java.io.LineNumberReader Maven / Gradle / Ivy
Show all versions of qbicc-rt-java.base Show documentation
/*
* Copyright (c) 1996, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code 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. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code 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 in the LICENSE file that
* accompanied this code).
*
* 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.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 {@link #setLineNumber(int)} and {@link
* #getLineNumber()} for setting and getting the current line number
* respectively.
*
* By default, line numbering begins at 0. This number increments at every
* line terminator as the data is read, and at the end of the
* stream if the last character in the stream is not a line terminator. This
* number can be changed with a call to {@code setLineNumber(int)}. Note
* however, that {@code setLineNumber(int)} does not actually change the current
* position in the stream; it only changes the value that will be returned by
* {@code getLineNumber()}.
*
*
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, or any of the previous terminators followed by
* end of stream, or end of stream not preceded by another terminator.
*
* @author Mark Reinhold
* @since 1.1
*/
public class LineNumberReader extends BufferedReader {
/** Previous character types */
private static final int NONE = 0; // no previous character
private static final int CHAR = 1; // non-line terminator
private static final int EOL = 2; // line terminator
private static final int EOF = 3; // end-of-file
/** The previous character type */
private int prevChar = NONE;
/** The current line number */
private int lineNumber = 0;
/** The line number of the mark, if any */
private int markedLineNumber; // Defaults to 0
/** 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. The current line
* number is incremented whenever a line terminator is read, or when the
* end of the stream is reached and the last character in the stream is
* not a line terminator.
*
* @return The character read, or -1 if the end of the stream has been
* reached
*
* @throws IOException
* If an I/O error occurs
*/
@SuppressWarnings("fallthrough")
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++;
prevChar = EOL;
return '\n';
case -1:
if (prevChar == CHAR)
lineNumber++;
prevChar = EOF;
break;
default:
prevChar = CHAR;
break;
}
return c;
}
}
/**
* Reads characters into a portion of an array. This method will block
* until some input is available, an I/O error occurs, or the end of the
* stream is reached.
*
*
If {@code len} is zero, then no characters are read and {@code 0} is
* returned; otherwise, there is an attempt to read at least one character.
* If no character is available because the stream is at its end, the value
* {@code -1} is returned; otherwise, at least one character is read and
* stored into {@code cbuf}.
*
*
Line terminators are compressed into single newline
* ('\n') characters. The current line number is incremented whenever a
* line terminator is read, or when the end of the stream is reached and
* the last character in the stream is not a line terminator.
*
* @param cbuf {@inheritDoc}
* @param off {@inheritDoc}
* @param len {@inheritDoc}
*
* @return {@inheritDoc}
*
* @throws IndexOutOfBoundsException {@inheritDoc}
* @throws IOException {@inheritDoc}
*/
@SuppressWarnings("fallthrough")
public int read(char cbuf[], int off, int len) throws IOException {
synchronized (lock) {
int n = super.read(cbuf, off, len);
if (n == -1) {
if (prevChar == CHAR)
lineNumber++;
prevChar = EOF;
return -1;
}
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;
}
}
if (n > 0) {
switch ((int)cbuf[off + n - 1]) {
case '\r':
case '\n': /* Fall through */
prevChar = EOL;
break;
default:
prevChar = CHAR;
break;
}
}
return n;
}
}
/**
* Read a line of text. Line terminators are compressed
* into single newline ('\n') characters. The current line number is
* incremented whenever a line terminator is read, or when the end of the
* stream is reached and the last character in the stream is not a line
* terminator.
*
* @return A String containing the contents of the line, not including
* any line termination characters, or
* {@code null} if the end of the stream has been reached
*
* @throws IOException
* If an I/O error occurs
*/
public String readLine() throws IOException {
synchronized (lock) {
boolean[] term = new boolean[1];
String l = super.readLine(skipLF, term);
skipLF = false;
if (l != null) {
lineNumber++;
prevChar = term[0] ? EOL : EOF;
} else { // l == null
if (prevChar == CHAR)
lineNumber++;
prevChar = EOF;
}
return l;
}
}
/** Maximum skip-buffer size */
private static final int maxSkipBufferSize = 8192;
/** Skip buffer, null until allocated */
private char skipBuffer[] = null;
/**
* {@inheritDoc}
*/
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;
}
if (n - r > 0) {
prevChar = NONE;
}
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.
*
* @throws IOException
* If an I/O error occurs
*/
public void mark(int readAheadLimit) throws IOException {
synchronized (lock) {
// If the most recently read character is '\r', then increment the
// read ahead limit as in this case if the next character is '\n',
// two characters would actually be read by the next read().
if (skipLF)
readAheadLimit++;
super.mark(readAheadLimit);
markedLineNumber = lineNumber;
markedSkipLF = skipLF;
}
}
/**
* Reset the stream to the most recent mark.
*
* @throws 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;
}
}
}