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Java example source code file (BCELFactory.java)

This example Java source code file (BCELFactory.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraylist, bcelfactory, branchhandle, branchinstruction, codeexceptiongen, constants, hashmap, instructionhandle, printwriter, select, store, string, stringbuffer, type, util

The BCELFactory.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
package com.sun.org.apache.bcel.internal.util;

import com.sun.org.apache.bcel.internal.generic.*;
import com.sun.org.apache.bcel.internal.classfile.Utility;
import com.sun.org.apache.bcel.internal.Constants;
import java.io.PrintWriter;
import java.util.*;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002 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/>.
 */

/**
 * Factory creates il.append() statements, and sets instruction targets.
 * A helper class for BCELifier.
 *
 * @see BCELifier
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm
 */
class BCELFactory extends EmptyVisitor {
  private MethodGen       _mg;
  private PrintWriter     _out;
  private ConstantPoolGen _cp;

  BCELFactory(MethodGen mg, PrintWriter out) {
    _mg  = mg;
    _cp  = mg.getConstantPool();
    _out = out;
  }

  private HashMap branch_map = new HashMap(); // Map<Instruction, InstructionHandle>

  public void start() {
    if(!_mg.isAbstract() && !_mg.isNative()) {
      for(InstructionHandle ih = _mg.getInstructionList().getStart();
          ih != null; ih = ih.getNext()) {
        Instruction i = ih.getInstruction();

        if(i instanceof BranchInstruction) {
          branch_map.put(i, ih); // memorize container
        }

        if(ih.hasTargeters()) {
          if(i instanceof BranchInstruction) {
            _out.println("    InstructionHandle ih_" + ih.getPosition() + ";");
          } else {
            _out.print("    InstructionHandle ih_" + ih.getPosition() + " = ");
          }
        } else {
          _out.print("    ");
        }

        if(!visitInstruction(i))
          i.accept(this);
      }

      updateBranchTargets();
      updateExceptionHandlers();
    }
  }

  private boolean visitInstruction(Instruction i) {
    short opcode = i.getOpcode();

    if((InstructionConstants.INSTRUCTIONS[opcode] != null) &&
       !(i instanceof ConstantPushInstruction) &&
       !(i instanceof ReturnInstruction)) { // Handled below
      _out.println("il.append(InstructionConstants." +
                   i.getName().toUpperCase() + ");");
      return true;
    }

    return false;
  }

  public void visitLocalVariableInstruction(LocalVariableInstruction i) {
    short  opcode = i.getOpcode();
    Type   type   = i.getType(_cp);

    if(opcode == Constants.IINC) {
      _out.println("il.append(new IINC(" + i.getIndex() + ", " +
                   ((IINC)i).getIncrement() + "));");
    } else {
      String kind   = (opcode < Constants.ISTORE)? "Load" : "Store";
      _out.println("il.append(_factory.create" + kind + "(" +
                   BCELifier.printType(type) + ", " +
                   i.getIndex() + "));");
    }
  }

  public void visitArrayInstruction(ArrayInstruction i) {
    short  opcode = i.getOpcode();
    Type   type   = i.getType(_cp);
    String kind   = (opcode < Constants.IASTORE)? "Load" : "Store";

    _out.println("il.append(_factory.createArray" + kind + "(" +
                 BCELifier.printType(type) + "));");
  }

  public void visitFieldInstruction(FieldInstruction i) {
    short  opcode = i.getOpcode();

    String class_name = i.getClassName(_cp);
    String field_name = i.getFieldName(_cp);
    Type   type       = i.getFieldType(_cp);

    _out.println("il.append(_factory.createFieldAccess(\"" +
                 class_name + "\", \"" + field_name + "\", " +
                 BCELifier.printType(type) + ", " +
                 "Constants." + Constants.OPCODE_NAMES[opcode].toUpperCase() +
                 "));");
  }

  public void visitInvokeInstruction(InvokeInstruction i) {
    short  opcode      = i.getOpcode();
    String class_name  = i.getClassName(_cp);
    String method_name = i.getMethodName(_cp);
    Type   type        = i.getReturnType(_cp);
    Type[] arg_types   = i.getArgumentTypes(_cp);

    _out.println("il.append(_factory.createInvoke(\"" +
                 class_name + "\", \"" + method_name + "\", " +
                 BCELifier.printType(type) + ", " +
                 BCELifier.printArgumentTypes(arg_types) + ", " +
                 "Constants." + Constants.OPCODE_NAMES[opcode].toUpperCase() +
                 "));");
  }

  public void visitAllocationInstruction(AllocationInstruction i) {
    Type type;

    if(i instanceof CPInstruction) {
      type = ((CPInstruction)i).getType(_cp);
    } else {
      type = ((NEWARRAY)i).getType();
    }

    short opcode = ((Instruction)i).getOpcode();
    int   dim    = 1;

    switch(opcode) {
    case Constants.NEW:
      _out.println("il.append(_factory.createNew(\"" +
                   ((ObjectType)type).getClassName() + "\"));");
      break;

