
- *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- * ====================================================================
- *
- * This software consists of voluntary contributions made by many
- * individuals on behalf of the Apache Software Foundation. For more
- * information on the Apache Software Foundation, please see
- * <http://www.apache.org/>.
- */
-
- import com.sun.org.apache.bcel.internal.Constants;
- import com.sun.org.apache.bcel.internal.classfile.Utility;
- import com.sun.org.apache.bcel.internal.classfile.ConstantPool;
- import java.io.*;
- import com.sun.org.apache.bcel.internal.util.ByteSequence;
-
- /**
- * Abstract super class for all Java byte codes.
- *
- * @version $Id: Instruction.java,v 1.1.1.1 2001/10/29 20:00:18 jvanzyl Exp $
- * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
- */
- public abstract class Instruction implements Cloneable, Serializable {
- protected short length = 1; // Length of instruction in bytes
- protected short opcode = -1; // Opcode number
-
- /**
- * Empty constructor needed for the Class.newInstance() statement in
- * Instruction.readInstruction(). Not to be used otherwise.
- */
- Instruction() {}
-
- public Instruction(short opcode, short length) {
- this.length = length;
- this.opcode = opcode;
- }
-
- /**
- * Dump instruction as byte code to stream out.
- * @param out Output stream
- */
- public void dump(DataOutputStream out) throws IOException {
- out.writeByte(opcode); // Common for all instructions
- }
-
- /**
- * Long output format:
- *
- * <name of opcode> "["<opcode number>"]"
- * "("<length of instruction>")"
- *
- * @param verbose long/short format switch
- * @return mnemonic for instruction
- */
- public String toString(boolean verbose) {
- if(verbose)
- return Constants.OPCODE_NAMES[opcode] + "[" + opcode + "](" + length + ")";
- else
- return Constants.OPCODE_NAMES[opcode];
- }
-
- /**
- * @return mnemonic for instruction in verbose format
- */
- public String toString() {
- return toString(true);
- }
-
- /**
- * @return mnemonic for instruction with sumbolic references resolved
- */
- public String toString(ConstantPool cp) {
- return toString(false);
- }
-
- /**
- * Use with caution, since `BranchInstruction's have a `target' reference which
- * is not copied correctly (only basic types are). This also applies for
- * `Select' instructions with their multiple branch targets.
- *
- * @see BranchInstruction
- * @return (shallow) copy of an instruction
- */
- public Instruction copy() {
- Instruction i = null;
-
- // "Constant" instruction, no need to duplicate
- if(InstructionConstants.INSTRUCTIONS[this.getOpcode()] != null)
- i = this;
- else {
- try {
- i = (Instruction)clone();
- } catch(CloneNotSupportedException e) {
- System.err.println(e);
- }
- }
-
- return i;
- }
-
- /**
- * Read needed data (e.g. index) from file.
- *
- * @param bytes byte sequence to read from
- * @param wide "wide" instruction flag
- */
- protected void initFromFile(ByteSequence bytes, boolean wide)
- throws IOException
- {}
-
- /**
- * Read an instruction from (byte code) input stream and return the
- * appropiate object.
- *
- * @param file file to read from
- * @return instruction object being read
- */
- public static final Instruction readInstruction(ByteSequence bytes)
- throws IOException
- {
- boolean wide = false;
- short opcode = (short)bytes.readUnsignedByte();
- Instruction obj = null;
-
- if(opcode == Constants.WIDE) { // Read next opcode after wide byte
- wide = true;
- opcode = (short)bytes.readUnsignedByte();
- }
-
- if(InstructionConstants.INSTRUCTIONS[opcode] != null)
- return InstructionConstants.INSTRUCTIONS[opcode]; // Used predefined immutable object, if available
-
- /* Find appropiate class, instantiate an (empty) instruction object
- * and initialize it by hand.
- */
- Class clazz;
- try {
- clazz = Class.forName(className(opcode));
- }
- catch (ClassNotFoundException cnfe){
- // If a class by that name does not exist, the opcode is illegal.
- // Note that IMPDEP1, IMPDEP2, BREAKPOINT are also illegal in a sense.
- throw new ClassGenException("Illegal opcode detected.");
- }
- try {
- obj = (Instruction)clazz.newInstance();
-
- if(wide && !((obj instanceof LocalVariableInstruction) || (obj instanceof IINC) ||
- (obj instanceof RET)))
- throw new Exception("Illegal opcode after wide: " + opcode);
-
- obj.setOpcode(opcode);
- obj.initFromFile(bytes, wide); // Do further initializations, if any
- // Byte code offset set in InstructionList
- } catch(Exception e) { throw new ClassGenException(e.toString()); }
-
- return obj;
- }
-
- private static final String className(short opcode) {
- String name = Constants.OPCODE_NAMES[opcode].toUpperCase();
-
- /* ICONST_0, etc. will be shortened to ICONST, etc., since ICONST_0 and the like
- * are not implemented (directly).
- */
- try {
- int len = name.length();
- char ch1 = name.charAt(len - 2), ch2 = name.charAt(len - 1);
-
- if((ch1 == '_') && (ch2 >= '0') && (ch2 <= '5'))
- name = name.substring(0, len - 2);
-
- if(name.equals("ICONST_M1")) // Special case
- name = "ICONST";
- } catch(StringIndexOutOfBoundsException e) { System.err.println(e); }
-
- return "com.sun.org.apache.bcel.internal.generic." + name;
- }
-
- /**
- * This method also gives right results for instructions whose
- * effect on the stack depends on the constant pool entry they
- * reference.
- * @return Number of words consumed from stack by this instruction,
- * or Constants.UNPREDICTABLE, if this can not be computed statically
- */
- public int consumeStack(ConstantPoolGen cpg) {
- return Constants.CONSUME_STACK[opcode];
- }
-
- /**
- * This method also gives right results for instructions whose
- * effect on the stack depends on the constant pool entry they
- * reference.
- * @return Number of words produced onto stack by this instruction,
- * or Constants.UNPREDICTABLE, if this can not be computed statically
- */
- public int produceStack(ConstantPoolGen cpg) {
- return Constants.PRODUCE_STACK[opcode];
- }
-
- /**
- * @return this instructions opcode
- */
- public short getOpcode() { return opcode; }
-
- /**
- * @return length (in bytes) of instruction
- */
- public int getLength() { return length; }
-
- /**
- * Needed in readInstruction.
- */
- private void setOpcode(short opcode) { this.opcode = opcode; }
-
- /** Some instructions may be reused, so don't do anything by default.
- */
- void dispose() { }
-
- /**
- * Call corresponding visitor method(s). The order is:
- * Call visitor methods of implemented interfaces first, then
- * call methods according to the class hierarchy in descending order,
- * i.e., the most specific visitXXX() call comes last.
- *
- * @param v Visitor object
- */
- public abstract void accept(Visitor v);
- }