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 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
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package com.sun.org.apache.bcel.internal.generic;


import com.sun.org.apache.bcel.internal.Constants;
import com.sun.org.apache.bcel.internal.classfile.Constant;
import com.sun.org.apache.bcel.internal.util.ByteSequence;
import java.io.*;
import java.util.Iterator;
import java.util.HashMap;
import java.util.ArrayList;

This class is a container for a list of Instruction objects. Instructions can
be appended, inserted, moved, deleted, etc.. Instructions are being
wrapped into InstructionHandles objects that
are returned upon append/insert operations. They give the user
(read only) access to the list structure, such that it can be traversed and
manipulated in a controlled way.
A list is finally dumped to a byte code array with getByteCode.
Author:
 M. Dahm
See Also:
Instruction
InstructionHandle
BranchHandle/**
 * This class is a container for a list of <a
 * href="Instruction.html">Instruction</a> objects. Instructions can
 * be appended, inserted, moved, deleted, etc.. Instructions are being
 * wrapped into <a
 * href="InstructionHandle.html">InstructionHandles</a> objects that
 * are returned upon append/insert operations. They give the user
 * (read only) access to the list structure, such that it can be traversed and
 * manipulated in a controlled way.
 *
 * A list is finally dumped to a byte code array with <a
 * href="#getByteCode()">getByteCode</a>.
 *
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 * @see     Instruction
 * @see     InstructionHandle
 * @see BranchHandle
 */
public class InstructionList implements Serializable {
  private InstructionHandle start  = null, end = null;
  private int               length = 0; // number of elements in list
  private int[]             byte_positions; // byte code offsets corresponding to instructions

  
Create (empty) instruction list.
/**
   * Create (empty) instruction list.
   */
  public InstructionList() {}

  
Create instruction list containing one instruction.
Params:
i – initial instruction/**
   * Create instruction list containing one instruction.
   * @param i initial instruction
   */
  public InstructionList(Instruction i) {
    append(i);
  }

  
Create instruction list containing one instruction.
Params:
i – initial instruction/**
   * Create instruction list containing one instruction.
   * @param i initial instruction
   */
  public InstructionList(BranchInstruction i) {
    append(i);
  }

  
Initialize list with (nonnull) compound instruction. Consumes argument
list, i.e., it becomes empty.
Params:
c – compound instruction (list)/**
   * Initialize list with (nonnull) compound instruction. Consumes argument
   * list, i.e., it becomes empty.
   *
   * @param c compound instruction (list)
   */
  public InstructionList(CompoundInstruction c) {
    append(c.getInstructionList());
  }

  
Test for empty list.
/**
   * Test for empty list.
   */
  public boolean isEmpty() { return start == null; } // && end == null

  
Find the target instruction (handle) that corresponds to the given target
position (byte code offset).
Params:
ihs – array of instruction handles, i.e. il.getInstructionHandles()
pos – array of positions corresponding to ihs, i.e. il.getInstructionPositions()
count – length of arrays
target – target position to search for
Returns:
target position's instruction handle if available/**
   * Find the target instruction (handle) that corresponds to the given target
   * position (byte code offset).
   *
   * @param ihs array of instruction handles, i.e. il.getInstructionHandles()
   * @param pos array of positions corresponding to ihs, i.e. il.getInstructionPositions()
   * @param count length of arrays
   * @param target target position to search for
   * @return target position's instruction handle if available
   */
  public static InstructionHandle findHandle(InstructionHandle[] ihs,
                                             int[] pos, int count,
                                             int target) {
    int l=0, r = count - 1;

    /* Do a binary search since the pos array is orderd.
     */
    do {
      int i = (l + r) / 2;
      int j = pos[i];

      if(j == target) // target found
        return ihs[i];
      else if(target < j) // else constrain search area
        r = i - 1;
      else // target > j
        l = i + 1;
    } while(l <= r);

    return null;
  }

  
Get instruction handle for instruction at byte code position pos.
This only works properly, if the list is freshly initialized from a byte array or
setPositions() has been called before this method.
Params:
pos – byte code position to search for
Returns:
target position's instruction handle if available/**
   * Get instruction handle for instruction at byte code position pos.
   * This only works properly, if the list is freshly initialized from a byte array or
   * setPositions() has been called before this method.
   *
   * @param pos byte code position to search for
   * @return target position's instruction handle if available
   */
  public InstructionHandle findHandle(int pos) {
    InstructionHandle[] ihs = getInstructionHandles();
    return findHandle(ihs, byte_positions, length, pos);
  }

  
Initialize instruction list from byte array.
Params:
code – byte array containing the instructions/**
   * Initialize instruction list from byte array.
   *
   * @param code byte array containing the instructions
   */
  public InstructionList(byte[] code) {
    ByteSequence        bytes = new ByteSequence(code);
    InstructionHandle[] ihs   = new InstructionHandle[code.length];
    int[]               pos   = new int[code.length]; // Can't be more than that
    int                 count = 0; // Contains actual length

    /* Pass 1: Create an object for each byte code and append them
     * to the list.
     */
    try {
      while(bytes.available() > 0) {
        // Remember byte offset and associate it with the instruction
        int off =  bytes.getIndex();
        pos[count] = off;

