https://openjdk.java.net/ 
/*
 * Copyright (c) 2017, 2019, 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.classfile;

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

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


This class represents a local variable within a method. It contains its
scope, name, signature and index on the method's frame.  It is used both
to represent an element of the LocalVariableTable as well as an element
of the LocalVariableTypeTable.  The nomenclature used here may be a bit confusing;
while the two items have the same layout in a class file, a LocalVariableTable
attribute contains a descriptor_index, not a signature_index.  The
LocalVariableTypeTable attribute does have a signature_index.

See Also:
@LastModified: Jan 2020
/**
 * This class represents a local variable within a method. It contains its
 * scope, name, signature and index on the method's frame.  It is used both
 * to represent an element of the LocalVariableTable as well as an element
 * of the LocalVariableTypeTable.  The nomenclature used here may be a bit confusing;
 * while the two items have the same layout in a class file, a LocalVariableTable
 * attribute contains a descriptor_index, not a signature_index.  The
 * LocalVariableTypeTable attribute does have a signature_index.
 * @see com.sun.org.apache.bcel.internal.classfile.Utility for more details on the difference.
 *
 * @see     LocalVariableTable
 * @see     LocalVariableTypeTable
 * @LastModified: Jan 2020
 */
public final class LocalVariable implements Cloneable, Node {

    private int start_pc; // Range in which the variable is valid
    private int length;
    private int name_index; // Index in constant pool of variable name
    // Technically, a decscriptor_index for a local variable table entry
    // and a signature_index for a local variable type table entry.
    private int signature_index; // Index of variable signature
    private int index; /* Variable is index'th local variable on
     * this method's frame.
     */
    private ConstantPool constant_pool;
    private int orig_index; // never changes; used to match up with LocalVariableTypeTable entries


    
Initializes from another LocalVariable. Note that both objects use the same
references (shallow copy). Use copy() for a physical copy.

Params:
  • localVariable – Another LocalVariable.
/**
     * Initializes from another LocalVariable. Note that both objects use the same
     * references (shallow copy). Use copy() for a physical copy.
     *
     * @param localVariable Another LocalVariable.
     */
    public LocalVariable(final LocalVariable localVariable) {
        this(localVariable.getStartPC(), localVariable.getLength(), localVariable.getNameIndex(),
                localVariable.getSignatureIndex(), localVariable.getIndex(), localVariable.getConstantPool());
        this.orig_index = localVariable.getOrigIndex();
    }

    
Constructs object from file stream.

Params:
  • file – Input stream
Throws:
/**
     * Constructs object from file stream.
     * @param file Input stream
     * @throws IOException
     */
    LocalVariable(final DataInput file, final ConstantPool constant_pool) throws IOException {
        this(file.readUnsignedShort(), file.readUnsignedShort(), file.readUnsignedShort(), file
                .readUnsignedShort(), file.readUnsignedShort(), constant_pool);
    }


    
Params:
  • start_pc – Range in which the variable
  • length – ... is valid
  • name_index – Index in constant pool of variable name
  • signature_index – Index of variable's signature
  • index – Variable is `index'th local variable on the method's frame
  • constant_pool – Array of constants
/**
     * @param start_pc Range in which the variable
     * @param length ... is valid
     * @param name_index Index in constant pool of variable name
     * @param signature_index Index of variable's signature
     * @param index Variable is `index'th local variable on the method's frame
     * @param constant_pool Array of constants
     */
    public LocalVariable(final int start_pc, final int length, final int name_index, final int signature_index, final int index,
            final ConstantPool constant_pool) {
        this.start_pc = start_pc;
        this.length = length;
        this.name_index = name_index;
        this.signature_index = signature_index;
        this.index = index;
        this.constant_pool = constant_pool;
        this.orig_index = index;
    }


    
Params:
  • start_pc – Range in which the variable
  • length – ... is valid
  • name_index – Index in constant pool of variable name
  • signature_index – Index of variable's signature
  • index – Variable is `index'th local variable on the method's frame
  • constant_pool – Array of constants
  • orig_index – Variable is `index'th local variable on the method's frame prior to any changes
/**
     * @param start_pc Range in which the variable
     * @param length ... is valid
     * @param name_index Index in constant pool of variable name
     * @param signature_index Index of variable's signature
     * @param index Variable is `index'th local variable on the method's frame
     * @param constant_pool Array of constants
     * @param orig_index Variable is `index'th local variable on the method's frame prior to any changes
     */
    public LocalVariable(final int start_pc, final int length, final int name_index, final int signature_index, final int index,
            final ConstantPool constant_pool, final int orig_index) {
        this.start_pc = start_pc;
        this.length = length;
        this.name_index = name_index;
        this.signature_index = signature_index;
        this.index = index;
        this.constant_pool = constant_pool;
        this.orig_index = orig_index;
    }


    
Called by objects that are traversing the nodes of the tree implicitely
defined by the contents of a Java class. I.e., the hierarchy of methods,
fields, attributes, etc. spawns a tree of objects.

