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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.classfile;
import java.io.DataInput;
import java.io.DataOutputStream;
import java.io.IOException;
import org.apache.bcel.Const;
import org.apache.bcel.Constants;
/**
* This class represents a local variable within a method. It contains its
* scope, name, signature and index on the method's frame.
*
* @version $Id$
* @see LocalVariableTable
*/
public final class LocalVariable implements Cloneable, Node, Constants {
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
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
/**
* Initialize from another object. Note that both objects use the same
* references (shallow copy). Use copy() for a physical copy.
*/
public LocalVariable(final LocalVariable c) {
this(c.getStartPC(), c.getLength(), c.getNameIndex(), c.getSignatureIndex(), c.getIndex(),
c.getConstantPool());
this.orig_index = c.getOrigIndex();
}
/**
* Construct 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);
}
/**
* @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;
}
/**
* @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.
*
* @param v Visitor object
*/
@Override
public void accept( final Visitor v ) {
v.visitLocalVariable(this);
}
/**
* Dump local variable to file stream in binary format.
*
* @param file Output file stream
* @throws IOException
*/
public final void dump( final DataOutputStream file ) throws IOException {
file.writeShort(start_pc);
file.writeShort(length);
file.writeShort(name_index);
file.writeShort(signature_index);
file.writeShort(index);
}
/**
* @return Constant pool used by this object.
*/
public final ConstantPool getConstantPool() {
return constant_pool;
}
/**
* @return Variable is valid within getStartPC() .. getStartPC()+getLength()
*/
public final int getLength() {
return length;
}
/**
* @return Variable name.
*/
public final String getName() {
ConstantUtf8 c;
c = (ConstantUtf8) constant_pool.getConstant(name_index, Const.CONSTANT_Utf8);
return c.getBytes();
}
/**
* @return Index in constant pool of variable name.
*/
public final int getNameIndex() {
return name_index;
}
/**
* @return Signature.
*/
public final String getSignature() {
ConstantUtf8 c;
c = (ConstantUtf8) constant_pool.getConstant(signature_index, Const.CONSTANT_Utf8);
return c.getBytes();
}
/**
* @return Index in constant pool of variable signature.
*/
public final int getSignatureIndex() {
return signature_index;
}
/**
* @return index of register where variable is stored
*/
public final int getIndex() {
return index;
}
/**
* @return index of register where variable was originally stored
*/
public final int getOrigIndex() {
return orig_index;
}
/**
* @return Start of range where he variable is valid
*/
public final int getStartPC() {
return start_pc;
}
/*
* Helper method shared with LocalVariableTypeTable
*/
final 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 + ")";
}
/**
* @param constant_pool Constant pool to be used for this object.
*/
public final void setConstantPool( final ConstantPool constant_pool ) {
this.constant_pool = constant_pool;
}
/**
* @param length the length of this local variable
*/
public final void setLength( final int length ) {
this.length = length;
}
/**
* @param name_index the index into the constant pool for the name of this variable
*/
public final void setNameIndex( final int name_index ) { // TODO unused
this.name_index = name_index;
}
/**
* @param signature_index the index into the constant pool for the signature of this variable
*/
public final void setSignatureIndex( final int signature_index ) { // TODO unused
this.signature_index = signature_index;
}
/**
* @param index the index in the local variable table of this variable
*/
public final void setIndex( final int index ) { // TODO unused
this.index = index;
}
/**
* @param start_pc Specify range where the local variable is valid.
*/
public final void setStartPC( final int start_pc ) { // TODO unused
this.start_pc = start_pc;
}
/**
* @return string representation.
*/
@Override
public final String toString() {
return toStringShared(false);
}
/**
* @return deep copy of this object
*/
public LocalVariable copy() {
try {
return (LocalVariable) clone();
} catch (final CloneNotSupportedException e) {
// TODO should this throw?
}
return null;
}
}
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