LocalVariableAttribute.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.IOException;
import java.util.Map;
/**
* <code>LocalVariableTable_attribute</code>.
*/
public class LocalVariableAttribute extends AttributeInfo {
/**
* The name of this attribute <code>"LocalVariableTable"</code>.
*/
public static final String tag = "LocalVariableTable";
/**
* The name of the attribute <code>"LocalVariableTypeTable"</code>.
*/
public static final String typeTag = "LocalVariableTypeTable";
/**
* Constructs an empty LocalVariableTable.
*/
public LocalVariableAttribute(ConstPool cp) {
super(cp, tag, new byte[2]);
ByteArray.write16bit(0, info, 0);
}
/**
* Constructs an empty LocalVariableTable.
*
* @param name the attribute name.
* <code>LocalVariableAttribute.tag</code> or
* <code>LocalVariableAttribute.typeTag</code>.
* @see #tag
* @see #typeTag
* @since 3.1
* @deprecated
*/
@Deprecated
public LocalVariableAttribute(ConstPool cp, String name) {
super(cp, name, new byte[2]);
ByteArray.write16bit(0, info, 0);
}
LocalVariableAttribute(ConstPool cp, int n, DataInputStream in)
throws IOException
{
super(cp, n, in);
}
LocalVariableAttribute(ConstPool cp, String name, byte[] i) {
super(cp, name, i);
}
/**
* Appends a new entry to <code>local_variable_table</code>.
*
* @param startPc <code>start_pc</code>
* @param length <code>length</code>
* @param nameIndex <code>name_index</code>
* @param descriptorIndex <code>descriptor_index</code>
* @param index <code>index</code>
*/
public void addEntry(int startPc, int length, int nameIndex,
int descriptorIndex, int index) {
int size = info.length;
byte[] newInfo = new byte[size + 10];
ByteArray.write16bit(tableLength() + 1, newInfo, 0);
for (int i = 2; i < size; ++i)
newInfo[i] = info[i];
ByteArray.write16bit(startPc, newInfo, size);
ByteArray.write16bit(length, newInfo, size + 2);
ByteArray.write16bit(nameIndex, newInfo, size + 4);
ByteArray.write16bit(descriptorIndex, newInfo, size + 6);
ByteArray.write16bit(index, newInfo, size + 8);
info = newInfo;
}
@Override
void renameClass(String oldname, String newname) {
ConstPool cp = getConstPool();
int n = tableLength();
for (int i = 0; i < n; ++i) {
int pos = i * 10 + 2;
int index = ByteArray.readU16bit(info, pos + 6);
if (index != 0) {
String desc = cp.getUtf8Info(index);
desc = renameEntry(desc, oldname, newname);
ByteArray.write16bit(cp.addUtf8Info(desc), info, pos + 6);
}
}
}
String renameEntry(String desc, String oldname, String newname) {
return Descriptor.rename(desc, oldname, newname);
}
@Override
void renameClass(Map<String,String> classnames) {
ConstPool cp = getConstPool();
int n = tableLength();
for (int i = 0; i < n; ++i) {
int pos = i * 10 + 2;
int index = ByteArray.readU16bit(info, pos + 6);
if (index != 0) {
String desc = cp.getUtf8Info(index);
desc = renameEntry(desc, classnames);
ByteArray.write16bit(cp.addUtf8Info(desc), info, pos + 6);
}
}
}
String renameEntry(String desc, Map<String,String> classnames) {
return Descriptor.rename(desc, classnames);
}
/**
* For each <code>local_variable_table[i].index</code>,
* this method increases <code>index</code> by <code>delta</code>.
*
* @param lessThan the index does not change if it
* is less than this value.
*/
public void shiftIndex(int lessThan, int delta) {
int size = info.length;
for (int i = 2; i < size; i += 10){
int org = ByteArray.readU16bit(info, i + 8);
if (org >= lessThan)
ByteArray.write16bit(org + delta, info, i + 8);
}
}
/**
* Returns <code>local_variable_table_length</code>.
* This represents the number of entries in the table.
*/
public int tableLength() {
return ByteArray.readU16bit(info, 0);
}
/**
* Returns <code>local_variable_table[i].start_pc</code>.
* This represents the index into the code array from which the local
* variable is effective.
*
* @param i the i-th entry.
*/
public int startPc(int i) {
return ByteArray.readU16bit(info, i * 10 + 2);
}
/**
* Returns <code>local_variable_table[i].length</code>.
* This represents the length of the code region in which the local
* variable is effective.
*
* @param i the i-th entry.
*/
public int codeLength(int i) {
return ByteArray.readU16bit(info, i * 10 + 4);
}
/**
* Adjusts start_pc and length if bytecode is inserted in a method body.
*/
void shiftPc(int where, int gapLength, boolean exclusive) {
int n = tableLength();
for (int i = 0; i < n; ++i) {
int pos = i * 10 + 2;
int pc = ByteArray.readU16bit(info, pos);
int len = ByteArray.readU16bit(info, pos + 2);
/* if pc == 0, then the local variable is a method parameter.