        /* Read one instruction from the byte stream, the byte position is set
         * accordingly.
         */
        Instruction       i = Instruction.readInstruction(bytes);
        InstructionHandle ih;
        if(i instanceof BranchInstruction) // Use proper append() method
          ih = append((BranchInstruction)i);
        else
          ih = append(i);

        ih.setPosition(off);
        ihs[count] = ih;

        count++;
      }
    } catch(IOException e) { throw new ClassGenException(e.toString()); }

    byte_positions = new int[count]; // Trim to proper size
    System.arraycopy(pos, 0, byte_positions, 0, count);

    /* Pass 2: Look for BranchInstruction and update their targets, i.e.,
     * convert offsets to instruction handles.
     */
    for(int i=0; i < count; i++) {
      if(ihs[i] instanceof BranchHandle) {
        BranchInstruction bi = (BranchInstruction)ihs[i].instruction;
        int target = bi.position + bi.getIndex(); /* Byte code position:
                                                   * relative -> absolute. */
        // Search for target position
        InstructionHandle ih = findHandle(ihs, pos, count, target);

        if(ih == null) // Search failed
          throw new ClassGenException("Couldn't find target for branch: " + bi);

        bi.setTarget(ih); // Update target

        // If it is a Select instruction, update all branch targets
        if(bi instanceof Select) { // Either LOOKUPSWITCH or TABLESWITCH
          Select s       = (Select)bi;
          int[]  indices = s.getIndices();

          for(int j=0; j < indices.length; j++) {
            target = bi.position + indices[j];
            ih     = findHandle(ihs, pos, count, target);

            if(ih == null) // Search failed
              throw new ClassGenException("Couldn't find target for switch: " + bi);

            s.setTarget(j, ih); // Update target
          }
        }
      }
    }
  }

  
Append another list after instruction (handle) ih contained in this list.
Consumes argument list, i.e., it becomes empty.
Params:
ih – where to append the instruction list
il – Instruction list to append to this one
Returns:
instruction handle pointing to the first appended instruction/**
   * Append another list after instruction (handle) ih contained in this list.
   * Consumes argument list, i.e., it becomes empty.
   *
   * @param ih where to append the instruction list
   * @param il Instruction list to append to this one
   * @return instruction handle pointing to the <B>first</B> appended instruction
   */
  public InstructionHandle append(InstructionHandle ih, InstructionList il) {
    if(il == null)
      throw new ClassGenException("Appending null InstructionList");

    if(il.isEmpty()) // Nothing to do
      return ih;

    InstructionHandle next = ih.next, ret = il.start;

    ih.next = il.start;
    il.start.prev = ih;

    il.end.next = next;

    if(next != null) // i == end ?
      next.prev = il.end;
    else
      end = il.end; // Update end ...

    length += il.length; // Update length

    il.clear();

    return ret;
  }

  
Append another list after instruction i contained in this list.
Consumes argument list, i.e., it becomes empty.
Params:
i –  where to append the instruction list
il – Instruction list to append to this one
Returns:
instruction handle pointing to the first appended instruction/**
   * Append another list after instruction i contained in this list.
   * Consumes argument list, i.e., it becomes empty.
   *
   * @param i  where to append the instruction list
   * @param il Instruction list to append to this one
   * @return instruction handle pointing to the <B>first</B> appended instruction
   */
  public InstructionHandle append(Instruction i, InstructionList il) {
    InstructionHandle ih;

    if((ih = findInstruction2(i)) == null) // Also applies for empty list
      throw new ClassGenException("Instruction " + i +
                                  " is not contained in this list.");

    return append(ih, il);
  }

  
Append another list to this one.
Consumes argument list, i.e., it becomes empty.
Params:
il – list to append to end of this list
Returns:
instruction handle of the first appended instruction/**
   * Append another list to this one.
   * Consumes argument list, i.e., it becomes empty.
   *
   * @param il list to append to end of this list
   * @return instruction handle of the <B>first</B> appended instruction
   */
  public InstructionHandle append(InstructionList il) {
    if(il == null)
      throw new ClassGenException("Appending null InstructionList");

    if(il.isEmpty()) // Nothing to do
      return null;

    if(isEmpty()) {
      start  = il.start;
      end    = il.end;
      length = il.length;

      il.clear();

      return start;
    } else
      return append(end, il);  // was end.instruction
  }

  
Append an instruction to the end of this list.
Params:
ih – instruction to append/**
   * Append an instruction to the end of this list.
   *
   * @param ih instruction to append
   */
  private void append(InstructionHandle ih) {
    if(isEmpty()) {
      start = end = ih;
      ih.next = ih.prev = null;
    }
    else {
      end.next = ih;
      ih.prev  = end;
      ih.next  = null;
      end      = ih;
    }

    length++; // Update length
  }

  
Append an instruction to the end of this list.
Params:
i – instruction to append
Returns:
instruction handle of the appended instruction/**
   * Append an instruction to the end of this list.
   *
   * @param i instruction to append
   * @return instruction handle of the appended instruction
   */
  public InstructionHandle append(Instruction i) {
    InstructionHandle ih = InstructionHandle.getInstructionHandle(i);
    append(ih);

    return ih;
  }

  
Append a branch instruction to the end of this list.
Params:
i – branch instruction to append
Returns:
branch instruction handle of the appended instruction/**
   * Append a branch instruction to the end of this list.
   *
   * @param i branch instruction to append
   * @return branch instruction handle of the appended instruction
   */
  public BranchHandle append(BranchInstruction i) {
    BranchHandle ih = BranchHandle.getBranchHandle(i);
    append(ih);

    return ih;
  }

  
Append a single instruction j after another instruction i, which
must be in this list of course!
Params:
i – Instruction in list
j – Instruction to append after i in list
Returns:
instruction handle of the first appended instruction/**
   * Append a single instruction j after another instruction i, which
   * must be in this list of course!
   *
   * @param i Instruction in list
   * @param j Instruction to append after i in list
   * @return instruction handle of the first appended instruction
   */
  public InstructionHandle append(Instruction i, Instruction j) {
    return append(i, new InstructionList(j));
  }

