Java tutorial
package org.aspectj.apache.bcel.classfile; /* ==================================================================== * The Apache Software License, Version 1.1 * * Copyright (c) 2001 The Apache Software Foundation. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. The end-user documentation included with the redistribution, * if any, must include the following acknowledgment: * "This product includes software developed by the * Apache Software Foundation (http://www.apache.org/)." * Alternately, this acknowledgment may appear in the software itself, * if and wherever such third-party acknowledgments normally appear. * * 4. The names "Apache" and "Apache Software Foundation" and * "Apache BCEL" must not be used to endorse or promote products * derived from this software without prior written permission. For * written permission, please contact apache@apache.org. * * 5. Products derived from this software may not be called "Apache", * "Apache BCEL", nor may "Apache" appear in their name, without * prior written permission of the Apache Software Foundation. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. */ import java.io.ByteArrayInputStream; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.IOException; import org.aspectj.apache.bcel.Constants; /** * This class represents a table of line numbers for debugging purposes. This attribute is used by the <em>Code</em> attribute. It * contains pairs of PCs and line numbers. * * @version $Id: LineNumberTable.java,v 1.8 2009/09/15 19:40:12 aclement Exp $ * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A> * @see Code changes: asc Feb06 Made unpacking lazy */ public final class LineNumberTable extends Attribute { // if 'isInPackedState' then this data needs unpacking private boolean isInPackedState = false; private byte[] data; // discarded once unpacked private int tableLength; private LineNumber[] table; /* * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a physical * copy. */ public LineNumberTable(LineNumberTable c) { this(c.getNameIndex(), c.getLength(), c.getLineNumberTable(), c.getConstantPool()); } public LineNumberTable(int nameIndex, int length, LineNumber[] lineNumberTable, ConstantPool constantPool) { super(Constants.ATTR_LINE_NUMBER_TABLE, nameIndex, length, constantPool); setLineNumberTable(lineNumberTable); isInPackedState = false; } /** * Construct object from file stream. * * @param name_index Index of name * @param length Content length in bytes * @param file Input stream * @throws IOException * @param constant_pool Array of constants */ LineNumberTable(int name_index, int length, DataInputStream file, ConstantPool constant_pool) throws IOException { this(name_index, length, (LineNumber[]) null, constant_pool); data = new byte[length]; file.readFully(data); isInPackedState = true; // assert(bytesRead==length) } // Unpacks the byte array into the table private void unpack() { if (isInPackedState) { try { ByteArrayInputStream bs = new ByteArrayInputStream(data); DataInputStream dis = new DataInputStream(bs); tableLength = (dis.readUnsignedShort()); table = new LineNumber[tableLength]; for (int i = 0; i < tableLength; i++) { table[i] = new LineNumber(dis); } dis.close(); data = null; // throw it away now } catch (IOException e) { throw new RuntimeException("Unpacking of LineNumberTable attribute failed"); } isInPackedState = false; } } /** * 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(ClassVisitor v) { unpack(); v.visitLineNumberTable(this); } /** * Dump line number 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); if (isInPackedState) { file.write(data); } else { file.writeShort(tableLength); for (int i = 0; i < tableLength; i++) { table[i].dump(file); } } } /** * @return Array of (pc offset, line number) pairs. */ public final LineNumber[] getLineNumberTable() { unpack(); return table; } /** * @param line_number_table. */ public final void setLineNumberTable(LineNumber[] line_number_table) { this.data = null; this.isInPackedState = false; this.table = line_number_table; this.tableLength = (line_number_table == null) ? 0 : line_number_table.length; } /** * @return String representation. */ @Override public final String toString() { unpack(); StringBuffer buf = new StringBuffer(); StringBuffer line = new StringBuffer(); for (int i = 0; i < tableLength; i++) { line.append(table[i].toString()); if (i < tableLength - 1) { line.append(", "); } if (line.length() > 72) { line.append('\n'); buf.append(line); line.setLength(0); } } buf.append(line); return buf.toString(); } /** * Map byte code positions to source code lines. * * @param pos byte code offset * @return corresponding line in source code */ public int getSourceLine(int pos) { unpack(); int l = 0, r = tableLength - 1; if (r < 0) // array is empty return -1; int min_index = -1, min = -1; /* * Do a binary search since the array is ordered. */ do { int i = (l + r) / 2; int j = table[i].getStartPC(); if (j == pos) return table[i].getLineNumber(); else if (pos < j) // else constrain search area r = i - 1; else // pos > j l = i + 1; /* * If exact match can't be found (which is the most common case) return the line number that corresponds to the greatest * index less than pos. */ if (j < pos && j > min) { min = j; min_index = i; } } while (l <= r); /* * It's possible that we did not find any valid entry for the bytecode offset we were looking for. */ if (min_index < 0) return -1; return table[min_index].getLineNumber(); } /** * @return deep copy of this attribute */ // @Override // public Attribute copy(ConstantPool constant_pool) { // unpack(); // LineNumberTable newTable = (LineNumberTable) clone(); // newTable.table = new LineNumber[tableLength]; // for (int i = 0; i < tableLength; i++) { // newTable.table[i] = table[i].copy(); // } // newTable.cpool = constant_pool; // return newTable; // } public final int getTableLength() { unpack(); return tableLength; } }