/*
* @(#)LineNumberReader.java 1.20 06/10/10
*
* Copyright 1990-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 only, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License version 2 for more details (a copy is
* included at /legal/license.txt).
*
* You should have received a copy of the GNU General Public License
* version 2 along with this work; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*
*/
package java.io;
/**
* A buffered character-input stream that keeps track of line numbers.
* This class defines methods <CODE>void setLineNumber(int)</CODE> and
* <CODE>int getLineNumber()</CODE> for setting and getting the current
* line number respectively.
* <P>
* By default, line numbering begins at 0. This number increments as data is
* read, and can be changed with a call to <CODE>setLineNumber(int)</CODE>.
* Note however, that <CODE>setLineNumber(int)</CODE> does not actually change the current
* position in the stream; it only changes the value that will be returned
* by <CODE>getLineNumber()</CODE>.
* <P>
* A line is considered to be terminated by any one of a line feed ('\n'), a carriage
* return ('\r'), or a carriage return followed immediately by a linefeed.
*
* @version 1.13, 00/02/02
* @author Mark Reinhold
* @since JDK1.1
*/
public class LineNumberReader extends BufferedReader {
/** The current line number */
private int lineNumber = 0;
/** The line number of the mark, if any */
private int markedLineNumber;
/** If the next character is a line feed, skip it */
private boolean skipLF;
/** The skipLF flag when the mark was set */
private boolean markedSkipLF;
/**
* Create a new line-numbering reader, using the default input-buffer
* size.
*
* @param in a Reader object to provide the underlying stream.
*/
public LineNumberReader(Reader in) {
super(in);
}
/**
* Create a new line-numbering reader, reading characters into a buffer of
* the given size.
*
* @param in a Reader object to provide the underlying stream.
* @param sz an int specifying the size of the buffer.
*/
public LineNumberReader(Reader in, int sz) {
super(in, sz);
}
/**
* Set the current line number.
*
* @param lineNumber an int specifying the line number.
* @see #getLineNumber
*/
public void setLineNumber(int lineNumber) {
this.lineNumber = lineNumber;
}
/**
* Get the current line number.
*
* @return The current line number.
* @see #setLineNumber
*/
public int getLineNumber() {
return lineNumber;
}
/**
* Read a single character. Line terminators are compressed into single
* newline ('\n') characters.
*
* @return The character read, or -1 if the end of the stream has been
* reached
*
* @exception IOException If an I/O error occurs
*/
public int read() throws IOException {
synchronized (lock) {
int c = super.read();
if (skipLF) {
if (c == '\n')
c = super.read();
skipLF = false;
}
switch (c) {
case '\r':
skipLF = true;
case '\n': /* Fall through */
lineNumber++;
return '\n';
}
return c;
}
}
/**
* Read characters into a portion of an array.
*
* @param cbuf Destination buffer
* @param off Offset at which to start storing characters
* @param len Maximum number of characters to read
*
* @return The number of bytes read, or -1 if the end of the stream has
* already been reached
*
* @exception IOException If an I/O error occurs
*/
public int read(char cbuf[], int off, int len) throws IOException {
synchronized (lock) {
int n = super.read(cbuf, off, len);
for (int i = off; i < off + n; i++) {
int c = cbuf[i];
if (skipLF) {
skipLF = false;
if (c == '\n')
continue;
}
switch (c) {
case '\r':
skipLF = true;
case '\n': /* Fall through */
lineNumber++;
break;
}
}
return n;
}
}
/**
* Read a line of text. A line is considered to be terminated by any one
* of a line feed ('\n'), a carriage return ('\r'), or a carriage return
* followed immediately by a linefeed.
*
* @return A String containing the contents of the line, not including
* any line-termination characters, or null if the end of the
* stream has been reached
*
* @exception IOException If an I/O error occurs
*/
public String readLine() throws IOException {
synchronized (lock) {
String l = super.readLine(skipLF);
skipLF = false;
if (l != null)
lineNumber++;
return l;
}
}
/** Maximum skip-buffer size */
private static final int maxSkipBufferSize = 8192;
/** Skip buffer, null until allocated */
private char skipBuffer[] = null;
/**
* Skip characters.
*
* @param n The number of characters to skip
*
* @return The number of characters actually skipped
*
* @exception IOException If an I/O error occurs
*/
public long skip(long n) throws IOException {
if (n < 0)
throw new IllegalArgumentException("skip() value is negative");
int nn = (int) Math.min(n, maxSkipBufferSize);
synchronized (lock) {
if ((skipBuffer == null) || (skipBuffer.length < nn))
skipBuffer = new char[nn];
long r = n;
while (r > 0) {
int nc = read(skipBuffer, 0, (int) Math.min(r, nn));
if (nc == -1)
break;
r -= nc;
}
return n - r;
}
}
/**
* Mark the present position in the stream. Subsequent calls to reset()
* will attempt to reposition the stream to this point, and will also reset
* the line number appropriately.
*
* @param readAheadLimit Limit on the number of characters that may be
* read while still preserving the mark. After
* reading this many characters, attempting to
* reset the stream may fail.
*
* @exception IOException If an I/O error occurs
*/
public void mark(int readAheadLimit) throws IOException {
synchronized (lock) {
super.mark(readAheadLimit);
markedLineNumber = lineNumber;
markedSkipLF = skipLF;
}
}
/**
* Reset the stream to the most recent mark.
*
* @exception IOException If the stream has not been marked,
* or if the mark has been invalidated
*/
public void reset() throws IOException {
synchronized (lock) {
super.reset();
lineNumber = markedLineNumber;
skipLF = markedSkipLF;
}
}
}