1 /*
2 * Copyright (c) 1996, 2011, Oracle and/or its affiliates. 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * 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 @SuppressWarnings("fallthrough")
124 public int read() throws IOException {
125 synchronized (lock) {
126 int c = super.read();
127 if (skipLF) {
128 if (c == '\n')
129 c = super.read();
130 skipLF = false;
131 }
132 switch (c) {
133 case '\r':
134 skipLF = true;
135 case '\n': /* Fall through */
136 lineNumber++;
137 return '\n';
138 }
139 return c;
140 }
141 }
142
143 /**
144 * Read characters into a portion of an array. Whenever a <a
145 * href="#lt">line terminator</a> is read the current line number is
146 * incremented.
147 *
148 * @param cbuf
149 * Destination buffer
150 *
151 * @param off
152 * Offset at which to start storing characters
153 *
154 * @param len
155 * Maximum number of characters to read
156 *
157 * @return The number of bytes read, or -1 if the end of the stream has
158 * already been reached
159 *
160 * @throws IOException
161 * If an I/O error occurs
162 */
163 @SuppressWarnings("fallthrough")
164 public int read(char cbuf[], int off, int len) throws IOException {
165 synchronized (lock) {
166 int n = super.read(cbuf, off, len);
167
168 for (int i = off; i < off + n; i++) {
169 int c = cbuf[i];
170 if (skipLF) {
171 skipLF = false;
172 if (c == '\n')
173 continue;
174 }
175 switch (c) {
176 case '\r':
177 skipLF = true;
178 case '\n': /* Fall through */
179 lineNumber++;
180 break;
181 }
182 }
183
184 return n;
185 }
186 }
187
188 /**
189 * Read a line of text. Whenever a <a href="#lt">line terminator</a> is
190 * read the current line number is incremented.
191 *
192 * @return A String containing the contents of the line, not including
193 * any <a href="#lt">line termination characters</a>, or
194 * <tt>null</tt> if the end of the stream has been reached
195 *
196 * @throws IOException
197 * If an I/O error occurs
198 */
199 public String readLine() throws IOException {
200 synchronized (lock) {
201 String l = super.readLine(skipLF);
202 skipLF = false;
203 if (l != null)
204 lineNumber++;
205 return l;
206 }
207 }
208
209 /** Maximum skip-buffer size */
210 private static final int maxSkipBufferSize = 8192;
211
212 /** Skip buffer, null until allocated */
213 private char skipBuffer[] = null;
214
215 /**
216 * Skip characters.
217 *
218 * @param n
219 * The number of characters to skip
220 *
221 * @return The number of characters actually skipped
222 *
223 * @throws IOException
224 * If an I/O error occurs
225 *
226 * @throws IllegalArgumentException
227 * If <tt>n</tt> is negative
228 */
229 public long skip(long n) throws IOException {
230 if (n < 0)
231 throw new IllegalArgumentException("skip() value is negative");
232 int nn = (int) Math.min(n, maxSkipBufferSize);
233 synchronized (lock) {
234 if ((skipBuffer == null) || (skipBuffer.length < nn))
235 skipBuffer = new char[nn];
236 long r = n;
237 while (r > 0) {
238 int nc = read(skipBuffer, 0, (int) Math.min(r, nn));
239 if (nc == -1)
240 break;
241 r -= nc;
242 }
243 return n - r;
244 }
245 }
246
247 /**
248 * Mark the present position in the stream. Subsequent calls to reset()
249 * will attempt to reposition the stream to this point, and will also reset
250 * the line number appropriately.
251 *
252 * @param readAheadLimit
253 * Limit on the number of characters that may be read while still
254 * preserving the mark. After reading this many characters,
255 * attempting to reset the stream may fail.
256 *
257 * @throws IOException
258 * If an I/O error occurs
259 */
260 public void mark(int readAheadLimit) throws IOException {
261 synchronized (lock) {
262 super.mark(readAheadLimit);
263 markedLineNumber = lineNumber;
264 markedSkipLF = skipLF;
265 }
266 }
267
268 /**
269 * Reset the stream to the most recent mark.
270 *
271 * @throws IOException
272 * If the stream has not been marked, or if the mark has been
273 * invalidated
274 */
275 public void reset() throws IOException {
276 synchronized (lock) {
277 super.reset();
278 lineNumber = markedLineNumber;
279 skipLF = markedSkipLF;
280 }
281 }
282
283 }