LineNumberTable.java
/*
* 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 java.util.Arrays;
import java.util.Iterator;
import java.util.stream.Stream;
import org.apache.bcel.Const;
import org.apache.bcel.util.Args;
/**
* 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.
*
* @see Code
* @see LineNumber
*/
public final class LineNumberTable extends Attribute implements Iterable<LineNumber> {
private static final int MAX_LINE_LENGTH = 72;
private LineNumber[] lineNumberTable; // Table of line/numbers pairs
/**
* Constructs object from input stream.
*
* @param nameIndex Index of name
* @param length Content length in bytes
* @param input Input stream
* @param constantPool Array of constants
* @throws IOException if an I/O Exception occurs in readUnsignedShort
*/
LineNumberTable(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
this(nameIndex, length, (LineNumber[]) null, constantPool);
final int lineNumberTableLength = input.readUnsignedShort();
lineNumberTable = new LineNumber[lineNumberTableLength];
for (int i = 0; i < lineNumberTableLength; i++) {
lineNumberTable[i] = new LineNumber(input);
}
}
/*
* @param nameIndex Index of name
*
* @param length Content length in bytes
*
* @param lineNumberTable Table of line/numbers pairs
*
* @param constantPool Array of constants
*/
public LineNumberTable(final int nameIndex, final int length, final LineNumber[] lineNumberTable, final ConstantPool constantPool) {
super(Const.ATTR_LINE_NUMBER_TABLE, nameIndex, length, constantPool);
this.lineNumberTable = lineNumberTable != null ? lineNumberTable : LineNumber.EMPTY_ARRAY;
Args.requireU2(this.lineNumberTable.length, "lineNumberTable.length");
}
/*
* Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
* physical copy.
*/
public LineNumberTable(final LineNumberTable c) {
this(c.getNameIndex(), c.getLength(), c.getLineNumberTable(), c.getConstantPool());
}
/**
* Called by objects that are traversing the nodes of the tree implicitly 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.visitLineNumberTable(this);
}
/**
* @return deep copy of this attribute
*/
@Override
public Attribute copy(final ConstantPool constantPool) {
// TODO could use the lower level constructor and thereby allow
// lineNumberTable to be made final
final LineNumberTable c = (LineNumberTable) clone();
c.lineNumberTable = new LineNumber[lineNumberTable.length];
Arrays.setAll(c.lineNumberTable, i -> lineNumberTable[i].copy());
c.setConstantPool(constantPool);
return c;
}
/**
* Dump line number table attribute to file stream in binary format.
*
* @param file Output file stream
* @throws IOException if an I/O Exception occurs in writeShort
*/
@Override
public void dump(final DataOutputStream file) throws IOException {
super.dump(file);
file.writeShort(lineNumberTable.length);
for (final LineNumber lineNumber : lineNumberTable) {
lineNumber.dump(file);
}
}
/**
* @return Array of (pc offset, line number) pairs.
*/
public LineNumber[] getLineNumberTable() {
return lineNumberTable;
}
/**
* Map byte code positions to source code lines.
*
* @param pos byte code offset
* @return corresponding line in source code
*/
public int getSourceLine(final int pos) {
int l = 0;
int r = lineNumberTable.length - 1;
if (r < 0) {
return -1;
}
int minIndex = -1;
int min = -1;
/*
* Do a binary search since the array is ordered.
*/
do {
final int i = l + r >>> 1;
final int j = lineNumberTable[i].getStartPC();
if (j == pos) {
return lineNumberTable[i].getLineNumber();
}
if (pos < j) {
r = i - 1;
} else {
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;
minIndex = i;
}
} while (l <= r);
/*
* It's possible that we did not find any valid entry for the bytecode offset we were looking for.
*/
if (minIndex < 0) {
return -1;
}
return lineNumberTable[minIndex].getLineNumber();
}
public int getTableLength() {
return lineNumberTable == null ? 0 : lineNumberTable.length;
}
@Override
public Iterator<LineNumber> iterator() {
return Stream.of(lineNumberTable).iterator();
}
/**
* @param lineNumberTable the line number entries for this table
*/
public void setLineNumberTable(final LineNumber[] lineNumberTable) {
this.lineNumberTable = lineNumberTable;
}
/**
* @return String representation.
*/
@Override
public String toString() {
final StringBuilder buf = new StringBuilder();
final StringBuilder line = new StringBuilder();
final String newLine = System.getProperty("line.separator", "\n");
for (int i = 0; i < lineNumberTable.length; i++) {
line.append(lineNumberTable[i].toString());
if (i < lineNumberTable.length - 1) {
line.append(", ");
}
if (line.length() > MAX_LINE_LENGTH && i < lineNumberTable.length - 1) {
line.append(newLine);
buf.append(line);
line.setLength(0);
}
}
buf.append(line);
return buf.toString();
}
}