LocalVariableGen.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 org.apache.bcel.Const;
import org.apache.bcel.classfile.LocalVariable;
/**
* Represents a local variable within a method. It contains its scope, name and type. The generated LocalVariable object
* can be obtained with getLocalVariable which needs the instruction list and the constant pool as parameters.
*
* @see LocalVariable
* @see MethodGen
*/
public class LocalVariableGen implements InstructionTargeter, NamedAndTyped, Cloneable {
private int index;
private String name;
private Type type;
private InstructionHandle start;
private InstructionHandle end;
private int origIndex; // never changes; used to match up with LocalVariableTypeTable entries
private boolean liveToEnd;
/**
* Generate a local variable that with index 'index'. Note that double and long variables need two indexs. Index indices
* have to be provided by the user.
*
* @param index index of local variable
* @param name its name
* @param type its type
* @param start from where the instruction is valid (null means from the start)
* @param end until where the instruction is valid (null means to the end)
*/
public LocalVariableGen(final int index, final String name, final Type type, final InstructionHandle start, final InstructionHandle end) {
if (index < 0 || index > Const.MAX_SHORT) {
throw new ClassGenException("Invalid index: " + index);
}
this.name = name;
this.type = type;
this.index = index;
setStart(start);
setEnd(end);
this.origIndex = index;
this.liveToEnd = end == null;
}
/**
* Generates a local variable that with index 'index'. Note that double and long variables need two indexs. Index
* indices have to be provided by the user.
*
* @param index index of local variable
* @param name its name
* @param type its type
* @param start from where the instruction is valid (null means from the start)
* @param end until where the instruction is valid (null means to the end)
* @param origIndex index of local variable prior to any changes to index
*/
public LocalVariableGen(final int index, final String name, final Type type, final InstructionHandle start, final InstructionHandle end,
final int origIndex) {
this(index, name, type, start, end);
this.origIndex = origIndex;
}
@Override
public Object clone() {
try {
return super.clone();
} catch (final CloneNotSupportedException e) {
throw new UnsupportedOperationException("Clone Not Supported", e); // never happens
}
}
/**
* @return true, if ih is target of this variable
*/
@Override
public boolean containsTarget(final InstructionHandle ih) {
return start == ih || end == ih;
}
/**
* Clear the references from and to this variable when it's removed.
*/
void dispose() {
setStart(null);
setEnd(null);
}
/**
* We consider to local variables to be equal, if the use the same index and are valid in the same range.
*/
@Override
public boolean equals(final Object o) {
if (!(o instanceof LocalVariableGen)) {
return false;
}
final LocalVariableGen l = (LocalVariableGen) o;
return l.index == index && l.start == start && l.end == end;
}
public InstructionHandle getEnd() {
return end;
}
public int getIndex() {
return index;
}
public boolean getLiveToEnd() {
return liveToEnd;
}
/**
* Gets LocalVariable object.
*
* This relies on that the instruction list has already been dumped to byte code or that the 'setPositions' methods
* has been called for the instruction list.
*
* Note that due to the conversion from byte code offset to InstructionHandle, it is impossible to tell the difference
* between a live range that ends BEFORE the last insturction of the method or a live range that ends AFTER the last
* instruction of the method. Hence the liveToEnd flag to differentiate between these two cases.
*
* @param cp constant pool
*/
public LocalVariable getLocalVariable(final ConstantPoolGen cp) {
int startPc = 0;
int length = 0;
if (start != null && end != null) {
startPc = start.getPosition();
length = end.getPosition() - startPc;
if (end.getNext() == null && liveToEnd) {
length += end.getInstruction().getLength();
}
}
final int nameIndex = cp.addUtf8(name);
final int signatureIndex = cp.addUtf8(type.getSignature());
return new LocalVariable(startPc, length, nameIndex, signatureIndex, index, cp.getConstantPool(), origIndex);
}
@Override
public String getName() {
return name;
}
public int getOrigIndex() {
return origIndex;
}
public InstructionHandle getStart() {
return start;
}
@Override
public Type getType() {
return type;
}
@Override
public int hashCode() {
// If the user changes the name or type, problems with the targeter hashmap will occur.
// Note: index cannot be part of hash as it may be changed by the user.
return name.hashCode() ^ type.hashCode();
}
public void setEnd(final InstructionHandle end) { // TODO could be package-protected?
BranchInstruction.notifyTarget(this.end, end, this);
this.end = end;
}
public void setIndex(final int index) {
this.index = index;
}
public void setLiveToEnd(final boolean liveToEnd) {
this.liveToEnd = liveToEnd;
}
@Override
public void setName(final String name) {
this.name = name;
}
public void setStart(final InstructionHandle start) { // TODO could be package-protected?
BranchInstruction.notifyTarget(this.start, start, this);
this.start = start;
}
@Override
public void setType(final Type type) {
this.type = type;
}
@Override
public String toString() {
return "LocalVariableGen(" + name + ", " + type + ", " + start + ", " + end + ")";
}
/**
* @param oldIh old target, either start or end
* @param newIh new target
*/
@Override
public void updateTarget(final InstructionHandle oldIh, final InstructionHandle newIh) {
boolean targeted = false;
if (start == oldIh) {
targeted = true;
setStart(newIh);
}
if (end == oldIh) {
targeted = true;
setEnd(newIh);
}
if (!targeted) {
throw new ClassGenException("Not targeting " + oldIh + ", but {" + start + ", " + end + "}");
}
}
}