  
Append a compound instruction, after instruction i.
Params:
i – Instruction in list
c – The composite instruction (containing an InstructionList)
Returns:
instruction handle of the first appended instruction/**
   * Append a compound instruction, after instruction i.
   *
   * @param i Instruction in list
   * @param c The composite instruction (containing an InstructionList)
   * @return instruction handle of the first appended instruction
   */
  public InstructionHandle append(Instruction i, CompoundInstruction c) {
    return append(i, c.getInstructionList());
  }

  
Append a compound instruction.
Params:
c – The composite instruction (containing an InstructionList)
Returns:
instruction handle of the first appended instruction/**
   * Append a compound instruction.
   *
   * @param c The composite instruction (containing an InstructionList)
   * @return instruction handle of the first appended instruction
   */
  public InstructionHandle append(CompoundInstruction c) {
    return append(c.getInstructionList());
  }

  
Append a compound instruction.
Params:
ih – where to append the instruction list
c – The composite instruction (containing an InstructionList)
Returns:
instruction handle of the first appended instruction/**
   * Append a compound instruction.
   *
   * @param ih where to append the instruction list
   * @param c The composite instruction (containing an InstructionList)
   * @return instruction handle of the first appended instruction
   */
  public InstructionHandle append(InstructionHandle ih, CompoundInstruction c) {
    return append(ih, c.getInstructionList());
  }

  
Append an instruction after instruction (handle) ih contained in this list.
Params:
ih – where to append the instruction list
i – Instruction to append
Returns:
instruction handle pointing to the first appended instruction/**
   * Append an instruction after instruction (handle) ih contained in this list.
   *
   * @param ih where to append the instruction list
   * @param i Instruction to append
   * @return instruction handle pointing to the <B>first</B> appended instruction
   */
  public InstructionHandle append(InstructionHandle ih, Instruction i) {
    return append(ih, new InstructionList(i));
  }

  
Append an instruction after instruction (handle) ih contained in this list.
Params:
ih – where to append the instruction list
i – Instruction to append
Returns:
instruction handle pointing to the first appended instruction/**
   * Append an instruction after instruction (handle) ih contained in this list.
   *
   * @param ih where to append the instruction list
   * @param i Instruction to append
   * @return instruction handle pointing to the <B>first</B> appended instruction
   */
  public BranchHandle append(InstructionHandle ih, BranchInstruction i) {
    BranchHandle    bh = BranchHandle.getBranchHandle(i);
    InstructionList il = new InstructionList();
    il.append(bh);

    append(ih, il);

    return bh;
  }

  
Insert another list before Instruction handle ih contained in this list.
Consumes argument list, i.e., it becomes empty.
Params:
i –  where to append the instruction list
il – Instruction list to insert
Returns:
instruction handle of the first inserted instruction/**
   * Insert another list before Instruction handle ih contained in this list.
   * Consumes argument list, i.e., it becomes empty.
   *
   * @param i  where to append the instruction list
   * @param il Instruction list to insert
   * @return instruction handle of the first inserted instruction
   */
  public InstructionHandle insert(InstructionHandle ih, InstructionList il) {
    if(il == null)
      throw new ClassGenException("Inserting null InstructionList");

    if(il.isEmpty()) // Nothing to do
      return ih;

    InstructionHandle prev = ih.prev, ret = il.start;

    ih.prev = il.end;
    il.end.next = ih;

    il.start.prev = prev;

    if(prev != null) // ih == start ?
      prev.next = il.start;
    else
      start = il.start; // Update start ...

    length += il.length; // Update length

    il.clear();

    return ret;
  }

  
Insert another list.
Params:
il – list to insert before start of this list
Returns:
instruction handle of the first inserted instruction/**
   * Insert another list.
   *
   * @param il list to insert before start of this list
   * @return instruction handle of the first inserted instruction
   */
  public InstructionHandle insert(InstructionList il) {
    if(isEmpty()) {
      append(il); // Code is identical for this case
      return start;
    }
    else
      return insert(start, il);
  }

