org.apache.bcel.generic.LocalVariableInstruction Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of bcel Show documentation
Show all versions of bcel Show documentation
Apache Commons Bytecode Engineering Library
/*
* 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.Const;
import org.apache.bcel.util.ByteSequence;
/**
* Abstract super class for instructions dealing with local variables.
*
* @version $Id: LocalVariableInstruction.java 1806200 2017-08-25 16:33:06Z ggregory $
*/
public abstract class LocalVariableInstruction extends Instruction implements TypedInstruction,
IndexedInstruction {
/**
* @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
*/
@Deprecated
protected int n = -1; // index of referenced variable
private short c_tag = -1; // compact version, such as ILOAD_0
private short canon_tag = -1; // canonical tag such as ILOAD
private boolean wide() {
return n > Const.MAX_BYTE;
}
/**
* Empty constructor needed for the Class.newInstance() statement in
* Instruction.readInstruction(). Not to be used otherwise.
* tag and length are defined in readInstruction and initFromFile, respectively.
*/
LocalVariableInstruction(final short canon_tag, final short c_tag) {
super();
this.canon_tag = canon_tag;
this.c_tag = c_tag;
}
/**
* Empty constructor needed for the Class.newInstance() statement in
* Instruction.readInstruction(). Also used by IINC()!
*/
LocalVariableInstruction() {
}
/**
* @param opcode Instruction opcode
* @param c_tag Instruction number for compact version, ALOAD_0, e.g.
* @param n local variable index (unsigned short)
*/
protected LocalVariableInstruction(final short opcode, final short c_tag, final int n) {
super(opcode, (short) 2);
this.c_tag = c_tag;
canon_tag = opcode;
setIndex(n);
}
/**
* Dump instruction as byte code to stream out.
* @param out Output stream
*/
@Override
public void dump( final DataOutputStream out ) throws IOException {
if (wide()) {
out.writeByte(Const.WIDE);
}
out.writeByte(super.getOpcode());
if (super.getLength() > 1) { // Otherwise ILOAD_n, instruction, e.g.
if (wide()) {
out.writeShort(n);
} else {
out.writeByte(n);
}
}
}
/**
* Long output format:
*
* <name of opcode> "["<opcode number>"]"
* "("<length of instruction>")" "<"< local variable index>">"
*
* @param verbose long/short format switch
* @return mnemonic for instruction
*/
@Override
public String toString( final boolean verbose ) {
final short _opcode = super.getOpcode();
if (((_opcode >= Const.ILOAD_0) && (_opcode <= Const.ALOAD_3))
|| ((_opcode >= Const.ISTORE_0) && (_opcode <= Const.ASTORE_3))) {
return super.toString(verbose);
}
return super.toString(verbose) + " " + n;
}
/**
* Read needed data (e.g. index) from file.
*
* (ILOAD <= tag <= ALOAD_3) || (ISTORE <= tag <= ASTORE_3)
*
*/
@Override
protected void initFromFile( final ByteSequence bytes, final boolean wide ) throws IOException {
if (wide) {
n = bytes.readUnsignedShort();
super.setLength(4);
} else {
final short _opcode = super.getOpcode();
if (((_opcode >= Const.ILOAD) && (_opcode <= Const.ALOAD))
|| ((_opcode >= Const.ISTORE) && (_opcode <= Const.ASTORE))) {
n = bytes.readUnsignedByte();
super.setLength(2);
} else if (_opcode <= Const.ALOAD_3) { // compact load instruction such as ILOAD_2
n = (_opcode - Const.ILOAD_0) % 4;
super.setLength(1);
} else { // Assert ISTORE_0 <= tag <= ASTORE_3
n = (_opcode - Const.ISTORE_0) % 4;
super.setLength(1);
}
}
}
/**
* @return local variable index (n) referred by this instruction.
*/
@Override
public final int getIndex() {
return n;
}
/**
* Set the local variable index.
* also updates opcode and length
* TODO Why?
* @see #setIndexOnly(int)
*/
@Override
public void setIndex( final int n ) { // TODO could be package-protected?
if ((n < 0) || (n > Const.MAX_SHORT)) {
throw new ClassGenException("Illegal value: " + n);
}
this.n = n;
// Cannot be < 0 as this is checked above
if (n <= 3) { // Use more compact instruction xLOAD_n
super.setOpcode((short) (c_tag + n));
super.setLength(1);
} else {
super.setOpcode(canon_tag);
if (wide()) {
super.setLength(4);
} else {
super.setLength(2);
}
}
}
/** @return canonical tag for instruction, e.g., ALOAD for ALOAD_0
*/
public short getCanonicalTag() {
return canon_tag;
}
/**
* Returns the type associated with the instruction -
* in case of ALOAD or ASTORE Type.OBJECT is returned.
* This is just a bit incorrect, because ALOAD and ASTORE
* may work on every ReferenceType (including Type.NULL) and
* ASTORE may even work on a ReturnaddressType .
* @return type associated with the instruction
*/
@Override
public Type getType( final ConstantPoolGen cp ) {
switch (canon_tag) {
case Const.ILOAD:
case Const.ISTORE:
return Type.INT;
case Const.LLOAD:
case Const.LSTORE:
return Type.LONG;
case Const.DLOAD:
case Const.DSTORE:
return Type.DOUBLE;
case Const.FLOAD:
case Const.FSTORE:
return Type.FLOAT;
case Const.ALOAD:
case Const.ASTORE:
return Type.OBJECT;
default:
throw new ClassGenException("Oops: unknown case in switch" + canon_tag);
}
}
/**
* Sets the index of the referenced variable (n) only
* @since 6.0
* @see #setIndex(int)
*/
final void setIndexOnly(final int n) {
this.n = n;
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy