    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
    024/**
    025 * This class represents a (PC offset, line number) pair, i.e., a line number in
    026 * the source that corresponds to a relative address in the byte code. This
    027 * is used for debugging purposes.
    028 *
    029 * @see     LineNumberTable
    030 */
    031public final class LineNumber implements Cloneable, Node {
    032
    033    /** Program Counter (PC) corresponds to line */
    034    private short start_pc;
    035
    036    /** number in source file */
    037    private short line_number;
    038
    039    /**
    040     * Initialize from another object.
    041     *
    042     * @param c the object to copy
    043     */
    044    public LineNumber(final LineNumber c) {
    045        this(c.getStartPC(), c.getLineNumber());
    046    }
    047
    048
    049    /**
    050     * Construct object from file stream.
    051     *
    052     * @param file Input stream
    053     * @throws IOException if an I/O Exception occurs in readUnsignedShort
    054     */
    055    LineNumber(final DataInput file) throws IOException {
    056        this(file.readUnsignedShort(), file.readUnsignedShort());
    057    }
    058
    059
    060    /**
    061     * @param start_pc Program Counter (PC) corresponds to
    062     * @param line_number line number in source file
    063     */
    064    public LineNumber(final int start_pc, final int line_number) {
    065        this.start_pc = (short) start_pc;
    066        this.line_number = (short)line_number;
    067    }
    068
    069
    070    /**
    071     * Called by objects that are traversing the nodes of the tree implicitely
    072     * defined by the contents of a Java class. I.e., the hierarchy of methods,
    073     * fields, attributes, etc. spawns a tree of objects.
    074     *
    075     * @param v Visitor object
    076     */
    077    @Override
    078    public void accept( final Visitor v ) {
    079        v.visitLineNumber(this);
    080    }
    081
    082
    083    /**
    084     * Dump line number/pc pair to file stream in binary format.
    085     *
    086     * @param file Output file stream
    087     * @throws IOException if an I/O Exception occurs in writeShort
    088     */
    089    public void dump( final DataOutputStream file ) throws IOException {
    090        file.writeShort(start_pc);
    091        file.writeShort(line_number);
    092    }
    093
    094
    095    /**
    096     * @return Corresponding source line
    097     */
    098    public int getLineNumber() {
    099        return 0xffff & line_number;
    100    }
    101
    102
    103    /**
    104     * @return PC in code
    105     */
    106    public int getStartPC() {
    107        return  0xffff & start_pc;
    108    }
    109
    110
    111    /**
    112     * @param line_number the source line number
    113     */
    114    public void setLineNumber( final int line_number ) {
    115        this.line_number = (short) line_number;
    116    }
    117
    118
    119    /**
    120     * @param start_pc the pc for this line number
    121     */
    122    public void setStartPC( final int start_pc ) {
    123        this.start_pc = (short) start_pc;
    124    }
    125
    126
    127    /**
    128     * @return String representation
    129     */
    130    @Override
    131    public String toString() {
    132        return "LineNumber(" + start_pc + ", " + line_number + ")";
    133    }
    134
    135
    136    /**
    137     * @return deep copy of this object
    138     */
    139    public LineNumber copy() {
    140        try {
    141            return (LineNumber) clone();
    142        } catch (final CloneNotSupportedException e) {
    143            // TODO should this throw?
    144        }
    145        return null;
    146    }
    147}