  
Insert an instruction at start of this list.
Params:
ih – instruction to insert/**
   * Insert an instruction at start of this list.
   *
   * @param ih instruction to insert
   */
  private void insert(InstructionHandle ih) {
    if(isEmpty()) {
      start = end = ih;
      ih.next = ih.prev = null;
    } else {
      start.prev = ih;
      ih.next    = start;
      ih.prev    = null;
      start      = ih;
    }

    length++;
  }

  
Insert another list before Instruction i contained in this list.
Consumes argument list, i.e., it becomes empty.
Params:
i –  where to append the instruction list
il – Instruction list to insert
Returns:
instruction handle pointing to the first inserted instruction,
i.e., il.getStart()/**
   * Insert another list before Instruction i contained in this list.
   * Consumes argument list, i.e., it becomes empty.
   *
   * @param i  where to append the instruction list
   * @param il Instruction list to insert
   * @return instruction handle pointing to the first inserted instruction,
   * i.e., il.getStart()
   */
  public InstructionHandle insert(Instruction i, InstructionList il) {
    InstructionHandle ih;

    if((ih = findInstruction1(i)) == null)
      throw new ClassGenException("Instruction " + i +
                                  " is not contained in this list.");

    return insert(ih, il);
  }

  
Insert an instruction at start of this list.
Params:
i – instruction to insert
Returns:
instruction handle of the inserted instruction/**
   * Insert an instruction at start of this list.
   *
   * @param i instruction to insert
   * @return instruction handle of the inserted instruction
   */
  public InstructionHandle insert(Instruction i) {
    InstructionHandle ih = InstructionHandle.getInstructionHandle(i);
    insert(ih);

    return ih;
  }

  
Insert a branch instruction at start of this list.
Params:
i – branch instruction to insert
Returns:
branch instruction handle of the appended instruction/**
   * Insert a branch instruction at start of this list.
   *
   * @param i branch instruction to insert
   * @return branch instruction handle of the appended instruction
   */
  public BranchHandle insert(BranchInstruction i) {
    BranchHandle ih = BranchHandle.getBranchHandle(i);
    insert(ih);
    return ih;
  }

  
Insert a single instruction j before another instruction i, which
must be in this list of course!
Params:
i – Instruction in list
j – Instruction to insert before i in list
Returns:
instruction handle of the first inserted instruction/**
   * Insert a single instruction j before another instruction i, which
   * must be in this list of course!
   *
   * @param i Instruction in list
   * @param j Instruction to insert before i in list
   * @return instruction handle of the first inserted instruction
   */
  public InstructionHandle insert(Instruction i, Instruction j) {
    return insert(i, new InstructionList(j));
  }

  
Insert a compound instruction before instruction i.
Params:
i – Instruction in list
c – The composite instruction (containing an InstructionList)
Returns:
instruction handle of the first inserted instruction/**
   * Insert a compound instruction before instruction i.
   *
   * @param i Instruction in list
   * @param c The composite instruction (containing an InstructionList)
   * @return instruction handle of the first inserted instruction
   */
  public InstructionHandle insert(Instruction i, CompoundInstruction c) {
    return insert(i, c.getInstructionList());
  }

  
Insert a compound instruction.
Params:
c – The composite instruction (containing an InstructionList)
Returns:
instruction handle of the first inserted instruction/**
   * Insert a compound instruction.
   *
   * @param c The composite instruction (containing an InstructionList)
   * @return instruction handle of the first inserted instruction
   */
  public InstructionHandle insert(CompoundInstruction c) {
    return insert(c.getInstructionList());
  }

  
Insert an instruction before instruction (handle) ih contained in this list.
Params:
ih – where to insert to the instruction list
i – Instruction to insert
Returns:
instruction handle of the first inserted instruction/**
   * Insert an instruction before instruction (handle) ih contained in this list.
   *
   * @param ih where to insert to the instruction list
   * @param i Instruction to insert
   * @return instruction handle of the first inserted instruction
   */
  public InstructionHandle insert(InstructionHandle ih, Instruction i) {
    return insert(ih, new InstructionList(i));
  }

  
Insert a compound instruction.
Params:
ih – where to insert the instruction list
c – The composite instruction (containing an InstructionList)
Returns:
instruction handle of the first inserted instruction/**
   * Insert a compound instruction.
   *
   * @param ih where to insert the instruction list
   * @param c The composite instruction (containing an InstructionList)
   * @return instruction handle of the first inserted instruction
   */
  public InstructionHandle insert(InstructionHandle ih, CompoundInstruction c) {
    return insert(ih, c.getInstructionList());
  }

  
Insert an instruction before instruction (handle) ih contained in this list.
Params:
ih – where to insert to the instruction list
i – Instruction to insert
Returns:
instruction handle of the first inserted instruction/**
   * Insert an instruction before instruction (handle) ih contained in this list.
   *
   * @param ih where to insert to the instruction list
   * @param i Instruction to insert
   * @return instruction handle of the first inserted instruction
   */
  public BranchHandle insert(InstructionHandle ih, BranchInstruction i) {
    BranchHandle    bh = BranchHandle.getBranchHandle(i);
    InstructionList il = new InstructionList();
    il.append(bh);

    insert(ih, il);

    return bh;
  }

  
Take all instructions (handles) from "start" to "end" and append them after the
new location "target". Of course, "end" must be after "start" and target must
not be located withing this range. If you want to move something to the start of
the list use null as value for target.

