Java tutorial
/* * 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.commons.bcel6.classfile; import java.io.DataInput; import java.io.DataOutputStream; import java.io.IOException; import org.apache.commons.bcel6.Constants; /** * This class represents colection of local variables in a * method. This attribute is contained in the <em>Code</em> attribute. * * @version $Id$ * @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A> * @see Code * @see LocalVariable */ public class LocalVariableTable extends Attribute { private static final long serialVersionUID = 6780929007774637689L; private LocalVariable[] local_variable_table; // variables /** * Initialize from another object. Note that both objects use the same * references (shallow copy). Use copy() for a physical copy. */ public LocalVariableTable(LocalVariableTable c) { this(c.getNameIndex(), c.getLength(), c.getLocalVariableTable(), c.getConstantPool()); } /** * @param name_index Index in constant pool to `LocalVariableTable' * @param length Content length in bytes * @param local_variable_table Table of local variables * @param constant_pool Array of constants */ public LocalVariableTable(int name_index, int length, LocalVariable[] local_variable_table, ConstantPool constant_pool) { super(Constants.ATTR_LOCAL_VARIABLE_TABLE, name_index, length, constant_pool); setLocalVariableTable(local_variable_table); } /** * Construct object from input stream. * @param name_index Index in constant pool * @param length Content length in bytes * @param input Input stream * @param constant_pool Array of constants * @throws IOException */ LocalVariableTable(int name_index, int length, DataInput input, ConstantPool constant_pool) throws IOException { this(name_index, length, (LocalVariable[]) null, constant_pool); int local_variable_table_length = (input.readUnsignedShort()); local_variable_table = new LocalVariable[local_variable_table_length]; for (int i = 0; i < local_variable_table_length; i++) { local_variable_table[i] = new LocalVariable(input, constant_pool); } } /** * 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(Visitor v) { v.visitLocalVariableTable(this); } /** * Dump local variable table attribute to file stream in binary format. * * @param file Output file stream * @throws IOException */ @Override public final void dump(DataOutputStream file) throws IOException { super.dump(file); file.writeShort(local_variable_table.length); for (LocalVariable variable : local_variable_table) { variable.dump(file); } } /** * @return Array of local variables of method. */ public final LocalVariable[] getLocalVariableTable() { return local_variable_table; } /** * * @param index the variable slot * * @return the first LocalVariable that matches the slot or null if not found * * @deprecated since 5.2 because multiple variables can share the * same slot, use getLocalVariable(int index, int pc) instead. */ @java.lang.Deprecated public final LocalVariable getLocalVariable(int index) { for (LocalVariable variable : local_variable_table) { if (variable.getIndex() == index) { return variable; } } return null; } /** * * @param index the variable slot * @param pc the current pc that this variable is alive * * @return the LocalVariable that matches or null if not found */ public final LocalVariable getLocalVariable(int index, int pc) { for (LocalVariable variable : local_variable_table) { if (variable.getIndex() == index) { int start_pc = variable.getStartPC(); int end_pc = start_pc + variable.getLength(); if ((pc >= start_pc) && (pc <= end_pc)) { return variable; } } } return null; } public final void setLocalVariableTable(LocalVariable[] local_variable_table) { this.local_variable_table = local_variable_table; } /** * @return String representation. */ @Override public final String toString() { StringBuilder buf = new StringBuilder(); for (int i = 0; i < local_variable_table.length; i++) { buf.append(local_variable_table[i].toString()); if (i < local_variable_table.length - 1) { buf.append('\n'); } } return buf.toString(); } /** * @return deep copy of this attribute */ @Override public Attribute copy(ConstantPool _constant_pool) { LocalVariableTable c = (LocalVariableTable) clone(); c.local_variable_table = new LocalVariable[local_variable_table.length]; for (int i = 0; i < local_variable_table.length; i++) { c.local_variable_table[i] = local_variable_table[i].copy(); } c.constant_pool = _constant_pool; return c; } public final int getTableLength() { return local_variable_table == null ? 0 : local_variable_table.length; } }