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 * @version $Id: LineNumberTable.java 1806200 2017-08-25 16:33:06Z ggregory $
032 * @see     Code
033 * @see LineNumber
034 */
035public final class LineNumberTable extends Attribute {
036
037    private static final int MAX_LINE_LENGTH = 72;
038    private LineNumber[] line_number_table; // Table of line/numbers pairs
039
040
041    /*
042     * Initialize from another object. Note that both objects use the same
043     * references (shallow copy). Use copy() for a physical copy.
044     */
045    public LineNumberTable(final LineNumberTable c) {
046        this(c.getNameIndex(), c.getLength(), c.getLineNumberTable(), c.getConstantPool());
047    }
048
049
050    /*
051     * @param name_index Index of name
052     * @param length Content length in bytes
053     * @param line_number_table Table of line/numbers pairs
054     * @param constant_pool Array of constants
055     */
056    public LineNumberTable(final int name_index, final int length, final LineNumber[] line_number_table,
057            final ConstantPool constant_pool) {
058        super(Const.ATTR_LINE_NUMBER_TABLE, name_index, length, constant_pool);
059        this.line_number_table = line_number_table;
060    }
061
062
063    /**
064     * Construct object from input stream.
065     * @param name_index Index of name
066     * @param length Content length in bytes
067     * @param input Input stream
068     * @param constant_pool Array of constants
069     * @throws IOEXception if an I/O Exception occurs in readUnsignedShort
070     */
071    LineNumberTable(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool)
072            throws IOException {
073        this(name_index, length, (LineNumber[]) null, constant_pool);
074        final int line_number_table_length = input.readUnsignedShort();
075        line_number_table = new LineNumber[line_number_table_length];
076        for (int i = 0; i < line_number_table_length; i++) {
077            line_number_table[i] = new LineNumber(input);
078        }
079    }
080
081
082    /**
083     * Called by objects that are traversing the nodes of the tree implicitely
084     * defined by the contents of a Java class. I.e., the hierarchy of methods,
085     * fields, attributes, etc. spawns a tree of objects.
086     *
087     * @param v Visitor object
088     */
089    @Override
090    public void accept( final Visitor v ) {
091        v.visitLineNumberTable(this);
092    }
093
094
095    /**
096     * Dump line number table attribute to file stream in binary format.
097     *
098     * @param file Output file stream
099     * @throws IOEXception if an I/O Exception occurs in writeShort
100     */
101    @Override
102    public final void dump( final DataOutputStream file ) throws IOException {
103        super.dump(file);
104        file.writeShort(line_number_table.length);
105        for (final LineNumber lineNumber : line_number_table) {
106            lineNumber.dump(file);
107        }
108    }
109
110
111    /**
112     * @return Array of (pc offset, line number) pairs.
113     */
114    public final LineNumber[] getLineNumberTable() {
115        return line_number_table;
116    }
117
118
119    /**
120     * @param line_number_table the line number entries for this table
121     */
122    public final void setLineNumberTable( final LineNumber[] line_number_table ) {
123        this.line_number_table = line_number_table;
124    }
125
126
127    /**
128     * @return String representation.
129     */
130    @Override
131    public final String toString() {
132        final StringBuilder buf = new StringBuilder();
133        final StringBuilder line = new StringBuilder();
134        final String newLine = System.getProperty("line.separator", "\n");
135        for (int i = 0; i < line_number_table.length; i++) {
136            line.append(line_number_table[i].toString());
137            if (i < line_number_table.length - 1) {
138                line.append(", ");
139            }
140            if ((line.length() > MAX_LINE_LENGTH) && (i < line_number_table.length - 1)) {
141                line.append(newLine);
142                buf.append(line);
143                line.setLength(0);
144            }
145        }
146        buf.append(line);
147        return buf.toString();
148    }
149
150
151    /**
152     * Map byte code positions to source code lines.
153     *
154     * @param pos byte code offset
155     * @return corresponding line in source code
156     */
157    public int getSourceLine( final int pos ) {
158        int l = 0;
159        int r = line_number_table.length - 1;
160        if (r < 0) {
161            return -1;
162        }
163        int min_index = -1;
164        int min = -1;
165        /* Do a binary search since the array is ordered.
166         */
167        do {
168            final int i = (l + r) / 2;
169            final int j = line_number_table[i].getStartPC();
170            if (j == pos) {
171                return line_number_table[i].getLineNumber();
172            } else if (pos < j) {
173                r = i - 1;
174            } else {
175                l = i + 1;
176            }
177            /* If exact match can't be found (which is the most common case)
178             * return the line number that corresponds to the greatest index less
179             * than pos.
180             */
181            if (j < pos && j > min) {
182                min = j;
183                min_index = i;
184            }
185        } while (l <= r);
186        /* It's possible that we did not find any valid entry for the bytecode
187         * offset we were looking for.
188         */
189        if (min_index < 0) {
190            return -1;
191        }
192        return line_number_table[min_index].getLineNumber();
193    }
194
195
196    /**
197     * @return deep copy of this attribute
198     */
199    @Override
200    public Attribute copy( final ConstantPool _constant_pool ) {
201        // TODO could use the lower level constructor and thereby allow
202        // line_number_table to be made final
203        final LineNumberTable c = (LineNumberTable) clone();
204        c.line_number_table = new LineNumber[line_number_table.length];
205        for (int i = 0; i < line_number_table.length; i++) {
206            c.line_number_table[i] = line_number_table[i].copy();
207        }
208        c.setConstantPool(_constant_pool);
209        return c;
210    }
211
212
213    public final int getTableLength() {
214        return line_number_table == null ? 0 : line_number_table.length;
215    }
216}