Any instruction targeters pointing to handles within the block, keep their targets.
Params:
start –  of moved block
end –    of moved block
target – of moved block/**
   * Take all instructions (handles) from "start" to "end" and append them after the
   * new location "target". Of course, "end" must be after "start" and target must
   * not be located withing this range. If you want to move something to the start of
   * the list use null as value for target.<br>
   * Any instruction targeters pointing to handles within the block, keep their targets.
   *
   * @param start  of moved block
   * @param end    of moved block
   * @param target of moved block
   */
  public void move(InstructionHandle start, InstructionHandle end, InstructionHandle target) {
    // Step 1: Check constraints

    if((start == null) || (end == null))
      throw new ClassGenException("Invalid null handle: From " + start + " to " + end);

    if((target == start) || (target == end))
      throw new ClassGenException("Invalid range: From " + start + " to " + end +
                                  " contains target " + target);

    for(InstructionHandle ih = start; ih != end.next; ih = ih.next) {
      if(ih == null) // At end of list, end not found yet
        throw new ClassGenException("Invalid range: From " + start + " to " + end);
      else if(ih == target) // target may be null
        throw new ClassGenException("Invalid range: From " + start + " to " + end +
                                    " contains target " + target);
    }

    // Step 2: Temporarily remove the given instructions from the list

    InstructionHandle prev = start.prev, next = end.next;

    if(prev != null)
      prev.next = next;
    else // start == this.start!
      this.start = next;

    if(next != null)
      next.prev = prev;
    else // end == this.end!
      this.end = prev;

    start.prev = end.next = null;

    // Step 3: append after target

    if(target == null) { // append to start of list
      end.next = this.start;
      this.start = start;
    } else {
      next = target.next;

      target.next = start;
      start.prev  = target;
      end.next    = next;

      if(next != null)
        next.prev = end;
    }
  }

  
Move a single instruction (handle) to a new location.
Params:
ih –     moved instruction
target – new location of moved instruction/**
   * Move a single instruction (handle) to a new location.
   *
   * @param ih     moved instruction
   * @param target new location of moved instruction
   */
  public void move(InstructionHandle ih, InstructionHandle target) {
    move(ih, ih, target);
  }

  
Remove from instruction `prev' to instruction `next' both contained
in this list. Throws TargetLostException when one of the removed instruction handles
is still being targeted.
Params:
prev – where to start deleting (predecessor, exclusive)
next – where to end deleting (successor, exclusive)/**
   * Remove from instruction `prev' to instruction `next' both contained
   * in this list. Throws TargetLostException when one of the removed instruction handles
   * is still being targeted.
   *
   * @param prev where to start deleting (predecessor, exclusive)
   * @param next where to end deleting (successor, exclusive)
   */
  private void remove(InstructionHandle prev, InstructionHandle next)
    throws TargetLostException
  {
    InstructionHandle first, last; // First and last deleted instruction

    if((prev == null) && (next == null)) { // singleton list
      first = last = start;
      start = end = null;
    } else {
      if(prev == null) { // At start of list
        first = start;
        start = next;
      } else {
        first     = prev.next;
        prev.next = next;
      }

      if(next == null) { // At end of list
        last = end;
        end  = prev;
      } else {
        last      = next.prev;
        next.prev = prev;
      }
    }

    first.prev = null; // Completely separated from rest of list
    last.next  = null;

    ArrayList target_vec = new ArrayList();

    for(InstructionHandle ih=first; ih != null; ih = ih.next)
      ih.getInstruction().dispose(); // e.g. BranchInstructions release their targets

    StringBuffer buf = new StringBuffer("{ ");
    for(InstructionHandle ih=first; ih != null; ih = next) {
      next = ih.next;
      length--;

      if(ih.hasTargeters()) { // Still got targeters?
        target_vec.add(ih);
        buf.append(ih.toString(true) + " ");
        ih.next = ih.prev = null;
      } else
        ih.dispose();
    }

    buf.append("}");

    if(!target_vec.isEmpty()) {
      InstructionHandle[] targeted = new InstructionHandle[target_vec.size()];
      target_vec.toArray(targeted);
      throw new TargetLostException(targeted, buf.toString());
    }
  }

  
Remove instruction from this list. The corresponding Instruction
handles must not be reused!
Params:
ih – instruction (handle) to remove/**
   * Remove instruction from this list. The corresponding Instruction
   * handles must not be reused!
   *
   * @param ih instruction (handle) to remove
   */
  public void delete(InstructionHandle ih) throws TargetLostException {
    remove(ih.prev, ih.next);
  }

  
Remove instruction from this list. The corresponding Instruction
handles must not be reused!
Params:
i – instruction to remove/**
   * Remove instruction from this list. The corresponding Instruction
   * handles must not be reused!
   *
   * @param i instruction to remove
   */
  public void delete(Instruction i) throws TargetLostException {
    InstructionHandle ih;

    if((ih = findInstruction1(i)) == null)
      throw new ClassGenException("Instruction " + i +
                                  " is not contained in this list.");
    delete(ih);
  }

  
Remove instructions from instruction `from' to instruction `to' contained
in this list. The user must ensure that `from' is an instruction before
`to', or risk havoc. The corresponding Instruction handles must not be reused!
Params:
from – where to start deleting (inclusive)
to –   where to end deleting (inclusive)/**
   * Remove instructions from instruction `from' to instruction `to' contained
   * in this list. The user must ensure that `from' is an instruction before
   * `to', or risk havoc. The corresponding Instruction handles must not be reused!
   *
   * @param from where to start deleting (inclusive)
   * @param to   where to end deleting (inclusive)
   */
  public void delete(InstructionHandle from, InstructionHandle to)
    throws TargetLostException
  {
    remove(from.prev, to.next);
  }

