Select.java
/*
* 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} property as the default target.
*
* @see LOOKUPSWITCH
* @see TABLESWITCH
* @see InstructionList
*/
public abstract class Select extends BranchInstruction implements VariableLengthInstruction, StackConsumer /* @since 6.0 */, StackProducer {
/**
* @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
*/
@Deprecated
protected int[] match; // matches, i.e., case 1: ... TODO could be package-protected?
/**
* @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
*/
@Deprecated
protected int[] indices; // target offsets TODO could be package-protected?
/**
* @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
*/
@Deprecated
protected InstructionHandle[] targets; // target objects in instruction list TODO could be package-protected?
/**
* @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
*/
@Deprecated
protected int fixed_length; // fixed length defined by subclasses TODO could be package-protected?
/**
* @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
*/
@Deprecated
protected int match_length; // number of cases TODO could be package-protected?
/**
* @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
*/
@Deprecated
protected int padding; // number of pad bytes for alignment TODO could be package-protected?
/**
* Empty constructor needed for 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(final short opcode, final int[] match, final InstructionHandle[] targets, final InstructionHandle defaultTarget) {
// don't set default target before instruction is built
super(opcode, null);
this.match = match;
this.targets = targets;
// now it's safe to set default target
setTarget(defaultTarget);
for (final InstructionHandle target2 : targets) {
notifyTarget(null, target2, this);
}
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];
}
@Override
protected Object clone() throws CloneNotSupportedException {
final Select copy = (Select) super.clone();
copy.match = match.clone();
copy.indices = indices.clone();
copy.targets = targets.clone();
return copy;
}
/**
* @return true, if ih is target of this instruction
*/
@Override
public boolean containsTarget(final InstructionHandle ih) {
if (super.getTarget() == ih) {
return true;
}
for (final InstructionHandle target2 : targets) {
if (target2 == ih) {
return true;
}
}
return false;
}
/**
* Inform targets that they're not targeted anymore.
*/
@Override
void dispose() {
super.dispose();
for (final InstructionHandle target2 : targets) {
target2.removeTargeter(this);
}
}
/**
* Dump instruction as byte code to stream out.
*
* @param out Output stream
*/
@Override
public void dump(final DataOutputStream out) throws IOException {
out.writeByte(super.getOpcode());
for (int i = 0; i < padding; i++) {
out.writeByte(0);
}
super.setIndex(getTargetOffset()); // Write default target offset
out.writeInt(super.getIndex());
}
/**
* @return the fixed_length
* @since 6.0
*/
final int getFixedLength() {
return fixed_length;
}
/**
* @return array of match target offsets
*/
public int[] getIndices() {
return indices;
}
/**
* @return index entry from indices
* @since 6.0
*/
final int getIndices(final int index) {
return indices[index];
}
/**
* @return match entry
* @since 6.0
*/
final int getMatch(final int index) {
return match[index];
}
/**
* @return the match_length
* @since 6.0
*/
final int getMatchLength() {
return match_length;
}
/**
* @return array of match indices
*/
public int[] getMatchs() {
return match;
}
/**
*
* @return the padding
* @since 6.0
*/
final int getPadding() {
return padding;
}
/**
* @return target entry
* @since 6.0
*/
final InstructionHandle getTarget(final int index) {
return targets[index];
}
/**
* @return array of match targets
*/
public InstructionHandle[] getTargets() {
return targets;
}
/**
* Read needed data (e.g. index) from file.
*/
@Override
protected void initFromFile(final ByteSequence bytes, final 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)
super.setIndex(bytes.readInt());
}
/**
* @param fixedLength the fixed_length to set
* @since 6.0
*/
final void setFixedLength(final int fixedLength) {
this.fixed_length = fixedLength;
}
/** @since 6.0 */
final int setIndices(final int i, final int value) {
indices[i] = value;
return value; // Allow use in nested calls
}
/**
*
* @param array
* @since 6.0
*/
final void setIndices(final int[] array) {
indices = array;
}
/**
*
* @param index
* @param value
* @since 6.0
*/
final void setMatch(final int index, final int value) {
match[index] = value;
}
/**
*
* @param array
* @since 6.0
*/
final void setMatches(final int[] array) {
match = array;
}
/**
* @param matchLength the match_length to set
* @since 6.0
*/
final int setMatchLength(final int matchLength) {
this.match_length = matchLength;
return matchLength;
}
/**
* Sets branch target for 'i'th case
*/
public void setTarget(final int i, final InstructionHandle target) { // TODO could be package-protected?
notifyTarget(targets[i], target, this);
targets[i] = target;
}
/**
*
* @param array
* @since 6.0
*/
final void setTargets(final InstructionHandle[] array) {
targets = array;
}
/**
* @return mnemonic for instruction
*/
@Override
public String toString(final boolean verbose) {
final StringBuilder buf = new StringBuilder(super.toString(verbose));
if (verbose) {
for (int i = 0; i < match_length; i++) {
String s = "null";
if (targets[i] != null) {
if (targets[i].getInstruction() == this) {
s = "<points to itself>";
} else {
s = targets[i].getInstruction().toString();
}
}
buf.append("(").append(match[i]).append(", ").append(s).append(" = {").append(indices[i]).append("})");
}
} else {
buf.append(" ...");
}
return buf.toString();
}
/**
* 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 maxOffset 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(final int offset, final int maxOffset) {
setPosition(getPosition() + offset); // Additional offset caused by preceding SWITCHs, GOTOs, etc.
final short oldLength = (short) super.getLength();
/*
* Alignment on 4-byte-boundary, + 1, because of tag byte.
*/
padding = (4 - (getPosition() + 1) % 4) % 4;
super.setLength((short) (fixed_length + padding)); // Update length
return super.getLength() - oldLength;
}
/**
* @param oldIh old target
* @param newIh new target
*/
@Override
public void updateTarget(final InstructionHandle oldIh, final InstructionHandle newIh) {
boolean targeted = false;
if (super.getTarget() == oldIh) {
targeted = true;
setTarget(newIh);
}
for (int i = 0; i < targets.length; i++) {
if (targets[i] == oldIh) {
targeted = true;
setTarget(i, newIh);
}
}
if (!targeted) {
throw new ClassGenException("Not targeting " + oldIh);
}
}
}