LineNumberInputStreampublic class LineNumberInputStream extends FilterInputStream | 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. |
| Fields Summary |
|---|
| int | pushBack | | int | lineNumber | | int | markLineNumber | | int | markPushBack |
| Constructors Summary |
|---|
public LineNumberInputStream(InputStream in)Constructs a newline number input stream that reads its input
from the specified input stream.
super(in);
|
| Methods Summary |
|---|
| public int | available()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 (pushBack == -1) ? super.available()/2 : super.available()/2 + 1;
| | public int | getLineNumber()Returns the current line number.
return lineNumber;
| | public void | mark(int readlimit)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.
markLineNumber = lineNumber;
markPushBack = pushBack;
in.mark(readlimit);
| | public int | read()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.
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;
| | public int | read(byte[] b, int off, int len)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.
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;
| | public void | reset()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.
lineNumber = markLineNumber;
pushBack = markPushBack;
in.reset();
| | public void | setLineNumber(int lineNumber)Sets the line number to the specified argument.
this.lineNumber = lineNumber;
| | public long | skip(long n)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.
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;
|
|
