/*
* @(#)LineNumberInputStream.java 1.7 95/08/10 Arthur van Hoff
*
* Copyright (c) 1994 Sun Microsystems, Inc. All Rights Reserved.
*
* Permission to use, copy, modify, and distribute this software
* and its documentation for NON-COMMERCIAL purposes and without
* fee is hereby granted provided that this copyright notice
* appears in all copies. Please refer to the file "copyright.html"
* for further important copyright and licensing information.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
* THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
* TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
* ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
* DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
*/
package java.io;
/**
* An input stream that keeps track of line numbers.
*
* @version 1.7, 10 Aug 1995
* @author Arthur van Hoff
*/
public
class LineNumberInputStream extends FilterInputStream {
int pushBack = -1;
int lineNumber;
int markLineNumber;
/**
* Constructs a new LineNumberInputStream initialized with
* the specified input stream
* @param in the input stream
*/
public LineNumberInputStream(InputStream in) {
super(in);
}
/**
* Reads a byte of data. The method will block if no input is
* available.
* @return the byte read, or -1 if the end of the
* stream is reached.
* @exception IOException If an I/O error has occurred.
*/
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 into an array of bytes. This method will
* blocks until some input is available.
* @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 actual number of bytes read, -1 is
* returned when the end of the stream is reached.
* @exception IOException If an I/O error has occurred.
*/
public int read(byte b[], int off, int len) throws IOException {
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;
}
/**
* Sets the current line number.
* @param lineNumber the line number to be set
*/
public void setLineNumber(int lineNumber) {
this.lineNumber = lineNumber;
}
/**
* Returns the current line number.
*/
public int getLineNumber() {
return lineNumber;
}
/**
* Skips n bytes of input.
* @param n the number of bytes to be skipped
* @return the actual number of bytes skipped.
* @exception IOException If an I/O error has occurred.
*/
public long skip(long n) throws IOException {
return read(new byte[(int)n]);
}
/**
* Returns the number of bytes that can be read.
* without blocking.
* @return the number of available bytes
*/
public int available() throws IOException {
return (pushBack == -1) ? super.available() : super.available() + 1;
}
/**
* Marks the current position in the input stream. A subsequent
* call to reset() will reposition the stream at the last
* marked position so that subsequent reads will re-read
* the same bytes. The stream promises to allow readlimit bytes
* to be read before the mark position gets invalidated.
*
* @param readlimit the maximum limit of bytes allowed to be read
* before the mark position becomes invalid.
*/
public void mark(int readlimit) {
markLineNumber = lineNumber;
in.mark(readlimit);
}
/**
* Repositions the stream to the last marked position. If the
* stream has not been marked, or if the mark has been invalidated,
* an IOException is thrown. 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.
*/
public void reset() throws IOException {
lineNumber = markLineNumber;
in.reset();
}
}