/*
* 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
* limitations under the License.
*
*/
package org.apache.bcel.generic;
import java.io.DataOutputStream;
import java.io.IOException;
import org.apache.bcel.util.ByteSequence;
/**
* Select - Abstract super class for LOOKUPSWITCH and TABLESWITCH instructions.
*
* <p>We use our super's <code>target</code> property as the default target.
*
* @version $Id: Select.java 1590070 2014-04-25 16:07:54Z ebourg $
* @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
* @see LOOKUPSWITCH
* @see TABLESWITCH
* @see InstructionList
*/
public abstract class Select extends BranchInstruction implements VariableLengthInstruction,
StackConsumer, StackProducer {
private static final long serialVersionUID = 2806771744559217250L;
protected int[] match; // matches, i.e., case 1: ...
protected int[] indices; // target offsets
protected InstructionHandle[] targets; // target objects in instruction list
protected int fixed_length; // fixed length defined by subclasses
protected int match_length; // number of cases
protected int padding = 0; // number of pad bytes for alignment
/**
* Empty constructor needed for the Class.newInstance() statement in
* Instruction.readInstruction(). Not to be used otherwise.
*/
Select() {
}
/**
* (Match, target) pairs for switch.
* `Match' and `targets' must have the same length of course.
*
* @param match array of matching values
* @param targets instruction targets
* @param defaultTarget default instruction target
*/
Select(short opcode, int[] match, InstructionHandle[] targets, InstructionHandle defaultTarget) {
super(opcode, defaultTarget);
this.targets = targets;
for (InstructionHandle target2 : targets) {
notifyTarget(null, target2, this);
}
this.match = match;
if ((match_length = match.length) != targets.length) {
throw new ClassGenException("Match and target array have not the same length: Match length: " + match.length + " Target length: " + targets.length);
}
indices = new int[match_length];
}
/**
* Since this is a variable length instruction, it may shift the following
* instructions which then need to update their position.
*
* Called by InstructionList.setPositions when setting the position for every
* instruction. In the presence of variable length instructions `setPositions'
* performs multiple passes over the instruction list to calculate the
* correct (byte) positions and offsets by calling this function.
*
* @param offset additional offset caused by preceding (variable length) instructions
* @param max_offset the maximum offset that may be caused by these instructions
* @return additional offset caused by possible change of this instruction's length
*/
@Override
protected int updatePosition( int offset, int max_offset ) {
position += offset; // Additional offset caused by preceding SWITCHs, GOTOs, etc.
short old_length = length;
/* Alignment on 4-byte-boundary, + 1, because of tag byte.
*/
padding = (4 - ((position + 1) % 4)) % 4;
length = (short) (fixed_length + padding); // Update length
return length - old_length;
}
/**
* Dump instruction as byte code to stream out.
* @param out Output stream
*/
@Override
public void dump( DataOutputStream out ) throws IOException {
out.writeByte(opcode);
for (int i = 0; i < padding; i++) {
out.writeByte(0);
}
index = getTargetOffset(); // Write default target offset
out.writeInt(index);
}
/**
* Read needed data (e.g. index) from file.
*/
@Override
protected void initFromFile( ByteSequence bytes, boolean wide ) throws IOException {
padding = (4 - (bytes.getIndex() % 4)) % 4; // Compute number of pad bytes
for (int i = 0; i < padding; i++) {
bytes.readByte();
}
// Default branch target common for both cases (TABLESWITCH, LOOKUPSWITCH)
index = bytes.readInt();
}
/**
* @return mnemonic for instruction
*/
@Override
public String toString( boolean verbose ) {
StringBuilder buf = new StringBuilder(super.toString(verbose));
if (verbose) {
for (int i = 0; i < match_length; i++) {
String s = "null";
if (targets[i] != null) {
s = targets[i].getInstruction().toString();
}
buf.append("(").append(match[i]).append(", ").append(s).append(" = {").append(
indices[i]).append("})");
}
} else {
buf.append(" ...");
}
return buf.toString();
}
/**
* Set branch target for `i'th case
*/
public void setTarget( int i, InstructionHandle target ) {
notifyTarget(targets[i], target, this);
targets[i] = target;
}
/**
* @param old_ih old target
* @param new_ih new target
*/
@Override
public void updateTarget( InstructionHandle old_ih, InstructionHandle new_ih ) {
boolean targeted = false;
if (target == old_ih) {
targeted = true;
setTarget(new_ih);
}
for (int i = 0; i < targets.length; i++) {
if (targets[i] == old_ih) {
targeted = true;
setTarget(i, new_ih);
}
}
if (!targeted) {
throw new ClassGenException("Not targeting " + old_ih);
}
}
/**
* @return true, if ih is target of this instruction
*/
@Override
public boolean containsTarget( InstructionHandle ih ) {
if (target == ih) {
return true;
}
for (InstructionHandle target2 : targets) {
if (target2 == ih) {
return true;
}
}
return false;
}
@Override
protected Object clone() throws CloneNotSupportedException {
Select copy = (Select) super.clone();
copy.match = match.clone();
copy.indices = indices.clone();
copy.targets = targets.clone();
return copy;
}
/**
* Inform targets that they're not targeted anymore.
*/
@Override
void dispose() {
super.dispose();
for (InstructionHandle target2 : targets) {
target2.removeTargeter(this);
}
}
/**
* @return array of match indices
*/
public int[] getMatchs() {
return match;
}
/**
* @return array of match target offsets
*/
public int[] getIndices() {
return indices;
}
/**
* @return array of match targets
*/
public InstructionHandle[] getTargets() {
return targets;
}
}