/*
* Copyright 2000-2004 The Apache Software Foundation
*
* Licensed 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
* limitations under the License.
*
*/
package org.apache.bcel.generic;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.apache.bcel.Constants;
import org.apache.bcel.classfile.Constant;
import org.apache.bcel.util.ByteSequence;
/**
* 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>.
*
* @version $Id: InstructionList.java 386056 2006-03-15 11:31:56Z tcurdt $
* @author <A HREF="mailto:m.dahm@gmx.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.
*/
public InstructionList() {
}
/**
* Create instruction list containing one instruction.
* @param i initial instruction
*/
public InstructionList(Instruction i) {
append(i);
}
/**
* 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.
*
* @param c compound instruction (list)
*/
public InstructionList(CompoundInstruction c) {
append(c.getInstructionList());
}
/**
* 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).
*
* @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) {
return ihs[i];
} else if (target < j) {
r = i - 1;
} else {
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.
*
* @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.
*
* @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) {
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) {
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) {
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.
*
* @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()) {
return ih;
}
InstructionHandle next = ih.next, ret = il.start;
ih.next = il.start;
il.start.prev = ih;
il.end.next = next;
if (next != null) {
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.
*
* @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) {
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.
*
* @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()) {
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.
*
* @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.
*
* @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.
*
* @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!
*
* @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.
*
* @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.
*
* @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.
*
* @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.
*
* @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.
*
* @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.
*
* @param ih 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()) {
return ih;
}
InstructionHandle prev = ih.prev, ret = il.start;
ih.prev = il.end;
il.end.next = ih;
il.start.prev = prev;
if (prev != null) {
prev.next = il.start;
} else {
start = il.start; // Update start ...
}
length += il.length; // Update length
il.clear();
return ret;
}
/**
* 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.
*
* @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.
*
* @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.
*
* @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.
*
* @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!
*
* @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.
*
* @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.
*
* @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.
*
* @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.
*
* @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.
*
* @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.<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) {
throw new ClassGenException("Invalid range: From " + start + " to " + end);
} else if (ih == target) {
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 {
this.start = next;
}
if (next != null) {
next.prev = prev;
} else {
this.end = prev;
}
start.prev = end.next = null;
// Step 3: append after target
if (target == null) { // append to start of list
if (this.start != null) {
this.start.prev = end;
}
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;
} else {
this.end = end;
}
}
}
/**
* 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.
*
* @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;
List 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!
*
* @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!
*
* @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!
*
* @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!
*
* @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.
*
* @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
*
* @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.
*
* @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.
*
* @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();
}
/**
* @return an array of instructions without target information for branch instructions.
*/
public Instruction[] getInstructions() {
ByteSequence bytes = new ByteSequence(getByteCode());
List instructions = new ArrayList();
try {
while (bytes.available() > 0) {
instructions.add(Instruction.readInstruction(bytes));
}
} catch (IOException e) {
throw new ClassGenException(e.toString());
}
return (Instruction[]) instructions.toArray(new Instruction[instructions.size()]);
}
public String toString() {
return toString(true);
}
/**
* @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)).append("\n");
}
return buf.toString();
}
/**
* @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;
}
};
}
/**
* @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.
*
* @return array containing all instruction's offset in byte code
*/
public int[] getInstructionPositions() {
return byte_positions;
}
/**
* @return complete, i.e., deep copy of this list
*/
public InstructionList copy() {
Map 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
*/
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
* <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();
}
/**
* @return start of list
*/
public InstructionHandle getStart() {
return start;
}
/**
* @return end of list
*/
public InstructionHandle getEnd() {
return end;
}
/**
* @return length of list (Number of instructions, not bytes)
*/
public int getLength() {
return length;
}
/**
* @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.
*
* @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++) {
if (targets[j] == old_target) {
((Select) b).setTarget(j, new_target);
}
}
}
}
}
}
/**
* 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.
*
* @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 List observers;
/** Add observer for this object.
*/
public void addObserver( InstructionListObserver o ) {
if (observers == null) {
observers = new ArrayList();
}
observers.add(o);
}
/** 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.
*/
public void update() {
if (observers != null) {
for (Iterator e = observers.iterator(); e.hasNext();) {
((InstructionListObserver) e.next()).notify(this);
}
}
}
}