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Javassist (JAVA programming ASSISTant) makes Java bytecode manipulation
simple. It is a class library for editing bytecodes in Java.
/*
* Javassist, a Java-bytecode translator toolkit.
* Copyright (C) 1999- Shigeru Chiba. All Rights Reserved.
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. Alternatively, the contents of this file may be used under
* the terms of the GNU Lesser General Public License Version 2.1 or later,
* or the Apache License Version 2.0.
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*/
package javassist.bytecode;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
class ExceptionTableEntry {
int startPc;
int endPc;
int handlerPc;
int catchType;
ExceptionTableEntry(int start, int end, int handle, int type) {
startPc = start;
endPc = end;
handlerPc = handle;
catchType = type;
}
}
/**
* exception_table[] of Code_attribute.
*/
public class ExceptionTable implements Cloneable {
private ConstPool constPool;
private List entries;
/**
* Constructs an exception_table[].
*
* @param cp constant pool table.
*/
public ExceptionTable(ConstPool cp) {
constPool = cp;
entries = new ArrayList();
}
ExceptionTable(ConstPool cp, DataInputStream in) throws IOException {
constPool = cp;
int length = in.readUnsignedShort();
List list = new ArrayList(length);
for (int i = 0; i < length; ++i) {
int start = in.readUnsignedShort();
int end = in.readUnsignedShort();
int handle = in.readUnsignedShort();
int type = in.readUnsignedShort();
list.add(new ExceptionTableEntry(start, end, handle, type));
}
entries = list;
}
/**
* Creates and returns a copy of this object.
* The constant pool object is shared between this object
* and the cloned object.
*/
@Override
public Object clone() throws CloneNotSupportedException {
ExceptionTable r = (ExceptionTable)super.clone();
r.entries = new ArrayList(entries);
return r;
}
/**
* Returns exception_table_length, which is the number
* of entries in the exception_table[].
*/
public int size() {
return entries.size();
}
/**
* Returns startPc of the n-th entry.
*
* @param nth the n-th (>= 0).
*/
public int startPc(int nth) {
return entries.get(nth).startPc;
}
/**
* Sets startPc of the n-th entry.
*
* @param nth the n-th (>= 0).
* @param value new value.
*/
public void setStartPc(int nth, int value) {
entries.get(nth).startPc = value;
}
/**
* Returns endPc of the n-th entry.
*
* @param nth the n-th (>= 0).
*/
public int endPc(int nth) {
return entries.get(nth).endPc;
}
/**
* Sets endPc of the n-th entry.
*
* @param nth the n-th (>= 0).
* @param value new value.
*/
public void setEndPc(int nth, int value) {
entries.get(nth).endPc = value;
}
/**
* Returns handlerPc of the n-th entry.
*
* @param nth the n-th (>= 0).
*/
public int handlerPc(int nth) {
return entries.get(nth).handlerPc;
}
/**
* Sets handlerPc of the n-th entry.
*
* @param nth the n-th (>= 0).
* @param value new value.
*/
public void setHandlerPc(int nth, int value) {
entries.get(nth).handlerPc = value;
}
/**
* Returns catchType of the n-th entry.
*
* @param nth the n-th (>= 0).
* @return an index into the constant_pool table,
* or zero if this exception handler is for all exceptions.
*/
public int catchType(int nth) {
return entries.get(nth).catchType;
}
/**
* Sets catchType of the n-th entry.
*
* @param nth the n-th (>= 0).
* @param value new value.
*/
public void setCatchType(int nth, int value) {
entries.get(nth).catchType = value;
}
/**
* Copies the given exception table at the specified position
* in the table.
*
* @param index index (>= 0) at which the entry is to be inserted.
* @param offset the offset added to the code position.
*/
public void add(int index, ExceptionTable table, int offset) {
int len = table.size();
while (--len >= 0) {
ExceptionTableEntry e = table.entries.get(len);
add(index, e.startPc + offset, e.endPc + offset,
e.handlerPc + offset, e.catchType);
}
}
/**
* Adds a new entry at the specified position in the table.
*
* @param index index (>= 0) at which the entry is to be inserted.
* @param start startPc
* @param end endPc
* @param handler handlerPc
* @param type catchType
*/
public void add(int index, int start, int end, int handler, int type) {
if (start < end)
entries.add(index,
new ExceptionTableEntry(start, end, handler, type));
}
/**
* Appends a new entry at the end of the table.
*
* @param start startPc
* @param end endPc
* @param handler handlerPc
* @param type catchType
*/
public void add(int start, int end, int handler, int type) {
if (start < end)
entries.add(new ExceptionTableEntry(start, end, handler, type));
}
/**
* Removes the entry at the specified position in the table.
*
* @param index the index of the removed entry.
*/
public void remove(int index) {
entries.remove(index);
}
/**
* Makes a copy of this exception_table[].
* Class names are replaced according to the
* given Map object.
*
* @param newCp the constant pool table used by the new copy.
* @param classnames pairs of replaced and substituted
* class names.
*/
public ExceptionTable copy(ConstPool newCp, Map classnames) {
ExceptionTable et = new ExceptionTable(newCp);
ConstPool srcCp = constPool;
for (ExceptionTableEntry e:entries) {
int type = srcCp.copy(e.catchType, newCp, classnames);
et.add(e.startPc, e.endPc, e.handlerPc, type);
}
return et;
}
void shiftPc(int where, int gapLength, boolean exclusive) {
for (ExceptionTableEntry e:entries) {
e.startPc = shiftPc(e.startPc, where, gapLength, exclusive);
e.endPc = shiftPc(e.endPc, where, gapLength, exclusive);
e.handlerPc = shiftPc(e.handlerPc, where, gapLength, exclusive);
}
}
private static int shiftPc(int pc, int where, int gapLength,
boolean exclusive) {
if (pc > where || (exclusive && pc == where))
pc += gapLength;
return pc;
}
void write(DataOutputStream out) throws IOException {
out.writeShort(size()); // exception_table_length
for (ExceptionTableEntry e:entries) {
out.writeShort(e.startPc);
out.writeShort(e.endPc);
out.writeShort(e.handlerPc);
out.writeShort(e.catchType);
}
}
}