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/*
* 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 $Id$
*/
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.
* <pre>
* (ILOAD <= tag <= ALOAD_3) || (ISTORE <= tag <= ASTORE_3)
* </pre>
*/
@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;
}
}
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