  
Remove instructions from instruction `from' to instruction `to' contained
in this list. The user must ensure that `from' is an instruction before
`to', or risk havoc. The corresponding Instruction handles must not be reused!
Params:
from – where to start deleting (inclusive)
to –   where to end deleting (inclusive)/**
   * Remove instructions from instruction `from' to instruction `to' contained
   * in this list. The user must ensure that `from' is an instruction before
   * `to', or risk havoc. The corresponding Instruction handles must not be reused!
   *
   * @param from where to start deleting (inclusive)
   * @param to   where to end deleting (inclusive)
   */
  public void delete(Instruction from, Instruction to) throws TargetLostException {
    InstructionHandle from_ih, to_ih;

    if((from_ih = findInstruction1(from)) == null)
      throw new ClassGenException("Instruction " + from +
                                  " is not contained in this list.");

    if((to_ih = findInstruction2(to)) == null)
      throw new ClassGenException("Instruction " + to +
                                  " is not contained in this list.");
    delete(from_ih, to_ih);
  }

  
Search for given Instruction reference, start at beginning of list.
Params:
i – instruction to search for
Returns:
instruction found on success, null otherwise/**
   * Search for given Instruction reference, start at beginning of list.
   *
   * @param i instruction to search for
   * @return instruction found on success, null otherwise
   */
  private InstructionHandle findInstruction1(Instruction i) {
    for(InstructionHandle ih=start; ih != null; ih = ih.next)
      if(ih.instruction == i)
        return ih;

    return null;
  }

  
Search for given Instruction reference, start at end of list
Params:
i – instruction to search for
Returns:
instruction found on success, null otherwise/**
   * Search for given Instruction reference, start at end of list
   *
   * @param i instruction to search for
   * @return instruction found on success, null otherwise
   */
  private InstructionHandle findInstruction2(Instruction i) {
    for(InstructionHandle ih=end; ih != null; ih = ih.prev)
      if(ih.instruction == i)
        return ih;

    return null;
  }

  public boolean contains(InstructionHandle i) {
    if(i == null)
      return false;

    for(InstructionHandle ih=start; ih != null; ih = ih.next)
      if(ih == i)
        return true;

    return false;
  }

  public boolean contains(Instruction i) {
    return findInstruction1(i) != null;
  }

  public void setPositions() {
    setPositions(false);
  }

  
Give all instructions their position number (offset in byte stream), i.e.,
make the list ready to be dumped.
Params:
check – Perform sanity checks, e.g. if all targeted instructions really belong
to this list/**
   * Give all instructions their position number (offset in byte stream), i.e.,
   * make the list ready to be dumped.
   *
   * @param check Perform sanity checks, e.g. if all targeted instructions really belong
   * to this list
   */
  public void setPositions(boolean check) {
    int max_additional_bytes = 0, additional_bytes = 0;
    int index = 0, count = 0;
    int[] pos = new int[length];

    /* Pass 0: Sanity checks
     */
    if(check) {
      for(InstructionHandle ih=start; ih != null; ih = ih.next) {
        Instruction i = ih.instruction;

        if(i instanceof BranchInstruction) { // target instruction within list?
          Instruction inst = ((BranchInstruction)i).getTarget().instruction;
          if(!contains(inst))
            throw new ClassGenException("Branch target of " +
                                        Constants.OPCODE_NAMES[i.opcode] + ":" +
                                        inst + " not in instruction list");

          if(i instanceof Select) {
            InstructionHandle[] targets = ((Select)i).getTargets();

            for(int j=0; j < targets.length; j++) {
              inst = targets[j].instruction;
              if(!contains(inst))
                throw new ClassGenException("Branch target of " +
                                            Constants.OPCODE_NAMES[i.opcode] + ":" +
                                            inst + " not in instruction list");
            }
          }

          if(!(ih instanceof BranchHandle))
            throw new ClassGenException("Branch instruction " +
                                        Constants.OPCODE_NAMES[i.opcode] + ":" +
                                        inst + " not contained in BranchHandle.");

        }
      }
    }

    /* Pass 1: Set position numbers and sum up the maximum number of bytes an
     * instruction may be shifted.
     */
    for(InstructionHandle ih=start; ih != null; ih = ih.next) {
      Instruction i = ih.instruction;

      ih.setPosition(index);
      pos[count++] = index;

      /* Get an estimate about how many additional bytes may be added, because
       * BranchInstructions may have variable length depending on the target
       * offset (short vs. int) or alignment issues (TABLESWITCH and
       * LOOKUPSWITCH).
       */
      switch(i.getOpcode()) {
      case Constants.JSR: case Constants.GOTO:
        max_additional_bytes += 2;
        break;

      case Constants.TABLESWITCH: case Constants.LOOKUPSWITCH:
        max_additional_bytes += 3;
        break;
      }

      index += i.getLength();
    }

    /* Pass 2: Expand the variable-length (Branch)Instructions depending on
     * the target offset (short or int) and ensure that branch targets are
     * within this list.
     */
    for(InstructionHandle ih=start; ih != null; ih = ih.next)
      additional_bytes += ih.updatePosition(additional_bytes, max_additional_bytes);

    /* Pass 3: Update position numbers (which may have changed due to the
     * preceding expansions), like pass 1.
     */
    index=count=0;
    for(InstructionHandle ih=start; ih != null; ih = ih.next) {
      Instruction i = ih.instruction;

      ih.setPosition(index);
      pos[count++] = index;
      index += i.getLength();
    }

    byte_positions = new int[count]; // Trim to proper size
    System.arraycopy(pos, 0, byte_positions, 0, count);
  }

