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Java > Open Source Codes > com > sun > org > apache > bcel > internal > classfile > LineNumberTable


1 package com.sun.org.apache.bcel.internal.classfile;
2
3 /* ====================================================================
4  * The Apache Software License, Version 1.1
5  *
6  * Copyright (c) 2001 The Apache Software Foundation. All rights
7  * reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  *
13  * 1. Redistributions of source code must retain the above copyright
14  * notice, this list of conditions and the following disclaimer.
15  *
16  * 2. Redistributions in binary form must reproduce the above copyright
17  * notice, this list of conditions and the following disclaimer in
18  * the documentation and/or other materials provided with the
19  * distribution.
20  *
21  * 3. The end-user documentation included with the redistribution,
22  * if any, must include the following acknowledgment:
23  * "This product includes software developed by the
24  * Apache Software Foundation (http://www.apache.org/)."
25  * Alternately, this acknowledgment may appear in the software itself,
26  * if and wherever such third-party acknowledgments normally appear.
27  *
28  * 4. The names "Apache" and "Apache Software Foundation" and
29  * "Apache BCEL" must not be used to endorse or promote products
30  * derived from this software without prior written permission. For
31  * written permission, please contact apache@apache.org.
32  *
33  * 5. Products derived from this software may not be called "Apache",
34  * "Apache BCEL", nor may "Apache" appear in their name, without
35  * prior written permission of the Apache Software Foundation.
36  *
37  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40  * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48  * SUCH DAMAGE.
49  * ====================================================================
50  *
51  * This software consists of voluntary contributions made by many
52  * individuals on behalf of the Apache Software Foundation. For more
53  * information on the Apache Software Foundation, please see
54  * <http://www.apache.org/>.
55  */
56
57 import com.sun.org.apache.bcel.internal.Constants;
58 import java.io.*;
59
60 /**
61  * This class represents a table of line numbers for debugging
62  * purposes. This attribute is used by the <em>Code</em> attribute. It
63  * contains pairs of PCs and line numbers.
64  *
65  * @version $Id: LineNumberTable.java,v 1.1.1.1 2001/10/29 20:00:02 jvanzyl Exp $
66  * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
67  * @see Code
68  * @see LineNumber
69  */
70 public final class LineNumberTable extends Attribute {
71   private int line_number_table_length;
72   private LineNumber[] line_number_table; // Table of line/numbers pairs
73
74   /*
75    * Initialize from another object. Note that both objects use the same
76    * references (shallow copy). Use copy() for a physical copy.
77    */
78   public LineNumberTable(LineNumberTable c) {
79     this(c.getNameIndex(), c.getLength(), c.getLineNumberTable(),
80      c.getConstantPool());
81   }
82
83   /*
84    * @param name_index Index of name
85    * @param length Content length in bytes
86    * @param line_number_table Table of line/numbers pairs
87    * @param constant_pool Array of constants
88    */
89   public LineNumberTable(int name_index, int length,
90              LineNumber[] line_number_table,
91              ConstantPool constant_pool)
92   {
93     super(Constants.ATTR_LINE_NUMBER_TABLE, name_index, length, constant_pool);
94     setLineNumberTable(line_number_table);
95   }
96    
97   /**
98    * Construct object from file stream.
99    * @param name_index Index of name
100    * @param length Content length in bytes
101    * @param file Input stream
102    * @throw IOException
103    * @param constant_pool Array of constants
104    */
105   LineNumberTable(int name_index, int length, DataInputStream file,
106           ConstantPool constant_pool) throws IOException
107   {
108     this(name_index, length, (LineNumber[])null, constant_pool);
109     line_number_table_length = (file.readUnsignedShort());
110     line_number_table = new LineNumber[line_number_table_length];
111
112     for(int i=0; i < line_number_table_length; i++)
113       line_number_table[i] = new LineNumber(file);
114   }
115   /**
116    * Called by objects that are traversing the nodes of the tree implicitely
117    * defined by the contents of a Java class. I.e., the hierarchy of methods,
118    * fields, attributes, etc. spawns a tree of objects.
119    *
120    * @param v Visitor object
121    */
122   public void accept(Visitor v) {
123     v.visitLineNumberTable(this);
124   }
125   /**
126    * Dump line number table attribute to file stream in binary format.
127    *
128    * @param file Output file stream
129    * @throw IOException
130    */
131   public final void dump(DataOutputStream file) throws IOException
132   {
133     super.dump(file);
134     file.writeShort(line_number_table_length);
135     for(int i=0; i < line_number_table_length; i++)
136       line_number_table[i].dump(file);
137   }
138    
139   /**
140    * @return Array of (pc offset, line number) pairs.
141    */
142   public final LineNumber[] getLineNumberTable() { return line_number_table; }
143
144   /**
145    * @param line_number_table.
146    */
147   public final void setLineNumberTable(LineNumber[] line_number_table) {
148     this.line_number_table = line_number_table;
149
150     line_number_table_length = (line_number_table == null)? 0 :
151       line_number_table.length;
152   }
153
154   /**
155    * @return String representation.
156    */
157   public final String JavaDoc toString() {
158     StringBuffer JavaDoc buf = new StringBuffer JavaDoc();
159     StringBuffer JavaDoc line = new StringBuffer JavaDoc();
160
161     for(int i=0; i < line_number_table_length; i++) {
162       line.append(line_number_table[i].toString());
163
164       if(i < line_number_table_length - 1)
165     line.append(", ");
166
167       if(line.length() > 72) {
168     line.append('\n');
169     buf.append(line);
170     line.setLength(0);
171       }
172     }
173
174     buf.append(line);
175
176     return buf.toString();
177   }
178
179   /**
180    * Map byte code positions to source code lines.
181    *
182    * @param pos byte code offset
183    * @return corresponding line in source code
184    */
185   public int getSourceLine(int pos) {
186     int l = 0, r = line_number_table_length-1;
187
188     if(r < 0) // array is empty
189 return -1;
190
191     int min_index = -1, min=-1;
192     
193     /* Do a binary search since the array is ordered.
194      */
195     do {
196       int i = (l + r) / 2;
197       int j = line_number_table[i].getStartPC();
198
199       if(j == pos)
200     return line_number_table[i].getLineNumber();
201       else if(pos < j) // else constrain search area
202 r = i - 1;
203       else // pos > j
204 l = i + 1;
205
206       /* If exact match can't be found (which is the most common case)
207        * return the line number that corresponds to the greatest index less
208        * than pos.
209        */
210       if(j < pos && j > min) {
211         min = j;
212         min_index = i;
213       }
214     } while(l <= r);
215
216     return line_number_table[min_index].getLineNumber();
217   }
218
219   /**
220    * @return deep copy of this attribute
221    */
222   public Attribute copy(ConstantPool constant_pool) {
223     LineNumberTable c = (LineNumberTable)clone();
224
225     c.line_number_table = new LineNumber[line_number_table_length];
226     for(int i=0; i < line_number_table_length; i++)
227       c.line_number_table[i] = line_number_table[i].copy();
228
229     c.constant_pool = constant_pool;
230     return c;
231   }
232
233   public final int getTableLength() { return line_number_table_length; }
234 }
235
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