Source code

    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 *  Unless required by applicable law or agreed to in writing, software
    012 *  distributed under the License is distributed on an "AS IS" BASIS,
    013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 *  See the License for the specific language governing permissions and
    015 *  limitations under the License.
    016 *
    017 */
    018package org.apache.bcel.classfile;
    019
    020import java.io.DataInput;
    021import java.io.DataOutputStream;
    022import java.io.IOException;
    023
    024import org.apache.bcel.Const;
    025
    026/**
    027 * This class represents a table of line numbers for debugging
    028 * purposes. This attribute is used by the <em>Code</em> attribute. It
    029 * contains pairs of PCs and line numbers.
    030 *
    031 * @see     Code
    032 * @see LineNumber
    033 */
    034public final class LineNumberTable extends Attribute {
    035
    036    private static final int MAX_LINE_LENGTH = 72;
    037    private LineNumber[] line_number_table; // Table of line/numbers pairs
    038
    039
    040    /*
    041     * Initialize from another object. Note that both objects use the same
    042     * references (shallow copy). Use copy() for a physical copy.
    043     */
    044    public LineNumberTable(final LineNumberTable c) {
    045        this(c.getNameIndex(), c.getLength(), c.getLineNumberTable(), c.getConstantPool());
    046    }
    047
    048
    049    /*
    050     * @param name_index Index of name
    051     * @param length Content length in bytes
    052     * @param line_number_table Table of line/numbers pairs
    053     * @param constant_pool Array of constants
    054     */
    055    public LineNumberTable(final int name_index, final int length, final LineNumber[] line_number_table,
    056            final ConstantPool constant_pool) {
    057        super(Const.ATTR_LINE_NUMBER_TABLE, name_index, length, constant_pool);
    058        this.line_number_table = line_number_table;
    059    }
    060
    061
    062    /**
    063     * Construct object from input stream.
    064     * @param name_index Index of name
    065     * @param length Content length in bytes
    066     * @param input Input stream
    067     * @param constant_pool Array of constants
    068     * @throws IOException if an I/O Exception occurs in readUnsignedShort
    069     */
    070    LineNumberTable(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool)
    071            throws IOException {
    072        this(name_index, length, (LineNumber[]) null, constant_pool);
    073        final int line_number_table_length = input.readUnsignedShort();
    074        line_number_table = new LineNumber[line_number_table_length];
    075        for (int i = 0; i < line_number_table_length; i++) {
    076            line_number_table[i] = new LineNumber(input);
    077        }
    078    }
    079
    080
    081    /**
    082     * Called by objects that are traversing the nodes of the tree implicitely
    083     * defined by the contents of a Java class. I.e., the hierarchy of methods,
    084     * fields, attributes, etc. spawns a tree of objects.
    085     *
    086     * @param v Visitor object
    087     */
    088    @Override
    089    public void accept( final Visitor v ) {
    090        v.visitLineNumberTable(this);
    091    }
    092
    093
    094    /**
    095     * Dump line number table attribute to file stream in binary format.
    096     *
    097     * @param file Output file stream
    098     * @throws IOException if an I/O Exception occurs in writeShort
    099     */
    100    @Override
    101    public void dump( final DataOutputStream file ) throws IOException {
    102        super.dump(file);
    103        file.writeShort(line_number_table.length);
    104        for (final LineNumber lineNumber : line_number_table) {
    105            lineNumber.dump(file);
    106        }
    107    }
    108
    109
    110    /**
    111     * @return Array of (pc offset, line number) pairs.
    112     */
    113    public LineNumber[] getLineNumberTable() {
    114        return line_number_table;
    115    }
    116
    117
    118    /**
    119     * @param line_number_table the line number entries for this table
    120     */
    121    public void setLineNumberTable( final LineNumber[] line_number_table ) {
    122        this.line_number_table = line_number_table;
    123    }
    124
    125
    126    /**
    127     * @return String representation.
    128     */
    129    @Override
    130    public String toString() {
    131        final StringBuilder buf = new StringBuilder();
    132        final StringBuilder line = new StringBuilder();
    133        final String newLine = System.getProperty("line.separator", "\n");
    134        for (int i = 0; i < line_number_table.length; i++) {
    135            line.append(line_number_table[i].toString());
    136            if (i < line_number_table.length - 1) {
    137                line.append(", ");
    138            }
    139            if ((line.length() > MAX_LINE_LENGTH) && (i < line_number_table.length - 1)) {
    140                line.append(newLine);
    141                buf.append(line);
    142                line.setLength(0);
    143            }
    144        }
    145        buf.append(line);
    146        return buf.toString();
    147    }
    148
    149
    150    /**
    151     * Map byte code positions to source code lines.
    152     *
    153     * @param pos byte code offset
    154     * @return corresponding line in source code
    155     */
    156    public int getSourceLine( final int pos ) {
    157        int l = 0;
    158        int r = line_number_table.length - 1;
    159        if (r < 0) {
    160            return -1;
    161        }
    162        int min_index = -1;
    163        int min = -1;
    164        /* Do a binary search since the array is ordered.
    165         */
    166        do {
    167            final int i = (l + r) >>> 1;
    168            final int j = line_number_table[i].getStartPC();
    169            if (j == pos) {
    170                return line_number_table[i].getLineNumber();
    171            } else if (pos < j) {
    172                r = i - 1;
    173            } else {
    174                l = i + 1;
    175            }
    176            /* If exact match can't be found (which is the most common case)
    177             * return the line number that corresponds to the greatest index less
    178             * than pos.
    179             */
    180            if (j < pos && j > min) {
    181                min = j;
    182                min_index = i;
    183            }
    184        } while (l <= r);
    185        /* It's possible that we did not find any valid entry for the bytecode
    186         * offset we were looking for.
    187         */
    188        if (min_index < 0) {
    189            return -1;
    190        }
    191        return line_number_table[min_index].getLineNumber();
    192    }
    193
    194
    195    /**
    196     * @return deep copy of this attribute
    197     */
    198    @Override
    199    public Attribute copy( final ConstantPool _constant_pool ) {
    200        // TODO could use the lower level constructor and thereby allow
    201        // line_number_table to be made final
    202        final LineNumberTable c = (LineNumberTable) clone();
    203        c.line_number_table = new LineNumber[line_number_table.length];
    204        for (int i = 0; i < line_number_table.length; i++) {
    205            c.line_number_table[i] = line_number_table[i].copy();
    206        }
    207        c.setConstantPool(_constant_pool);
    208        return c;
    209    }
    210
    211
    212    public int getTableLength() {
    213        return line_number_table == null ? 0 : line_number_table.length;
    214    }
    215}