  
When everything is finished, use this method to convert the instruction
list into an array of bytes.
Returns:
the byte code ready to be dumped/**
   * When everything is finished, use this method to convert the instruction
   * list into an array of bytes.
   *
   * @return the byte code ready to be dumped
   */
  public byte[] getByteCode() {
    // Update position indices of instructions
    setPositions();

    ByteArrayOutputStream b   = new ByteArrayOutputStream();
    DataOutputStream      out = new DataOutputStream(b);

    try {
      for(InstructionHandle ih=start; ih != null; ih = ih.next) {
        Instruction i = ih.instruction;
        i.dump(out); // Traverse list
      }
    } catch(IOException e) {
      System.err.println(e);
      return null;
    }

    return b.toByteArray();
  }

  
Returns:
an array of instructions without target information for branch instructions./**
   * @return an array of instructions without target information for branch instructions.
   */
  public Instruction[] getInstructions() {
    ByteSequence  bytes        = new ByteSequence(getByteCode());
    ArrayList     instructions = new ArrayList();

    try {
      while(bytes.available() > 0) {
        instructions.add(Instruction.readInstruction(bytes));
      }
    } catch(IOException e) { throw new ClassGenException(e.toString()); }

    Instruction[] result = new Instruction[instructions.size()];
    instructions.toArray(result);
    return result;
  }

  public String toString() {
    return toString(true);
  }

  
Params:
verbose – toggle output format
Returns:
String containing all instructions in this list./**
   * @param verbose toggle output format
   * @return String containing all instructions in this list.
   */
  public String toString(boolean verbose) {
    StringBuffer buf = new StringBuffer();

    for(InstructionHandle ih=start; ih != null; ih = ih.next) {
      buf.append(ih.toString(verbose) + "\n");
    }

    return buf.toString();
  }

  
Returns:
Enumeration that lists all instructions (handles)/**
   * @return Enumeration that lists all instructions (handles)
   */
  public Iterator iterator() {
    return new Iterator() {
      private InstructionHandle ih = start;

      public Object next() {
        InstructionHandle i = ih;
        ih = ih.next;
        return i;
      }

      public void remove() {
        throw new UnsupportedOperationException();
      }

      public boolean hasNext() { return ih != null; }
    };
  }

  
Returns:
array containing all instructions (handles)/**
   * @return array containing all instructions (handles)
   */
  public InstructionHandle[] getInstructionHandles() {
    InstructionHandle[] ihs = new InstructionHandle[length];
    InstructionHandle   ih  = start;

    for(int i=0; i < length; i++) {
      ihs[i] = ih;
      ih = ih.next;
    }

    return ihs;
  }

  
Get positions (offsets) of all instructions in the list. This relies on that
the list has been freshly created from an byte code array, or that setPositions()
has been called. Otherwise this may be inaccurate.
Returns:
array containing all instruction's offset in byte code/**
   * Get positions (offsets) of all instructions in the list. This relies on that
   * the list has been freshly created from an byte code array, or that setPositions()
   * has been called. Otherwise this may be inaccurate.
   *
   * @return array containing all instruction's offset in byte code
   */
  public int[] getInstructionPositions() { return byte_positions; }

  
Returns:
complete, i.e., deep copy of this list/**
   * @return complete, i.e., deep copy of this list
   */
  public InstructionList copy() {
    HashMap         map = new HashMap();
    InstructionList il  = new InstructionList();

    /* Pass 1: Make copies of all instructions, append them to the new list
     * and associate old instruction references with the new ones, i.e.,
     * a 1:1 mapping.
     */
    for(InstructionHandle ih=start; ih != null; ih = ih.next) {
      Instruction i = ih.instruction;
      Instruction c = i.copy(); // Use clone for shallow copy

      if(c instanceof BranchInstruction)
        map.put(ih, il.append((BranchInstruction)c));
      else
        map.put(ih, il.append(c));
    }

    /* Pass 2: Update branch targets.
     */
    InstructionHandle ih=start;
    InstructionHandle ch=il.start;

    while(ih != null) {
      Instruction i = ih.instruction;
      Instruction c = ch.instruction;

      if(i instanceof BranchInstruction) {
        BranchInstruction bi      = (BranchInstruction)i;
        BranchInstruction bc      = (BranchInstruction)c;
        InstructionHandle itarget = bi.getTarget(); // old target

        // New target is in hash map
        bc.setTarget((InstructionHandle)map.get(itarget));

        if(bi instanceof Select) { // Either LOOKUPSWITCH or TABLESWITCH
          InstructionHandle[] itargets = ((Select)bi).getTargets();
          InstructionHandle[] ctargets = ((Select)bc).getTargets();

          for(int j=0; j < itargets.length; j++) { // Update all targets
            ctargets[j] = (InstructionHandle)map.get(itargets[j]);
          }
        }
      }

      ih = ih.next;
      ch = ch.next;
    }

    return il;
  }

  
Replace all references to the old constant pool with references to the new
 constant pool
/** Replace all references to the old constant pool with references to the new
   *  constant pool
   */
  public void replaceConstantPool(ConstantPoolGen old_cp, ConstantPoolGen new_cp) {
    for(InstructionHandle ih=start; ih != null; ih = ih.next) {
      Instruction i = ih.instruction;