    case Constants.MULTIANEWARRAY:
      dim = ((MULTIANEWARRAY)i).getDimensions();

    case Constants.ANEWARRAY:
    case Constants.NEWARRAY:
      _out.println("il.append(_factory.createNewArray(" +
                   BCELifier.printType(type) + ", (short) " + dim + "));");
      break;

    default:
      throw new RuntimeException("Oops: " + opcode);
    }
  }

  private void createConstant(Object value) {
    String embed = value.toString();

    if(value instanceof String)
      embed = '"' + Utility.convertString(value.toString()) + '"';
    else if(value instanceof Character)
      embed = "(char)0x" + Integer.toHexString(((Character)value).charValue());

    _out.println("il.append(new PUSH(_cp, " + embed + "));");
  }

  public void visitLDC(LDC i) {
    createConstant(i.getValue(_cp));
  }

  public void visitLDC2_W(LDC2_W i) {
    createConstant(i.getValue(_cp));
  }

  public void visitConstantPushInstruction(ConstantPushInstruction i) {
    createConstant(i.getValue());
  }

  public void visitINSTANCEOF(INSTANCEOF i) {
    Type type = i.getType(_cp);

    _out.println("il.append(new INSTANCEOF(_cp.addClass(" +
                 BCELifier.printType(type) + ")));");
  }

  public void visitCHECKCAST(CHECKCAST i) {
    Type type = i.getType(_cp);

    _out.println("il.append(_factory.createCheckCast(" +
                 BCELifier.printType(type) + "));");
  }

  public void visitReturnInstruction(ReturnInstruction i) {
    Type type = i.getType(_cp);

    _out.println("il.append(_factory.createReturn(" +
                 BCELifier.printType(type) + "));");
  }

  // Memorize BranchInstructions that need an update
  private ArrayList branches = new ArrayList();

  public void visitBranchInstruction(BranchInstruction bi) {
    BranchHandle bh   = (BranchHandle)branch_map.get(bi);
    int          pos  = bh.getPosition();
    String       name = bi.getName() + "_" + pos;

    if(bi instanceof Select) {
      Select s = (Select)bi;
      branches.add(bi);

      StringBuffer args   = new StringBuffer("new int[] { ");
      int[]        matchs = s.getMatchs();

      for(int i=0; i < matchs.length; i++) {
        args.append(matchs[i]);

        if(i < matchs.length - 1)
          args.append(", ");
      }

      args.append(" }");

      _out.print("    Select " + name + " = new " +
                 bi.getName().toUpperCase() + "(" + args +
                 ", new InstructionHandle[] { ");

      for(int i=0; i < matchs.length; i++) {
        _out.print("null");

        if(i < matchs.length - 1)
          _out.print(", ");
      }

      _out.println(");");
    } else {
      int    t_pos  = bh.getTarget().getPosition();
      String target;

      if(pos > t_pos) {
        target = "ih_" + t_pos;
      } else {
        branches.add(bi);
        target = "null";
      }

      _out.println("    BranchInstruction " + name +
                   " = _factory.createBranchInstruction(" +
                   "Constants." + bi.getName().toUpperCase() + ", " +
                   target + ");");
    }

    if(bh.hasTargeters())
      _out.println("    ih_" + pos + " = il.append(" + name + ");");
    else
      _out.println("    il.append(" + name + ");");
  }

  public void visitRET(RET i) {
    _out.println("il.append(new RET(" + i.getIndex() + ")));");
  }

  private void updateBranchTargets() {
    for(Iterator i = branches.iterator(); i.hasNext(); ) {
      BranchInstruction bi    = (BranchInstruction)i.next();
      BranchHandle      bh    = (BranchHandle)branch_map.get(bi);
      int               pos   = bh.getPosition();
      String            name  = bi.getName() + "_" + pos;
      int               t_pos = bh.getTarget().getPosition();

      _out.println("    " + name + ".setTarget(ih_" + t_pos + ");");

      if(bi instanceof Select) {
        InstructionHandle[] ihs = ((Select)bi).getTargets();

        for(int j = 0; j < ihs.length; j++) {
          t_pos = ihs[j].getPosition();

          _out.println("    " + name + ".setTarget(" + j +
                       ", ih_" + t_pos + ");");
        }
      }
    }
  }

  private void updateExceptionHandlers() {
    CodeExceptionGen[] handlers = _mg.getExceptionHandlers();

    for(int i=0; i < handlers.length; i++) {
      CodeExceptionGen h    = handlers[i];
      String           type = (h.getCatchType() == null)?
        "null" : BCELifier.printType(h.getCatchType());

      _out.println("    method.addExceptionHandler(" +
                   "ih_" + h.getStartPC().getPosition() + ", " +
                   "ih_" + h.getEndPC().getPosition() + ", " +
                   "ih_" + h.getHandlerPC().getPosition() + ", " +
                   type + ");");
    }
  }
}

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