java.io.LineNumberInputStream Maven / Gradle / Ivy
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* 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
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*/
package java.io;
/**
* This class is an input stream filter that provides the added
* functionality of keeping track of the current line number.
*
* A line is a sequence of bytes ending with a carriage return
* character ('\r'), a newline character
* ('\n'), or a carriage return character followed
* immediately by a linefeed character. In all three cases, the line
* terminating character(s) are returned as a single newline character.
*
* The line number begins at 0, and is incremented by
* 1 when a read returns a newline character.
*
* @author Arthur van Hoff
* @see java.io.LineNumberReader
* @since JDK1.0
* @deprecated This class incorrectly assumes that bytes adequately represent
* characters. As of JDK 1.1, the preferred way to operate on
* character streams is via the new character-stream classes, which
* include a class for counting line numbers.
*/
@Deprecated
public
class LineNumberInputStream extends FilterInputStream {
int pushBack = -1;
int lineNumber;
int markLineNumber;
int markPushBack = -1;
/**
* Constructs a newline number input stream that reads its input
* from the specified input stream.
*
* @param in the underlying input stream.
*/
public LineNumberInputStream(InputStream in) {
super(in);
}
/**
* Reads the next byte of data from this input stream. The value
* byte is returned as an int in the range
* 0 to 255. If no byte is available
* because the end of the stream has been reached, the value
* -1 is returned. This method blocks until input data
* is available, the end of the stream is detected, or an exception
* is thrown.
*
* The read method of
* LineNumberInputStream calls the read
* method of the underlying input stream. It checks for carriage
* returns and newline characters in the input, and modifies the
* current line number as appropriate. A carriage-return character or
* a carriage return followed by a newline character are both
* converted into a single newline character.
*
* @return the next byte of data, or -1 if the end of this
* stream is reached.
* @exception IOException if an I/O error occurs.
* @see java.io.FilterInputStream#in
* @see java.io.LineNumberInputStream#getLineNumber()
*/
public int read() throws IOException {
int c = pushBack;
if (c != -1) {
pushBack = -1;
} else {
c = in.read();
}
switch (c) {
case '\r':
pushBack = in.read();
if (pushBack == '\n') {
pushBack = -1;
}
case '\n':
lineNumber++;
return '\n';
}
return c;
}
/**
* Reads up to len bytes of data from this input stream
* into an array of bytes. This method blocks until some input is available.
*
* The read method of
* LineNumberInputStream repeatedly calls the
* read method of zero arguments to fill in the byte array.
*
* @param b the buffer into which the data is read.
* @param off the start offset of the data.
* @param len the maximum number of bytes read.
* @return the total number of bytes read into the buffer, or
* -1 if there is no more data because the end of
* this stream has been reached.
* @exception IOException if an I/O error occurs.
* @see java.io.LineNumberInputStream#read()
*/
public int read(byte b[], int off, int len) throws IOException {
if (b == null) {
throw new NullPointerException();
} else if ((off < 0) || (off > b.length) || (len < 0) ||
((off + len) > b.length) || ((off + len) < 0)) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return 0;
}
int c = read();
if (c == -1) {
return -1;
}
b[off] = (byte)c;
int i = 1;
try {
for (; i < len ; i++) {
c = read();
if (c == -1) {
break;
}
if (b != null) {
b[off + i] = (byte)c;
}
}
} catch (IOException ee) {
}
return i;
}
/**
* Skips over and discards n bytes of data from this
* input stream. The skip method may, for a variety of
* reasons, end up skipping over some smaller number of bytes,
* possibly 0. The actual number of bytes skipped is
* returned. If n is negative, no bytes are skipped.
*
* The skip method of LineNumberInputStream creates
* a byte array and then repeatedly reads into it until
* n bytes have been read or the end of the stream has
* been reached.
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
* @exception IOException if an I/O error occurs.
* @see java.io.FilterInputStream#in
*/
public long skip(long n) throws IOException {
int chunk = 2048;
long remaining = n;
byte data[];
int nr;
if (n <= 0) {
return 0;
}
data = new byte[chunk];
while (remaining > 0) {
nr = read(data, 0, (int) Math.min(chunk, remaining));
if (nr < 0) {
break;
}
remaining -= nr;
}
return n - remaining;
}
/**
* Sets the line number to the specified argument.
*
* @param lineNumber the new line number.
* @see #getLineNumber
*/
public void setLineNumber(int lineNumber) {
this.lineNumber = lineNumber;
}
/**
* Returns the current line number.
*
* @return the current line number.
* @see #setLineNumber
*/
public int getLineNumber() {
return lineNumber;
}
/**
* Returns the number of bytes that can be read from this input
* stream without blocking.
*
* Note that if the underlying input stream is able to supply
* k input characters without blocking, the
* LineNumberInputStream can guarantee only to provide
* k/2 characters without blocking, because the
* k characters from the underlying input stream might
* consist of k/2 pairs of '\r' and
* '\n', which are converted to just
* k/2 '\n' characters.
*
* @return the number of bytes that can be read from this input stream
* without blocking.
* @exception IOException if an I/O error occurs.
* @see java.io.FilterInputStream#in
*/
public int available() throws IOException {
return (pushBack == -1) ? super.available()/2 : super.available()/2 + 1;
}
/**
* Marks the current position in this input stream. A subsequent
* call to the reset method repositions this stream at
* the last marked position so that subsequent reads re-read the same bytes.
*
* The mark method of
* LineNumberInputStream remembers the current line
* number in a private variable, and then calls the mark
* method of the underlying input stream.
*
* @param readlimit the maximum limit of bytes that can be read before
* the mark position becomes invalid.
* @see java.io.FilterInputStream#in
* @see java.io.LineNumberInputStream#reset()
*/
public void mark(int readlimit) {
markLineNumber = lineNumber;
markPushBack = pushBack;
in.mark(readlimit);
}
/**
* Repositions this stream to the position at the time the
* mark method was last called on this input stream.
*
* The reset method of
* LineNumberInputStream resets the line number to be
* the line number at the time the mark method was
* called, and then calls the reset method of the
* underlying input stream.
*
* Stream marks are intended to be used in
* situations where you need to read ahead a little to see what's in
* the stream. Often this is most easily done by invoking some
* general parser. If the stream is of the type handled by the
* parser, it just chugs along happily. If the stream is not of
* that type, the parser should toss an exception when it fails,
* which, if it happens within readlimit bytes, allows the outer
* code to reset the stream and try another parser.
*
* @exception IOException if an I/O error occurs.
* @see java.io.FilterInputStream#in
* @see java.io.LineNumberInputStream#mark(int)
*/
public void reset() throws IOException {
lineNumber = markLineNumber;
pushBack = markPushBack;
in.reset();
}
}