    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 */
    017package org.apache.bcel.classfile;
    018
    019import java.io.DataInput;
    020import java.io.DataOutputStream;
    021import java.io.IOException;
    022
    023/**
    024 * This class represents a (PC offset, line number) pair, i.e., a line number in the source that corresponds to a
    025 * relative address in the byte code. This is used for debugging purposes.
    026 *
    027 * @see LineNumberTable
    028 */
    029public final class LineNumber implements Cloneable, Node {
    030
    031    /** Program Counter (PC) corresponds to line */
    032    private short startPc;
    033
    034    /** number in source file */
    035    private short lineNumber;
    036
    037    /**
    038     * Construct object from file stream.
    039     *
    040     * @param file Input stream
    041     * @throws IOException if an I/O Exception occurs in readUnsignedShort
    042     */
    043    LineNumber(final DataInput file) throws IOException {
    044        this(file.readUnsignedShort(), file.readUnsignedShort());
    045    }
    046
    047    /**
    048     * @param startPc Program Counter (PC) corresponds to
    049     * @param lineNumber line number in source file
    050     */
    051    public LineNumber(final int startPc, final int lineNumber) {
    052        this.startPc = (short) startPc;
    053        this.lineNumber = (short) lineNumber;
    054    }
    055
    056    /**
    057     * Initialize from another object.
    058     *
    059     * @param c the object to copy
    060     */
    061    public LineNumber(final LineNumber c) {
    062        this(c.getStartPC(), c.getLineNumber());
    063    }
    064
    065    /**
    066     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
    067     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    068     *
    069     * @param v Visitor object
    070     */
    071    @Override
    072    public void accept(final Visitor v) {
    073        v.visitLineNumber(this);
    074    }
    075
    076    /**
    077     * @return deep copy of this object
    078     */
    079    public LineNumber copy() {
    080        try {
    081            return (LineNumber) clone();
    082        } catch (final CloneNotSupportedException e) {
    083            // TODO should this throw?
    084        }
    085        return null;
    086    }
    087
    088    /**
    089     * Dump line number/pc pair to file stream in binary format.
    090     *
    091     * @param file Output file stream
    092     * @throws IOException if an I/O Exception occurs in writeShort
    093     */
    094    public void dump(final DataOutputStream file) throws IOException {
    095        file.writeShort(startPc);
    096        file.writeShort(lineNumber);
    097    }
    098
    099    /**
    100     * @return Corresponding source line
    101     */
    102    public int getLineNumber() {
    103        return lineNumber & 0xffff;
    104    }
    105
    106    /**
    107     * @return PC in code
    108     */
    109    public int getStartPC() {
    110        return startPc & 0xffff;
    111    }
    112
    113    /**
    114     * @param lineNumber the source line number
    115     */
    116    public void setLineNumber(final int lineNumber) {
    117        this.lineNumber = (short) lineNumber;
    118    }
    119
    120    /**
    121     * @param startPc the pc for this line number
    122     */
    123    public void setStartPC(final int startPc) {
    124        this.startPc = (short) startPc;
    125    }
    126
    127    /**
    128     * @return String representation
    129     */
    130    @Override
    131    public String toString() {
    132        return "LineNumber(" + getStartPC() + ", " + getLineNumber() + ")";
    133    }
    134}