Params:
  • v – Visitor object
/**
     * Called by objects that are traversing the nodes of the tree implicitely
     * defined by the contents of a Java class. I.e., the hierarchy of methods,
     * fields, attributes, etc. spawns a tree of objects.
     *
     * @param v Visitor object
     */
    @Override
    public void accept( final Visitor v ) {
        v.visitLocalVariable(this);
    }


    
Dumps local variable to file stream in binary format.

Params:
  • dataOutputStream – Output file stream
Throws:
See Also:
  • FilterOutputStream.out
/**
     * Dumps local variable to file stream in binary format.
     *
     * @param dataOutputStream Output file stream
     * @exception IOException if an I/O error occurs.
     * @see java.io.FilterOutputStream#out
     */
    public void dump(final DataOutputStream dataOutputStream) throws IOException {
        dataOutputStream.writeShort(start_pc);
        dataOutputStream.writeShort(length);
        dataOutputStream.writeShort(name_index);
        dataOutputStream.writeShort(signature_index);
        dataOutputStream.writeShort(index);
    }

    
Returns:Constant pool used by this object.
/**
     * @return Constant pool used by this object.
     */
    public ConstantPool getConstantPool() {
        return constant_pool;
    }


    
Returns:Variable is valid within getStartPC() .. getStartPC()+getLength()
/**
     * @return Variable is valid within getStartPC() .. getStartPC()+getLength()
     */
    public int getLength() {
        return length;
    }


    
Returns:Variable name.
/**
     * @return Variable name.
     */
    public String getName() {
        ConstantUtf8 c;
        c = (ConstantUtf8) constant_pool.getConstant(name_index, Const.CONSTANT_Utf8);
        return c.getBytes();
    }


    
Returns:Index in constant pool of variable name.
/**
     * @return Index in constant pool of variable name.
     */
    public int getNameIndex() {
        return name_index;
    }


    
Returns:Signature.
/**
     * @return Signature.
     */
    public String getSignature() {
        ConstantUtf8 c;
        c = (ConstantUtf8) constant_pool.getConstant(signature_index, Const.CONSTANT_Utf8);
        return c.getBytes();
    }


    
Returns:Index in constant pool of variable signature.
/**
     * @return Index in constant pool of variable signature.
     */
    public int getSignatureIndex() {
        return signature_index;
    }


    
Returns:index of register where variable is stored
/**
     * @return index of register where variable is stored
     */
    public int getIndex() {
        return index;
    }


    
Returns:index of register where variable was originally stored
/**
     * @return index of register where variable was originally stored
     */
    public int getOrigIndex() {
        return orig_index;
    }


    
Returns:Start of range where the variable is valid
/**
     * @return Start of range where the variable is valid
     */
    public int getStartPC() {
        return start_pc;
    }


    /*
     * Helper method shared with LocalVariableTypeTable
     */
    String toStringShared( final boolean typeTable ) {
        final String name = getName();
        final String signature = Utility.signatureToString(getSignature(), false);
        final String label = "LocalVariable" + (typeTable ? "Types" : "" );
        return label + "(start_pc = " + start_pc + ", length = " + length + ", index = "
                + index + ":" + signature + " " + name + ")";
    }


    
Params:
  • constant_pool – Constant pool to be used for this object.
/**
     * @param constant_pool Constant pool to be used for this object.
     */
    public void setConstantPool( final ConstantPool constant_pool ) {
        this.constant_pool = constant_pool;
    }


    
Params:
  • length – the length of this local variable
/**
     * @param length the length of this local variable
     */
    public void setLength( final int length ) {
        this.length = length;
    }


    
Params:
  • name_index – the index into the constant pool for the name of this variable
/**
     * @param name_index the index into the constant pool for the name of this variable
     */
    public void setNameIndex( final int name_index ) { // TODO unused
        this.name_index = name_index;
    }


    
Params:
  • signature_index – the index into the constant pool for the signature of this variable
/**
     * @param signature_index the index into the constant pool for the signature of this variable
     */
    public void setSignatureIndex( final int signature_index ) { // TODO unused
        this.signature_index = signature_index;
    }


    
Params:
  • index – the index in the local variable table of this variable
/**
     * @param index the index in the local variable table of this variable
     */
    public void setIndex( final int index ) { // TODO unused
        this.index = index;
    }


    
Params:
  • start_pc – Specify range where the local variable is valid.
/**
     * @param start_pc Specify range where the local variable is valid.
     */
    public void setStartPC( final int start_pc ) { // TODO unused
        this.start_pc = start_pc;
    }


    
Returns:string representation.
/**
     * @return string representation.
     */
    @Override
    public String toString() {
        return toStringShared(false);
    }


    
Returns:deep copy of this object
/**
     * @return deep copy of this object
     */
    public LocalVariable copy() {
        try {
            return (LocalVariable) clone();
        } catch (final CloneNotSupportedException e) {
            // TODO should this throw?
        }
        return null;
    }
}