1 /* 2 * Copyright (c) 1996, 2006, 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 */ read()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 */ read(char cbuf[], int off, int len)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 */ readLine()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 */ skip(long n)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 */ mark(int readAheadLimit)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 */ reset()273 public void reset() throws IOException { 274 synchronized (lock) { 275 super.reset(); 276 lineNumber = markedLineNumber; 277 skipLF = markedSkipLF; 278 } 279 } 280 281 } 282