1 /*
2 * Copyright 1996-2006 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package java.io;
27
28
29 /**
30 * A buffered character-input stream that keeps track of line numbers. This
31 * class defines methods {@link #setLineNumber(int)} and {@link
32 * #getLineNumber()} for setting and getting the current line number
33 * respectively.
34 *
35 * <p> By default, line numbering begins at 0. This number increments at every
36 * <a href="#lt">line terminator</a> as the data is read, and can be changed
37 * with a call to <tt>setLineNumber(int)</tt>. Note however, that
38 * <tt>setLineNumber(int)</tt> does not actually change the current position in
39 * the stream; it only changes the value that will be returned by
40 * <tt>getLineNumber()</tt>.
41 *
42 * <p> A line is considered to be <a name="lt">terminated</a> by any one of a
43 * line feed ('\n'), a carriage return ('\r'), or a carriage return followed
44 * immediately by a linefeed.
45 *
46 * @author Mark Reinhold
47 * @since JDK1.1
48 */
49
50 public class LineNumberReader extends BufferedReader {
51
52 /** The current line number */
53 private int lineNumber = 0;
54
55 /** The line number of the mark, if any */
56 private int markedLineNumber; // Defaults to 0
57
58 /** If the next character is a line feed, skip it */
59 private boolean skipLF;
60
61 /** The skipLF flag when the mark was set */
62 private boolean markedSkipLF;
63
64 /**
65 * Create a new line-numbering reader, using the default input-buffer
66 * size.
67 *
68 * @param in
69 * A Reader object to provide the underlying stream
70 */
71 public LineNumberReader(Reader in) {
72 super(in);
73 }
74
75 /**
76 * Create a new line-numbering reader, reading characters into a buffer of
77 * the given size.
78 *
79 * @param in
80 * A Reader object to provide the underlying stream
81 *
82 * @param sz
83 * An int specifying the size of the buffer
84 */
85 public LineNumberReader(Reader in, int sz) {
86 super(in, sz);
87 }
88
89 /**
90 * Set the current line number.
91 *
92 * @param lineNumber
93 * An int specifying the line number
94 *
95 * @see #getLineNumber
96 */
97 public void setLineNumber(int lineNumber) {
98 this.lineNumber = lineNumber;
99 }
100
101 /**
102 * Get the current line number.
103 *
104 * @return The current line number
105 *
106 * @see #setLineNumber
107 */
108 public int getLineNumber() {
109 return lineNumber;
110 }
111
112 /**
113 * Read a single character. <a href="#lt">Line terminators</a> are
114 * compressed into single newline ('\n') characters. Whenever a line
115 * terminator is read the current line number is incremented.
116 *
117 * @return The character read, or -1 if the end of the stream has been
118 * reached
119 *
120 * @throws IOException
121 * If an I/O error occurs
122 */
123 public int read() throws IOException {
124 synchronized (lock) {
125 int c = super.read();
126 if (skipLF) {
127 if (c == '\n')
128 c = super.read();
129 skipLF = false;
130 }
131 switch (c) {
132 case '\r':
133 skipLF = true;
134 case '\n': /* Fall through */
135 lineNumber++;
136 return '\n';
137 }
138 return c;
139 }
140 }
141
142 /**
143 * Read characters into a portion of an array. Whenever a <a
144 * href="#lt">line terminator</a> is read the current line number is
145 * incremented.
146 *
147 * @param cbuf
148 * Destination buffer
149 *
150 * @param off
151 * Offset at which to start storing characters
152 *
153 * @param len
154 * Maximum number of characters to read
155 *
156 * @return The number of bytes read, or -1 if the end of the stream has
157 * already been reached
158 *
159 * @throws IOException
160 * If an I/O error occurs
161 */
162 public int read(char cbuf[], int off, int len) throws IOException {
163 synchronized (lock) {
164 int n = super.read(cbuf, off, len);
165
166 for (int i = off; i < off + n; i++) {
167 int c = cbuf[i];
168 if (skipLF) {
169 skipLF = false;
170 if (c == '\n')
171 continue;
172 }
173 switch (c) {
174 case '\r':
175 skipLF = true;
176 case '\n': /* Fall through */
177 lineNumber++;
178 break;
179 }
180 }
181
182 return n;
183 }
184 }
185
186 /**
187 * Read a line of text. Whenever a <a href="#lt">line terminator</a> is
188 * read the current line number is incremented.
189 *
190 * @return A String containing the contents of the line, not including
191 * any <a href="#lt">line termination characters</a>, or
192 * <tt>null</tt> if the end of the stream has been reached
193 *
194 * @throws IOException
195 * If an I/O error occurs
196 */
197 public String readLine() throws IOException {
198 synchronized (lock) {
199 String l = super.readLine(skipLF);
200 skipLF = false;
201 if (l != null)
202 lineNumber++;
203 return l;
204 }
205 }
206
207 /** Maximum skip-buffer size */
208 private static final int maxSkipBufferSize = 8192;
209
210 /** Skip buffer, null until allocated */
211 private char skipBuffer[] = null;
212
213 /**
214 * Skip characters.
215 *
216 * @param n
217 * The number of characters to skip
218 *
219 * @return The number of characters actually skipped
220 *
221 * @throws IOException
222 * If an I/O error occurs
223 *
224 * @throws IllegalArgumentException
225 * If <tt>n</tt> is negative
226 */
227 public long skip(long n) throws IOException {
228 if (n < 0)
229 throw new IllegalArgumentException("skip() value is negative");
230 int nn = (int) Math.min(n, maxSkipBufferSize);
231 synchronized (lock) {
232 if ((skipBuffer == null) || (skipBuffer.length < nn))
233 skipBuffer = new char[nn];
234 long r = n;
235 while (r > 0) {
236 int nc = read(skipBuffer, 0, (int) Math.min(r, nn));
237 if (nc == -1)
238 break;
239 r -= nc;
240 }
241 return n - r;
242 }
243 }
244
245 /**
246 * Mark the present position in the stream. Subsequent calls to reset()
247 * will attempt to reposition the stream to this point, and will also reset
248 * the line number appropriately.
249 *
250 * @param readAheadLimit
251 * Limit on the number of characters that may be read while still
252 * preserving the mark. After reading this many characters,
253 * attempting to reset the stream may fail.
254 *
255 * @throws IOException
256 * If an I/O error occurs
257 */
258 public void mark(int readAheadLimit) throws IOException {
259 synchronized (lock) {
260 super.mark(readAheadLimit);
261 markedLineNumber = lineNumber;
262 markedSkipLF = skipLF;
263 }
264 }
265
266 /**
267 * Reset the stream to the most recent mark.
268 *
269 * @throws IOException
270 * If the stream has not been marked, or if the mark has been
271 * invalidated
272 */
273 public void reset() throws IOException {
274 synchronized (lock) {
275 super.reset();
276 lineNumber = markedLineNumber;
277 skipLF = markedSkipLF;
278 }
279 }
280
281 }
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