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 */ LineNumberReader(Reader in)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 */ LineNumberReader(Reader in, int sz)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 */ setLineNumber(int lineNumber)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 */ getLineNumber()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") read()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") read(char cbuf[], int off, int len)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 */ readLine()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 */ skip(long n)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 */ mark(int readAheadLimit)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 */ reset()275 public void reset() throws IOException { 276 synchronized (lock) { 277 super.reset(); 278 lineNumber = markedLineNumber; 279 skipLF = markedSkipLF; 280 } 281 } 282 283 } 284