      if(i instanceof CPInstruction) {
        CPInstruction ci = (CPInstruction)i;
        Constant      c  = old_cp.getConstant(ci.getIndex());
        ci.setIndex(new_cp.addConstant(c, old_cp));
      }
    }
  }

  private void clear() {
    start = end = null;
    length = 0;
  }

  
Delete contents of list. Provides besser memory utilization,
because the system then may reuse the instruction handles. This
method is typically called right after
MethodGen.getMethod().
/**
   * Delete contents of list. Provides besser memory utilization,
   * because the system then may reuse the instruction handles. This
   * method is typically called right after
   * <href="MethodGen.html#getMethod()">MethodGen.getMethod()</a>.
   */
  public void dispose() {
    // Traverse in reverse order, because ih.next is overwritten
    for(InstructionHandle ih=end; ih != null; ih = ih.prev)
      /* Causes BranchInstructions to release target and targeters, because it
       * calls dispose() on the contained instruction.
       */
      ih.dispose();

    clear();
  }

  
Returns:
start of list/**
   * @return start of list
   */
  public InstructionHandle getStart() { return start; }

  
Returns:
end of list/**
   * @return end of list
   */
  public InstructionHandle getEnd()   { return end; }

  
Returns:
length of list (Number of instructions, not bytes)/**
   * @return length of list (Number of instructions, not bytes)
   */
  public int getLength() { return length; }

  
Returns:
length of list (Number of instructions, not bytes)/**
   * @return length of list (Number of instructions, not bytes)
   */
  public int size() { return length; }

  
Redirect all references from old_target to new_target, i.e., update targets
of branch instructions.
Params:
old_target – the old target instruction handle
new_target – the new target instruction handle/**
   * Redirect all references from old_target to new_target, i.e., update targets
   * of branch instructions.
   *
   * @param old_target the old target instruction handle
   * @param new_target the new target instruction handle
   */
  public void redirectBranches(InstructionHandle old_target,
                               InstructionHandle new_target) {
    for(InstructionHandle ih = start; ih != null; ih = ih.next) {
      Instruction i  = ih.getInstruction();

      if(i instanceof BranchInstruction) {
        BranchInstruction b      = (BranchInstruction)i;
        InstructionHandle target = b.getTarget();

        if(target == old_target)
          b.setTarget(new_target);

        if(b instanceof Select) { // Either LOOKUPSWITCH or TABLESWITCH
          InstructionHandle[] targets = ((Select)b).getTargets();

          for(int j=0; j < targets.length; j++) // Update targets
            if(targets[j] == old_target)
              ((Select)b).setTarget(j, new_target);
        }
      }
    }
  }

  
Redirect all references of local variables from old_target to new_target.
Params:
lg – array of local variables
old_target – the old target instruction handle
new_target – the new target instruction handle
See Also:
MethodGen/**
   * Redirect all references of local variables from old_target to new_target.
   *
   * @param lg array of local variables
   * @param old_target the old target instruction handle
   * @param new_target the new target instruction handle
   * @see MethodGen
   */
  public void redirectLocalVariables(LocalVariableGen[] lg,
                                     InstructionHandle old_target,
                                     InstructionHandle new_target) {
    for(int i=0; i < lg.length; i++) {
      InstructionHandle start = lg[i].getStart();
      InstructionHandle end   = lg[i].getEnd();

      if(start == old_target)
        lg[i].setStart(new_target);

      if(end == old_target)
        lg[i].setEnd(new_target);
    }
  }

  
Redirect all references of exception handlers from old_target to new_target.
Params:
exceptions – array of exception handlers
old_target – the old target instruction handle
new_target – the new target instruction handle
See Also:
MethodGen/**
   * Redirect all references of exception handlers from old_target to new_target.
   *
   * @param exceptions array of exception handlers
   * @param old_target the old target instruction handle
   * @param new_target the new target instruction handle
   * @see MethodGen
   */
  public void redirectExceptionHandlers(CodeExceptionGen[] exceptions,
                                        InstructionHandle old_target,
                                        InstructionHandle new_target) {
    for(int i=0; i < exceptions.length; i++) {
      if(exceptions[i].getStartPC() == old_target)
        exceptions[i].setStartPC(new_target);

      if(exceptions[i].getEndPC() == old_target)
        exceptions[i].setEndPC(new_target);

      if(exceptions[i].getHandlerPC() == old_target)
        exceptions[i].setHandlerPC(new_target);
    }
  }

  private ArrayList observers;

  
Add observer for this object.
/** Add observer for this object.
   */
  public void addObserver(InstructionListObserver o) {
    if(observers == null)
      observers = new ArrayList();

    observers.add(o);
  }

  
Remove observer for this object.
/** Remove observer for this object.
   */
  public void removeObserver(InstructionListObserver o) {
    if(observers != null)
      observers.remove(o);
  }

  
Call notify() method on all observers. This method is not called
automatically whenever the state has changed, but has to be
called by the user after he has finished editing the object.
/** Call notify() method on all observers. This method is not called
   * automatically whenever the state has changed, but has to be
   * called by the user after he has finished editing the object.
   */
  public void update() {
    if(observers != null)
      for(Iterator e = observers.iterator(); e.hasNext(); )
        ((InstructionListObserver)e.next()).notify(this);
  }
}