*/
if (pc > where || (exclusive && pc == where && pc != 0))
ByteArray.write16bit(pc + gapLength, info, pos);
else if (pc + len > where || (exclusive && pc + len == where))
ByteArray.write16bit(len + gapLength, info, pos + 2);
}
}
/**
* Returns the value of <code>local_variable_table[i].name_index</code>.
* This represents the name of the local variable.
*
* @param i the i-th entry.
*/
public int nameIndex(int i) {
return ByteArray.readU16bit(info, i * 10 + 6);
}
/**
* Returns the name of the local variable
* specified by <code>local_variable_table[i].name_index</code>.
*
* @param i the i-th entry.
*/
public String variableName(int i) {
return getConstPool().getUtf8Info(nameIndex(i));
}
/**
* Returns the name of the local variable with given index.
* If you want to get the parameter name of method with correct order,
* you should using this method.
*
* @param index the index of the local variable.
*/
public String variableNameByIndex(int index) {
for (int i = 0; i < tableLength(); i++) {
if (index(i) == index) {
return variableName(i);
}
}
throw new ArrayIndexOutOfBoundsException();
}
/**
* Returns the value of
* <code>local_variable_table[i].descriptor_index</code>.
* This represents the type descriptor of the local variable.
* <p>
* If this attribute represents a LocalVariableTypeTable attribute,
* this method returns the value of
* <code>local_variable_type_table[i].signature_index</code>.
* It represents the type of the local variable.
*
* @param i the i-th entry.
*/
public int descriptorIndex(int i) {
return ByteArray.readU16bit(info, i * 10 + 8);
}
/**
* This method is equivalent to <code>descriptorIndex()</code>.
* If this attribute represents a LocalVariableTypeTable attribute,
* this method should be used instead of <code>descriptorIndex()</code>
* since the method name is more appropriate.
*
* @param i the i-th entry.
* @see #descriptorIndex(int)
* @see SignatureAttribute#toFieldSignature(String)
*/
public int signatureIndex(int i) {
return descriptorIndex(i);
}
/**
* Returns the type descriptor of the local variable
* specified by <code>local_variable_table[i].descriptor_index</code>.
* <p>
* If this attribute represents a LocalVariableTypeTable attribute,
* this method returns the type signature of the local variable
* specified by <code>local_variable_type_table[i].signature_index</code>.
*
* @param i the i-th entry.
*/
public String descriptor(int i) {
return getConstPool().getUtf8Info(descriptorIndex(i));
}
/**
* This method is equivalent to <code>descriptor()</code>.
* If this attribute represents a LocalVariableTypeTable attribute,
* this method should be used instead of <code>descriptor()</code>
* since the method name is more appropriate.
*
* <p>To parse the string, call <code>toFieldSignature(String)</code>
* in <code>SignatureAttribute</code>.
*
* @param i the i-th entry.
* @see #descriptor(int)
* @see SignatureAttribute#toFieldSignature(String)
*/
public String signature(int i) {
return descriptor(i);
}
/**
* Returns <code>local_variable_table[i].index</code>.
* This represents the index of the local variable.
*
* @param i the i-th entry.
*/
public int index(int i) {
return ByteArray.readU16bit(info, i * 10 + 10);
}
/**
* Makes a copy.
*
* @param newCp the constant pool table used by the new copy.
* @param classnames should be null.
*/
@Override
public AttributeInfo copy(ConstPool newCp, Map<String,String> classnames) {
byte[] src = get();
byte[] dest = new byte[src.length];
ConstPool cp = getConstPool();
LocalVariableAttribute attr = makeThisAttr(newCp, dest);
int n = ByteArray.readU16bit(src, 0);
ByteArray.write16bit(n, dest, 0);
int j = 2;
for (int i = 0; i < n; ++i) {
int start = ByteArray.readU16bit(src, j);
int len = ByteArray.readU16bit(src, j + 2);
int name = ByteArray.readU16bit(src, j + 4);
int type = ByteArray.readU16bit(src, j + 6);
int index = ByteArray.readU16bit(src, j + 8);
ByteArray.write16bit(start, dest, j);
ByteArray.write16bit(len, dest, j + 2);
if (name != 0)
name = cp.copy(name, newCp, null);
ByteArray.write16bit(name, dest, j + 4);
if (type != 0) {
String sig = cp.getUtf8Info(type);
sig = Descriptor.rename(sig, classnames);
type = newCp.addUtf8Info(sig);
}
ByteArray.write16bit(type, dest, j + 6);
ByteArray.write16bit(index, dest, j + 8);
j += 10;
}
return attr;
}
// LocalVariableTypeAttribute overrides this method.
LocalVariableAttribute makeThisAttr(ConstPool cp, byte[] dest) {
return new LocalVariableAttribute(cp, tag, dest);
}
}