001 /*
002 * Copyright 1996-2006 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package java.io;
027
028 /**
029 * A buffered character-input stream that keeps track of line numbers. This
030 * class defines methods {@link #setLineNumber(int)} and {@link
031 * #getLineNumber()} for setting and getting the current line number
032 * respectively.
033 *
034 * <p> By default, line numbering begins at 0. This number increments at every
035 * <a href="#lt">line terminator</a> as the data is read, and can be changed
036 * with a call to <tt>setLineNumber(int)</tt>. Note however, that
037 * <tt>setLineNumber(int)</tt> does not actually change the current position in
038 * the stream; it only changes the value that will be returned by
039 * <tt>getLineNumber()</tt>.
040 *
041 * <p> A line is considered to be <a name="lt">terminated</a> by any one of a
042 * line feed ('\n'), a carriage return ('\r'), or a carriage return followed
043 * immediately by a linefeed.
044 *
045 * @version 1.29, 07/05/05
046 * @author Mark Reinhold
047 * @since JDK1.1
048 */
049
050 public class LineNumberReader extends BufferedReader {
051
052 /** The current line number */
053 private int lineNumber = 0;
054
055 /** The line number of the mark, if any */
056 private int markedLineNumber; // Defaults to 0
057
058 /** If the next character is a line feed, skip it */
059 private boolean skipLF;
060
061 /** The skipLF flag when the mark was set */
062 private boolean markedSkipLF;
063
064 /**
065 * Create a new line-numbering reader, using the default input-buffer
066 * size.
067 *
068 * @param in
069 * A Reader object to provide the underlying stream
070 */
071 public LineNumberReader(Reader in) {
072 super (in);
073 }
074
075 /**
076 * Create a new line-numbering reader, reading characters into a buffer of
077 * the given size.
078 *
079 * @param in
080 * A Reader object to provide the underlying stream
081 *
082 * @param sz
083 * An int specifying the size of the buffer
084 */
085 public LineNumberReader(Reader in, int sz) {
086 super (in, sz);
087 }
088
089 /**
090 * Set the current line number.
091 *
092 * @param lineNumber
093 * An int specifying the line number
094 *
095 * @see #getLineNumber
096 */
097 public void setLineNumber(int lineNumber) {
098 this .lineNumber = lineNumber;
099 }
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(
230 "skip() value is negative");
231 int nn = (int) Math.min(n, maxSkipBufferSize);
232 synchronized (lock) {
233 if ((skipBuffer == null) || (skipBuffer.length < nn))
234 skipBuffer = new char[nn];
235 long r = n;
236 while (r > 0) {
237 int nc = read(skipBuffer, 0, (int) Math.min(r, nn));
238 if (nc == -1)
239 break;
240 r -= nc;
241 }
242 return n - r;
243 }
244 }
245
246 /**
247 * Mark the present position in the stream. Subsequent calls to reset()
248 * will attempt to reposition the stream to this point, and will also reset
249 * the line number appropriately.
250 *
251 * @param readAheadLimit
252 * Limit on the number of characters that may be read while still
253 * preserving the mark. After reading this many characters,
254 * attempting to reset the stream may fail.
255 *
256 * @throws IOException
257 * If an I/O error occurs
258 */
259 public void mark(int readAheadLimit) throws IOException {
260 synchronized (lock) {
261 super .mark(readAheadLimit);
262 markedLineNumber = lineNumber;
263 markedSkipLF = skipLF;
264 }
265 }
266
267 /**
268 * Reset the stream to the most recent mark.
269 *
270 * @throws IOException
271 * If the stream has not been marked, or if the mark has been
272 * invalidated
273 */
274 public void reset() throws IOException {
275 synchronized (lock) {
276 super.reset();
277 lineNumber = markedLineNumber;
278 skipLF = markedSkipLF;
279 }
280 }
281
282 }
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