/*
 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
 */
/*
 * 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 com.sun.org.apache.bcel.internal.generic;

import java.io.DataOutputStream;
import java.io.IOException;

import com.sun.org.apache.bcel.internal.Const;
import com.sun.org.apache.bcel.internal.util.ByteSequence;

Abstract super class for instructions dealing with local variables.
Version:$Id: LocalVariableInstruction.java 1747278 2016-06-07 17:28:43Z britter $
/** * Abstract super class for instructions dealing with local variables. * * @version $Id: LocalVariableInstruction.java 1747278 2016-06-07 17:28:43Z * britter $ */
public abstract class LocalVariableInstruction extends Instruction implements TypedInstruction, IndexedInstruction { private 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.
/** * 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()!
/** * Empty constructor needed for the Class.newInstance() statement in * Instruction.readInstruction(). Also used by IINC()! */
LocalVariableInstruction() { }
Params:
  • opcode – Instruction opcode
  • c_tag – Instruction number for compact version, ALOAD_0, e.g.
  • n – local variable index (unsigned short)
/** * @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.
Params:
  • out – Output stream
/** * 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>">"
Params:
  • verbose – long/short format switch
Returns:mnemonic for instruction
/** * Long output format: * * &lt;name of opcode&gt; "["&lt;opcode number&gt;"]" "("&lt;length of * instruction&gt;")" "&lt;"&lt; local variable index&gt;"&gt;" * * @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)
/** * Read needed data (e.g. index) from file. * <pre> * (ILOAD &lt;= tag &lt;= ALOAD_3) || (ISTORE &lt;= tag &lt;= 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); } } }
Returns:local variable index (n) referred by this instruction.
/** * @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 Also:
  • setIndexOnly(int)
/** * 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); } } }
Returns:canonical tag for instruction, e.g., ALOAD for ALOAD_0
/** * @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 .
Returns:type associated with the instruction
/** * 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
See Also:
Since:6.0
/** * Sets the index of the referenced variable (n) only * * @since 6.0 * @see #setIndex(int) */
final void setIndexOnly(final int n) { this.n = n; } }